Alpheus websteri Kingsley, 1880

Anker, Arthur, Hurt, Carla & Knowlton, Nancy, 2008, Revision of the Alpheus websteri Kingsley, 1880 species complex (Crustacea: Decapoda: Alpheidae), with revalidation of A. arenensis (Chace, 1937), Zootaxa 1694, pp. 51-68 : 54-59

Alpheus websteri Kingsley, 1880

Figs. 1 , 2, 3A–D, 4A

Alpheus websteri Kingsley 1880: 416 ; Abele & Kim 1986: 197, 208–209, fig. a; Martínez-Iglesias et al. 1993: 11; Martínez-Iglesias et al. 1996: 34; Martínez-Iglesias et al. 1997: 425, fig. 18; Salazar-Rosas 1995: 59, pl. 17; Christoffersen 1998: 361; McClure 2005: 156 (not fig. 24); Coelho et al. 2006: 52.

Not Alpheus websteri — Wicksten 1983: 42 (part.); Wicksten & Hendrickx 1985: 572; Kim & Abele 1988: 28, fig. 11; Villalobos Hiriart et al. 1989: 17; Wicksten & Hendrickx 1992: 5 (part.); Wicksten 1993: 151; Hendrickx 1993a: 306; Hendrickx 1993b: 6; Hendrickx 1995: 432; Camacho 1996: 64; Vargas & Cortés 1999: 902; Villalobos 2000: 66, fig. 33; Wicksten & Hendrickx 2003: 65 (part.); McClure 2005: 157, fig. 24 (= A. arenensis (Chace, 1937)) .

Alpheus Ridleyi Pocock 1890: 518 .

Alpheus ridleyi — Crosnier & Forest 1966: 230, 232, 233, 236, 237; Chace 1972: 69; Coelho & Ramos 1972: 150; Fausto Filho 1974: 5; Fausto Filho 1980: 113; Rodríguez 1980: 149, fig. 42d–f; Cubit & Williams 1983: 24; Rodríguez 1986: 153; Márquez 1988: 35, fig. 22; Hernández Aguilera et al. 1996: 34.

Not Alpheus ridleyi — Grajal & Laughlin 1984: 224 (= A. cf. armatus Rathbun, 1901 , see Rodríguez 1986).

Alpheus nigro-spinatus Rankin 1898: 249, pl. 30, fig. 6.

Crangon nigrospinatus — Schmitt, 1924: 71.

Material examined.— Dominican Republic. 1 male (CL 7.9), MNHN-Na 16362, Bayahibe, from crevices in coral rocks, depth 1–2 m, coll. A. Anker, 5 Jan 2005 [fcn 05-020, specimen sequenced]. Guadeloupe. 1 male (CL 9.2), MNHN-Na 16241, Grand Cul de Sac, shallow subtidal, coll. F. Fasquel, 2002 [02-006]. Panama (Caribbean coast). 1 ovig. female (CL 7.2), USNM 1109181, Isla Grande, south of Miraculo, from coral rocks, coll. N. Knowlton et al., 15–16 Jun 1995 [fcn C-1403, B-421, specimen dissected]; 1 male (CL 8.6), 1 ovig. female (CL 6.9), USNM 1109182, same collection data as previous specimen [fcn C-1398 + C-1399, B- 426]; 1 male (CL 7.5), 1 ovig. female (CL 6.4), USNM 1109183, same collection data as previous specimens [fcn C-1401 + C-1402, B-428]; 1 male (CL 9.5), USNM 1109184, same collection data as previous specimens [fcn C-1410, B-432]; 1 ovig. female (CL 6.9), USNM 1109185, Isla Grande, from coral rocks, coll. N. Knowlton et al., 15 Nov 1991 [fcn C-171, B-36]; 1 male (CL 7.5), USNM 1109186, same collection data as previous specimen [fcn C-172, B-37]; 1 male (CL 4.7), OUMNH-ZC 2007-13 -033, Isla Grande, NE side, exposed rocky platform, from crevices in rocks, coll. A. Anker, J. Luque and J. Vera Caripe, 16 Sep 2007 [fcn 07-263]; 1 male (CL 8.7), 1 ovig. female (CL 7.3), UP, Panama, Caribbean coast, N. Knowlton et al. coll. 15– 16 Jun 1995 [fcn B-427, B-430]; 1 specimen (sex and CL not determined), Panama, Bocas del Toro, Isla Colon, Bocas del Drago [fcn 06-500, specimen preserved in RNAlater and sequenced, not deposited]. Honduras. 1 male (CL 4.4), OUMNH-ZC 2007-20 -002, Bay Islands, Utila, southern shore, Coral View reef, 1605.326’ N 086º54.652’ W, hand collecting, from coral rocks, depth 1 m, coll. A. Anker and S. De Grave, 5 Jul 2007 [fcn H173]. Brazil. 1 ovig. female (CL 9.5), MNRJ 20149, Atol das Rocas, Piscina das Rocas, in calcareous algae, coll. P.S. Young, P.C. Paiva and A.A. Aguiar, 26 Oct 2000 [specimen dissected and sequenced].

