taxonID	type	description	language	source
03D1E37CFF9BFFBA479ECFF3FE20F857.taxon	diagnosis	Diagnosis The diagnosis of this tribe is slightly modified from Wittmann et al. (2014) due to certain spine-like cuticle structures of the telson being now interpreted as laminae (see ‘ Methods’ and species descriptions below): Antennal scale setose all around (exceptionally with blunt spine on outer margin) and with short apical segment; carpopropodus of thoracic endopod 6 with 1 – 3 segments; two pairs of well-developed oostegites, rudimentary oostegite on thoracic endopod 6; pleopods rudimentary in both sexes, except male pleopod 4 and to a minor extent also pleopod 3; third male pleopod uniramous, unsegmented, mostly rudimentary as in females or reduced to small endopod fused with sympod; exopod of fourth male pleopod with total of 1 – 2 modified setae (1 – 2 on apical segment, 0 – 1 on subapical segment); uropods without spines; telson shorter than ultimate pleonite, terminally entire or with apical cleft, lateral margins bare or furnished with spines or laminae; spines (if present) on lateral margins arranged in continuous series, not arranged in groups of large spines with smaller spines in between; telson always devoid of setae.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9CFFBC443ECB77FB9BFCBB.taxon	type_taxon	Type species Macromysis gracilis Dana, 1852, currently acknowledged in revised combination as Mysidium gracil e (Dana, 1852).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9CFFBC443ECB77FB9BFCBB.taxon	diagnosis	Diagnosis Compiled with the reservation that not every one of the following characters is known in Mysidium iliffei Băcescu, 1991 (see Discussion): Anisomysini with eyes normal, eyestalks and cornea well developed. Antennular trunk terminally with the usual two flagella in both sexes, no accessory flagellum developed. Appendix masculina large, setose. Antennal scale lanceolate, without spines, but setose all around, with small terminal segment. Mandibles normal, palp three-segmented, cutting edges with well-developed pars incisiva, lacinia mobilis and pars molaris. Distal segment of maxillary palp with setae, but without denticles. Thoracopods essentially normal, endopods with 2 - or three-segmented carpopropodus. All pleopods of females and pleopods 1 – 3, 5 of males are vestigial, setose, uniramous, unsegmented. Male pleopod 3 larger than pleopods 1 – 2, 5. Male pleopod 4 even longer, modified, with distinct sympod, unsegmented endopod and 3 - or 4 - segmented, slender exopod. Terminal two segments of exopod each bearing a large modified seta, remaining segments usually without setae, at most with one small seta on the basal segment. Uropods setose all around, without spines; exopods longer than endopods. Telson longer than broad, with entire or incised terminal margin; with spines and laminae on distal half.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9CFFBC443ECB77FB9BFCBB.taxon	etymology	Etymology Derivation and gender of Mysidia and Mysidium not stated by Dana (1850, 1852). Neutral gender of Mysidium implicitly fixed by Czerniavsky (1887: 85) upon proposing the revised combination Mysidium gracile (Dana, 1852).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9DFFBC4453C953FC30FAB6.taxon	diagnosis	Diagnosis Subdivision of the genus Mysidium Dana, 1852, characterized by three-segmented carpopropodus of third thoracic endopod. Merus of this endopod with non-serrated setae exclusively, with the reservation that this feature is unknown in M. rickettsi Harrison & Bowman, 1987. Third male pleopod with medial widening at 40 – 60 % distance from basis. Sympod of fourth male pleopod without setae on rostral face. Its exopod four-segmented; the two proximal segments without setae; the two distal segments each with one unbranched modified seta. Telson entire, or at most with a rounded, shallow indentation.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9DFFBC4453C953FC30FAB6.taxon	distribution	Distribution Littoral and sublittoral waters of Atlantic and Pacific coasts of subtropical to tropical America (32 ° N to 24 ° S), including Caribbean, Gulf of Mexico and Gulf of California.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9DFFB14446CF36FDB1FBA0.taxon	description	Fig. 1	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9DFFB14446CF36FDB1FBA0.taxon	materials_examined	Type material Not examined. Other material examined BONAIRE • 7 ♀♀ ad. bl 4.4 – 5.2 mm, 21 ♂♂ ad. bl 3.4 – 5.1 mm, 1 subad.; # B 11; ZMH K- 55262 • 1 ♂ ad. bl 4.6 mm; # B 12; MINGA MYS 439. CURAÇAO • 1 ♂ ad. bl 5.6 mm, 6 subad.; # C 7; MINGA MYS 434. SE-BRAZIL • 19 ♀♀ ad. bl 4.8 – 6.3 mm, 15 ♂♂ ad. bl 5.2 – 6.6 mm, 13 subad.; # F 13; NHMW 26482. Type locality (Sub) tropical SW-Atlantic, harbour of Rio de Janeiro (Dana 1852), about 22.90 ° S, 43.17 ° W. The present sample off Cabo Frio is at about 145 km east along the shoreline from this harbour.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9DFFB14446CF36FDB1FBA0.taxon	discussion	Revised definition All features as diagnosed for the genus and its subgenus Mysidium Dana, 1852. Cornea globose in lateral view, calotte-shaped in dorsal view, with diameter 1.7 – 3.2 times as long as terminal segment of antennular trunk. Eyestalks smooth. Rostrum short, triangular, apically rounded to obtusely pointed, not extending beyond basis of eyestalks. Antero-lateral edges of carapace rounded. Only males with anterior margin of antennular trunk dorsally with rounded, shield-like, mediodistal extension (Fig. 1 A – B); plumose seta at anterior margin of this extension showing 0.9 – 1.4 times extension length; longitudinal series of 6 – 8 shorter (partly minute) setae all over this extension plus a short proximal stretch. Appendix masculina bilobate, 1.6 – 2.7 times as long as terminal segment of antennular trunk. Length of antennal scale 4 – 6 times maximum width; scale clearly reaching beyond antennular trunk. Median segment of mandibular palp with setae on both margins. About evenly rounded hump on the outer face of the distal segment of the maxillula. Carpopropodus of first to eighth thoracic endopods with 2, 2, 3, 3, 3, 3, 3 – 2, and 2 – 3 segments, respectively. Basal segment occupies half total length of carpopropodus of endopod 3. Pleopod 1 rod-like to indistinctly bilobate in both sexes. Sympod of pleopod 4 with endite missing or reduced to weak medial hump. Basal segment occupies 56 – 69 % total length of exopod. Endopod reduced to lobe with 12 – 18 % sympod length; apically with one long seta and more proximally additional 4 – 7 shorter, barbed setae. Endopod of uropods 0.6 – 0.8 times length of exopod. Telson subrectangular, length 1.4 – 2.0 times maximum width near basis; lateral margins slightly tapering or parallel. Proximal 46 – 64 % of lateral margins smooth, distal portion of each margin with dense, continuous series of 11 – 15 acute spines. Terminal margin concave, densely furnished with 15 – 21 apically blunt laminae.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9DFFB14446CF36FDB1FBA0.taxon	description	Descriptive notes Adult females of present material with 4.4 – 6.3 mm (n = 26) body length, males 3.4 – 6.6 mm (n = 38). Antennular trunk extends – 5 % up to + 23 % its length beyond (artificially aligned) eyes (Fig. 1 A). Antennal scale 1.3 – 1.8 times trunk. Sympod of antenna produced into spiniform extension on outer distal corner. Thoracic endopod 8 (when stretched) reaching backwards at most to the middle of pleonite 4 and forwards to mandibles; its carpopropodus 83 – 94 % length of merus or 29 – 53 % of telson. Pleonites 1 – 5 are 0.5 – 0.7, 0.6 – 0.8, 0.6 – 0.8, 0.5 – 0.7 or 0.5 – 0.8 times as long as pleonite 6, respectively. Sizes increase from pleopods 1 to 4, while pleopod 5 ranges between pleopods 1 and 2 in both sexes; amplitude of this variation much stronger in males than females. Pleopod 1 (Fig. 1 D) stouter compared to remaining pleopods. Pleopods 2 – 5 of females and 2, 5 of males are essentially rod-like. Pleopods 1 – 3 with a ventrolaterally directed fan of plumose setae in both sexes. Setae forming the fan of pleopod 1 larger compared to those of pleopods 2 – 5 in females and 2, 3, 5 in males. Male pleopod 4 (Fig. 1 F) very long, exopod reaching at most to basal third of telson; its subapical seta up to the apex of telson. Endopod with apical seta 2.2 – 4.6 times endopod length. Sympod with field of scales on its medial hump, or in analogous position upon missing hump. Scutellum paracaudale triangular with acute apex; upper margin weakly convex, lower margin concave or S-shaped. Uropodal endopod 1.0 – 1.4 times, exopod 1.3 – 1.9 times as long as pleonite 6. Exopod extends 0.2 – 0.4 times its length beyond endopod, or 0.5 – 0.7 times beyond telson; endopod 0.2 – 0.6 times its length beyond telson. Telson (Fig. 1 G) length 0.4 – 0.6 times uropodal exopod, 0.5 – 0.7 times endopod and 0.7 – 0.8 times pleonite 6. Statoliths composed of fluorite. Structure of foregut and nauplioid larvae essentially as in M. triangulare sp. nov. (Fig. 8 A – F, N – M).