taxonID	type	description	language	source
0388B820FFEEFF9FFF5D8547D4A7FD06.taxon	description	Figures 1 – 4	en	Anker, Arthur, Pachelle, Paulo P. G. (2019): Alpheus perlas, sp. nov., a new infaunal snapping shrimp from the Pacific coast of Panama (Malacostraca: Decapoda: Alpheidae). Zootaxa 4651 (1): 75-84, DOI: 10.11646/zootaxa.4651.1.5
0388B820FFEEFF9FFF5D8547D4A7FD06.taxon	materials_examined	Type material. Holotype: male (cl 6.7 mm), MNHN-IU- 2019 - 2301, Panama, Pacific coast, Bay of Panama, Las Perlas Archipelago, Isla Casayeta, 8 ° 31 ’ 14.6 ” N 79 ° 01 ’ 26.4 ” W, small shallow bay with mudflat fringed by rocks and mangroves, depth: less than 0.5 m at low tide, in burrow, suction pump, leg. A. Anker, 20 April 2015. Description. Small-sized species of Alpheus (holotype at cl 6.7 mm). Carapace smooth, glabrous, not setose, not pubescent. Rostrum very short, subtriangular, as long as broad at base, subacute distally, not reaching mid-length of first article of antennular peduncle; rostral carina feebly developed, rounded dorsally, gradually fading posteriorly to eye level (Fig. 1 A, B). Orbital hoods moderately developed, not particularly swollen, semi-open frontally, with anterior margin broadly rounded; frontal margin between rostrum and orbital hoods slightly concave; adrostral furrows absent (Fig. 1 A, B). Pterygostomial angle rounded, not protruding anteriorly (Fig. 1 B); cardiac notch well developed. Telson very broad, subrectangular, tapering distally, about 1.8 times as long as maximal width, with lateral margins slightly convex, not constricted; dorsal surface with two pairs of short cuspidate setae both inserted far from lateral margin, first pair at about mid-length, second pair at about 0.8 length of telson; posterior margin broadly rounded, without spiniform setae; each posterolateral angle with pair of slender spiniform setae, mesial about three times as long as lateral (Fig. 1 C). Antennular peduncle moderately stout; stylocerite broad, inflated, with small sharp point almost reaching distal margin of first article; ventromesial carina with strong, anteriorly directed tooth; second article moderately elongate, almost twice as long as wide; lateral antennular flagellum with secondary ramus fused to main ramus over most of its length, with numerous groups of aesthetascs starting at eighth joint (Fig. 1 A, B, D). Antenna with basicerite moderately stout, its distoventral margin bearing small acute tooth; scaphocerite with well-developed blade, straight to faintly concave lateral margin and strong broad distolateral tooth overreaching blade but not distal margin of antennular peduncle; carpocerite reaching far beyond both scaphocerite and end of antennular peduncle (Fig. 1 A, B). Mouthparts typical for genus in external observation. Third maxilliped moderately stout; coxa with projecting, distally subacute lateral plate; antepenultimate article flattened ventrolaterally, with straight mesial margin; penultimate article relatively short, widening distally, about twice as long as maximal (distal) width; ultimate article tapering distally, with numerous rows of short serrulate setae and longer stiff setae, distally unarmed; arthrobranch well developed, with smaller accessory branch reminiscent of small pleurobranch (Fig. 1 E, F). Male major cheliped overall moderately robust for species of A. edwardsii group; ischium very short, stout, unarmed; merus relatively stout, about 2.4 times as long as wide, distodorsal margin ending bluntly, mesial margin smooth, without spiniform setae, unarmed (without tooth) on distomesial margin; carpus very short, cup-shaped; chela elongate, slightly compressed; palm oval in cross-section, about 1.5 times as long as fingers; palm surface mostly smooth, without tubercles, not excessively setose; dorsal transverse groove broad, adjacent shoulder sloping smoothly, not overhanging groove; ventral transverse groove well marked, however, not significantly extending onto mesial surface, adjacent shoulder broadly rounded, not protruding anteriorly to overhang groove; mesial face of palm with deep longitudinal groove stretching from mesial extension of dorsal transverse groove posteriorly, almost reaching linea impressa; lateral face of palm with similar longitudinal groove stretching from lateral extension of dorsal transverse groove towards posterior half of palm, reaching linea impressa; dactylus slightly longer than pollex, distally rounded, not twisted, with short, moderately stout, distally truncate plunger, latter with numerous stamen-shaped sensillae; adhesive disks small (Fig. 2 A – D). Male minor