Revision of the Alpheus formosus Gibbes, 1850 complex, with redescription of A. formosus and description of a new species from the tropical western Atlantic (Crustacea: Decapoda: Alpheidae) Author Anker, Arthur Author Hurt, Carla Author Knowlton, Nancy text Zootaxa 2008 1707 1 22 journal article 10.5281/zenodo.180922 484248a6-23dc-46d2-8bfd-db910d966b10 1175-5326 180922 Alpheus paraformosus n. sp. Figs. 5 , 6 , 7 f–h Alpheus formosus -b—Knowlton & Mills 1992 : 2 . Alpheus formosus sp. b—Knowlton et al . 1993: 1630. Alpheus formosus B—Williams et al . 2001: 377. Type material .— Panama (Caribbean coast). Holotype : 1 male (CL 6.6), USNM 1100703, Bocas del Toro, San Cristóbal , Punta Coco, shallow subtidal ( 1–1.5 m ), from rock and coral rubble crevices, coll. A. Anker, 29 Oct 2005 [fcn 05-099, specimen dissected]. Paratypes : 1 ovig. female (CL 6.9), USNM 1100704, same collection data as for holotype [fcn 05-099]; 1 ovig. female (CL 7.2), USNM 1100705, Bocas del Toro, Isla Colón, Boca del Drago, from crevices in coral rubble, depth less than 2 m , coll. A. Anker and J.A. Vera Caripe, 11 Nov 2006 [fcn 06-546]. Additional material examined.— Panama (Caribbean coast). 1 male (CL 4.6), 1 ovig. female (CL 5.5), MNHN-Na 16361, Isla Grande, southern shore, shallow subtidal ( 1–1.5 m ), from crevices in coral rubble and algal clumps, coll. A. Anker, 4 Sep 2006 [fcn 06-454]. Honduras . 1 male (CL 5.1), 1 ovigerous female (CL 5.5), OUMNH-ZC 2007-20 -001, Bay Islands, Utila, southern shore, small bay towards town, 1605.458’ N 086º54.533’ W from rubble, depth 1 m , coll. A. Anker and S. De Grave, 3 Jul 2007 [fcn H76]. Description .—Carapace glabrous, non-setose, somewhat compressed laterally. Rostrum well developed, dorsally flattened; margins fringed with some sidewards directed setae ( Fig. 5 a, k); tip acute, not reaching distal margin of first segment of antennular peduncle ( Fig. 5 a, k); rostral carina absent; orbito-rostral process broad, round W-shaped. Orbital hoods with acute teeth inserted at some distance from anterior margin ( Fig. 5 a, k). Adrostral furrows deep, narrow, abruptly delimited from rostrum, posteriorly extending almost to about mid-length of cornea ( Fig. 5 a). Pterygostomial angle rounded, slightly protruding anteriorly ( Fig. 5 b); cardiac notch well developed. Eyes completely concealed in dorsal, lateral and partly in frontal view. Ocellar beak vertically protruding towards rostrum, usually visible in lateral view ( Fig. 5 b). Antennular peduncles relatively stout, second segment shorter than dorsally visible portion of first segment, about 1.2 times as long as wide ( Fig. 5 a); stylocerite with acute tip, distinctly overreaching distal margin of first segment ( Fig. 5 a, b); mesioventral carina of first segment with large, bluntly protruding tooth (nearly identical to that of A. formosus , cf. Fig. 1 c); lateral flagellum with numerous tufts of aesthetascs, ascessory ramus rudimentary ( Fig. 5 b). Antenna with stout basicerite bearing strong acute ventrolateral tooth, its tip not reaching level of stylocerite tip ( Fig. 5 b); carpocerite moderately stout, reaching slightly beyond distolateral tooth of scaphocerite; scaphocerite with very strong distolateral tooth separated from narrow blade by deep cleft ( Fig. 5 a), tip of distolateral tooth reaching far beyond blade and slightly exceeding end of antennular peduncle ( Fig. 5 a); lateral margin of scaphocerite straight to very slightly concave at mid-length ( Fig. 5 a). Mouthparts (mandible, maxillule, maxilla, first and second maxillipeds) typical for Alpheus . Third maxilliped moderately stout ( Fig. 5 d); coxa with distally acute lateral plate; exopod reaching penultimate segment; antepenultimate segment slightly flattened, ventral margin straight; penultimate segment about three times as long as wide; arthrobranch well developed ( Fig. 5 d). FIGURE 5. Alpheus paraformosus n. sp. , holotype male from Bocas del Toro, Panama (USNM 1100703) [a–j]; paratype female from Bocas del Toro, Panama (USNM 1100704) [k]: a, frontal region, dorsal; b, same, lateral; c, scaphocerite, dorsal; d, third maxilliped, lateral; e, second pereiopod, lateral; f, third