taxonID	type	description	language	source
F77987B8FFB6FF9B11E0CE77AE82F955.taxon	description	urn: lsid: zoobank. org: act: D 5 A 2 F 0 B 5 - 3 E 68 - 403 C-A 751 - 6951 DE 740 D 9 F	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFB6FF9B11E0CE77AE82F955.taxon	type_taxon	TYPE SPECIES. — Callianassa zeta Rathbun, 1936 (Callianassa alpha Rathbun, 1935 a; non Callianassa alpha Stenzel, 1935), by present designation.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFB6FF9B11E0CE77AE82F955.taxon	etymology	ETYMOLOGY. — The genus name is a combination of “ alpha ”, referring to the homonymous species name Callianassa alpha, and “ cheles ” meaning “ claw ”. Gender: masculine.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFB6FF9B11E0CE77AE82F955.taxon	diagnosis	DIAGNOSIS. — As for the type species.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFB6FF9B11E0CE77AE82F955.taxon	discussion	REMARKS Shortly after the description of Callianassa alpha Rathbun, 1935 a, it was revealed that the name had already been used by Stenzel (1935) for yet another fossil ghost shrimp assigned to Callianassa. A rectification was published in the following year, renaming C. alpha to C. zeta Rathbun, 1936. Callianassa zeta differs from all known extant and extinct ghost shrimp taxa by its tuberculate area (“ densely punctate excrescence ” sensu Rathbun [1935 a]; “ triangular patch of granules ” sensu Feldmann et al. [2019]) at the base of the fixed finger which is present at the outer and inner lateral surfaces. This character has been considered a diagnostic feature of this species (Rathbun 1935 a; Feldmann et al. 2019). Its taxonomic significance is herein elevated to the genus level, and hence a new genus is proposed to accommodate this species. So far, only propodi and dactyli are known for Alphacheles zeta (Rathbun, 1936) n. comb. Most specimens represent major claws, whereas in one case also a minor claw is identified (Fig. 5 O). Their morphology is rather close to that of extant species of Gourretia and Paragourretia, based on which the new genus is classified within the family Ctenochelidae. Nevertheless, the familial placement of Alphacheles n. gen. should be considered preliminary until more complete material is found. Alphacheles n. gen. shares with the above-mentioned genera the following set of characters: major cheliped propodus distinctly longer than high and subrectangular in outline, relatively long fingers exceeding half of the propodus palm length, and dactylus occlusal surface with simple dentition (cf. Le Loeuff & Intès 1974; Sakai 2002, 2004; Ngoc-Ho 2003). These characters are shared also with Cretagourretia, an exclusively fossil genus known from the Early Cretaceous (Albian) of Spain. This set of characters mentioned above is rarely seen in other ghost shrimp families (Poore & Ahyong 2023). As mentioned above, Alphacheles n. gen. differs from all ghost shrimp genera known to date by the presence of a tuberculate area at the base of the fixed finger. It differs also from yet another exclusively fossil ctenochelid genus, Ahazianassa, from the Late Cretaceous (Maastrichtian) of Japan. Additionally, Alphacheles n. gen. possesses a more elongate palm than Ahazianassa does. Besides Callianassa alpha, Rathbun (1935 a) described also “ C. alpha var. ” from the Upper Eocene Jackson Group of Mississippi. A new variety of C. alpha is based on a single incomplete propodus and a pleon found at the same locality. Because the isolated propodus does not appear to show a densely tuberculate area at the base of the fixed finger, “ C. alpha var. ” is not considered closely related to Alphacheles zeta n. comb. Given the large temporal separation of c. 25 million years, these specimens might represent a new species, but a restudy of the specimens is needed.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBAFF9912DFCC15AE42F872.taxon	description	(Figs 5; 6)	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBAFF9912DFCC15AE42F872.taxon	materials_examined	TYPE MATERIAL. — Holotype. United States • Alabama, Wilcox County, Prairie Creek region; Porters Creek Formation; Paleocene (upper Danian); USNM MO 371506. Paratypes. United States • 1 specimen; same as for the holotype; USNM PAL 336022 A • 10 specimens; idem; USNM PAL 336022 B. ADDITIONAL MATERIAL EXAMINED. — United States • 1 specimen; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); ALMNH: Paleo: 21511 (propodus) • 1 specimen; idem; ALMNH: Paleo: 21512 (propodus) • 1 specimen; idem; ALMN-H: Paleo: 21513 (propodus) • 2 specimens; idem; MMNS IP- 7255 (2 specimens, partial propodus and dactylus and propodus and dactylus) • 1 specimen; idem; UF 303822 (propodus). TYPE HORIZON. — Porters Creek Formation (Sucarnoochee beds in Rathbun 1935 a), upper Danian. TYPE LOCALITY. — Prairie Creek region, Wilcox County, Alabama, United States.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBAFF9912DFCC15AE42F872.taxon	diagnosis	DIAGNOSIS. — Major cheliped propodus palm slightly longer than high (L / H = 1.1 - 1.3), upper and lower margins carinate, subparallel with each other, inner and outer surfaces with densely tuberculate, sharply delineated areas at base of fixed finger, forming part of broad longitudinal ridges; fixed finger approximately 0.7 as long as upper palm length, slender, occlusal surface with continuous row of microdenticles; major cheliped dactylus upper margin convex, occlusal margin sinuous.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBAFF9912DFCC15AE42F872.taxon	description	MEASUREMENTS. — Palm length in mm: ALMNH: Paleo: 21511: c. 5.0, USNM MO 371506: 6.8. DESCRIPTION Major cheliped propodus palm slightly longer than high: 1.1 - 1.3 as long as high (measured at upper margin), highest at palm mid-length; proximo-lower corner rounded; upper and lower margins subparallel with each other, lower margin with slight concavity at junction with fixed finger; upper and lower margins sharply carinate, carinae accompanied with rows of small setal pores on both sides (inner and outer); outer lateral largely surface smooth, with few setal pores and two densely tuberculated, sharply delineated areas: circular patch of tubercles positioned below articulation with dactylus and oval patch of tubercles forming broad longitudinal ridge at base of fixed finger; inner lateral surface with similar tuberculate longitudinal ridge and several scattered tubercles close to articulation with dactylus. Fixed finger approximately 0.7 as long as upper palm length, slender, subcircular in cross section, distal half bent slightly upward; occlusal surface with continuous row of microdenticles. Major cheliped dactylus upper margin convex; outer and inner lateral surfaces with rows of setal pores along upper margin and occlusal margin; occlusal margin sinuous forming elongate convexity proximally and slightly shorter concavity distally. Minor cheliped propodus palm 1.4 as long as high (measured at upper margin), upper and lower margin subparallel; fixed finger presumably as long as palm, occlusal surface with one tooth at mid-length; dactylus slender, occlusal margin continuous.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBAFF9912DFCC15AE42F872.taxon	discussion	REMARKS Rathbun (1935 a: pl. 15.23 - 15.25, 15.27) figured two specimens, one of which is the holotype (USNM MO 371506). The Smithsonian Institution assigned USNM PAL 336022 A to the figured propodus considered a paratype and USNM PAL 336022 B to 10 other paratype propodi specimens, verified by AAK in 2018. This totals 12 specimens rather than the 11 specimensRathbun (1935 a) mentioned.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFB8FF9911ADCBD3ABF2FEC1.taxon	materials_examined	TYPE SPECIES. — Ctenocheles balssi Kishinouye, 1926, by monotypy.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFB8FF9911ADCBD3ABF2FEC1.taxon	diagnosis	DIAGNOSIS. — See Poore et al. (2019: 119).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF9E12BACA92AE12FCF6.taxon	type_taxon	TYPE GENUS. — Eucalliax Manning & Felder, 1991.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF9E12BACA92AE12FCF6.taxon	discussion	REMARKS The family has a well-documented fossil record with a stratigraphic span reaching back to Late Cretaceous (Cenomanian) (Charbonnier et al. 2017). The assignment of the fossil material consisting of isolated cheliped elements to various eucalliacid genera was discussed in several studies (Hyžný 2012; Hyžný & Hudáčková 2012; Hyžný & Gašparič 2014). However, recent revisions of extant representatives based both on molecular and morphological characters (Poore et al. 2019; Robles et al. 2020; Poore 2021) call for re-evaluation of the fossil record of these animals.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF9E1315C8B1AB3FFEE8.taxon	materials_examined	TYPE SPECIES. — Eucalliax cearaensis Rodrigues & Manning, 1992, by original designation and monotypy. INCLUDED FOSSIL SPECIES. — Eucalliaxiopsis alabamensis (Rathbun, 1935 a) n. comb.; E. pseudorakosensis (Lőrenthey in Lőrenthey & Beurlen, 1929).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF9E1315C8B1AB3FFEE8.taxon	diagnosis	DIAGNOSIS. — See Sakai (2011: 503, 504).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF9E1315C8B1AB3FFEE8.taxon	discussion	REMARKS The assignment of Callianassa alabamensis Rathbun, 1935, to Eucalliaxiopsis is based on the combination of the following characters: a subquadrate manus, a triangular fixed finger with an oblique longitudinal ridge, and a smooth lower margin of cheliped merus. The oblique longitudinal ridge is also present in Calliaxina Ngoc-Ho, 2003 (Hyžný 2012; Poore 2021), but it is accompanied by a lateral concavity in the minor chela in this genus (Hyžný 2012), a character which is not identified in C. alabamensis. In Calliaxina, the lower margin of the cheliped merus has denticles (Poore 2021), whereas it is smooth in C. alabamensis. The observed variation of two morphotypes of cheliped dactylus in C. alabamensis corresponds to differences between major and minor claws as exemplified in extant species of Eucalliaxiopsis (Poore 2021). At least some fossil species of Eucalliax Manning & Felder, 1991, as listed by Schweitzer et al. (2010) and Hyžný & Klompmaker (2015), probably belong to Eucalliaxiopsis. This is because they were assigned to Eucalliax largely based on similarities with some extant species, previously classified within Eucalliax. Recent revisions (Poore et al. 2019; Robles et al. 2020; Poore 2021) recognized the genus Eucalliax to be monotypic, with the only extant representative being its type species, E. quadracuta (Biffar, 1970), while the species previously treated under Eucalliax were reassigned to other eucalliacid genera. In this respect, Hyžný & Dulai (2021) reassigned Eucalliax pseudorakosensis (Lőrenthey in Lőrenthey & Beurlen, 1929) from the Miocene of Central Europe to Eucalliaxiopsis. Other fossil species of Eucalliax are still pending revision.