cheliped significantly smaller than major cheliped, with much weaker, shorter chela; ischium short, stout, unarmed; merus somewhat slenderer, about 2.8 times as long as wide, otherwise similar to that of major cheliped; carpus also noticeably longer, cup-shaped; chela not particularly elongate, moderately slender, with palm subcylindrical in cross-section, somewhat shorter than fingers; palm surface smooth, without grooves or notches; fingers subequal in length, crossing distally, simple, not balaeniceps; dactylus not expanded, more conical distally, with simple blade-like cutting edge; pollex shallowly excavated along lateral side cutting edge; adhesive disks not discernable (Fig. 2 E, F). Female minor cheliped unknown. Second pereiopod moderately slender; ischium and merus subequal in length; carpus with five subdivisions, first longest, ratio of carpal subdivisions approximately equal to 3.2 / 2.4 / 1.2 / 1.0 / 1.8; chela as long as two distal-most carpal subdivisions combined (Fig. 3 A). Third pereiopod rather stout; ischium with very small cuspidate seta on ventrolateral surface; merus about 3.5 times as long as maximal width, slightly inflated, unarmed; carpus about half- length of merus, much slenderer, with long stiff distoventral seta; propodus noticeably longer than carpus but shorter than merus, with seven or so irregularly inserted, stout spiniform setae along ventral and ventrolateral margin, in addition to one pair of spiniform setae near dactylar base; dactylus about half-length of propodus, stout, conical, very slightly expanded and curved (Fig. 3 B – D). Fourth pereiopod generally similar to third, slightly slenderer. Fifth pereiopod much slenderer than third and fourth; ischium unarmed; merus not inflated, about six times as long as wide; carpus slightly less than 0.8 times length of merus; propodus with three spiniform setae along ventromesial margin and one distal pair of spiniform setae near articulation with dactylus; distal third of propodus with welldeveloped rows of serrulate setae on ventrolateral surface; dactylus about 0.4 length of propodus, conical, simple, almost straight (Fig. 3 E). Male first pleopod with protopod bearing conspicuous subacute process on subdistal ventral (posterior) margin, distally carrying single thickened seta; endopod very small, fringed with setae (Fig. 1 G). Male second pleopod with protopod bearing similar subacute process, but situated slightly more distally on ventral (posterior) margin and without thickened seta; appendix interna longer than appendix masculina, latter furnished with numerous stiff setae on apex and with some stiff setae also on subapical surface and distal half (Fig. 1 H, I). Uropod with both mesial and lateral lobes of protopod ending in subacute tooth; exopod and endopod very broad, ovoid; exopod with fairly stout distolateral tooth adjacent to strong distolateral spiniform seta and unarmed distal margin; diaeresis somewhat sinuous, with broadly triangular lobe adjacent and mesial to distolateral spiniform seta; endopod with short row of small spiniform setae on distal margin (Fig. 1 J). Colour pattern. General body background semitransparent creamy with straw-yellow tinge; carapace with fields of reddish chromatophores, e. g. in postrostral area, along anterolateral margin and on posterodorsal surface; pleon with reddish chromatophores forming broad, transverse, rather diffuse bands, less conspicuous on last pleonite; telson and uropods also with some reddish chromatophores; chelipeds creamy-yellowish, tips of major chela fingers pale pinkish; walking legs semitransparent (Fig. 4). Etymology. The new species is named after the type locality, Las Perlas Archipelago; used as a plural noun (perlas, from the Spanish word perla = pearl) in apposition. Ecology. Alpheus perlas sp. nov. appears to be associated with burrows of unknown hosts on shallow subtidal mudflats. Sympatric burrowing animals collected at the type locality included Axianassa christyi Anker & Pachelle, 2016, Neocallichirus sp. [in study], as well as several unidentified echiurans (possibly Ochetostoma sp. or Listriolobus sp.). Remarks. Alpheus perlas sp. nov. plainly belongs to the A. edwardsii species group, as redefined by Anker et al. (2009) for the dorsal notch of the major chela palm extends posteriorly on the mesial face (Fig. 2 A). Within the A. edwardsii group, the new species belongs to a non-monophyletic assemblage of species, in which (1) the male minor chela is not balaeniceps (= fingers do not possess the so-called “ balaeniceps ridges ” furnished with rows of densely inserted thick plumose