pereiopod, lateral; g, second pleopod, detail of appendix interna and appendix masculina; h, uropod, dorsal (setae omitted); i, distal margin of endopod (setae omitted); j, telson, dorsal; k, rostrum and orbital hoods, dorsal. Scale bars = 1 mm. FIGURE 6. Alpheus paraformosus n. sp. , holotype male from Bocas del Toro, Panama (USNM 1100703) [a–f]; paratype female from Bocas del Toro, Panama (USNM 1100704) [g]: a, major cheliped, mesial; b, same, lateral; c, same, chela and carpus, mesial; d, same, distal portion of chela, fingers opened (setae omitted); e, male minor cheliped, lateral; f, same, chela, mesial; g, female minor cheliped, mesial. Scale bars = 1 mm. Male major cheliped ( Fig. 6 a–d) with short, stout ischium; merus stout, about 2.5 times as long as wide proximally, dorsal margin distally protruding ( Fig. 6 a, b); ventrolateral margin straight; ventromesial margin straight, with small spinules ( Fig. 6 a), distally with acute tooth ( Fig. 6 a); carpus very short, cup-shaped; chela large, subcylindrical, broadly oval in cross section; palm smooth, moderately setose distally; distomesial margin with blunt to subacute tooth ( Fig. 6 a, c); linea impressa conspicuous ( Fig. 6 b); adhesive discs relatively large ( Fig. 6 b, d); fingers more than half-length of palm, dactylus usually reaching slightly beyond pollex, with large plunger, latter distally with stamen-shaped sensillae ( Fig. 6 d). Female major cheliped similar to that of male, except for somewhat smaller size and different proportions of fingers to palm. FIGURE 7. Color patterns of species of the Alpheus formosus Gibbes, 1850 complex: Alpheus panamensis Kingsley, 1878 [a, b]; A. formosus Gibbes, 1850 [c–e]; A. paraformosus n. sp. [f–h]: a, male from Río Mar, Panama (USNM 1100693); b, ovigerous female from La Chorrera, Panama (not preserved); c, male from Isla Grande, Panama (USNM 1100700); d, ovigerous female from Cahuita, Costa Rica (USNM 1100698); e, neotype female from Big Pine Key, Florida Keys (USNM 1100697); f, g, paratype ovigerous female from Bocas del Toro, Panama (USNM 1100705); h, holotype male from Bocas del Toro, Panama (USNM 1100703). Male minor cheliped ( Fig. 6 e) and female minor cheliped ( Fig. 6 g) similar; ischium short, stout; merus more than three times as long as wide proximally; ventrolateral margin straight; ventromesial margin somewhat rugose, usually with spinules ( Fig. 6 g), distally with acute tooth ( Fig. 6 g); carpus cup-shaped; chela smooth, ovate in cross-section, moderately setose distomesially ( Fig. 6 f); distomesial margin of palm with strong blunt or subacute tooth ( Fig. 6 e, f); linea impressa well marked ( Fig. 6 e); adhesive discs very small; fingers about as long as palm, without distinct rows of balaeniceps setae ( Fig. 6 f), tips strongly curved, crossing when chela closed. Second pereiopod with ischium subequal to merus ( Fig. 5 e); carpus five-segmented, ratio of carpal segments (from proximal to distal) approximately: 5/2/1.5/1.5/2 ( Fig. 5 e); chela simple, with fingers longer than palm. Third pereiopod relatively slender; ischium with ventrolateral spine ( Fig. 5 f); merus unarmed, about six times as long as wide; carpus unarmed; propodus with series of stout spines or pairs of spines along ventral margin and two spines distoventrally near articulation with dactylus ( Fig. 5 f); dactylus about 1/3 propodus length, simple, conical, gradually curved towards acute tip, with some setae ( Fig. 5 f). Fourth pereiopod similar to third pereiopod. Fifth pereiopod shorter and more slender than third and fourth pereiopods; ischium unarmed; propodus with row of spines and at least seven rows of grooming setae distolaterally; dactylus conical, as in third pereiopod. Abdominal pleura with posteroventral margins broadly rounded; sixth somite without articulated flap, dorsolateral projections on each side of telson bluntly rounded. Male second pleopod with appendix masculina reaching beyond appendix interna, with numerous slender setae along margins and on apex ( Fig. 5 g). Uropod with protopod bearing elongate acute distolateral tooth ( Fig. 5 h); exopod with strong acute distolateral tooth adjacent to distolateral