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF9DFFB14446CF36FDB1FBA0.taxon	distribution	Distribution and habitat Widely distributed, mainly in sublittoral, also in littoral waters of the West Atlantic in the range of 32 ° N to 24 ° S (Bermuda to coast near São Sebastião, Brazil), including the Caribbean (Price & Heard 2004; Ortiz et al. 2017 b). Masses were recorded from the surface zone of a sandy beach in Venezuela (Esteves-Astudillo et al. 2017). Distribution mostly euhaline, also found in the metahaline reach of a lagoon by Zoppi de Roa et al. (1989). The species forms swarms close to the bottom in a variety of coral reef habitats (Emery 1968; Brattegard 1969). Swarms may hover near the sea urchin Diadema antillarum Philippi, 1845, where they withdraw to the safety of the interspaces between the spines when threatened (Randall et al. 1964). They may also crowd in the nest caves of pomacentrid fish when a predator approaches (Emery 1968). The swarms disperse during the night and the individuals show homing behaviour by regrouping at the same location in the morning (Twining et al. 2000). Present records from Curaçao, Bonaire, and SE-Brazil; in swarms hovering during the daytime over the sea floor at a depth of 3 – 35 m, also found between corals.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF90FFB24785CE21FED5FDA3.taxon	description	Fig. 2	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF90FFB24785CE21FED5FDA3.taxon	materials_examined	Type material Not examined. Other material examined CURAÇAO • 18 ♀♀ ad. bl 4.9 – 6.3 mm, 27 ♂♂ ad. 4.1 – 5.5 mm, 15 subad.; # C 6; NHMW 26481 • 6 subad. bl 2.8 – 4.1 mm; # C 7; MINGA MYS 437 • 51 ♀♀ ad. bl 3.8 – 5.9 mm, 32 ♂♂ ad. bl 4.0 – 5.1 mm, 5 subad.; # C 9; MINGA MYS 437 • 88 ♀♀ ad. bl 3.8 – 5.9 mm, 25 ♂♂ ad. bl 3.2 – 5.2 mm, 20 subad.; # C 10; ZMH K- 55261. SE-BRAZIL • 6 ♀♀ ad. bl 4.8 – 6.0 mm, 33 ♂♂ ad. bl 4.3 – 6.1 mm, 6 subad.; # F 13; ZMH K- 55265. Type locality Tropical NW-Atlantic, Cruz Bay, St. John, Virgin Islands (W. M. Tattersall 1951). Coordinates estimated by present authors as 18.3322 ° N, 64.7967 ° W.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF90FFB24785CE21FED5FDA3.taxon	discussion	Revised definition All features diagnosed above for genus and subgenus Mysidium Dana, 1852. Cornea globose in lateral view; calotte-shaped in dorsal view, with diameter 1.6 – 2.4 times as long as terminal segment of antennular trunk. Eyestalks smooth. Rostrum broadly triangular, apically bluntly pointed to well rounded, not extending beyond basis of eyestalks. Antero-lateral edges of carapace rounded. Only males with anterior margin of antennular trunk dorsally with rounded, shield-like, mediodistal extension (Fig. 2 A – B); longitudinal series of 4 – 6 setae all over this extension plus a short proximal stretch. The largest seta 0.3 – 0.5 times extension length. Appendix masculina bilobate, all along inner margins fringed by large setae; its length 1.1 – 2.5 times terminal segment of antennular trunk. Length of antennal scale 4 – 5 times maximum width; scale reaching well beyond antennular trunk. Median segment of mandibular palp with setae on both margins. Weak, about evenly rounded hump on outer face of distal segment of the maxillula. Carpopropodus of first to eighth thoracic endopods with 2, 2, 3, 3, 3, 3 – 2, 3 – 2, and 2 – 3 segments, respectively. Basal segment occupies half total length of carpopropodus of endopod 3. Pleopod 1 representing a stout, bilobate plate in both sexes. Sympod of male pleopod 4 with endite reduced to weak medial hump or missing. Basal segment of exopod measures 49 – 63 % total length. Endopod reduced to setose lobe with 11 – 24 % sympod length; apically with 1 – 2 setae and more proximally additional 4 – 6 barbed setae, total of 5 – 7 setae. Endopod of uropods 0.7 times as long as exopod. Telson spatulate, caudally gradually narrowing; length 1.5 – 1.8 times maximum width near basis; latero-terminal corners rounded; terminal margin traverse to convex. Proximal 52 – 62 % of lateral margins smooth, distal portion of each margin with dense, continuous series of 13 – 25 acute spines. This series extending up to the latero-terminal corner. Terminal margin lined by 12 – 20 densely set, acute (Fig. 2 G) or blunt (Fig. 2 H) laminae. These laminae more slender compared to the neighboring lateroterminal spines.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF90FFB24785CE21FED5FDA3.taxon	description	Descriptive notes Adult females of present material with 3.8 – 6.3 mm (n = 163) body length, males 3.2 – 6.1 mm (n = 117). Antennular trunk extends 9 – 57 % its length beyond (artificially aligned) eyes (Fig. 2 A). Antennal scale 1.3 – 1.5 times as long as trunk. Sympod of antenna produced into spiniform extension on outer distal corner. Thoracic endopod 8 (when stretched) reaching backwards at most to middle of pleonite 4 and forwards to mandibles; its carpopropodus 69 – 84 % as long as merus or 38 – 53 % times telson length. Pleonites 1 – 5 are 0.6 – 0.8, 0.6 – 0.7, 0.6 – 0.7, 0.5 – 0.6 or 0.6 – 0.7 times as long as pleonite 6, respectively. Sizes increase from pleopods 1 to 4, while pleopod 5 ranges between 1 and 2 in both sexes; amplitude of this variation much stronger in males than females. Pleopod 1 (Fig. 2 D) stouter compared to the remaining pleopods. Pleopods 2 – 5 of females and 2, 5 of males are essentially rod-like. Pleopods 1 – 3 with a ventro-laterally directed fan of plumose setae in both sexes. Setae forming the fan of pleopod 1 are larger compared to those of pleopods 2 – 5 in females and 2, 3, 5 in males. Male pleopod 4 (Fig. 2 F) reaching at most to basal third of telson, its subapical seta up to basal third of uropodal exopod. Sympod with field of scales on its medial hump, or in analogous position upon missing hump. Endopod with its larger apical seta 1.8 – 3.1 times endopod length. Scutellum paracaudale triangular with acute apex; upper margin convex to concave, lower margin straight to slightly convex or S-shaped. Uropodal endopod 1.1 – 1.2 times, exopod 1.6 – 1.8 times as long as pleonite 6. Exopod extends 0.2 – 0.4 times its length beyond endopod, or 0.6 – 0.7 times beyond telson; endopod 0.5 – 0.6 times its length beyond telson. Telson (Fig. 2 G – H) length 0.4 – 0.5 times uropodal exopod, 0.5 – 0.7 times endopod or 0.7 – 0.8 times pleonite 6. Statoliths composed of fluorite. Structure of foregut and nauplioid larvae essentially as in M. triangulare sp. nov. (Fig. 8 A – F, M – N).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF90FFB24785CE21FED5FDA3.taxon	distribution	Distribution and habitat Reported from euhaline coastal waters of Bermuda, Bahamas, Caribbean and Gulf of Mexico (Brattegard 1970, 1973; Ortiz et al. 2017 b). The present record from the Brazilian coast off Cabo Frio represents a strong extension of the known distribution to the south, yielding a total range from 32 ° N to 23 ° S along the coasts of the West Atlantic. According to Zoppi de Roa & Alonso (1997) these mysids form swarms close to the bottom of diverse coral reef and mangrove habitats, also found among spines of the sea urchin Diadema antillarum. The present data from Curaçao and SE-Brazil were recorded during the daytime at a depth of 0 – 35 m, on swarms mostly hovering around, between or above rock and coral blocks, also from the entrance area of a cave. Most surprising was sample C 9 (Table 1) from the water edge where the mysids showed a striking green body color upon swarming above algae at a depth of only 5 cm.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF93FFB44795C821FBE5FAF2.taxon	description	Fig. 3	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF93FFB44795C821FBE5FAF2.taxon	materials_examined	Type material examined Holotype CUBA • adult ♂, partly dissected, bl 4.5 mm; in front of Marine Research Center, Habana, at the entrance of a small underwater cave; 23.1334 ° N, 82.3334 ° W; 13 m; 13 May 1983; Manolo Ortiz leg.; Mihai Băcescu det.; MINGA 49346 / 601 a. Other material examined CURAÇAO • 104 ♀♀ ad. bl 3.9 – 5.5 mm, 70 ♂♂ ad. bl 3.4 – 5.2 mm, 32 subad.; # C 3; NHMW 26478 • 2 ♀♀ ad. bl 3.6 – 4.1 mm; # C 4; ZMH K- 55257 • 383 ♀♀ ad. bl 4.2 – 5.8 mm, 96 ♂♂ ad. bl 3.1 – 5.9 mm, 15 subad.; # C 5; MINGA MYS 432 • 15 ♀♀ ad. bl 3.7 – 5.8 mm, 3 ♂♂ ad. bl 3.0 – 4.7 mm, 10 subad.; # C 8; ZMH K- 55259. BONAIRE • 20 ♀♀ ad. bl 3.2 – 4.4 mm, 5 ♂♂ ad. bl 3.3 – 4.0 mm, 10 subad.; # B 11; MINGA MYS 438. Type locality Miramar, La Habana, Cuba (Băcescu & Ortiz 1984), 23.1334 ° N, 82.3334 ° W.