Comparative material of Alpheus thomasi : Panama (Caribbean coast). 1 male (CL 5.8), USNM 1109187, Bocas del Toro, Isla Colón, between Big Creek and Playa Bluff, from crevices in coral rocks, depth 1–2 m, coll. A. Anker, 18 Oct 2005 [fcn 05-158]; 1 ovig. female (CL 7.7), USNM 1109188, Bocas del Toro, hospital Point, under large rock, depth 0.5–1 m, coll. A. Anker, 16 Oct 2005 [05-159]; 2 males (CL 8.0, 7.3), 2 ovig. females (CL 8.1, 7.8), MNHN-Na 16707, Bocas del Toro, Isla Colón, Boca del Drago, from crevices in coral rocks, depth 0.5–1 m, coll. A. Anker, 20 Oct 2005 [fcn 05-160]; 1 ovig. female (CL 6.5), USNM 1109189, Bocas del Toro, Isla Colón, Boca del Drago, from crevices in coral rocks, depth 0.5–1 m, coll. A. Anker, 20 Oct 2005 [fcn 05-157]; 1 ovig. female (CL 7.9), OUMNH-ZC 2007-13 -032, Isla Grande, southern shore, from coral rubble conglomerate, depth 0.5–1 m, coll. A. Anker, 4 Sep 2006 [fcn 06-430].

FIGURE. 2. Alpheus websteri Kingsley, 1880 , ovigerous female from Atol das Rocas, Brazil ( MNRJ 20149); A, frontal region, dorsal view; B, same, lateral view; C, orbito-rostral process, frontal view; D, tooth on ventromesial carina of first segment of antennular peduncle, lateral view; E, lateral antennular flagellum, lateral view; F, scaphocerite of antenna, dorsal view; G, mandible, mesial view; H, third maxilliped, lateral view; I, same, detail of coxa and arthrobranch; J, major cheliped, mesial view; K, same, chela and carpus, lateral view; L, same, coxa to carpus, lateral view; M, same, detail of pollex and dactylus with setae omitted, lateral view; N, minor cheliped, lateral view; O, same, chela and carpus, mesial view; P, second pereiopod, lateral view; Q, third pereiopod, lateral view; R, same, propodus and dactylus, lateral view; S, fifth pereiopod, lateral view; T, same, propodus and dactylus, ventrolateral view; U, right uropod, dorsal view; V, telson, dorsal view. Scale bars: 1 mm.

Description.—Carapace smooth, not setose, laterally not compressed. Rostrum relatively short, tip slightly descendant, subacute distally, fringed with long setae ( Fig. 1 A); rostral carina bluntly rounded, broad, reaching beyond eyes posteriorly ( Fig. 1 A); orbito-rostral process well developed, broadly W-shaped in frontal view, with deep, rounded median notch (Fig. 2B, C). Orbital hoods moderately inflated, distally with acute teeth ( Fig. 1 A), rarely without teeth (Fig. 2A). Frontal margin between orbital teeth and rostrum concave and sometimes slightly angular ( Fig. 1 A, R). Adrostral grooves moderately deep and narrow, not abruptly delimited from rostrum and orbital hood ( Fig. 1 A, R). Pterygostomial angle rounded, not protruding ( Fig. 1 B); cardiac notch well developed. Eyes completely concealed in dorsal, lateral and frontal view. Ocellar beak partly concealed by orbito-rostral process, vertically protruding towards rostrum, not visible in lateral view.

Antennular peduncles relatively stout, second segment distinctly longer than first, twice or more as long as wide ( Fig. 1 A, R); stylocerite distally subacute, usually reaching or slightly overreaching distal margin of first segment ( Fig. 1 A), sometimes reaching only to about 4/5 length of first segment (Fig. 2A); mesioventral carina of first segment with minute subacute tooth as illustrated ( Fig. 1 C), sometimes blunt (Fig. 2D); lateral flagellum with numerous tufts of aesthetascs ( Fig. 1 B), secondary ramus rudimentary, composed of one or two fused segments (Fig. 2E). Antenna with basicerite bearing strong, acute ventrolateral tooth, reaching to level of stylocerite tip ( Fig. 1 B); carpocerite stout, reaching slightly beyond distolateral spine of scaphocerite; distolateral tooth of scaphocerite strong, exceeding distal margin of antennular peduncle, and reaching well beyond blade ( Figs. 1 A, 2F); lateral margin of scaphocerite slightly concave ( Fig. 1 A); blade narrow, subtriangular, separated from distolateral tooth by deep cleft ( Figs. 1 A, 2F).