setae); (2) the rostral carina does not form a sharply delimited, V- or U-shaped, flattened post-rostral plate; (3) the ventral shoulder of the major chela is not protruding anteriorly, overhanging the ventral notch; (4) the distoventral margin of the third pereiopod merus is blunt, i. e. not ending in a sharp tooth; and (5) the antepaenultimate article of the third maxilliped is not significantly expanded. In the eastern Pacific, the only species of the A. edwardsii group that have this combination of characters are: A. latus Kim & Abele, 1988, A. burukovskyi Anker & Pachelle, 2015, A. galapagensis Sivertsen, 1933 (= A. canalis Kim & Abele, 1988), A. millsae Anker, Hurt & Knowlton, 2007, A. mazatlanicus Wicksten, 1983, A. colombiensis Wicksten, 1988 (= A. hamus Kim & Abele, 1988), A. agrogon Ramos, 1997, and A. spinicaudus Lockington, 1878 [nomen dubium] (Kim & Abele 1988; Anker et al. 2007; Anker & Pachelle 2015). All other eastern Pacific species of this group can be separated from A. perlas sp. nov. by at least one of the five characteristics mentioned above, with most of these taxa having either strongly balaeniceps minor chelae in males or an abruptly delimited post-rostral plate (Kim & Abele 1988; Anker & Pachelle 2015; Salgado-Barragán et al. 2017).	en	Anker, Arthur, Pachelle, Paulo P. G. (2019): Alpheus perlas, sp. nov., a new infaunal snapping shrimp from the Pacific coast of Panama (Malacostraca: Decapoda: Alpheidae). Zootaxa 4651 (1): 75-84, DOI: 10.11646/zootaxa.4651.1.5
0388B820FFEEFF9FFF5D8547D4A7FD06.taxon	description	In addition, A. perlas sp. nov. differs from both A. latus and A. burukovskyi by its bland, pale-yellow and reddish-banded colour pattern, contrasting to the much darker olive-greenish colouration of A. latus (A. Anker, unpublished data) and the uniform bright red-orange colouration of A. burukovskyi (Anker & Pachelle 2015: fig. 3).	en	Anker, Arthur, Pachelle, Paulo P. G. (2019): Alpheus perlas, sp. nov., a new infaunal snapping shrimp from the Pacific coast of Panama (Malacostraca: Decapoda: Alpheidae). Zootaxa 4651 (1): 75-84, DOI: 10.11646/zootaxa.4651.1.5
0388B820FFEEFF9FFF5D8547D4A7FD06.taxon	materials_examined	It must be noted here that Ramos’ (1997) description of A. agrogon contains some inaccuracies, especially in the illustration of the rostro-orbital area of the carapace. Ramos (1997: fig. 1 B) illustrated an interrupted rostral carina followed by a V-shaped post-rostral plate, similar to the configuration seen in some species of the A. armillatus complex. The first author (AA) examined the holotype and the only known specimen of A. agrogon, deposited in the National Museum of Natural History, Smithsonian Institution, Washington DC, USA (USNM). The holotype of A. agrogon indeed has a marked rostral carina interrupted between the orbital hoods, i. e. separating the proper rostral carina from a short post-rostral (in fact, post-orbital) crest, gradually flattening posteriorly; however, it does not possess a triangular V-shaped plate, as figured by Ramos (1997: fig. 1 B). Collection of more material in the shallow intertidal areas of Gorgona Island off Colombia, the type locality of A. agrogon, will be necessary to confirm the validity and uniqueness of this character and to elucidate the phylogenetic relationships of this species.	en	Anker, Arthur, Pachelle, Paulo P. G. (2019): Alpheus perlas, sp. nov., a new infaunal snapping shrimp from the Pacific coast of Panama (Malacostraca: Decapoda: Alpheidae). Zootaxa 4651 (1): 75-84, DOI: 10.11646/zootaxa.4651.1.5
0388B820FFEEFF9FFF5D8547D4A7FD06.taxon	description	The presence of a subacute process on the subdistal-ventral margin of the protopod of the first and second pleopods in A. perlas sp. nov. (Fig. 1 G, H) may be the only true autopomorphic feature of the new taxon. However, the absence of such a process in other species of Alpheus needs confirmation as the protopods are not always carefully observed and / or drawn; this is especially true for the protopod of the first pleopod. In the authors’ personal experience, most American species of Alpheus do not have such a process on the first and second pleopods. The only other conspicuous modification of the pleopodal protopods is observed in A. colombiensis, in which they are armed with row (s) of stout sharp teeth, especially in ovigerous females (Wicksten 1988; Kim & Abele 1988).	en	Anker, Arthur, Pachelle, Paulo P. G. (2019): Alpheus perlas, sp. nov., a new infaunal snapping shrimp from the Pacific coast of Panama (Malacostraca: Decapoda: Alpheidae). Zootaxa 4651 (1): 75-84, DOI: 10.11646/zootaxa.4651.1.5