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF93FFB44795C821FBE5FAF2.taxon	discussion	Revised definition All features diagnosed above for genus and subgenus Mysidium Dana, 1852. Cornea large, globose to ellipsoidal in lateral view, calotte-shaped to crescent-like in dorsal view, with ‘ diameter’ 2.6 – 4.1 times as long as terminal segment of antennular trunk. Eyestalks smooth. Rostrum (sub) triangular, apically bluntly pointed to well rounded, not extending beyond basis of eyestalks. Antero-lateral edges of carapace rounded. Only males with anterior margin of antennular trunk dorsally with rounded, shield-like, mediodistal extension (Fig. 3 A – B); longitudinal series of 4 – 6 setae extending all over this extension plus a short proximal stretch. The largest seta 0.2 – 0.4 times extension length. Appendix masculina bilobate, all along inner margins fringed by large setae; its length 1.1 – 2.3 times terminal segment of antennular trunk. Length of antennal scale 4 – 6 times maximum width; scale reaching beyond antennular trunk. Median segment of mandibular palp with setae on both margins. Large, about evenly rounded hump on outer face of distal segment of maxillula. Carpopropodus with two segments in thoracic endopods 1 – 2, 8, versus three segments in endopods 3 – 7. Basal segment occupies half total length of carpopropodus of endopod 3. Pleopod 1 bilobate in both sexes. Sympod of male pleopod 4 with endite reduced to weak medial hump or missing. Basal segment of exopod occupies 54 – 61 % total length. Endopod reduced to lobe with 14 – 18 % sympod length; apically with one long seta and more proximally additional 4 – 6 shorter, barbed setae. Endopod of uropods 0.6 – 0.8 times as long as exopod. Telson subrectangular to trapezoid; length 1.6 – 2.1 times maximum width near basis; its lateral margins slightly concave to almost straight; latero-terminal corners rounded; terminal margin traverse to convex. Proximal 48 – 73 % of lateral margins smooth, distal portion of each margin with dense, continuous series of 7 – 16 acute spines. This series extending up to the rounded, latero-terminal corner. Terminal margin lined by 12 – 20 densely set, apically blunt or weakly pointed laminae.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF93FFB44795C821FBE5FAF2.taxon	description	Descriptive notes Adult females of present material with 3.2 – 5.8 mm (n = 524) body length, males 3.0 – 5.9 mm (n = 174). Antennular trunk extends 0 – 20 % its length beyond (artificially aligned) eyes (Fig. 3 A). Antennal scale 1.1 – 1.4 times as long as trunk. Sympod of antenna produced into spiniform extension on outer distal corner. Thoracic endopod 8 (when stretched) reaching backwards at most to end of pleonite 4 and forwards to mandibles; its carpopropodus 60 – 83 % as long as merus or 26 – 45 % times as long as telson. Pleonites 1 – 5 are 0.5 – 0.6, 0.5 – 0.6, 0.5 – 0.7, 0.5 – 0.7 or 0.5 – 0.7 times as long as pleonite 6, respectively. Sizes increase from pleopods 1 to 4, while pleopod 5 ranges between 1 and 2 in both sexes; amplitude of this variation much stronger in males than females. Pleopods 1 and 3 stouter compared to remaining pleopods. Pleopods 2 – 5 of females and 2, 5 of males are essentially rod-like. Pleopods 1 – 3 with a ventrolaterally directed fan of plumose setae in both sexes. Setae forming the fan of pleopod 1 (Fig. 3 D) larger than those of pleopods 2 – 5 in females and 2, 3, 5 in males. Male pleopod 4 (Fig. 3 F) reaching at most to distal 4 / 5 of pleonite 6; its subapical seta up to end of telson. Endopod with apical seta 1.4 – 2.8 times endopod length. Sympod with field of scales on its weak medial hump, or in analogous position upon missing hump. Scutellum paracaudale triangular with acute apex; upper margin convex or S-shaped, lower margin straight to slightly convex or S-shaped. Uropodal endopod 1.1 times, exopod 1.4 – 1.6 times as long as pleonite 6. Exopod extends 0.3 – 0.4 times its length beyond endopod, or 0.4 – 0.6 times its length beyond telson; endopod 0.3 – 0.4 times its length beyond telson. Telson (Fig. 3 G) length 0.5 – 0.6 times as long as uropodal exopod, 0.6 – 0.7 times endopod and 0.7 – 0.8 times pleonite 6. Statoliths composed of fluorite. Structure of foregut and nauplioid larvae essentially as in M. triangulare sp. nov. (Fig. 8 A – F, M – N).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF93FFB44795C821FBE5FAF2.taxon	distribution	Distribution Euhaline coastal waters in the Gulf of Mexico, Bahamas, Cuba, Jamaica, Caribbean (Ortiz et al. 2017 b). The present records are the first for Bonaire and Curaçao, thus extending the known latitudinal range southward to 12 – 23 ° N. Most samples are from swarms between corals.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF95FFB647E1CFF1FB6AF998.taxon	description	Fig. 4	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF95FFB647E1CFF1FB6AF998.taxon	materials_examined	Type material examined Paratypes CUBA • 10 ♀♀ ad. bl 3.7 – 4.8 mm, 7 ♂♂ ad. bl 3.5 – 3.8 mm, 2 ♂♂ subad.; 10 m; Sep. 1983; Manolo Ortiz leg.; Mihai Băcescu det.; MINGA 49342 / 600. Type locality Miramar, La Habana, Cuba (Băcescu & Ortiz 1984), 23.1334 ° N, 82.3334 ° W.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF95FFB647E1CFF1FB6AF998.taxon	discussion	Revised definition All features diagnosed above for genus and subgenus Mysidium Dana, 1852. Cornea globose in lateral view, calotte-shaped in dorsal view, with diameter 1.9 – 2.9 times as long as terminal segment of antennular trunk. Eyestalks smooth. Rostrum (sub) triangular, with rounded to acute apex, rostrum not extending beyond basis of eyestalks. Antero-lateral edges of carapace rounded. Only males with anterior margin of antennular trunk dorsally with rounded, shield-like, mediodistal extension (Fig. 4 A – B) bearing a longitudinal series of 4 – 5 setae. The largest seta 0.1 – 0.3 times extension length. Appendix masculina bilobate, along inner margins fringed by large setae; its length 1.3 – 2.0 times terminal segment of antennular trunk. Length of antennal scale 4 – 5 times maximum width; scale reaching well beyond antennular trunk. Median segment of mandibular palp with setae on both margins. Large, moderately unevenly rounded hump on outer face of distal segment of the maxillula. Carpopropodus with two segments in thoracic endopods 1 – 2, 8, versus three segments in endopods 3 – 7. Basal segment occupies half total length of carpopropodus of endopod 3. Pleopod 1 minute, rod-like (Fig. 4 D) in both sexes, not considering the weak median widening at its vestigial endopodal portion. Sympod of male pleopod 4 with endite reduced to a weak medial hump or missing. Exopod with basal segment occupying 52 – 63 % total length. Endopod reduced to lobe with 13 – 17 % sympod length; apically with a long seta plus a minute seta and more proximally 2 – 4 additional small barbed setae. Endopod of uropods 0.7 – 0.8 times as long as exopod. Telson subrectangular, caudally narrowing by 30 – 54 %; length 1.5 – 1.8 times maximum width near basis; lateral margins slightly concave to almost straight; latero-terminal corners rounded; terminal margin slightly convex to traverse. Proximal 50 – 60 % of lateral margins smooth, distal portion of each margin with dense, continuous series of 8 – 12 acute spines. This series extending up to the rounded, latero-terminal corner. Terminal margin lined by 11 – 18 strong, apically blunt laminae; these last stouter compared to the neighboring latero-terminal spines.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF95FFB647E1CFF1FB6AF998.taxon	description	Descriptive notes Antennular trunk extends 0 – 30 % its length beyond (artificially aligned) eyes (Fig. 4 A). First to third segments occupy 40 – 43 %, 16 – 20 % or 39 – 44 % total length, respectively. Appendix masculina 0.5 – 0.7 times total trunk length. Antennal scale 1.2 – 1.4 times antennular trunk, its terminal segment occupying 12 – 19 % total length and bearing five plumose setae. Sympod of antenna produced into spiniform extension on outer distal corner. Thoracic endopod 8 (when stretched) reaching backwards at most to the middle of pleonite 4 and forwards to maxillula; its carpopropodus 62 – 69 % as long as merus or 0.3 – 0.5 times telson length. Pleonites 1 – 5 are 0.7 – 0.8, 0.6 – 0.8, 0.6 – 0.8, 0.5 – 0.6 or 0.5 – 0.6 times the length of pleonite 6, respectively. Both sexes with pleopods 1 – 3 bearing a ventro-laterally directed fan of plumose setae. Setae of pleopod 1 (Fig. 4 D) on average longer than those of pleopods 2, 3, 5 (Fig. 4 E). Male pleopod 4 (Fig. 4 F) reaching at most to middle of telson; its subapical seta up to ¾ as long as endopod of uropod. Endopod of male pleopod 4 with its apical seta 2.1 – 3.6 times endopod length. Sympod with field of scales on its medial hump, or in analogous position upon missing hump. Scutellum paracaudale triangular with acute apex; upper and lower margins weakly convex to concave. Uropodal endopod 1.0 – 1.5 times, exopod 1.3 – 1.8 times as long as pleonite 6. Exopod extends 0.2 – 0.3 times its length beyond endopod, or 0.5 – 0.7 times beyond telson; endopod 0.4 – 0.7 times its length beyond telson. Telson (Fig. 4 G) 0.4 – 0.5 times as long as exopod of uropods, 0.4 – 0.6 times endopod or 0.7 – 0.8 times pleonite 6. Statoliths composed of fluorite. Structure of foregut and nauplioid larvae essentially as in M. triangulare sp. nov. (Fig. 8 A – F, M – N).