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF821145CAB2AA81FEAB.taxon	description	(Figs 8 - 10)	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF821145CAB2AA81FEAB.taxon	materials_examined	TYPE MATERIAL. — Holotype. United States • Alabama, Wilcox County, Prairie Creek and Pine Barren section; Porters Creek Formation; Paleocene (upper Danian); USNM MO 371505. Paratypes. United States • 1 specimen; same as for the holotype; USNM PAL 327231 A • 5 specimens; idem; USNM PAL 327231. ADDITIONAL MATERIAL EXAMINED. — United States • 1 specimen; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); ALMNH: Paleo: 21509 (partial propodus) • 1 specimen; idem; ALMNH: Paleo: 21510 (base fixed finger) • 1 specimen; idem; MMNS IP- 7251 (cheliped) • 1 specimen; idem; ALMNH: Paleo: 21549 (fixed finger and dactylus) • 1 specimen; idem; ALMNH: Paleo: 21552 (fixed finger and dactylus) • 2 specimens; idem; ALMNH: Paleo: 21548 (dactyli) • 16 specimens; idem; ALMNH: Paleo: 21551 (dactyli) • 22 specimens; idem; ALMNH: Paleo: 21554 (dactyli) • 1 specimen; idem; MMNS IP- 7256.3 (dactylus) • 8 specimens; idem; MMNS IP- 7256.6 - 13 (dactyli) • 1 specimen; idem; UF 303824 (dactylus) • 1 specimen; idem; UF 303829 (dactylus) • 1 specimen; idem; UF 303830 (dactylus) • 1 specimen; idem; UF 303832 (dactylus) • 1 specimen; idem; UF 303833 (dactylus) • 1 specimen; idem; UF 303834 (dactylus) • 1 specimen; idem; UF 303835 (dactylus) • 1 specimen; idem; UF 303836 (dactylus) • 1 specimen; idem; UF 303837 (dactylus) • 1 specimen; idem; UF 303840 (dactylus) • 1 specimen; idem; UF 303841 (dactylus of? minor) • 1 specimen; idem; UF 303842 (dactylus) • 1 specimen; idem; UF 303843 (dactylus) • 1 specimen; idem; UF 303844 (dactylus) • 1 specimen; idem; UF 303845 (dactylus) • 1 specimen; idem; UF 303847 (dactylus) • 1 specimen; idem; UF 303848 (dactylus) • 1 specimen; idem; UF 303849 (dactylus) • 1 specimen; idem; UF 303850 (dactylus) • 1 specimen; idem; UF 303851 (dactylus) • 1 specimen; idem; UF 303853 (dactylus) • 1 specimen; idem; UF 303856 (dactylus) • 1 specimen; idem; UF 303857 (dactylus) • 1 specimen; idem; UF 303862 (dactylus) • 1 specimen; idem; UF 303863 (dactylus) • 1 specimen; idem; UF 303864 (dactylus) • 1 specimen; idem; UF 303865 (dactylus of? minor) • 7 specimens; idem; ALMNH: Paleo: 21550 (fixed fingers) • 6 specimens; idem; ALMNH: Paleo: 21553 (fixed fingers) • 2 specimens; idem; MMNS IP- 7256.4 - 5 (fixed fingers) • 1 specimen; idem; UF 303823 (fixed finger) • 1 specimen; idem; UF 303825 (fixed finger) • 1 specimen; idem; UF 303826 (fixed finger) • 1 specimen; idem; UF 303827 (fixed finger) • 1 specimen; idem; UF 303828 (fixed finger) • 1 specimen; idem; UF 303831 (fixed finger) • 1 specimen; idem; UF 303838 (fixed finger) • 1 specimen; idem; UF 303839 (fixed finger) • 1 specimen; idem; UF 303846 (fixed finger) • 1 specimen; idem; UF 303852 (fixed finger) • 1 specimen; idem; UF 303854 (fixed finger) • 1 specimen; idem; UF 303855 (fixed finger) • 1 specimen; idem; UF 303858 (fixed finger) • 1 specimen; idem; UF 303859 (fixed finger) • 1 specimen; idem; UF 303861 (fixed finger). TYPE HORIZON. — Porters Creek Formation (Sucarnoochee beds in Rathbun 1935 a), upper Danian. TYPE LOCALITY. — Prairie Creek and Pine Barren section, Wilcox County, Alabama, United States.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF821145CAB2AA81FEAB.taxon	diagnosis	DIAGNOSIS. — Cheliped merus 1.6 times as long as high; outer lateral surface with longitudinal ridge at mid-height; lower margin smooth. Cheliped carpus 1.5 times as high as length at upper margin. Cheliped propodus palm approximately as high as length at upper margin; upper and lower margins carinate, carinae accompanied with rows of setal pores on both sides (inner and outer), carina on lower margin forming microdenticles distally (along fixed finger); distal margin of outer lateral surface with blunt tooth just below articulation with dactylus. Fixed finger approximately as long as upper palm length; outer lateral surface with oblique longitudinal ridge; fixed finger occlusal surface with proximal blunt tooth, entire occlusal surface (incl. proximal tooth) with numerous equally sized denticles. Dactylus upper margin straight, carinate; occlusal surface of robust dactylus morphotype with proximal blunt tooth followed with finely denticulated edge; occlusal surface of slender dactylus morphotype without proximal tooth.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF821145CAB2AA81FEAB.taxon	description	MEASUREMENTS. — Palm length (mm): MMNS IP- 7251: 8.9, USNM MO 371505: c. 19.0. DESCRIPTION Cheliped merus oval in outline, 1.6 times as long as high; outer lateral surface with longitudinal ridge at mid-height; lower margin distinctly convex, smooth. Cheliped carpus 1.5 times as high as length at upper margin; proximal margin rounded; distolateral margin square at lower angle. Cheliped propodus palm approximately as high as length at upper margin, highest proximally; proximo-lower corner rounded; upper and lower margins carinate, carinae accompanied with rows of setal pores on both sides (inner and outer), carina on lower margin forming microdenticles distally (along fixed finger); inner lateral surface with numerous setal pores concentrated close to distal margin and forming subvertical irregular row; outer lateral surface with setal pores concentrated distally, highest number of pores present close to junction with fixed finger; distal margin of outer lateral surface with blunt tooth just below articulation with dactylus. Fixed finger approximately as long as upper palm length, broadly oval in cross section; outer lateral surface with oblique longitudinal ridge, numerous setal pores scattered below ridge and in row above it along entire fixed finger length; fixed finger occlusal surface with proximal blunt tooth, entire occlusal surface (incl. proximal tooth) with numerous equally sized denticles, tip slightly bent upward. Dactylus upper margin straight, carinate; outer lateral surface with rows of setal pore clusters along upper and occlusal margins; inner lateral surface with several setal pore clusters along mid-length; occlusal surface of robust dactylus morphotype with proximal blunt tooth followed with finely denticulated edge; occlusal surface of slender dactylus morphotype without proximal tooth; dactylus tip slightly bent.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFBFFF821145CAB2AA81FEAB.taxon	discussion	REMARKS Rathbun (1935 a: pl. 15.7 - 15.10) figured two type specimens, the dactylus paratype, which received a new number subsequently (USNM PAL 327231 A), but she also mentioned the presence of more specimens (20 propodi and three fingers). Five additional specimens (USNM PAL 327231) are listed as paratypes in the Smithsonian Institution database and seen by AAK in 2018, but another catalog number used in Rathbun (1935 a) (371504) does not return any match in their database. Thus, the whereabouts of 16 original specimens is uncertain. Newly collected specimens match the type material in most details. Slight differences relate to the mode of preservation. The type specimens are partly abraded hindering the observation of minute details while the cuticular surfaces are better preserved in the newly collected material. For instance, the development of microdenticles on the lower margin of the propodus, the dentition on the occlusal edges of fingers and morphological details of setal pores are not well observable in the type material. Setal pores are arranged in clusters; the clusters are oval, distinctly elongate or V-shaped. Elongate setal pore clusters, oriented perpendicularly to the occlusal margin, are present especially on the outer lateral surface of dactyli, whereas V-shaped clusters are sometimes present on the outer lateral surface of the fixed fingers. The number of setal pores / setal pore clusters slightly varies when comparing the same parts of various specimens. There are two morphotypes of dactyli identified in the newly collected material: the robust one, with the proximal tooth on the occlusal surface, and the slender one, without the respective tooth. The slender morphotype is interpreted to belong to a minor claw, whereas the robust morphotype is interpreted to belong to a major claw; such differences in the morphology of cheliped dactyli are known also in extant species of Eucalliacidae (Poore 2021). Based on the presence of a proximal tooth on the occlusal surface of the fixed finger, all studied propodi attributed to E. alabamensis n. comb. are interpreted to belong to major claws only; such a proximal tooth is missing in minor claws ofeucalliacid shrimps (Hyžný 2012; Hyžný & Hudáčková 2012; Poore 2021). Major chelipeds are sexually dimorphic in representatives of Eucalliaxiopsis, with males having the propodus palm proportionally longer than that of females (Poore 2021). The limited number of complete propodi does not allow an evaluation of this dimorphism in E. alabamensis n. comb., although one propodus (Fig. 8 F, G) indeed appears to be proportionally longer than others and might represent a male individual. The newly presented material of E. alabamensis n. comb. is the second report of the species, originally described nearly a century ago (Rathbun 1935 a). It also adds further details to the description of the species, especially the morphology of the carpus and merus, previously unknown for this taxon. The range of the species is expanded from the late Danian to the early Danian. From fossil congeners, Eucalliaxiopsis alabamensis n. comb. differs from E. pseudorakosensis mainly in the nature of major dactylus. In E. pseudorakosensis, the occlusal margin of the dactylus is armed with a distal tooth (Hyžný & Hudáčková 2012), which is entirely missing in E. alabamensis n. comb.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA3FF8211C9CAF2ABA0FDFA.taxon	type_taxon	TYPE SPECIES. — Paguristes hirtus Dana, 1851, by subsequent designation (Stimpson 1858: 235).