Alpheus paraformosus, Anker, Arthur, Hurt, Carla & Knowlton, Nancy, 2008

Anker, Arthur, Hurt, Carla & Knowlton, Nancy, 2008, 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), Zootaxa 1707, pp. 1-22 : 12-17

publication ID	https://doi.org/ 10.5281/zenodo.180922
DOI	https://doi.org/10.5281/zenodo.6233709
persistent identifier	https://treatment.plazi.org/id/D16A1836-FFA0-FFBA-8386-FE78FE85C5F0
treatment provided by	Plazi
scientific name	Alpheus paraformosus
status	sp. nov.

Treatment

Alpheus paraformosus View in CoL n. sp.

Figs. 5 View FIGURE 5 , 6 View FIGURE 6 , 7 View FIGURE 7 f–h

Alpheus formosus View in CoL -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 View FIGURE 5 a, k); tip acute, not reaching distal margin of first segment of antennular peduncle ( Fig. 5 View FIGURE 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 View FIGURE 5 a, k). Adrostral furrows deep, narrow, abruptly delimited from rostrum, posteriorly extending almost to about mid-length of cornea ( Fig. 5 View FIGURE 5 a). Pterygostomial angle rounded, slightly protruding anteriorly ( Fig. 5 View FIGURE 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 View FIGURE 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 View FIGURE 5 a); stylocerite with acute tip, distinctly overreaching distal margin of first segment ( Fig. 5 View FIGURE 5 a, b); mesioventral carina of first segment with large, bluntly protruding tooth (nearly identical to that of A. formosus , cf. Fig. 1 View FIGURE 1 c); lateral flagellum with numerous tufts of aesthetascs, ascessory ramus rudimentary ( Fig. 5 View FIGURE 5 b). Antenna with stout basicerite bearing strong acute ventrolateral tooth, its tip not reaching level of stylocerite tip ( Fig. 5 View FIGURE 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 View FIGURE 5 a), tip of distolateral tooth reaching far beyond blade and slightly exceeding end of antennular peduncle ( Fig. 5 View FIGURE 5 a); lateral margin of scaphocerite straight to very slightly concave at mid-length ( Fig. 5 View FIGURE 5 a).

Mouthparts (mandible, maxillule, maxilla, first and second maxillipeds) typical for Alpheus . Third maxilliped moderately stout ( Fig. 5 View FIGURE 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 View FIGURE 5 d).

Male major cheliped ( Fig. 6 View FIGURE 6 a–d) with short, stout ischium; merus stout, about 2.5 times as long as wide proximally, dorsal margin distally protruding ( Fig. 6 View FIGURE 6 a, b); ventrolateral margin straight; ventromesial margin straight, with small spinules ( Fig. 6 View FIGURE 6 a), distally with acute tooth ( Fig. 6 View FIGURE 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 View FIGURE 6 a, c); linea impressa conspicuous ( Fig. 6 View FIGURE 6 b); adhesive discs relatively large ( Fig. 6 View FIGURE 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 View FIGURE 6 d). Female major cheliped similar to that of male, except for somewhat smaller size and different proportions of fingers to palm.

Male minor cheliped ( Fig. 6 View FIGURE 6 e) and female minor cheliped ( Fig. 6 View FIGURE 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 View FIGURE 6 g), distally with acute tooth ( Fig. 6 View FIGURE 6 g); carpus cup-shaped; chela smooth, ovate in cross-section, moderately setose distomesially ( Fig. 6 View FIGURE 6 f); distomesial margin of palm with strong blunt or subacute tooth ( Fig. 6 View FIGURE 6 e, f); linea impressa well marked ( Fig. 6 View FIGURE 6 e); adhesive discs very small; fingers about as long as palm, without distinct rows of balaeniceps setae ( Fig. 6 View FIGURE 6 f), tips strongly curved, crossing when chela closed.

Second pereiopod with ischium subequal to merus ( Fig. 5 View FIGURE 5 e); carpus five-segmented, ratio of carpal segments (from proximal to distal) approximately: 5/2/1.5/1.5/2 ( Fig. 5 View FIGURE 5 e); chela simple, with fingers longer than palm. Third pereiopod relatively slender; ischium with ventrolateral spine ( Fig. 5 View FIGURE 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 View FIGURE 5 f); dactylus about 1/3 propodus length, simple, conical, gradually curved towards acute tip, with some setae ( Fig. 5 View FIGURE 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 View FIGURE 5 g). Uropod with protopod bearing elongate acute distolateral tooth ( Fig. 5 View FIGURE 5 h); exopod with strong acute distolateral tooth adjacent to distolateral spine; diaeresis bearing strong lateral tooth, mesial to distolateral spine ( Fig. 5 View FIGURE 5 h); distolateral spine stout, usually tan to dark brown ( Fig. 5 View FIGURE 5 h, 7h); distal margins of endopod with row of spinules ( Fig. 5 View FIGURE 5 i). Telson moderately broad, subrectangular, tapering towards posterior margin ( Fig. 5 View FIGURE 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 View FIGURE 5 j); posterior margin broadly rounded, with two pairs of posterolateral spines, mesial being much longer than lateral ( Fig. 5 View FIGURE 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 View FIGURE 7 f–h); eggs reddish orange ( Fig. 7 View FIGURE 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 View FIGURE 6 e, g) and the distinctly shorter orbitorostral grooves (compare Fig. 5 View FIGURE 5 a and Fig. 1 View FIGURE 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 View FIGURE 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).

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