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF95FFB647E1CFF1FB6AF998.taxon	distribution	Distribution Marine coastal waters of the Gulf of Mexico, Cuba (Ortiz et al. 2017 b), 22 – 23 ° N.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF97FFAF478ECC3BFC66FC44.taxon	description	urn: lsid: zoobank. org: act: B 0 EB 7822 - 4 D 13 - 4 D 05 - 8 C 40 - 2 A 7 F 01297301 Figs 5 – 8	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF97FFAF478ECC3BFC66FC44.taxon	etymology	Etymology The species name is a Latin adjective with neutral ending, referring to the triangular terminal portion of the telson.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF97FFAF478ECC3BFC66FC44.taxon	materials_examined	Type material examined Holotype (by present designation) CURAÇAO • ♂ ad. bl 5.2 mm; sublittoral marine waters of Curaçao, Playa Lagun; 12.3181 ° N, 69.1511 ° S. # C 8; NHMW 26487. Paratypes (by present designation) CURAÇAO • 57 ♂♂ ad. bl 3.8 – 5.7 mm, 44 ♀♀ ad. bl 4.8 – 5.9 mm, 8 subad.; same locality data as for holotype; # C 8; MINGA MYS 436, NHMW 26488, ZMH K- 55260. Other material examined CURAÇAO • 2 ♀♀ ad. bl 5.3 – 5.5 mm, 3 ♂♂ ad. bl 4.0 – 4.2 mm; # C 3; MINGA MYS 430 • 1 ♀ subad. bl 3.5 mm; associated with swarm of M. integrum freely swimming in the entrance area of cave; # C 10.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF97FFAF478ECC3BFC66FC44.taxon	discussion	Definition All features diagnosed above for genus and subgenus Mysidium Dana, 1852. Cornea globose in lateral view; calotte-shaped in dorsal view, with diameter 1.7 – 2.5 times as long as terminal segment of antennular trunk. Eyestalks smooth. Rostrum triangular, apically pointed to well rounded, not extending beyond basis of eyestalks. Antero-lateral edges of carapace rounded. Only males with anterior margin of antennular trunk dorsally with rounded, shield-like, mediodistal extension (Fig. 5 A – B); longitudinal series of 6 – 10 setae extending all over this extension plus a short proximal stretch. The largest seta 0.1 – 0.3 times extension length. Appendix masculina bilobate, densely setose; its length 1.5 – 2.0 times terminal segment of antennular trunk. Length of antennal scale 5 – 7 times maximum width, scale reaching far beyond antennular trunk. Median segment of mandibular palp with setae on both margins. Almost evenly rounded hump on outer face of distal segment of maxillula. Carpopropodus two-segmented in thoracic endopods 1 – 2, 8, or three-segmented in endopods 3 – 7, except that endopods 6, 7 may be twosegmented in some females. Basal segment occupies 0.4 – 0.5 times total length of carpopropodus of endopod 3. Pleopod 1 representing a stout, bilobate plate in both sexes. Sympod of male pleopod 4 with endite reduced to a weak medial hump or missing. Exopod with basal segment occupying 56 – 63 % total length. Endopod reduced to lobe with 10 – 16 % sympod length; lobe apically with one long, barbed seta and more proximally with additional 4 – 6 shorter, barbed setae. Endopod of uropods 0.6 – 0.8 times as long as exopod. Telson spatulate, length 1.9 – 2.1 times maximum width near basis; median portion with concave lateral margins, terminal portion triangular with rounded tip. Proximal 52 – 64 % of lateral margins smooth; distal portion of each margin with continuous series of 5 – 11 acute spines, this series extending up to the corner with the triangular apical portion. Margin of the triangular portion densely furnished with a total of 21 – 24 strong, apically blunt laminae.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF97FFAF478ECC3BFC66FC44.taxon	description	Description BODY SIZE. Adult females 4.8 – 5.9 mm (n = 46), males 3.8 – 5.7 mm (n = 61). ANTENNAL APPENDAGES (Fig. 5 A – B, F – G). Antennular trunk extends 10 – 50 % its length beyond (artificially aligned) eyes. First to third segments occupy 46 – 57 %, 15 – 18 % or 28 – 36 % total trunk length, respectively. Trunk dorsally with forward directed small, setose lobes near terminal margin of each segment: two lobes from basal, one from median, and one from terminal segment (not counting the mediodistal extension of anterior margin in males). Appendix masculina 0.4 – 0.5 times total trunk length, antennal scale 1.1 – 1.5 times trunk. Sympod of antenna produced into spiniform extension on outer distal corner. Antennal scale with terminal segment occupying 13 – 24 % total length and bearing five plumose setae. MOUTH PARTS (Figs 5 H, J, 6 A – C). Mandibular palp without spines; terminal segment with strong, modified, bent seta at apex, and barbed setae along inner and outer margins. Median segment of palp with angular, medially directed dilatation, both its margins setose. Proximal segment normal, with smooth margins. Distal segment of maxillula terminally with strong spines, subterminally with one barbed seta; tip of endite of maxillula with apically modified setae (armed with stiff barbs) plus several shorter setae with normal, fine barbs. Maxilla with well-developed exopod, moderately large, two-segmented palp, and three apically setose endites. Exopod with maximum width in median portions; its outer margin all along with series of plumose setae. Basal segment of palp with three barbed setae. Apical segment about two times as long as basal segment. Length of apical segment 2.0 – 2.5 times maximum width, densely setose on terminal margin but lined by small hairs along more than basal half of inner margin. Apex of palp with two strong, modified setae bearing strong, spine-like barbs along distal third of their inner margin. FOREGUT (Fig. 8 A – F). Essentially as in M. antillarum sp. nov. (Fig. 11 A – E). As main differences from that species, M. triangulare sp. nov. shows less strongly serrated, apically pronged, large spines: on each lateral half there are two spines (Fig. 8 E) on posterior part of lateralia; and a longer one (Fig. 8 F) on dorso-lateral infolding; the latter inserting in more median position than in M. antillarum sp. nov. THORAX OF BOTH SEXES (Figs 5 C – D, 6 D – G, 7 A – C). Carapace (Fig. 5 C – E) posteriorly emarginate, with well-rounded latero-terminal lobes; cervical sulcus strong; roughly V-shaped group of 11 – 14 pores (Fig. 5 E) in front of cervical sulcus, transverse linear series of 13 – 18 pores (Fig. 5 D) in cardial position (above heart). Sternites smooth; a plumose seta accompanied by a shorter barbed seta on the joint between each sternite and the corresponding thoracopods (Fig. 6 D). Sizes of endopods and exopods increase from thoracopod 1 to 4 or 5 and decrease from 5 to 8. Basal plate of exopods 1 – 7 with large, well rounded latero-distal expansion (Figs 6 D, F, 7 A – B). Flagellum 8 - segmented in exopod 1 versus 9 - segmented in exopods 2 – 7. First endopod (Fig. 6 D) with well developed, setose endites from basis, ischium, merus. First thoracic epipod bilobate, with smooth margins, without seta. Endopods 1 – 2 with large dactylus and strong claw (Fig. 6 D – E). Dactylus of thoracic endopod 2 with 3 – 6 modified and several smooth setae, no spine-like setae; modified setae each with two dense rows of strong, acute barbs along their median to subterminal portions. Endopods 3 – 7 with less stout, well developed dactylus bearing a long, needle-like claw (Fig. 6 G); endopod 8 with seta-like claw (Fig. 7 C). Endopod 8 (when stretched) reaching backwards at most to end of pleonite 3 and forwards to maxillula; its carpopropodus measures 0.4 – 0.5 times telson length. THORACOPODS OF FEMALES (Figs 7 A, 8 G). Basal plate of exopod 8 with short to indistinct latero-distal expansion; its flagellum only 8 - segmented. Oostegites of thoracopods 7 – 8 densely fringed with setae, together forming a large brood chamber. Thoracopod 6 (Fig. 7 A) with rudimentary oostegite bearing 1 – 2 long