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA3FF83119BC9B2AB33FB37.taxon	description	(Fig. 11)	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA3FF83119BC9B2AB33FB37.taxon	materials_examined	TYPE MATERIAL. — Holotype. United States • Alabama, Wilcox County, Prairie Creek and Pine Barren section; Porters Creek Formation; Paleocene (upper Danian); USNM MO 371705 (right propodus). Paratype. United States • 1 specimen; same as for the holotype; USNM MO 371706 (left minor propodus and dactylus). ADDITIONAL MATERIAL EXAMINED. — United States • 1 specimen; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); ALMNH: Paleo: 21483 (right propodus + base of dactylus) • 1 specimen; idem; ALMNH: Paleo: 21484 (left dactylus) • 1 specimen; idem; ALMNH: Paleo: 21485 (right dactylus) • 1 specimen; idem; ALMNH: Paleo: 21486 (? left fixed finger) • 1 specimen; idem; ALMNH: Paleo: 21487 (right dactylus) • 1 specimen; idem; ALMN-H: Paleo: 21555 (left merus) • 1 specimen; idem; UF 303860 (right dactylus) • 1 specimen; Alabama, Sumter County, Tombigbee River, Black Bluff (32 ° 22 ’ 22 ” N, 88 ° 2 ’ 38 ” W), ALMNH loc. 5; Porters Creek Formation; Paleocene (upper Danian); ALMNH: Paleo: 21495 (right propodus) • 1 specimen; idem; ALMNH: Paleo: 21496 (right dactylus) • 1 specimen; idem; GSA-I 21012 (right dactylus) • 1 specimen; Alabama, Wilcox County; Porters Creek Formation; Paleocene (upper Danian); GSA-I 20984 (right propodus). TYPE HORIZON. — Porters Creek Formation (Sucarnoochee beds in Rathbun 1935 a), upper Danian. TYPE LOCALITY. — Prairie Creek and Pine Barren section, Wilcox County, Alabama, United States.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA3FF83119BC9B2AB33FB37.taxon	diagnosis	DIAGNOSIS. — Major palm short; about as long as high; tubercles with pit in center; diamond-shaped in cross-section; with sharp, convex upper and lower margins; upper margin shorter than lower margin; rounded ridges on outer and inner sides. Major dactylus with tubercles with pit in center and non-tubercular patches with setal pores on outer, upper, and part of inner sides; occlusal surface with a few large teeth and a smaller tooth on outer side of first tooth proximally, and a row of connected small teeth toward distal end.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA3FF83119BC9B2AB33FB37.taxon	description	MEASUREMENTS. — Palm length (mm): ALMNH: Paleo: 21483: 5.4 (as preserved); USNM MO 371705: 15.6; ALMNH: Paleo: 21495: 10.4; GSA-I 20984: 10.6 (as preserved). DESCRIPTION Reference is made to Rathbun (1935 a: 78). Additionally: major dactylus curved inward; tubercles with pit in center and non-tubercular patches with setal pores on outer, upper, and part of inner sides; occlusal surface with a few large teeth and a smaller tooth on outer side of first tooth proximally, and a row of connected small teeth toward distal end.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA3FF83119BC9B2AB33FB37.taxon	discussion	REMARKS The single right propodus available (ALMNH: Paleo: 21483) from Mussel Creek is incomplete but closely resembles the holotype of Paguristes johnsoni (USNM MO 371705, right propodus) and other right propodi (ALMNH: Paleo: 21495, right propodus; GSA-I 20984, right propodus) from the upper Danian Porters Creek Formation in Alabama in terms of overall shape, size, and distribution of the ornamentation, and the ridge on the outer surface. The base of the dactylus is preserved along with the propodus from Mussel Creek (ALMNH: Paleo: 21483), showing the base of the first large tooth and an adjacent small accessory tooth on the outer side that large tooth. This pattern resembles other isolated dactyli from Mussel Creek and dactyli from the Porters Creek Formation (ALMNH: Paleo: 21496, GSA-I 21012), which allows us to assign these specimens to P. johnsoni as well. The sample also contains an isolated finger that could be a fixed finger of this taxon (Fig. 11 I, J). It contains a row of small teeth on the occlusal surface and might belong to the minor claw of this taxon because large teeth on the occlusal surface are often seen on both fingers of the major claw in paguroids, whereas small teeth are often seen on the minor claw in paguroids (e. g., Forest et al. 2000). The oblique row of small teeth on its inner proximal part matches that of the base of the fixed finger of the propodus (ALMN-H: Paleo: 21483). Dactyli of the major claw were unknown from this species thus far. A left merus possibly belonging to the same species was also found (ALMNH: Paleo: 21555). This species was briefly discussed in Bishop (1983: 419), citing a personal communication with Jaques Forest, who was in doubt that Paguristes whitteni Bishop, 1983, and P. johnsoni could be assigned to Paguristes or even paguroids. Tubercular propodi do not necessarily imply a paguroid affinity. Indeed, the propodi of Paguristes whitteni belong to carapace specimens of the brachyuran crab Dakoticancer australis Rathbun, 1935 a (see Kornecki et al. 2017), also common at the same locality in Mississippi. We cannot assign the tubercular elements herein to a brachyuran carapace from the same assemblage. The dactyli and propodi are too large for Alahexapus martini (Feldmann, Schweitzer & Portell, 2014) n. comb. and the (distal) cheliped elements of other brachyuran taxa (see below) do not resemble the propodi / dactyli of P. johnsoni. The cheliped elements also cannot be linked to a brachyuran carapace from the Porters Creek Formation. Given the extensive collecting efforts at the Mussel Creek roadcut since 2010, the likelihood of finding other brachyuran taxa to which the claw elements could belong is low. We therefore suggest that the specimens represent a paguroid. The fact that the right propodus is larger than the left propodus (see Rathbun 1935 a: pl. 14.13 - 14.17), if both isolated elements are indeed from the same species, is inconsistent with Diogenidae, members of which usually have a larger left propodus or (sub) equal propodi (e. g., Tudge et al. 2012: 305), including Paguristes, which is mentioned to have isochelous propodi (Fraaije et al. 2015: 590). An exception within diogenids is Petrochirus Stimpson, 1858, but this taxon has scabrous ornamentation in the type species Petrochirus diogenes (Linnaeus, 1758) (see Hyžný & Dulai 2021: fig. 43.7) not seen in P. johnsoni and various fossil Petrochirus (Beschin et al. 2002, 2006, 2012). The dactyli herein closely resemble a dactylus identified as Petrochirus sp. from the Early Miocene of Venezuela (Feldmann & Schweitzer 2004: pl. 1.2 - 1.4), but this record has more teeth on the occlusal surface. It is likely these species belong to the same genus. We have not found close matches with other Petrochirus spp. More complete material with both left and right cheliped would be necessary to further evaluate the genus and family placement. For now, we treat the specimens as “ Paguristes ” johnsoni within Paguroidea. The assignment of our material to P. johnsoni implies a range extension into the early Danian in Alabama. Cope et al. (2005) ascribed a propodus from the Clayton Formation of southern Illinois to P. johnsoni. The level of this specimen within the Clayton Formation was not reported, but potassium-argon dating on glauconite on the oldest sample from the Clayton Formation returned a date of 60.6 ± 1.3 Ma (Reed et al. 1977). This date suggests it is not the earliest Danian and that this propodus from Illinois is probably younger than the specimens herein.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA2FF811187CED7AD7EFE11.taxon	type_taxon	TYPE SPECIES. — Ranina laevis Latreille, 1825, by monotypy.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA2FF811187CED7AD7EFE11.taxon	diagnosis	DIAGNOSIS. — See Karasawa et al. (2014: 258).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA0FF871338CAD2AB21FB16.taxon	description	(Figs 12; 13; Appendices 1 I, J; 2) urn: lsid: zoobank. org: act: 6 B 1972 E 9 - 782 E- 4 B 4 C-AC 4 A- 2 BEAA 49 CC 8 CE	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA0FF871338CAD2AB21FB16.taxon	materials_examined	TYPE MATERIAL. — Holotype. United States • 1 specimen; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); ALMN-H: Paleo: 21488. Paratypes. United States • 1 specimen; same as for the holotype; ALMNH: Paleo: 5919 • 1 specimen; idem; ALMNH: Paleo: 21489 • 1 specimen; idem; ALMNH: Paleo: 21490 • 1 specimen; idem; ALMNH: Paleo: 21491 • 1 specimen; idem; ALMNH: Paleo: 21492.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA0FF871338CAD2AB21FB16.taxon	etymology	ETYMOLOGY. — danicus refers to the first species of Raninoides recognized from the Danian.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA0FF871338CAD2AB21FB16.taxon	materials_examined	ADDITIONAL MATERIAL EXAMINED. — United States • 5 specimens; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); ALMNH: Paleo: 21493 • 1 specimen; idem; ALMNH: Paleo: 21494 • 2 specimens; idem; MMNS IP- 7252 • 4 specimens; idem; MMNS IP- 7253 • 1 specimen; idem; MMNS IP- 8792 • 1 specimen; idem; UF 303873. TYPE HORIZON. — Pine Barren Member of the Clayton Formation, middle NP 2 nannofossil zone, lower Danian. TYPE LOCALITY. — ALMNH loc. 3: Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), Lowndes County, Alabama, United States.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA0FF871338CAD2AB21FB16.taxon	diagnosis	DIAGNOSIS. — Carapace length-width ratio c. 1.45 without rostrum and spines. Fronto-orbital width c. 70 % of maximum width; posterior margin 70 % of maximum width. Front with outer orbital spine curving inward to form straight part, lined with tubercles; intra-orbital spine surrounded by deep fissures, outer part top of spine steep-sided and lined with tubercles; outermost part rostral section of front concave, lined with tubercles. Anterolateral margin with one strong spine near outer orbital angle and directed anterolaterally, otherwise mostly straight and lined with tubercles. Sinuous band of tubercles just posterior to frontal margin. Sternite 4 longer than wide.