spine; diaeresis bearing strong lateral tooth, mesial to distolateral spine ( Fig. 5 h); distolateral spine stout, usually tan to dark brown ( Fig. 5 h, 7h); distal margins of endopod with row of spinules ( Fig. 5 i). Telson moderately broad, subrectangular, tapering towards posterior margin ( Fig. 5 j); dorsal surface without median groove, with two pairs of strong dorsal spines, situated at some distance from lateral margins, both pairs situated in posterior half length of telson ( Fig. 5 j); posterior margin broadly rounded, with two pairs of posterolateral spines, mesial being much longer than lateral ( Fig. 5 j); anal tubercles well developed. Gill formula typical for Alpheus . Size .—The paratype from Boca del Drago (USNM 1100705), an ovigerous female, is the largest specimen in the type series, with CL 7.2 mm and TL 20.7 mm ; other specimens range from 4.6 mm to 6.9 mm in CL. Color pattern .—Body dark purple-brown, with pale yellow mediodorsal band extending from rostrum tip to posterior margin of sixth abdominal somite; carapace with white lateral band extending from anterolateral margin to cardiac notch, continued by sinuous white band ending at sixth abdominal somite; second pleuron with white, ventrally directed oblique band; fourth pleuron with small white patch next to white band; rostrum yellow, bordered by reddish brown, posteriorly widening band on margins; carapace flanks below white band and area posterior to orbital hoods pale or whitish; telson and uropods dark purple-brown with large yellow patches and spots; walking legs and second pereiopods bluish to purplish; antennular peduncles gray-brown; antennal scaphocerite mostly grayish-blue, flagella pale gray-bluish; chelipeds gray-brown; major chela with pale orange patch proximally and orange-brown patch near articulation with dactylus; dactylus gray, distally pinkish; pollex tip whitish; minor chela mostly bluish-gray ( Fig. 7 f–h); eggs reddish orange ( Fig. 7 g). Etymology .—The specific name “ paraformosus ” reflects the great resemblance of this species—in both morphology and color pattern—to A. formosus . Ecology .—Lower intertidal and shallow subtidal ( 0–5 m ); mixed sand-rubble bottoms, in crevices of coral rocks or conglomerates of dead corals among turtle grass ( Thalassia testudinum ). Type locality .—Bocas del Toro, Panama . Distribution .—Western Atlantic: Panama : Bocas del Toro ( type locality), Isla Grande, San Blas Islands; Honduras : Utila; probably more widespread in the Caribbean Sea to southern Florida. Remarks .— Alpheus paraformosus n. sp. can be separated from both A. formosus and A. panamensis by the non-balaeniceps fingers of the minor chela in both sexes ( Fig. 6 e, g) and the distinctly shorter orbitorostral grooves (compare Fig. 5 a and Fig. 1 a). The new species also appears to be somewhat smaller than A. formosus and A. panamensis (CL range 4.4–7.2 mm for A. paraformosus n. sp. compared to 5.3–14.7 mm for A. formosus and 4.7–14.7 for A. panamensis ). Differences in the color pattern between A. paraformosus n. sp. , A. formosus and A. panamensis are shown in Fig. 7 and summarized in Table 1 below. TABLE 1 . Diagnostic color pattern differences among species of the Alpheus formosus species complex. See also Knowlton & Mills (1992) for less consistent differences (expressed in percentage of individuals).

Features Adult rostrum	A. panamensis Yellow to red, margins red-	A. formosus Usually entirely yellow	A. paraformosus Yellow , margins red-brown
Juvenile rostrum Mediodorsal band Second abdominal pleuron Fourth abdominal pleuron	brown Entirely yellow With grayish band Without posterior band Without white lateral patch	Entirely yellow Without grayish band Without posterior band Without white lateral patch	Yellow, margins red-brown With grayish band With posterior band With small white lateral
Major chela	Mostly brown-orange	Mostly pale brown to	patch Mostly grey or grey-brown
Telson and uropods Egg color	Without bluish patches Yellow-orange	orange-brown Without bluish patches Orange-red	With bluish patches Orange-red

GenBank number .— EF532614 (fcn 06-454, MNHN-Na 16361), EF532615 (fcn 98-266), AF308985 , AF309905 .