setae at apex. These setae spinulose at least along their apical third. More such setae present in proximal portions of oostegite from thoracopod 7 (Fig. 8 G). THORACOPODS OF MALES AND PENIS (Fig. 7 B – C). Basal plate of exopod 8 with yet distinct latero-distal expansion; its flagellum 9 - segmented. Penes pear-shaped, apically widening; 0.9 – 1.0 times as long as merus of endopod 8. Penes apically bilobate, with row of 4 – 5 smooth, bent setae flanking the ejaculatory opening. Two additional, smaller, straight setae subapically on margin opposite to bent setae. PLEON (Figs 7 D – M, 8 H – L). Pleonites 1 – 5 are 0.6 – 0.7, 0.7 – 0.8, 0.7 – 0.9, 0.8 – 0.9 or 0.7 – 0.9 times as long as pleonite 6, respectively. Scutellum paracaudale (Fig. 8 H, J) triangular, apically pointed to narrowly rounded; margins weakly concave to convex. Uropodal endopod (Fig. 8 K) 1.0 – 1.3 times, exopod 1.4 – 1.7 times as long as pleonite 6. Length of exopod 7 – 9 times maximum width. Exopod extends 0.2 – 0.3 times its length beyond endopod or 0.5 – 0.6 times beyond telson; endopod 0.3 – 0.5 times its length beyond telson. Telson (Fig. 8 L) 0.5 – 0.6 times as long as exopod of uropods, 0.7 – 0.8 times endopod or 0.8 – 0.9 times pleonite 6. PLEOPODS OF FEMALES (Fig. 7 D – G). Pleopods 1 – 5 subequal in length. Pleopods 1 – 2 reduced to small bilobate plates, pleopods 3 – 5 to small, setose rods. Pleopods 1 – 4 with a ventro-laterally directed fan of plumose setae. Pleopod 1 with clearly the largest setae, although not as large as in males. PLEOPODS OF MALES (Fig. 7 H – M). Length increases from pleopod 1 to 4. Pleopod 5 is about the same length as pleopod 1, but less stout. Pleopods 1 – 3 with a ventro-laterally directed fan of plumose setae; pleopod 1 with the largest setae of that kind. Fourth pleopod reaching to terminal 50 – 80 % of pleonite 6; its subapical seta reaching up to apex of telson. Its four-segmented exopod with basal segment longest, second segment longer than third, third segment longer than fourth. Subterminal segment of exopod with a very long seta bearing dense series of minute bristles along its distal half; short terminal segment with comparatively large but shorter seta at tip, this seta with characteristic set of barbs (Fig. 7 L) along its distal half. Endopod with apical seta 2.0 – 2.8 times endopod length. Sympod with field of scales on its medial widening, or in analogous position upon missing widening. STATOLITHS. Composed of fluorite; shape ellipsoidal to spherical in dorsal view (Fig. 8 K); discoidal in lateral view, maximum diameter 89 – 107 µm, thickness 45 – 54 µm, measured in 10 adults. Tegmen moderately, though always distinctly convex; fundus weakly concave. Sagittal section very similar to that figured by Wittmann et al. (1993: fig. 6 P) for Heteromysis formosa S. I. Smith, 1873. Statolith formula 2 + 3 + 1 + (8 – 13) = 14 – 19. NAUPLIOID LARVAE (Fig. 8 M – N). Smooth cuticle all around, except for a pair of minute furcal processes and a number of minute setae on the blunt end of the abdomen.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF97FFAF478ECC3BFC66FC44.taxon	distribution	Distribution and habitat So far only known from euhaline, sublittoral waters of Curaçao (12 ° N), where the mysids occur in swarms hovering during daytime around and between corals.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF8EFFA147EECE63FEF7FA50.taxon	materials_examined	Material examined None. Type locality Gulf of California, Punta Marcial, 25.5167 ° N, 111.0167 ° W (Harrison & Bowman 1987).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF8EFFA147EECE63FEF7FA50.taxon	description	Revised definition Adapted to the scheme in Table 2 by using published data (Harrison & Bowman 1987; Ortiz et al. 2017 b) on adults of both sexes: all features diagnosed above for genus and subgenus Mysidium Dana, 1852, with the reservation that the detailed structure of the setae on the merus of thoracic endopod 3 is unknown. Cornea calotte-shaped in dorsal view, its diameter 2.1 times as long as terminal segment of antennular trunk. Eyestalks smooth. Rostrum round-triangular, not extending beyond eyestalks. Appendix masculina obscurely bilobate, all along inner margins fringed by large setae; its length 1.5 times terminal segment of antennular trunk. Length of antennal scale four times maximum width; scale reaching well beyond antennular trunk. Median segment of mandibular palp with setae all along inner margin, whereas setae lacking on outer margin. Carpopropodus with two segments in thoracic endopods 1 – 2, 7 – 8, versus three segments in endopods 3 – 6. Basal segment is 0.6 times total length of carpopropodus of endopod 3. Male pleopod 1 stout, allusively bilobate. Sympod of male pleopod 4 without endite. Its exopod with basal segment occupying 58 % total length. Endopod reduced to lobe with = 11 % sympod length; apically with one long seta and more proximally six additional, smaller setae. Uropodal endopod 0.6 – 0.7 times as long as exopod. Telson linguiform, tapering posteriorly, length 1.9 times maximum width near basis; lateral margins slightly convex, almost straight; terminal margin clearly convex, well rounded. Proximal half of lateral margins smooth, distal half with dense series of 30 – 37 short, blunt or pointed spines on each side; lateral margins each with about 19 spines, terminal margin with about 24 spines.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF8EFFA147EECE63FEF7FA50.taxon	distribution	Distribution and habitat East Pacific coast of Mexico: Gulf of California, Islas Tres Marías, 21 – 26 ° N. Occurring in shallow, coastal marine waters where it forms dense epibenthic swarms (Gómez-Gutiérrez et. al. 2014). Also collected with night light at surface and from fish stomachs (Harrison & Bowman 1987; Ortiz et al. 2017 b).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF80FFA0446ACC5BFE4AFE49.taxon	description	urn: lsid: zoobank. org: act: EE 9 F 05 D 3 - 29 B 5 - 4 B 95 - BC 0 D- 2 A 6756 AAECE 5	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF80FFA0446ACC5BFE4AFE49.taxon	type_taxon	Type species Mysidium pumae Ortiz, Hendrickx & Winfield, 2017, by monotypy.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF80FFA0446ACC5BFE4AFE49.taxon	etymology	Etymology Noun in nominative singular with neutral ending, formed by amalgamation of the Latin noun ‘ occidens ’ with the generic name Mysidium, referring to the occurrence on the west coast of America.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF80FFA0446ACC5BFE4AFE49.taxon	diagnosis	Diagnosis Subdivision of the genus Mysidium Dana, 1852, characterized by two-segmented carpopropodus of third thoracic endopod; merus of this endopod without serrated setae. Third male pleopod with distinct endite at about ¾ distance from basis of medial margin. Sympod of fourth male pleopod without setae on rostral face. Its exopod four-segmented; basal segment with 0 – 1 seta, second segment without seta, subterminal segment with bifid modified seta, terminal segment with undivided modified seta. Telson entire (not incised).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF80FFA0446ACC5BFE4AFE49.taxon	distribution	Distribution As for type species.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF81FFA0476BC860FD99F965.taxon	materials_examined	Material examined None. Type locality Pacific coast of Mexico, Mazatlán Harbor, 23.1814 ° N, 106.4242 ° W (Ortiz et al. 2017 a).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF81FFA0476BC860FD99F965.taxon	discussion	Revised definition Adapted to the scheme in Table 2 by using published data (Ortiz et al. 2017 a, 2017 b) on adults of both sexes: all features diagnosed above for the genus Mysidium Dana, 1852, and its new subgenus Occimysidium. Cornea crescent-like in dorsal view, with ‘ diameter’ 1.5 times as long as terminal segment of antennular trunk. Eyestalks smooth. Rostrum triangular, apically bluntly pointed, not extending beyond eyestalks. Appendix masculina with separate inner and distal tufts of setae; its length 2.0 – 2.2 times terminal segment of antennular trunk. Length of antennal scale six times maximum width; scale reaching well beyond antennular trunk. Median segment of mandibular palp with setae on both margins. Carpopropodus of first to eighth thoracic endopods 2, 2, 2, 3, 3, 3, 2, and two-segmented, respectively. Basal segment occupies 0.8 times total length of carpopropodus of endopod 3. Pleopods 1 – 2, 5 rodlike, not considering the reduced endopodal portion (pseudobranchial lobe); male pleopod 3 with an additional, small endite. Length of male pleopods increases in order of pleopods 1, (subequal 2, 3, 5), 4. Sympod of male pleopod 4 without endite. Exopod with basal segment occupying 54 % total length. Endopod reduced to lobe with = 22 % sympod length; apically with one long seta and more proximally four additional shorter setae. Uropodal endopod 0.7 times as long as exopod. Telson spatulate, caudally gradually narrowing; length 2.3 times maximum width near basis; terminal margin convex, evenly rounded. Proximal 51 – 52 % of lateral margins smooth, distal portion of each margin with continuous series of 20 – 22 acute laminae. Terminal margin lined by 23 – 25 more densely set, acute laminae. These latter laminae more slender than the neighboring latero-terminal laminae.