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA0FF871338CAD2AB21FB16.taxon	description	MEASUREMENTS. — Maximum carapace width (mm): ALMNH: Paleo: 21488: 12.3, ALMNH: Paleo: 5919: 14.7, ALMNH: Paleo: 21490: 12.3, MMNS IP- 7252.1: 15.1, MMNS IP- 7253.1: 8.8. DESCRIPTION Carapace longer than wide (l / w ratio c. 1.45 without rostrum and spines), moderately vaulted transversely, weakly vaulted longitudinally, widest around third of length. Fronto-orbital width c. 70 % of maximum width; posterior margin 70 % of maximum width. Front incompletely known, but with outer orbital spine curving inward to form straight part, lined with tubercles; intra-orbital spine surrounded by deep fissures, outer part top of spine steep-sided and lined with tubercles; outermost part rostral section of front concave, lined with tubercles. Suborbital margin lined with tubercles, mostly straight except near outer orbital spines and with single deep fissure. Orbit wider than tall. Anterolateral margin with one strong spine near outer orbital angle and directed anterolaterally, otherwise mostly straight and lined with tubercles; convex transition to mostly straight and longer posterolateral margin lined with tubercles. Convex transition from posterolateral margin to posterior margin, which exhibits a slight concavity axially and is smoothrimmed. Axis of carapace with weak, rounded ridge. Carapace regions undefined, except for lateral parts of cardiac region in between concave-outward branchiocardiac grooves. Pair of posterior gastric pits in front of branchiocardiac grooves. Cuticle of dorsal carapace with widely spaced deep pits and more dense shallow pits, but with sinuous band of tubercles just posterior to frontal margin. Pterygostome with gentle ridge anteriorly, widening anteriorly, with sinuous buccal collar, with tubercular cuticle, uninterrupted transition to branchiostegite. Sternite 3 small, rounded laterally, with sharp tip and steep front; sternite 4 longer than wide, with concave lateral sides, episternites rounded; sternite 5 about equally long as wide, widening toward sternite 4, with axial groove; sternite 6 widening posteriorly, with concave posterior margin on either side of axis, with axial groove. Sternites 3 - 4 cuticular surface pitted but with tubercles along margins; tubercles on lateralmost parts of sternites 5 and 6 in dorsal view, and on transition from sternite 5 to 6. Pleurites 4 - 7 partly visible externally, smooth cuticular surface except for pleurite 4 and spines on pleurites 4 - 7 containing tubercles; pleurites with rims around pereiopod attachments. Coxae of maxilliped 3 curved forward, adjacent to lateral sides sternite 3. Oval attachment of cheliped pair to venter, circular for second pereiopod pair. Rostrum, pleon, and appendages not preserved.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA0FF871338CAD2AB21FB16.taxon	discussion	REMARKS Feldmann et al. (2019) ascribed three carapaces (MMNS IP- 7252 [2 specimens] and MMNS IP- 8792) to Giulianolyreidus johnsoni within Lyreidinae Guinot, 1993. The dorsal carapace is close to this species first described from the upper Danian Porters Creek Formation of Alabama (Rathbun 1935 a: pl. 17.12 - 17.17 [as Symethis johnsoni]; Bishop & Whitmore 1986: fig. 1 K [not 1 G, 1 H, 1 J]; Waugh et al. 2009: fig. 11; Karasawa et al. 2014: fig. 12 C, D) and later from the upper Danian Mexia Clay Member of the Wills Point Formation in Texas (Armstrong et al. 2009: fig. 4.1 - 4.2 [as Macroacaena johnsoni] [identification verified by AAK]), but the axial ridge is more prominent and the pits on the cuticular surface are larger in G. johnsoni. Moreover, the ventral side of multiple new specimens (ALMNH: Paleo: 5919, ALMN-H: Paleo: 21488 - 21490, ALMNH: Paleo: 21494) and MMNS IP- 8792 show marked differences, revealing an axial groove on sternites 5 and 6 (Figs 12 B; 13 A, which G. johnsoni lacks (Rathbun 1935 a: pl. 17.12). Comparable dorsal and ventral surfaces are found among Raninoidinae, such as Notosceles Bourne, 1922, and Raninoides. The main differences between these genera involve the development of the rostrum, orbital fissures, and the outer orbital spines (diagnoses in Karasawa et al. 2014, and Schweitzer et al. 2018 b), but these features are not well-preserved in the specimens from Mussel Creek. Karasawa et al. (2014) diagnosed that Notosceles exhibits short open fissures, but one specimen herein (ALMNH: Paleo: 21491) exhibits fairly deep fissures (Fig. 12 F). An additional difference we noted is that the anterolateral spine is substantially larger and more anterolaterally directed in Raninoides than in Notosceles, in which a small spine is consistently more forwardly directed across all species (see extant species and Notosceles bournei Rathbun, 1928, from the Paleocene of Texas, Alabama, and Arkansas, see Rathbun 1935 a). Many extant and fossil Raninoides have a strong anterolaterally directed spine, consistent with our specimens. This genus is diagnosed to exhibit a bifid outer orbital spine (Karasawa et al. 2014; Schweitzer et al. 2018 b), but this does not apply to all species assigned to this genus because several members have a straight plateau inward from a single spine rather than another spine (e. g., Paleocene R. borealis, extant R. crosnieri, extant R. longifrons, and extant R. personatus). None of the fossil specimens studied here have the tip of the outer orbital spine preserved, but two specimens show a straight plateau inward in addition to the base of the outer orbital spine (ALMNH: Paleo: 5919 and MMNS-IP 7253.2). Thus, we assign the specimens to Raninoides with confidence. Reasons for species separation often include the orientation, size, and location of the anterolateral spine; the development of the frontal margin and post-frontal ridge, and carapace proportions (e. g., Collins et al. 2003; Schweitzer et al. 2006, 2012; De Angeli et al. 2009). The early Danian Raninoides danicus n. sp. differs from all other species. The stratigraphically closest species are R. borealis from the middle Paleocene (Selandian) of West Greenland and R. granulofrons from the late Campanian-early Maastrichtian of Cuba. Based on a study of the type material by AAK, R. borealis bears an anterolateral spine that may be farther from the outer orbital margin, this spine is oriented more forward, and the intra-orbital spine is more rounded. Raninoides granulofrons bears an intra-orbital spine that is more rounded on top, and the preserved base of the anterolateral spine is smaller, mentioned to be short by Vega et al. (2024). We also compared this species to Eocene species, using the papers in which those species were first described and other papers as needed. Raninoides acanthocolus bears a shorter anterolateral spine further back on the anterolateral margin and the upper margin of the intraorbital spine slopes inward (Schweitzer et al. 2006: fig. 2.7). Raninoides araucana bears a smaller anterolateral spine (Philippi 1887: pl. 50.6). Raninoides budapestiniensis has an anterolateral spine further back on the anterolateral margin and a stronger postfrontal ridge (Lőrenthey 1898: pl. 1.2). Raninoides dickersoni, only known from a venter, has a wider spine on sternite 5 (Rathbun 1926: pl. 20.5). Raninoides fabianii apparently lacks anterolateral spines (Lőrenthey & Beurlen 1929: pl. 4.10). Raninoides fulgidus has a proportionally smaller anterolateral spine (Rathbun 1926: pl. 23.6; ALMNH: Paleo: 5937). Raninoides glabra has the axial groove more forward onto the posterior part of sternite 4 (near the center of episternite 4) and sternite 4 is proportionally longer (see Van Bakel et al. 2012: fig. 44 c, d). Raninoides goedertorum and R. notopoides exhibit smaller and more forwardly oriented anterolateral spines (Tucker 1998: fig. 13; Hyžný & Zorn 2016: pl. 9.3). Raninoides gottschei has a smaller anterolateral spine (Glaessner & Withers 1931: pls 20.1 - 2, 21.1). Raninoides perarmata and R. rathbunae have proportionally shorter sternites 4 (Feldmann 1991: figs 2, 4; Feldmann & Schweitzer 2004: fig. 1 B). Raninoides proracanthus bears a much smaller anterolateral spine (Feldmann & Schweitzer 2004: fig. 2.8). Raninoides pulchra exhibits an anterolateral spine that is bifid near its base (Beschin et al. 1988: pl. 4.1 - 3). Raninoides rioturbiensis has a longer intraorbital spine narrowing to the front and the base of the anterolateral spine is smaller (Schweitzer et al. 2012: fig. 4). Raninoides sinuosus exhibits a smaller base of the anterolateral spine and sternite 4 is proportionally shorter (Collins & Morris 1978: pl. 116.4 - 6). Raninoides slaki has a bifid intra-orbital spine and the maximum carapace width is located further posteriorly (Squires 2001: figs 47 - 55). Raninoides treldenaesensis bears a smaller anterolateral spine and sternite 4 is proportionally shorter (Collins & Jakobsen 2003: fig. 4, pl. 3.5). Raninoides vaderensis appears close but its anterolateral spine is oriented more forwardly (Rathbun 1926: pl. 22.5; Tucker 1998: fig. 17; Gustafson 2023: figs 16 - 19). Raninoides washburnei has a more forwardly oriented anterolateral spine and its carapace is proportionally wider (Rathbun 1926: pl. 22.6). We did not compare the new species to post-Eocene species because brachyuran species ranging for> 32 million years are extremely unlikely and unknown to us.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA6FF84117ECE77AB6CF872.taxon	type_taxon	TYPE SPECIES. — Costacopluma concava Collins & Morris, 1975, by original designation.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA6FF84117ECE77AB6CF872.taxon	diagnosis	DIAGNOSIS. — Small rectangular to ovoid carapace, wider than long; carapace surface distinctly flattened and traversed by three elevated, granular ridges, the anteriormost being complete and often biconvex forwards; posterior two ridges converging axially defining depressed, triangular to rectilinear, smooth mesobranchial region. Rostrum generally narrow, downturned, bilobed. Carapace flanks distinct, about perpendicular to dorsal surface and separated from it by beaded rim. Sternum broad, with well-defined sternites; sternites 5 - 7 each with prominent transverse, beaded ridge; male sternopleonal cavity deep, reaching end of sternite 4. Transverse ridges also present on pleonal somites. Pereiopod 5 subdorsal, reduced. Emended from Feldmann et al. (2014: 137).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA4FF8A12C3CED6ACC7F915.taxon	materials_examined	TYPE MATERIAL. — Holotype. United States • 1 specimen; Alabama, Covington County, Below Point A Dam (31 ° 21 ’ 32 ” N, 86 ° 31 ’ 11 ” W), ALMNH loc. 4; Tallahatta Formation, NP 14 nannofossil zone; Eocene (upper Ypresianlower Lutetian); UF 113749. Paratypes. United States • 1 specimen; same as for the holotype; UF 113748 • 1 specimen; idem; UF 113750 • 1 specimen; idem; UF 114747 • 1 specimen; idem; UF 115672 • 1 specimen; idem; UF 115793 • 1 specimen; idem; UF 115794 • 1 specimen; idem; UF 115795 • 1 specimen; idem; UF 115796. ADDITIONAL MATERIAL EXAMINED. — United States • 2 specimens; Alabama, Covington County, Below Point A Dam (31 ° 21 ’ 32 ” N, 86 ° 31 ’ 11 ” W), ALMNH loc. 4; Tallahatta Formation, NP 14 nannofossil zone; Eocene (upper Ypresianlower Lutetian); ALMNH: Paleo: 20598 • 1 specimen; idem; ALMNH: Paleo: 21440 • 3 specimens; idem; MMNS IP- 6491 • 1 specimen; idem; MMNS IP- 6492 • 2 specimens; idem; MMNS IP- 10046 • 1 specimen; idem; MMNS IP- 11213 • 1 specimen; idem; UF 116615 • 1 specimen; idem; UF 116619 • 1 specimen; idem; UF 142615 • 1 specimen; idem; UF 142616 • 1 specimen; idem; UF 116691 • 1 specimen; idem; UF 171033 • 1 specimen; idem; UF 171034 • 1 specimen; idem; UF 256410 • 1 specimen; Alabama, Conecuh County, Pigeon Creek (T 5 N, R 14 E, Sec. 20, NE ¼, NE ¼); Tallahatta Formation, NP 14 nannofossil zone; Eocene (upper Ypresianlower Lutetian); UF 287265 • 1 specimen; idem; UF 287266 • 1 specimen; idem; UF 349284 - 349310. TYPE HORIZON. — Tallahatta Formation, NP 14 nannofossil zone, Eocene (upper Ypresianlower Lutetian). TYPE LOCALITY. — Below Point A Dam (31 ° 21 ’ 32 ” N, 86 ° 31 ’ 11 ” W), Covington County, Alabama, United States.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA4FF8A12C3CED6ACC7F915.taxon	diagnosis	DIAGNOSIS. — Carapace relatively small (<15 mm maximum width), subrectangular, wider than long (l / w ratio c. 0.9), widest point posterior to mid-length. Fronto-orbital margin c. 70 % of maximum width; lateral margins somewhat diverging posteriorly, fairly straight, but more convex posteriorly; posterior margin nearly straight. Rostrum inclined downward, slightly longer than wide, minimum width in dorsal view c. 4 % of maximum carapace width. Outer orbital spine small, triangular, directed forward. Dorsal carapace containing three tubercular transverse ridges of narrow width on average, with rounded tops; anterior ridge sinuous, uninterrupted, diminishes toward but reaches lateral margins. Cardiac region raised, tubercular, with convex and flattened ridge anteriorly and raised extension axially directed posteriorly. Gentle swellings with tubercles just anterior to innermost part of posterolateral margins.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA4FF8A12C3CED6ACC7F915.taxon	description	MEASUREMENTS. — See Table 1. DESCRIPTION Referral is made to Feldmann & Portell (2007: 92). Additional specimens allow for improved description of rostrum, outer orbital spine, posterior margin, cheliped, sternum, and pleon. Outer orbital spine small, appears directed forward (UF 115796). Partial rostrum narrow, minimally c. 4 % of maximum carapace width in dorsal view. Posterior margin with one row of small tubercles on top of rim, curving somewhat forward in lateral parts, nearly straight to very slightly concave in axial part (MMNS IP- 11213, UF 171033). Outer side propodus (UF 287266) without tubercles as preserved, with a groove near base extending onto fixed finger, with at least four pits on fixed finger close to occlusal surface. Male sternite 4 with distinct, tubercular rim on outer side; less distinct rim on inner side, marking deep sternopleonal cavity for telson; generally smooth on cuticular surface in between. Somites male pleon unfused, with transverse, tubercular keels; telson with rounded tip.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFA4FF8A12C3CED6ACC7F915.taxon	discussion	REMARKS Several papers ascribed early Danian and Maastrichtian specimens to this species (Feldmann et al. 2014; Vega et al. 2016; Martínez-Díaz et al. 2016), but there are several morphological differences between the specimens from the Eocene and these c. 18 - 19 million years older specimens that warrant species-level separation. For the early Danian specimens, referral is made to the new species erected below. The Maastrichtian specimens also represent a different species of Costacopluma not treated further herein: they have an outer orbital spine directed anterolaterally instead of forward as in C. grayi (UF 115796), are proportionally wider, and have a greater maximum size (see Vega et al. 2016; Martínez-Díaz et al. 2016). Specimens with light to dark brown cuticle are embedded in tan / light brown fine sediment with some sand. Others occur in tan-brown sediment with more sand embedded, and a very dark brown cuticle. Finally, some occur in dark gray sediment and have dark brown cuticle. This applies to specimens from Point A Dam and Pigeon Creek. Some are listed as found in situ (UF 116615, UF 116619, UF 116691) or found in bed 5 of Copeland (1966) (UF 171033, UF 171034, type series), but the preservation style differs. It is likely that specimens underwent somewhat different taphonomic histories. Some specimens (MMNS IP- 11213 and MMNS IP- 10046) are listed to have come from the basal Lisbon Formation in “ Bed 5 ” of Copeland (1966), which Feldmann & Portell (2007) interpreted to be the Tallahatta Formation (see also Savrda et al. 2010). Additional specimens were briefly mentioned in a paper focused on the vertebrate fauna of Point A Dam (Clayton et al. 2013). Unfortunately, the whereabouts of those crabs is uncertain (pers. comm. AAK with the Chuck Ciampaglio, November 2023).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFABFF8B11FECDD5AD01F875.taxon	description	(Fig. 16; Table 1; Appendix 1 G, H)	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFABFF8B11FECDD5AD01F875.taxon	materials_examined	TYPE MATERIAL. — Holotype. United States • 1 specimen; Texas, Limestone County, quarry c. 2 miles west of Mexia (c. 31 ° 40 ’ 12 ” N, 96 ° 34 ’ 11 ” W); Wills Point Formation, Mexia Clay Member; Paleocene (upper Danian); NPL 31172. Paratypes. United States • 1 specimen; same as for the holotype; NPL 31173 • 1 specimen; idem; NPL 31174 • 1 specimen; idem; NPL 31175 • 1 specimen; idem; NPL 31176 • 1 specimen; idem; MGSB 75425. ADDITIONAL MATERIAL EXAMINED. — United States • 6 specimens; Texas, Limestone County, Hanson Quarry; Wills Point Formation, Mexia Clay Member; Paleocene (upper Danian); MMNS IP- 7396. TYPE HORIZON. — Mexia Clay Member of the Wills Point Formation, upper Danian. TYPE LOCALITY. — Quarry c. 2 miles west of Mexia (c. 31 ° 40 ’ 12 ” N, 96 ° 34 ’ 11 ” W), Limestone County, Texas, United States.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFABFF8B11FECDD5AD01F875.taxon	diagnosis	DIAGNOSIS. — Referral is made to Armstrong et al. (2009: 756).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFABFF8B11FECDD5AD01F875.taxon	description	MEASUREMENTS. — See Table 1. DESCRIPTION Referral is made to Armstrong et al. (2009: 756).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFABFF8B11FECDD5AD01F875.taxon	discussion	REMARKS Costacopluma texana is morphologically close to C. nicksabani n. sp., but differs in several aspects. For details see the comparisons under C. nicksabani n. sp.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFAAFF8D11C7CFF7AEE3F994.taxon	description	(Figs 17; 18; Table 1; Appendices 1 A-E; 3) urn: lsid: zoobank. org: act: 155 CD 778 - 8 DA 2 - 4484 - ADD 9 - 08427 C 6 AE 93 F	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFAAFF8D11C7CFF7AEE3F994.taxon	materials_examined	TYPE MATERIAL. — Holotype. United States • 1 specimen; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); ALMN-H: Paleo: 21453 (carapace). Paratypes. United States • 1 specimen; same as for the holotype; ALMNH: Paleo: 13539 (carapace) • 1 specimen; idem; ALMNH: Paleo: 21454 (carapace) • 1 specimen; idem; ALMNH: Paleo: 21455 (carapace) • 1 specimen; idem; ALMNH: Paleo: 21456 (carapace) • 1 specimen; idem; ALMNH: Paleo: 21457 (carapace) • 1 specimen; idem; ALMNH: Paleo: 21458 (carapace) • 1 specimen; idem; ALMNH: Paleo: 21459 (carapace) • 1 specimen; idem; MMNS IP- 7940.1 (carapace) • 1 specimen; idem; UF 247378 (pair of propodi and dactyli).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFAAFF8D11C7CFF7AEE3F994.taxon	etymology	ETYMOLOGY. — In honor of the legendary American college football coach Nick Saban, who led the University of Alabama team from 2007 - 2023, winning six national and nine SEC championships with the Crimson Tide. Also, Nick’s Kids Foundation has made a tremendous societal impact in Alabama and beyond.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFAAFF8D11C7CFF7AEE3F994.taxon	materials_examined	ADDITIONAL MATERIAL EXAMINED. — United States • 13 specimens; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); ALMNH: Paleo: 5918 (carapaces / venters) • 51 specimens; idem; ALMNH: Paleo: 21497 (51 carapaces / venters) • 1 specimen; idem; ALMNH: Paleo: 21498 (propodus) • 1 specimen; idem; ALMNH: Paleo: 21499 (carapace with meri and partial carpi) • 1 specimen; idem; ALMNH: Paleo: 21500 (merus) • 1 specimen; idem; ALMNH: Paleo: 21501 (carapace) • 1 specimen; idem; ALMN-H: Paleo: 21502 (venter) • 1 specimen; idem; ALMNH: Paleo: 21503 (merus) • 26 specimens; idem; ALMNH: Paleo: 21504 (carapaces / venters) • 1 specimen; idem; MMNS IP- 6478 (carapace) • 1 specimen; idem; MMNS IP- 6479 (carapace) • 1 specimen; idem; MMNS IP- 6480 (venter) • 1 specimen; idem; MMNS IP- 6481 (carapace) • 13 specimens; idem; MMNS IP- 7257 (carapaces, incl. carapace with base cheliped incl. merus) • 1 specimen; idem; MMNS IP- 7268 (carapace) • 3 specimens; idem; MMNS IP- 7296 (2 carapaces, 1 propodus) • 6 specimens; idem; MMNS IP- 7940.2 - 7 (carapaces) • 1 specimen; idem; UF 235556 (carapace) • 1 specimen; idem; UF 235557 (carapace) • 1 specimen; idem; UF 235558 (carapace) • 1 specimen; idem; UF 235559 (carapace) • 1 specimen; idem; UF 235560 (carapace) • 1 specimen; idem; UF 235562 (carapace) • 1 specimen; idem; UF 235563 (carapace) • 1 specimen; idem; UF 235564 (carapace) • 1 specimen; idem; UF 235565 (carapace) • 1 specimen; idem; UF 235566 (carapace) • 1 specimen; idem; UF 235567 (carapace) • 1 specimen; idem; UF 235568 (carapace) • 11 specimens; idem; UF 235569 (10 carapaces and 1 venter) • 1 specimen; idem; UF 235570 (fixed finger) • 1 specimen; idem; UF 235571 (propodus) • 1 specimen; idem; UF 235577 (carapace with propodus) • 1 specimen; idem; UF 247377 (cheliped propodus) • 1 specimen; idem; UF 254039 (carapace) • 1 specimen; idem; UF 303795 (carapace) • 1 specimen; idem; UF 303796 (carapace) • 1 specimen; idem; UF 303797 (carapace) • 1 specimen; idem; UF 303798 (carapace) • 1 specimen; idem; UF 303799 (carapace) • 1 specimen; idem; UF 303800 (carapace) • 1 specimen; idem; UF 303802 (carapace) • 1 specimen; idem; UF 303803 (carapace) • 1 specimen; idem; UF 303804 (carapace) • 1 specimen; idem; UF 303805 (carapace) • 1 specimen; idem; UF 303806 (venter) • 1 specimen; idem; UF 303807 (carapace) • 1 specimen; idem; UF 303808 (carapace) • 1 specimen; idem; UF 303809 (carapace) • 1 specimen; idem; UF 303810 (carapace) • 1 specimen; idem; UF 303811 (carapace) • 1 specimen; idem; UF 303813 (carapace) • 1 specimen; idem; UF 303814 (carapace) • 1 specimen; idem; UF 303816 (carapace) • 1 specimen; idem; UF 303817 (carapace) • 1 specimen; idem; UF 303818 (carapace) • 1 specimen; idem; UF 303820 (propodus) • 1 specimen; idem; UF 303821 (cheliped). TYPE HORIZON. — Pine Barren Member of the Clayton Formation, lower middle NP 2 nannofossil zone, lower Danian. TYPE LOCALITY. — ALMNH loc. 3: Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), Lowndes County, Alabama, United States.