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF81FFA0476BC860FD99F965.taxon	distribution	Distribution So far known only from type locality.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF81FFA34475CD6BFE3FFCA9.taxon	description	urn: lsid: zoobank. org: act: E 269 F 7 A 6 - 0187 - 4 AD 0 - 9 D 64 - 24 C 700 D 5126 D	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF81FFA34475CD6BFE3FFCA9.taxon	type_taxon	Type species Diamysis columbiae Zimmer, 1915, by present designation. This taxon acknowledged in revised combination as Mysidium (Orientomysidium) columbiae (Zimmer 1915).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF81FFA34475CD6BFE3FFCA9.taxon	etymology	Etymology Noun in nominative singular with neutral ending, formed by amalgamation of the Latin adjective ‘ orientale ’ with the generic name Mysidium, referring to the occurrence on the east coast of America.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF81FFA34475CD6BFE3FFCA9.taxon	diagnosis	Diagnosis Subdivision of the genus Mysidium Dana, 1852, characterized by three-segmented carpopropodus of third thoracic endopod; merus of this endopod with serrated setae. Third male pleopod with strong endite at about 50 – 60 % distance from basis of medial margin. Sympod of fourth male pleopod with series of setae on rostral face. Its exopod three-segmented; proximal segment without seta; the two distal segments each with one unbranched modified seta. Telson with terminal cleft.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF81FFA34475CD6BFE3FFCA9.taxon	distribution	Distribution Littoral and sublittoral waters at Atlantic coasts of tropical America (24 ° N to 8 ° S), including Gulf of Mexico and Caribbean.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF82FFA44713C928FA86F9B3.taxon	description	Figs 9, 13 E – J	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF82FFA44713C928FA86F9B3.taxon	materials_examined	Type material examined The three vials are from the same sample labelled “ Cartagena Kolumbien G. Gagzo leg. 18. IX. 1905 ded. 7. XI. 1906 ”, this material is brittle and delicate, limiting examination. The two specimens from vial 14074 with body parts and appendages sticking together. The respective missing appendages suggest that the lectotype has been partly dissected and figured by Zimmer (1915 a: figs 23 – 29). Lectotype (by present designation) COLOMBIA • ♂ ad. bl 4.4 mm; registered at the ZMH as “ Diamysis columbiae Zimmer, lectotype by present designation ”; 10.37 ° N, 75.52 ° W; ZMH K- 14073 a Paralectotypes COLOMBIA • 1 ♀ ad. bl 4.8 mm carrying two postnauplioid larvae; ZMH K- 14073 b • 1 ♂ ad. bl 4.6 mm, 1 ♀ ad. bl 5.0 mm; ZMH K- 14074. Other material examined CURAÇAO • 26 ♀♀ ad bl. 4.4 – 7.0 mm, 19 ♂♂ ad. bl 3.3 – 7.4 mm, 11 subad.; # C 3; MINGA MYS 431 • 13 ♀♀ ad. bl 5.9 – 7.0 mm, 7 ♂♂ ad. bl 5.8 – 7.8 mm, 8 subad.; # C 5; NHMW 26479. BONAIRE • 24 ♀♀ ad. bl 4.6 – 5.3 mm, 22 ♂♂ ad. bl 3.9 – 6.9 mm, 61 subad.; # B 11; ZMH K- 55263 • 13 ♀♀ ad. bl 5.0 – 7.9 mm, 26 ♂♂ ad. bl 5.7 – 6.5 mm, 7 subad.; # B 12; NHMW 26480. Type locality Cartagena at the Caribbean coast of Colombia (Zimmer 1915 a). Coordinates estimated by present authors are about 10.37 ° N, 75.52 ° W.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF82FFA44713C928FA86F9B3.taxon	discussion	Revised definition All features diagnosed above for the genus Mysidium Dana, 1852, and its new subgenus Orientomysidium. Cornea globose in lateral view; calotte-shaped in dorsal view, with diameter 1.5 – 2.0 times as long as terminal segment of antennular trunk. Eyestalks smooth. Rostrum triangular, with concave lateral margins, apically bluntly to acutely pointed, not or weakly extending beyond basis of eyestalks. Anterolateral edges of carapace rounded. Only males with anterior margin of antennular trunk dorsally with rounded, shield-like, mediodistal extension (Fig. 9 A – B) bearing 2 – 4 setae. The largest seta 0.1 – 0.2 times extension length. Appendix masculina bilobate, 2.0 – 3.3 times as long as terminal segment of antennular trunk; all along with brush of long setae. Length of antennal scale 7 – 8 times maximum width; scale reaching far beyond antennular trunk. Median segment of mandibular palp with setae on both margins. Distally angular hump on outer face of terminal segment of the maxillula. Carpopropodus of thoracic endopods 1 – 8 with 2, 2, 3, 3 – 2, 2 – 3, 2 – 3, 2 – 3 or 2 – 3 segments, respectively. Series of 2 – 6 serrated setae (Fig. 9 D) along merus of third thoracic endopod. Basal segment occupies half total length of carpopropodus of endopod 3. Pleopod 1 rod-like in both sexes, not considering the weak (sub) median widening at its vestigial endopodal portion (Fig. 9 F). Sympod of male pleopod 4 with strong endite at 2 / 5 sympod length from basis and with longitudinal series of 3 – 6 plumose setae on rostral face. Exopod with basal segment occupying 64 – 72 % total length. Endopod reduced to lobe with 27 – 48 % sympod length; with 7 – 10 barbed setae of various sizes. Endopod of uropods 0.6 – 0.7 times as long as exopod. Telson subrectangular, length 1.4 – 1.8 times maximum width near basis. Its lateral margins convex along proximal third; proximal 61 – 73 % of lateral margins smooth, distal portion of each margin with continuous series of 8 – 12 acute spines. Cleft penetrating 13 – 15 % telson length; cleft separating two broadly rounded, apical lobes; cleft and terminal portion of lobes densely lined in continuous series by a total of 22 – 30 stout, blunt laminae.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF82FFA44713C928FA86F9B3.taxon	description	Description of type (Fig. 9 A) All available features fit within the diagnosis. Antennular trunk extends 25 – 47 % its length beyond (artificially aligned) eyes. Sympod of antenna produced into spiniform extension on outer distal corner. Apical segment of maxillary palp about two times as long as basal segment. Carapace posteriorly emarginate, with well-rounded latero-terminal lobes; cervical sulcus strong. Dactylus of thoracic endopods 1 – 2 with moderately long, strong claw; dactylus 3 – 7 with long, needle-like claw; dactylus 8 with short seta-like claw. Sympod of fourth male pleopod with 3 – 4 plumose setae (this range wider in non-types examined) on rostral face plus 1 – 2 small, barbed setae on inner margin. Pleonites 1 – 5 are 0.5 – 0.8, 0.5 – 0.8, 0.6 – 0.8, 0.6 – 0.8 or 0.8 – 1.1 times the length of pleonite 6, respectively. Scutellum paracaudale triangular with blunt to acute apex; both margins weakly concave to weakly convex. Uropodal endopod 0.9 – 1.1 times, exopod 1.2 – 1.5 times as long as pleonite 6. Exopod extends 0.3 – 0.4 times its length beyond endopod, or 0.7 – 0.8 times beyond telson; endopod 0.4 – 0.6 times its length beyond telson. Telson with 0.5 – 0.7 times as long as exopod of uropods, 0.5 – 0.9 times endopod or 0.6 – 0.9 times pleonite 6.