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFAAFF8D11C7CFF7AEE3F994.taxon	diagnosis	DIAGNOSIS. — Carapace relatively small (usually <15 mm maximum width), subrectangular, wider than long (l / w ratio c. 0.89), widest point posterior to mid-length. Fronto-orbital margin c. 70 % of maximum width; lateral margins somewhat diverging posteriorly, fairly straight, but more convex anteriorly; posterior margin straight. Rostrum bilobed, inclined downward, slightly longer than wide, minimum width in dorsal view c. 8 % of maximum carapace width. Outer orbital spine small, triangular, directed forward, about as short as spine on lower orbital margin. Dorsal carapace containing three tubercular transverse ridges of intermediate width on average, with rounded tops; anterior ridge sinuous, uninterrupted, diminishes toward but reaches lateral margins. Cardiac region raised, tubercular, with convex and flattened ridge anteriorly and raised extension axially directed posteriorly. Gentle swellings with tubercles just anterior to innermost part of posterolateral margins. Pleon of male narrow, widening somewhat to posterior; with transverse ridges on somites 3 - 6; telson and sternite 6 unfused; somites 3 - 5 fused but with sutures visible. Pleon of female with transverse ridges on somites 2 - 5; all somites and telson unfused; somites 1 - 5 much wider than long; somite 6 wider than long; telson triangular with rounded tip.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFAAFF8D11C7CFF7AEE3F994.taxon	description	MEASUREMENTS. — See Table 1. DESCRIPTION Carapace relatively small (usually <15 mm maximum width), subrectangular, wider than long (l / w ratio c. 0.89), widest point posterior to mid-length, weakly vaulted transversely, moderately vaulted longitudinally. Margins rimmed with granules. Fronto-orbital margin c. 70 % of maximum width, sinuous; lateral margins somewhat diverging posteriorly, fairly straight, but more convex anteriorly; posterolateral margin slightly concave; posterior margin straight. Rostrum bilobed, inclined downward, slightly longer than wide, minimum width in dorsal view c. 8 % of maximum carapace width, narrowest point about halfway rostrum, with two lobes distally carrying tubercles, tip concave in dorsal view, lateral margins rimmed and with row of granules. Orbital margin rimmed with tubercles; upper orbital margin somewhat thicker than lateral and lower orbital margins; lower orbital margin with forwardly-directed spine; outer orbital spine small, triangular, directed forward, about as short as spine on lower orbital margin. Orbital cavity subovate but with angle at outer orbital spine, faint ridge of granules dividing outer and inner parts. Eyestalks elongated. Epigastric regions consisting of small, gentle swellings. Dorsal carapace containing three tubercular transverse ridges of intermediate width on average, with rounded tops; anterior ridge sinuous, uninterrupted, diminishes toward but reaches lateral margins; median ridges directed anterolaterally, straight, not connecting axially, reaching lateral margins; posterior ridges directed posterolaterally, not connecting axially, reaching posterolateral margins, curving more laterally in outermost part. Posterior part of mesogastric region raised, tubercular, connecting with anterior ridge where it narrows, with two posterior gastric pits near base. Cardiac region raised, tubercular, with convex and flattened ridge anteriorly and raised extension axially directed posteriorly. Gentle swellings with tubercles just anterior to innermost part of posterolateral margins. Other carapace regions not discernible. Dorsal carapace grooves absent except for short groove lateral to posterior part of mesogastric region ending in ovals pits anteriorly. Cuticular surface of dorsal carapace regions between ridges, in front of anterior ridge, and posterior to cardiac region pitted. Flanks straight; about a quarter in height of maximum carapace width; with groove starting at lateral margin, resulting sometimes in a weak notch, near position where anterior ridge connects to lateral margin; groove curving forward and becoming deeper near base of flank; flank tubercular in posterior part, mostly smooth in anterior third but with some tubercles in anteriormost part. Pterygostome subtriangular and with posterior extension, with rim posteriorly and inward margin, mostly smooth. Buccal area with pit axially. Maxillipeds not preserved. Sternum suboval, widest at 5 th sternite. Sternites 1 and 2 fused, separated by groove, triangular jointly; sternite 1 triangular with sharp tip, with tubercles; sternite 2 much wider than long, with short axial groove, with tubercles, widening toward sternite 3. Sternite 3 fused to sternite 4 but marked by transverse groove, with two lobes on posterior margin on either side of tip of sternopleonal cavity for males but with deep depression axially for females, straight anteriorly, tubercular. Sternite 4 trapezoidal, tubercular, not flattened but concave, widening more laterally; with small anterolaterally oriented projection in anterolateral corner, about straight on anterior side for females and males, not extending much if anything beyond sternite 3. Sternites 5 - 7 with transverse, tubercular ridge widening inward. Sternites 4 - 6 with long episternal projections pointing posteriorly, episternal projection not preserved for sternite 7. Sternite 8 poorly preserved. Sternopleonal cavity of male deep, narrow, smooth, with sutures of 4 / 5, 5 / 6, and 6 / 7 extending to base of cavity but not connecting, suture 7 / 8 partially preserved, axial slit at level of sternite 7; sternopleonal cavity extends to upper part of sternite 4 and marked by clear rim at tip, small press button on sternite 5 on upper part of slope near sternite 4. Sternopleonal cavity of female incompletely preserved, but broader than male; without press button, deep, smooth, with sutures of 4 / 5, 5 / 6, and 6 / 7 extending to base of sternopleonal cavity but not connecting, with flat bottom between sternites 4 - 6, sternopleonal cavity extends to upper part of sternite 3 and without rim at tip; position of tip of telson marked by granules without forming rim, near base of sternite 3; subcircular oviduct on anterior part of sternite 6 near sternite 5, adjacent to base of sternopleonal cavity. Pleon of male narrow, widening somewhat to posterior; with transverse ridges on somites 3 - 6, ridge of somite 6 with tubercles, ridges of somites 3 - 5 pitted; pitted telson triangular with rounded tip; telson and sternite 6 unfused; somites 3 - 5 fused but with sutures visible; somites 1 - 2 much shorter than other somites, without ridge in center, with rim on anterior margin for somite 1, with bump in center of somite 2. Pleon of female with pitted transverse ridges on somites 2 - 5; all somites and telson unfused; somites 1 - 5 much wider than long; somite 6 wider than long, with tubercles on transverse ridge; telson triangular with rounded tip, pitted. Male pleopod 1 (gonopod 1) curved, open at tip, at position of somite 6. Chelipeds isochelous or slightly heterochelous. Cheliped propodus without fixed finger wider than tall, upper margin with tubercular rim, lower margin rounded, subtrapezoidal in outer view; outer side convex, with shallow and longitudinal depression near upper margin, mostly pitted cuticular surface but with bands of tubercles near lower and upper margins; inner side flattened to slightly convex, with band of tubercles on lower third; fixed finger taller than wide in cross-section, flat bottom, occlusal surface with poorly preserved teeth decreasing in size to distal part, outer and inner sides with two ridges covered with granules near lower margin separated by groove, setal pits present on outer and inner sides, probably about as long as upper margin. Cheliped dactylus poorly preserved but with two ridges on upper margin of outer side, with setal pits on outer side. Cheliped carpus not preserved. Cheliped merus longer than tall, spines forming ridge on lower margin, scattered granules on convex outer surface, dense granules on upper margin, lower surface flat and mostly smooth. Cheliped ischium triangular, small, surface covered with tubercles, with two spines near articulation with merus. Non-cheliped appendages such as merus appear long; rest of these appendages not preserved.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFAAFF8D11C7CFF7AEE3F994.taxon	discussion	REMARKS Specimens from the early Danian of Mussel Creek were previously ascribed to C. grayi (Feldmann et al. 2014; Martínez-Díaz et al. 2016). A restudy of the type and new specimens of C. grayi from the Eocene of Alabama and additional specimens from Mussel Creek render this hypothesis untenable. Differences include a proportionally narrower rostrum for C. grayi (Figs 12 A, F; 13 B; 15 F, G; Table 1), a narrower median ridge with fewer tubercles (Figs 14; 17), an apparently less tubercular propodus compared to C. nicksabani n. sp. (Figs 14 D; 18 J), and a less tubercular sternite 4. Costacopluma nicksabani n. sp. differs from all other congenerics as well, compared alphabetically below, using the papers in which those species were first described and other papers as needed. Costacopluma australis has an overall similar outline, but the rostrum is protruding less prominently relative to the outer orbital spine than in the new species and the anteriormost transverse ridge appears to be concave forward (Feldmann et al. 1995: fig. 16) rather than sinuous. Costacopluma bifida has an anterior ridge said to be ‘ interrupted’ medially (Collins et al. 1994: 30), which is not the case in C. nicksabani n. sp. Moreover, this ridge is mentioned to not reach the lateral margin, but it does in the new species. Costacopluma bishopi has much broader transverse ridges (Vega & Feldmann 1992: fig. 4). Costacopluma binodosa does not have the front preserved, limiting the number of characters to compare to, but this species has somewhat more prominent nodes just anterior to the posterolateral margins (Collins & Wienberg Rasmussen 1992: fig. 23). Moreover, this species has a posterior portion of the cardiac region that is less raised based on a cast and photos of the type specimen