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF82FFA44713C928FA86F9B3.taxon	discussion	Notes on additional material (Figs 9 B – J, 13 E – J) Adult females of present material with 4.4 – 7.9 mm (n = 76) body length, males 3.3 – 7.8 mm (n = 74). Numbers of serrated setae (Fig. 9 C – D) along the merus of thoracic endopod 3 increase with increasing body size; also numbers of endopods with any setae of that type increase with body size, i. e., pertaining only to thoracopod 3 in smaller individuals and successively to thoracopods 4 – 7 as individuals become larger. Endopod 8 (when stretched) reaching backwards at most to the end of pleonite 4 and forwards to mandibles; its carpopropodus measures 0.4 – 0.5 times telson length. Male pleopod 4 comparatively short; exopod reaching at most to basal third of pleonite 6, its subapical seta up to terminal third. Endopod of male pleopod 4 (Fig. 9 H) with the most distal seta 1.4 – 4.4 times endopod length. Sympod with field of scales on its endite. Statoliths composed of fluorite. Foregut (Fig. 13 E – G) closely similar to that of M. antillarum sp. nov. (Fig. 11 A – E). As main differences from this species, M. columbiae shows different structure and variable numbers of large spines: on each lateral half there are 2 – 4 apically pronged spines on posterior part of lateralia, the teeth of these spines with dense sets of secondary denticles (Fig. 13 F); and there are 1 – 2 larger, apically pronged, serrated spines on dorso-lateral infolding, the latter spines flatter, more clavate, and with more slender teeth on basal ¾ (Fig. 13 G). Notes on individual development Nauplioid larvae (Fig. 13 H) with smooth cuticle all around, except for a pair of minute furcal processes and a number of minute setae on the blunt end of the abdomen (Fig. 13 J). Davis (1966: fig. 4) already reported apical, furcal ‘ spines’ in nauplioids of M. columbiae from Jamaica. In non-types of the present material, the differentiation of male sexual characteristics is visible in early subadults as small rudiments of penis and appendix masculina and of a bifid fourth pleopod. At this stage the exopod of pleopod 4 is less than 3 / 2 as long as endopod and the endite of the sympod is missing or indistinct. In the course of further development a distinct endite (representing an important diagnostic character) becomes visible as soon as the exopod exceeds two times the length of the endopod.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF82FFA44713C928FA86F9B3.taxon	distribution	Distribution and habitat From 24 ° N to 8 ° S in coastal waters of Bahamas, Caribbean, southern Gulf of Mexico, and Brazil (Price & Heard 2004; Miyashita & Calliari 2014). The present samples from Curaçao and Bonaire fit within this geographic range. The present material was encountered at a depth of 3 – 26 m, during daytime in swarms hovering around and between corals. During the night dispersed over the sea floor.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF85FF9D47E6CC36FD83FB59.taxon	description	urn: lsid: zoobank. org: act: 7 CCD 97 DD- 6848 - 46 AF-B 806 - 82 D 93 D 3 FF 3 BA Figs 10 – 12, 13 A – D	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF85FF9D47E6CC36FD83FB59.taxon	etymology	Etymology The species name is a Latinized Spanish noun in the genitive plural, referring to the occurrence at islands of the Antilles.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF85FF9D47E6CC36FD83FB59.taxon	materials_examined	Type material examined (by present designation) Holotype CURAÇAO • ♂ ad. bl 7.3 mm; shallow marine waters of Curaçao, Reef Sint Marie; 12.2122 ° N, 69.0850 ° W; # C 6; NHMW 26484. Paratypes CURAÇAO • 48 ♀♀ ad. bl 6.2 – 8.0 mm, 37 ♂♂ ad. bl 5.1 – 7.5 mm, 11 subad.; same locality data as for holotype; # C 6; MINGA MYS 433, NHMW 26485, ZMH K- 55258. Other material examined CURAÇAO • 13 ♀♀ ad. bl 6.3 – 7.5 mm, 11 ♂♂ ad. bl 5.8 – 7.7 mm; # C 1; MINGA MYS 429 • 20 ♀♀ ad. bl 6.2 – 8.2 mm, 6 ♂♂ ad. bl 4.9 – 6.3 mm, 11 subad.; # C 2; ZMH K- 55256 • 18 ♀♀ ad. bl 6.5 – 7.8 mm, 39 ♂♂ ad. bl 5.4 – 7.7 mm, 48 subad.; # C 4; NHMW 26483 • 3 ♀♀ ad. bl 6.1 – 6.6 mm, 3 ♂♂ ad. bl 6.0 – 6.3 mm, 109 subad.; # C 7; MINGA MYS 435 • 1 ♀ subad. bl 4.5 mm; # C 8 • 24 ♀♀ ad. bl 6.3 - 8.1 mm, 17 ♂♂ ad. bl 6.1 - 6.8 mm, 7 subad.; # C 10; NHMW 26486. BONAIRE • 65 ♀♀ ad. bl 5.8 – 8.0 mm, 83 ♂♂ ad. bl 5.8 – 7.6 mm, 9 subad.; # B 11; ZMH K- 55264.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF85FF9D47E6CC36FD83FB59.taxon	discussion	Definition All features diagnosed above for the genus Mysidium Dana, 1852, and its new subgenus Orientomysidium. Cornea globose in lateral view, calotte-shaped in dorsal view, with diameter 1.4 – 1.7 times as long as terminal segment of antennular trunk. Eyestalks smooth. Rostrum triangular, apically rounded or pointed, not extending beyond basis of eyestalks. Antero-lateral edges of carapace rounded. Only males with anterior margin of antennular trunk dorsally with rounded, shield-like, mediodistal extension (Fig. 10 A – B) bearing 2 – 3 setae. The largest seta 0.1 times extension length. Appendix masculina 2.2 – 3.9 times terminal segment of antennular trunk; its shorter, dorsal lobe with brush of long setae, its longer ventral lobe with less dense set of shorter setae. Length of antennal scale 7 – 11 times maximum width, scale clearly reaching beyond antennular trunk. Median segment of mandibular palp with setae on both margins. Distally angular hump on outer face of terminal segment of maxillula. Carpopropodus of thoracic endopods 1 – 8 with 2, 2, 3, 3, 2 – 3, 2 – 3, 2 – 3 or 2 segments, respectively. Basal segment occupies half total length of carpopropodus of endopod 3. Series of 2 – 7 serrated setae (Fig. 12 B) along merus of third thoracic endopod. Pleopod 1 rod-like in both sexes, not considering the weak (sub) median widening at its vestigial endopodal portion (Fig. 12 D, G). Sympod of male pleopod 4 with longitudinal series of 3 – 7 plumose setae on rostral face; without or with an indistinct medial widening (endite) at ¼ of sympod length from basis. Exopod with basal segment occupying 69 – 73 % total length. Endopod reduced to a terminally rounded lobe with 29 – 41 % sympod length; endopod with 5 – 12 mostly large, plumose setae of various sizes. Endopod of uropods 0.6 – 0.8 times as long as exopod. Telson subrectangular with apical cleft. Telson length 1.4 – 1.7 times maximum width near basis. Its lateral margins convex along proximal third and smooth along proximal 51 – 58 %; distal portion of each margin with dense, continuous series of 12 – 17 acute spines. Subtriangular apical cleft penetrating 11 – 14 % telson length; cleft separating two broadly rounded, apical lobes; cleft and terminal portion of lobes densely lined in continuous series by a total of 19 – 23 (sub) acutely pointed, stout laminae.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF85FF9D47E6CC36FD83FB59.taxon	description	Description SIZE. Adult females 5.8 – 8.2 mm (n = 191), males 4.9 – 7.7 mm (n = 197). ANTENNAL APPENDAGES (Fig. 10 A – B, F – G). Antennular trunk extends 35 – 56 % its length beyond (artificially aligned) eyes. First to third segments occupy 47 – 52 %, 14 – 18 % or 30 – 37 % total length of trunk, respectively. Trunk dorsally with forward-directed small, setose lobes near terminal margin of each segment: two lobes from the basal, one from the median, and one from the terminal segment (not counting the mediodistal extension of the anterior margin in males). Appendix masculina 0.7 – 1.4 times total trunk length, antennal scale 1.2 – 1.6 times trunk. Sympod of antenna (Fig. 10 G) produced into spiniform extension on outer distal corner. Antennal scale with terminal segment occupying 10 – 14 % total length and bearing five plumose setae. MOUTH PARTS (Figs 10 H, J, 11 F – H). Mandibular palp (Fig. 10 J) without spines; terminal segment with strong, modified, bent seta at apex, and barbed setae along inner and outer margins. Median segment of palp with angular, medially directed dilatation, both its margins setose. Proximal segment normal, with smooth margins. Distal segment of maxillula (Fig. 11 G) terminally with strong spines, subterminally with one barbed seta; tip of endite of maxillula with apically modified setae (armed with stiff barbs) plus several setae with normal, fine barbs. Maxilla (Fig. 11 H) with well-developed exopod, moderately large, two-segmented palp and three apically setose endites. Exopod with maximum width in submedian portions; its outer margin all along with continuous series of plumose setae. Basal segment of palp with three barbed setae. Apical segment about two times as long as basal segment. Length of apical segment 1.9 – 2.5 times maximum width. Apical segment densely setose on terminal margin but lined by small hairs along more than basal half of inner margin; apex with two strong, modified setae bearing strong, spine-like barbs along distal third of their inner margin. FOREGUT (Fig. 11 A – E). Setae, but no spines, close to inlet of oesophagus. Primary cardiac filter formed ventrally by dense combs of stiff setae behind this inlet. Lateralia and superomedianum densely covered by spines and / or setae. Apically coronate plus apically, weakly (Fig. 11 B) to strongly (Fig. 11 E) pronged, slender spines on anterior and median parts of lateralia. These spines with numerous minute denticles along distal 60 – 80 % of their shaft. Two powerful, stout, apically pronged, serrated spines (Fig. 11 C) on posterior part of lateralia; one additional, longer, more strongly serrated spine (Fig. 11 D) of that type on the dorso-lateral infolding; yielding a total of six such powerful spines. Secondary filter formed by dense rows of setae in pyloric part of foregut. THORAX OF BOTH SEXES (Figs 10 C – D, 11 J – K, 12 A – C, 13 A). Carapace (Fig. 10 C) posteriorly emarginate, with well-rounded latero-terminal lobes; cervical sulcus strong; roughly V-shaped group of 10 – 16 pores (Fig. 10 E) in front of cervical sulcus, transverse linear series of 16 – 23 pores (Fig. 10 D) in cardial position (above heart). Sternites (Fig. 11 J) smooth; a plumose seta accompanied by 1 – 2 shorter barbed setae on the joint between each sternite and its thoracopod. Endopod and exopod sizes increase from thoracopods 1 to 5 and decrease from 5 to 8. Basal plate of exopods with large, well-rounded laterodistal expansion in exopods 1 – 7. Flagellum 8 - segmented in exopods 1 and 8, versus 9 - segmented in remaining exopods. First thoracic epipod bilobate, with smooth margins, without seta. First endopod (Fig. 11 J) with well-developed, setose endites from basis, ischium, merus. Endopods 1 – 2 with large dactylus and strong claw. Dactylus of endopod 2 with 4 – 6 modified and several smooth setae, no spine-like setae; modified setae each with two dense rows of strong, acute barbs along their median to subterminal portions. Numbers of serrated setae (Fig. 12 B) along the merus of thoracic endopod 3 increase with increasing body size; also numbers of endopods with any setae of that type increase with body size, i. e., pertaining only to thoracopod 3 in smaller individuals and successively to thoracopods 4 – 8 as individuals become larger. Endopods 3 – 7 with less stout, well-developed dactylus bearing a long, needle-like claw; endopod 8 (Fig. 13 A) with even smaller dactylus and short seta-like claw. Endopod 8 (when stretched) reaching backwards at most to middle of pleonite 4 and forwards to mandibles; its carpopropodus measures 0.3 – 0.5 times telson length. THORACOPODS OF FEMALES (Fig. 12 C). Basal plate of exopod 8 with short to indistinct latero-distal expansion. The oostegites from thoracopods 7 – 8 densely fringed with setae, together forming a large brood chamber. Thoracopod 6 with rudimentary oostegite bearing 2 – 4 setae at apex. These setae spinulose at least along their apical third. More such setae present in proximal portions of the oostegite from thoracopod 7. THORACOPODS OF MALES AND PENIS (Fig. 13 A). Basal plate of exopod 8 with distinct latero-distal expansion. Penes tubular, 0.7 – 0.9 times as long as merus of endopod 8. Penes apically bilobate, with row of 5 – 9 smooth, bent setae flanking the ejaculatory opening. One or two additional, smaller setae subapically on margin opposite bent setae. PLEON (Figs 12 D – L, 13 B – D). Pleonites 1 – 5 are 0.5 – 0.6, 0.6, 0.6, 0.6 or 0.7 times the length of pleonite 6, respectively. Size increases from pleopods 1 to 4, with pleopod 5 ranging between 2 and 3 in both sexes. Pleopods 1 – 3 with a ventro-laterally directed fan of plumose setae. Setae of pleopod 1 (Fig. 12 D, G) not larger than those of pleopods 2, 3, 5. Female pleopods 1 – 5 (Fig. 12 D – F) and male pleopods 1 – 2, 5 (Fig. 12 G – H, L) vestigial, rod-like, not considering the weak (sub) median widening, if any, at the vestigial endopodal portion. Male pleopod 3 (Fig. 12 J) essentially rod-like as well, yet with hump-like endite at 60 % pleopod length from basis. Male pleopod 4 reaching with its subapical seta to pleonite 6 or even up to apex of endopod of uropods. Its exopod with basal segment longest, second segment longer than third. Subterminal segment of exopod with a very long seta bearing dense series of minute bristles along its distal 20 – 53 %; short terminal segment with shorter seta at tip, this seta with characteristic set of barbs (Fig. 12 K) along its distal third. Endopod with its largest distal seta 1.2 – 2.0 times endopod length. Sympod with field of scales on its medial widening, or in analogous position upon missing widening. Scutellum paracaudale (Fig. 13 B) subtriangular, apically pointed; upper margin concave, lower margin convex. Endopod of uropods (Fig. 13 C) 1.0 – 1.3 times as long as pleonite 6, exopod 1.6 – 1.9 times pleonite 6. Length of exopod 8 – 10 times its maximum width. Exopod extends 0.3 times its length beyond endopod or 0.6 – 0.7 times beyond telson; endopod 0.4 – 0.6 times its length beyond telson. Telson (Fig. 13 D) 0.4 – 0.5 times as long as exopod of uropods, 0.6 – 0.8 times endopod or 0.7 – 0.9 times pleonite 6. STATOLITHS. Composed of fluorite; shape ellipsoidal to spherical in dorsal view (Fig. 13 C), discoidal in lateral view, maximum diameter 126 – 188 µm, thickness 62 – 97 µm, measured in 10 adults. Tegmen moderately, though always distinctly convex; fundus weakly concave. Sagittal section very similar to that figured by Wittmann et al. (1993: Fig. 6 P) for Heteromysis formosa. Statolith formula 2 + 3 + (0 – 1) + (4 – 13) + (6 – 12) = 19 – 25. NAUPLIOID LARVAE. As in M. columbiae (Fig. 13 H, J).	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFF85FF9D47E6CC36FD83FB59.taxon	distribution	Distribution and habitat In euhaline, sublittoral to littoral waters of Curaçao and Bonaire, both islands at 12 ° N. The new species forms swarms during the day, hovering closely above the sea floor at a depth of 0 – 26 m. Also found near shore boulders, around and off piers.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFFBCFF9C4433CF3AFDE6FCF5.taxon	materials_examined	Material examined No material available, not assigned to any subspecies: see Discussion. Type locality Băcescu (1991) indicated “ Jamaica, St. D, 90.026 Sa Rba ” as sampling site of the types.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFFBCFF9C4433CF3AFDE6FCF5.taxon	discussion	Revised definition Adapted to the scheme in Table 2 by using published data (Băcescu 1991) on adult females and subadult males: Mysidium with cornea calotte-shaped in dorsal view; diameter 1.5 times as long as terminal segment of antennular trunk. Anterior margin of carapace rounded. First to third segments occupy 57 %, 13 % and 30 % total length of antennular trunk, respectively. Length of antennal scale six times maximum width, scale not reaching beyond antennular trunk. Carpopropodus three-segmented in thoracic endopod 3, and two-segmented in endopod 8. Basal segment occupies 0.4 times total length of carpopropodus of endopod 3. Uropodal endopod 0.8 times as long as exopod. Telson subrectangular with apical cleft. Telson length 1.6 times maximum width near basis. Its lateral margins slightly tapering and smooth along proximal 56 – 63 %; distal portion of each margin with dense continuous series of about 9 – 11 acute laminae. Subtriangular apical cleft penetrating 11 % telson length; cleft separating two broadly rounded, apical lobes; cleft and terminal portion of lobes densely lined in continuous series by about 17 – 22 acute laminae. Telson with a total of about 35 – 42 laminae.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFFBCFF9C4433CF3AFDE6FCF5.taxon	distribution	Distribution and habitat Only known from type locality. Băcescu (1991) reported T. Iliffe as collector, so the positional data are interpreted by the present authors according to a copy of the sampling protocol submitted by courtesy of Tom Iliffe: Jamaica, Westmoreland Parish, Negril, Joseph’s Caves, station 90.026, sea cave with swarm of mysids congregated at the cave entrance, collected from water column and sand bottom at depths of 1 – 3 m, 26 June 1990, leg. Tom Iliffe. Coordinates estimated by the present authors are 18.2680 ° N, 78.3681 ° W at the entrance of this touristic cave. Băcescu (1991) reported M. cubanense to co-occur with M. iliffei at this station.	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
03D1E37CFFBDFF9F46EEC909FA99FB6A.taxon	discussion	Anisomysini with well-developed eyes. Antennal scale lanceolate, without spines, but setose all around, with small terminal segment. Thoracopods essentially normal, endopods with 2 - or three-segmented carpopropodus. All pleopods of females and pleopods 1 – 3, 5 of males reduced, uniramous, unsegmented. Fourth male pleopod longest, biramous with setose, unsegmented endopod and with 3 - or 4 - segmented exopod; subterminal and terminal segments of exopod each ending in large modified seta. Uropods with setose margins, without spines. Telson longer than broad, with entire or incised terminal margin; with spines and laminae only on distal half. Genus Mysidium Dana, 1852 (endemic in tropical to subtropical, mainly euhaline, also metahaline coastal waters of the East Pacific at 21 – 26 ° N and the West Atlantic from 32 ° N to 24 ° S, including Gulf of California, Gulf of Mexico and Caribbean) ........................................................................ 1	en	Wittmann, Karl J., Wirtz, Peter (2019): Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera. European Journal of Taxonomy 495: 1-48, DOI: 10.5852/ejt.2019.495