made by AAK. Costacopluma maroccana has a more ovate outline resulting from more rounded lateral margins (Ossó-Morales et al. 2010: fig. 7; ALMNH: Paleo: 20599). Costacopluma mexicana has much broader transverse ridges (holotype in Luque et al. 2017: fig. 13 F). Costacopluma mamethioupamei exhibits narrower transverse ridges (Hyžný et al. 2016: fig. 5). Costacopluma nordestina exhibits a more rounded posterior margin, the lateral margins are more rounded, and the median ridge displays more tubercles (Feldmann & Martins-Neto 1995: fig. 1; Luque et al. 2017: fig. 5 G, H). Costacopluma salamanca is close in terms of ridges and their tubercles, but it is rounder anteriorly so that the fronto-orbital margin takes up a lower proportion of the maximum width (c. 63 % vs c. 70 % for C. nicksabani n. sp.), and the rostrum appears smaller (see Feldmann et al. 1997: fig. 3.2). Costacopluma senegalensis has much more rounded lateral margins (Gorodiski & Rémy 1959: pl. 19.1). Costacopluma squiresi exhibits a much more pronounced depression between the mesogastric and cardiac regions and the tubercles on the transverse ridges are smaller than in C. nicksabani n. sp. (Nyborg et al. 2009: fig. 2). Costacopluma texana is morphologically, geographically (Texas, United States), and stratigraphically (late Danian instead of early Danian) close to C. nicksabani n. sp., so a more detailed comparison is warranted. The median ridge is wider and flatter in C. texana, and the anterior and posterior ridges are flatter topped too. Moreover, C. texana has a significantly higher length-width ratio (Mann-Whitney p = 0.0005; Figs 15 - 18; Table 1), appears to exhibit a thicker upper orbital rim (Fig. 15 G, I vs Fig. 16 D, G; 17 B), has an oval-shaped oviduct rather than subcircular in C. nicksabani n. sp. (Fig. 16 K vs Fig. 17 M), the transverse ridges on sternites 5 - 6 are taller in at least females, the outer lateral margins of sternite 4 appear more flared up on average, and the press button on males is larger (Fig. 16 L vs Fig. 18 N). We did not observe obvious ontogenetic variation, perhaps because of the limited size range of specimens. Sexual dimorphism is not observed on the dorsal carapace, but it is evident on the ventral side (wider female pleon and other characters, see description). Intraspecific variation is limited despite the high number of specimens. For lesser preserved specimens with cuticle, the tubercles on the transverse ridges are less obvious. Carapace ornamentation is difficult to discern on internal molds (ALMN-H: Paleo: 21497 A, 1 specimen of UF 235569). The sediment surrounding Mussel Creek specimens varies from tan to dark gray and from friable to fully lithified. This observation may indicate differing taphonomic conditions. The gonopods preserved in three specimens of Costacopluma nicksabani n. sp. (ALMNH: Paleo: 21457, MMNS IP- 7940.1, UF 303806; Fig. 16 I, M) resemble those in extant retroplumids (de Saint Laurent 1989). The preservation of gonopods in fossil brachyurans is uncommon (e. g., Karasawa & Schweitzer 2006: 42; Garassino et al. 2013: 356), and they had not been recognized within Costacopluma and fossil Retroplumidae until this paper. These small pleonal appendages, often taxonomically important for extant crabs, are less calcified than walking appendages and claws and tend to be covered by the pleon within the sternopleonal cavity. Fossil brachyuran species with these structures have been more frequently recognized over the last decade, mostly in specimens that have the pleonal somites incompletely preserved exposing structures underneath (Smirnov 1929; Secrétan 1975; Karasawa & Kato 2001, 2019; Guinot & Breton 2006; Karasawa & Schweitzer 2006; Artal et al. 2008; Feldmann et al. 2011; Schweitzer & Feldmann 2015; Luque et al. 2018, 2019; Pereyra et al. 2019; Lima et al. 2020; Pereyra & Verde 2020; Hyžný et al. 2022; Kovalchuk et al. 2023). The preservation of delicate tips of gonopods herein is even rarer.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFACFFB2133DCDB6AC29F975.taxon	description	(Fig. 19)	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFACFFB2133DCDB6AC29F975.taxon	materials_examined	MATERIAL EXAMINED. — United States • 1 specimen; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); ALMNH: Paleo: 21482 (carapace) • 51 specimens; idem; ALMNH: Paleo: 21497 (51 carapaces / venters) • 1 specimen; idem; ALMNH: Paleo: 21505 (fixed finger) • 2 specimens; idem; ALMNH: Paleo: 21506 (fixed fingers) • 1 specimen; idem; MMNS IP- 7256.1 (fixed finger) • 1 specimen; idem; UF 303867 (fixed finger) • 1 specimen; idem; UF 303870 (fixed finger) • 1 specimen; idem; ALMNH: Paleo: 21507 (dactylus) • 4 specimens; idem; ALMNH: Paleo: 21508 (dactyli) • 1 specimen; idem; MMNS IP- 7256.2 (dactylus) • 1 specimen; idem; UF 303868 (dactylus) • 1 specimen; idem; UF 303869 (dactylus) • 1 specimen; idem; UF 303871 (dactylus) • 1 specimen; idem; UF 303872 (dactylus).	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFACFFB2133DCDB6AC29F975.taxon	description	MEASUREMENTS. — Maximum carapace width (mm): ALMN-H: Paleo: 21482: 24.6 DESCRIPTION Preserved carapace c. 24.6 mm wide without anterolateral projections, weakly vaulted transversely, moderately vaulted longitudinally. Fronto-orbital width c. 55 % of maximum width. Anterolateral margin with bases of four projections. Carapace with five large protuberances, one marking base of mesogastric region, two adjacent to anterior part of mesogastric region, and two lateral to cervical groove at level of mesogastric region base. Transverse row of small bumps anterolaterally of posteriormost set of protuberances. On cuticle, tubercles on protuberances and in front of anteriormost protuberances. Pit present in front of each side of posterior part of mesogastric region. Flanks steep. Preserved pterygostome appears subtriangular. Sternite 3 wider than long, separated from sternite 4 by a concave groove. Sternite 4 intersected by narrow sternopleonal cavity, both sides appear square-shaped. Coxa and basis of pereiopod 1, and parts of maxilliped 3 preserved. Sternum and appendages covered by tubercles, except for grooves and sternopleonal cavity. Rostrum, posterior carapace, most of ventral side, pleon, and appendages missing. Fixed finger robust; curved inward; with row of oval tubercles, variably sized, diminishing in size to tip on average; outer and inner lateral sides with row of pits. Dactylus curved; with strong tubercle on outer side of occlusal surface near base, followed by smaller, similar-sized tubercles toward tip.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FFACFFB2133DCDB6AC29F975.taxon	discussion	REMARKS The single carapace lacks the posterior portion, the frontal region including the orbital structure and the rostrum, and the projections on the anterolateral margins. The preserved characters fit those of Palaeoxanthopsidae (e. g., Schweitzer 2003; Schweitzer et al. 2018 a, 2025; Vega et al. 2018), including the location of the spherical swellings on the carapace and the anterolateral margins with bases of projections. Specimens of the Maastrichtian genera Palaeoxanthopsis Beurlen, 1958, and Parazanthopsis Vega, Feldmann, García-Barrera, Filkorn, Pimentel & Avendano, 2001, are morphologically close to the single, incomplete carapace specimen herein. The collection of more complete carapaces is necessary for identification beyond the family level. We also found various fingers attributable to Palaeoxanthopsidae. Both fixed fingers and dactyli conform well to those seen in Palaeoxanthopsidae such as Paraverrucoides alabamensis (Rathbun, 1935 a) from the upper Danian Porters Creek Formation of Alabama (GSA-I 21006 and GSA-I 21010) and Lobulata lobulata (Feldmann, Casadio, Chirino-Galvez & Aguirre-Urreta, 1995), from the Maastrichtian-Danian of Argentina (their fig. 7.6). It is very likely that these isolated fingers belong to the same species as the carapace, but associated chelipeds with a carapace are needed for verification.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF92FFB01338CBD3AE67FDA9.taxon	description	urn: lsid: zoobank. org: act: C 230 B 4 E 9 - 59 C 4 - 4322 - 9057 - 5513 F 4722 A 93	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF92FFB01338CBD3AE67FDA9.taxon	type_taxon	TYPE SPECIES. — Stevea martini Feldmann, Schweitzer & Portell, 2014, by present designation.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF92FFB01338CBD3AE67FDA9.taxon	etymology	ETYMOLOGY. — Ala - refers to Alabama and - hexapus refers to the type genus of Hexapodidae. Gender: masculine.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF92FFB01338CBD3AE67FDA9.taxon	diagnosis	DIAGNOSIS. — As for the type species.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF92FFB01338CBD3AE67FDA9.taxon	discussion	REMARKS Stevea martini was ascribed to Stevea based on a limited number of specimens then available without male and female pleons. Two additional specimens collected since 2014 with male and female pleons preserved suggest assignment to this genus is not tenable. Specifically, the female pleon from the only specimen of Stevea williamsi, the type and sole extant species of Stevea, was demonstrated to be narrow and have somites 2 - 6 fused (Guinot et al. 2010), whereas the female individual of Alahexapus martini n. comb. has proportionally wider pleonal somites 4 - 6 and these somites are unfused. Additional differences include the anterolateral borders passing below the outer orbital angle rather than joining the outer orbital angle as in A. martini n. comb., the rostrum has a concave border rather than a straight border as in A. martini n. comb., and the rostrum is widening distally rather than being straight laterally (UF 254042). The degree of fusion of pleonal somites and the pleonal width are considered important characters distinguishing between genera among extant hexapodids (Rahayu & Ng 2014). Other characters frequently used in that paper for genus diagnoses are carapace length-width ratios, cuticle ornamentation, groove development on the carapace, anterolateral margin shape, eye size, maxilliped morphology, ornamentation including stridulatory striae on the pterygostome, cheliped morphology, the degree of sternite and somite fusion, the shape of the pleon, and the shape and reach of the sternopleonal cavity. Many of the same characters are used to define genera present in the fossil record when preserved, but also other characters related to the carapace have been used including the widest point of the carapace, the frontal margin morphology and relative dimensions, and the orbital cavity size and shape (e. g., De Angeli et al. 2010; Schweitzer et al. 2022). Key differences between Alahexapus n. gen. and exclusively fossil genera exist. Bellhexapus is widest at the posterior margin, male somite 6 is longer, and male somites 3 - 5 are not fused (De Angeli et al. 2010: figs 2, 3). In Eohexapus, the orbits are circular rather than oval and the dorsal carapace is smooth rather than showing some grooves (De Angeli et al. 2010: figs 4 - 6). Eurohexapus exhibits a carapace about as long as wide rather than wider than long, its fronto-orbital width is greater (c. 65 % of maximum width vs 50 % for Alahexapus n. gen.), and male somites 2 - 6 are fused (De Angeli et al. 2010: figs 7 - 9). Goniocypoda has a relatively wide fronto-orbital width (c. 65 % of maximum width vs c. 50 % for Alahexapus n. gen.) (Schweitzer & Feldmann 2001: 335). For Headonipus, the “ grooves curving from the base of the cardiac region to the middle of the coxigeal incisions isolate elongated intestinal lobes ” (Quayle & Collins 2012: 40), are not observed in Alahexapus n. gen. Moreover, the posteriormost portion of the carapace of Headonipus appears much more depressed and the orbits are subcircular rather than oval (Quayle & Collins 2012: pl. 3.9 - 3.10; Schweitzer et al. 2022: fig. 7.5). For Holthuisea, carapace grooves are absent and male somites 3 - 6 are fused rather than somites 3 - 5 only (Guinot et al. 2010: figs 2 - 4). Lucahexapus has a proportionally greater fronto-orbital width (c. 67 % of maximum carapace width vs c. 50 %) and the cervical groove is much wider (De Angeli & Caporiondo 2022: figs 2.5, 3.5). For Palaeopinnixa, the carapace is widest just anterior to posterolateral reentrants (e. g., Hyžný & Artal 2018; Schweitzer et al. 2022; Gustafson 2023), but Alahexapus n. gen. is widest about mid-length and does not widen toward the posterior carapace. Moreover, somites 5 - 6 in females are fused for the type species P. rathbunae and this species does not exhibit stridulating apparatus / striae on the pterygostome (Schweitzer et al. 2000: 57). Rodneyellus lacks a U-shaped cervical groove and has a lower ratio of fronto-orbital width of maximum carapace width (0.37 vs 0.50). Key differences also exist with extant genera other than Stevea as discussed above, primarily using diagnoses in Manning & Holthuis (1981), Guinot (2006), and Rahayu & Ng (2014). Hexalaughlia exhibits a pterygostome without a row of stridulatory striae, and male somite 6 is much longer. Hexapinus has a carapace widening posteriorly, the carapace regions are not demarcated except for a poorly defined cardiac region, the orbits are much smaller, and male somite 6 is longer. For Hexaplax, the carapace regions are more indistinct, the orbits are larger and are subcircular rather than oval. For Hexapus, the carapace regions are less distinct, and the orbits are much smaller. Lambdophallus bears much smaller orbits and exhibits a male transverse sternal groove extending laterally from the sternopleonal cavity not seen in Alahexapus n. gen. Latohexapus has much more distinct carapace regions and its carapace widens posteriorly. Mariaplax has a carapace widening posteriorly, smaller orbits, and a much shorter male telson. Paeduma exhibits a much longer male somite 6 and carapace grooves are absent to very faint. Parahexapus bears a much longer male somite 6 that is narrower than male somites 3 - 5, and has orbits that are smaller. For Pseudohexapus, the pterygostome lacks a row of oblique striae. Rayapinus has a carapace without clear grooves, bears a relatively narrow female pleon, has female somites 1 - 5 fused, and has a male telson almost as long as somite 6. Spiroplax exhibits a carapace that is widening posteriorly, and has a much broader male pleon with a triangular telson. For Thaumastoplax, the pterygostome lacks a row of oblique striae, the orbits are smaller and circular, and the carapace regions are indistinct. Theoxapus has much smaller orbits and a proportionally longer male somite 6. Tritoplax has a male telson with a triangular tip, a male pleonal somite 6 that is divided longitudinally, and apparently smaller orbits. As none of the diagnoses of fossil and extant genera match the species under study, we erect Alahexapus n. gen. It is possible additional fossil species may belong to the new genus. For example, Palaeopinnixa rocaensis (Feldmann, Casadío, Chirino-Gálvez & Aguirre-Urreta, 1995), from the Danian of southern Argentina does not widen toward to posterior carapace as for the genus diagnosis of Palaeopinnixa (Schweitzer & Feldmann 2001). The fronto-orbital width is similar (45 % of maximum width vs c. 50 % for Alahexapus n. gen.), the outline is similar, the flanks for both taxa are straight, the length-width ratio is similar (0.71 vs c. 0.67 for Alahexapus n. gen.) (Feldmann et al. 1995: figs 14, 15). Unfortunately, no cuticle is preserved nor any ventral characters, which hinders further evaluation.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF91FFB0135FC971AA81F9B5.taxon	description	(Fig. 20; Appendix 1 K, L)	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF91FFB0135FC971AA81F9B5.taxon	materials_examined	TYPE MATERIAL. — Holotype. United States • 1 specimen; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); UF 228988. Paratype. United States • 1 specimen; same as for the holotype; UF 235561. ADDITIONAL MATERIAL EXAMINED. — United States • 1 specimen; Alabama, Lowndes County, Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), ALMNH loc. 3; Clayton Formation, Pine Barren Member, lower middle NP 2 nannofossil zone; Paleocene (lower Danian); ALMNH: Paleo: 5915 • 1 specimen; idem; ALMNH: Paleo: 21464 • 1 specimen; idem; MMNS IP- 7939 • 1 specimen; idem; UF 254040 • 1 specimen; idem; UF 254041 • 1 specimen; idem; UF 254042 • 1 specimen; idem; UF 303801. TYPE HORIZON. — Pine Barren Member of the Clayton Formation, lower middle NP 2 nannofossil zone, lower Danian. TYPE LOCALITY. — ALMNH loc. 3: Mussel Creek roadcut (31 ° 58 ’ 17 ” N, 86 ° 42 ’ 15 ” W), Lowndes County, Alabama, United States.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF91FFB0135FC971AA81F9B5.taxon	diagnosis	DIAGNOSIS. — Carapace length-width ratio c. 0.67, widest about mid-length. Fronto-orbital width c. 50 % of maximum carapace width. Orbits of moderate size, oval-shaped. Cervical groove widely U-shaped but diverging, fairly distinct, diminishing near orbits. Branchiocardiac grooves weaker, defining cardiac region laterally. Cuticle of carapace with densely covered fine granules. Pterygostome exhibiting stridulating apparatus with c. 15 striae. Female pleon with unfused, much wider than long somites; triangular telson with rounded tip; with gentle axial keel; pitted cuticular surface. Sternopleonal cavity of female appears to reach distal portion of sternite 3. Male pleon narrow, generally narrowing distally; telson longer than wide with rounded tip; somite 6 slightly wider than long, appears unfused, hexagonal, with rimmed lateral margins; somites 3 - 5 appear fused but with distinct suture marking boundaries; with pitted cuticular surface. Sternopleonal cavity of male appears to reach distal portion of sternite 4.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF91FFB0135FC971AA81F9B5.taxon	description	MEASUREMENTS. — Maximum carapace width (mm): ALMNH: Paleo: 5915: 7.1, ALMNH: Paleo: 21464: 11.1. UF 228988: 11.1, UF 254041: 8.9, MMNS IP- 7939: 11.4. DESCRIPTION Referral is made to Feldmann et al. (2014: 142 - 143). Some additional and revised characters are noted in new specimens. Carapace length-width ratio c. 0.67. Fronto-orbital width c. 50 % of maximum carapace width. Sternites with tubercular and pitted cuticular surface; pleonal sternite 2 narrow; sternites 3 - 4 fused; sternite 4 with curved, anterolaterally directed spine separated by sulcus. Female pleon with unfused, much wider than long somites; triangular telson with rounded tip; maximum width pleon c. 30 % of maximum carapace width; with gentle axial keel; pitted cuticular surface. Female pleonal somites 1 - 3 not preserved. Sternopleonal cavity of female appears to reach distal portion of sternite 3; with small press button on sternite 5 on upper part of slope near sternite 4; with subcircular oviduct on sternite 6, adjacent to base of sternopleonal cavity. Male pleon narrow, generally narrowing distally; telson longer than wide with rounded tip; somite 6 slightly wider than long, appears unfused, hexagonal, with rimmed lateral margins; somites 3 - 5 appear fused but with distinct line marking boundaries; with pitted cuticular surface. Sternopleonal cavity of male appears to reach distal portion of sternite 4. Third maxilliped partly preserved, with elongated exopod; boot-shaped, tubercular ischium, and about equally wide and long, rounded merus. Appendages not preserved.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
F77987B8FF91FFB0135FC971AA81F9B5.taxon	discussion	REMARKS This species is rare with only nine individuals reported herein after c. 15 years of collecting. This rarity is not primarily caused by the small size of the specimens, making them potentially more difficult to find, because many small specimens of other species were found (see above). Recently, Schweitzer (2024) ascribed four specimens to Stevea martini from a site near Streetman, Freestone County, Texas, United States, originating from the upper Danian-Selandian Wills Point Formation (see Armstrong et al. 2009, for age). However, the tubercles on the dorsal carapace are coarser on average and more uniform in the Texan specimens based on all available specimens; sternite 4 has a wider, hexagonal-shaped extension as preserved rather than anterolaterally directed, curved spines as in A. martini n. comb. (compare Schweitzer 2024: fig. 3.2 vs Fig. 20 E); and the pterygostome does not appear to bear the stridulating apparatus (Schweitzer 2024: fig. 3.6) characteristic for A. martini n. comb. (Fig. 20 L; Feldmann et al. 2014: pl. 3.2) though differential preservation may play a role here. Thus, the specimens from Texas may represent a different hexapodid species warranting further study.	en	Klompmaker, Adiël A., Martin, P. George, Hyžný, Matúš, Bowman, Andrew R., Phillips, George E., Portell, Roger W. (2025): Systematics, biodiversity, and paleoecology of an early Danian decapod crustacean assemblage from Alabama, United States. Geodiversitas 47 (13): 577-622, DOI: 10.5252/geodiversitas2024v47a13, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/geodiversitas2025v47a13.pdf