Mouthparts (mandible, maxillule, maxilla, first and second maxillipeds) typical for Alpheus ; mandible with incisor process bearing 10–11 rounded or subtriangular distal teeth (Fig. 2G). Third maxilliped moderately stout ( Fig. 1 D); antepenultimate segment slightly flattened, ventral margin straight; penultimate segment twice as long as wide, slightly broadening distally; ultimate segment setose, with very long setae, especially on apex ( Fig. 1 D); coxa with lateral plate ear-shaped distally, furnished with small setae ( Fig. 1 D); exopod almost reaching penultimate segment; arthrobranch well developed.

Male major cheliped ( Fig. 1 F–I, S) with short, robust ischium; merus stout, about three times as long as wide proximally, dorsal margin distally blunt ( Fig. 1 F, H); ventrolateral and ventromesial margins straight, latter distally with small acute tooth ( Fig. 1 H), rarely without tooth (Fig. 2J); carpus cup-shaped, without pronounced distal lobes ( Fig. 1 F); chela ovate, slightly compressed laterally; mesial surface of palm smooth, very setose ( Fig. 1 G); lateral surface of palm with shallow, longitudinal depression near pollex ( Fig. 1 E, S), ventral and dorsal margins of palm with shallow transverse constrictions subdistally, near fingers ( Fig. 1 E); linea impressa conspicuous ( Fig. 1 E); fingers about half-length of palm; dactylus distally rounded, with relatively short plunger, latter distally with stamen-shaped sensillae ( Fig. 1 I); adhesive discs large ( Fig. 1 E, S). Female major cheliped (Fig. 2J–M) similar to male major cheliped except for proportions of fingers to palm and general shape of palm. Male minor cheliped with merus about 2.5 times as long as wide proximally, ventrolateral and ventromesial margins straight, distally unarmed; carpus cup-shaped, distal margin with blunt process dorsomesially ( Fig. 1 K); chela palm with smooth mesial and lateral surfaces, mesial surface very setose ( Fig. 1 K); distomesial margin with triangular tooth ( Fig. 1 J, K); linea impressa conspicuous ( Fig. 1 J); fingers slightly longer than palm, not balaeniceps, with sharp, blade-like cutting margins ( Fig. 1 T), tips crossing when chela closed. Female minor cheliped (Figs. 2N, O) with merus about three times as long as wide proximally (Fig. 2N); carpus and chela as in male but distinctly more slender (Fig. 2O).

Second pereiopod slender ( Fig. 1 L); ischium slightly shorter than merus ( Fig. 1 L); carpus five-segmented, ratio of carpal segments (from proximal to distal) approximately equal to 5: 3: 1.5: 1.4: 2.2 ( Figs. 1 L, 2P); chela simple, with fingers slightly longer than palm. Third and fourth pereiopods similar in shape and length; third pereiopod with ventrally unarmed ischium ( Figs. 1 M, 2Q); merus unarmed, about four times as long as wide; carpus unarmed; propodus armed with seven spines on ventral margin, one spine on distodorsal margin and two spines on distoventral margin ( Figs. 1 N, 2R); dactylus conical, gradually curved towards acute tip, biunguiculate, secondary unguis situated on flexor margin at about 3/4 of dactylus length ( Figs. 1 N, 2R). Fifth pereiopod ( Fig. 1 S) smaller and more slender than third and fourth pereiopods; ischium unarmed ventrally; merus about six times as long as wide; propodus ventrally with six spines (including distoventral spine (Fig. 2T), ventrolaterally with at least nine rows of grooming setae (Fig. 2T); dactylus biunguiculate, conical, as in third and fourth pereiopods (Fig. 2T).

Abdominal segments with posteroventral margins broadly rounded; sixth segment without articulated flap, posterior margin straight, dorsolateral projections rounded; preanal plate rounded. Male second pleopod with appendix masculina reaching far beyond appendix interna, with slender, mostly apical setae ( Fig. 1 O); in larger males setae present along outer margin, from about mid-length to apex. Uropod ( Fig. 1 P) with protopod bearing one robust acute lateral tooth and one subacute mesial tooth distally; exopod with lateral portion of diaeresis bearing four teeth: one blunt tooth at about mid-length, one strong acute tooth mesial to distolateral spine and two acute teeth lateral to distolateral spine = doubled distolateral tooth ( Fig. 1 P); distolateral spine very stout, especially in males, reaching beyond posterior margin of exopod, black or dark brown ( Figs. 1 P, 2U); distal margins of exopod without spinules. Telson ( Figs. 1 Q, 2V) moderately broad, more or less tapering towards posterior margin; dorsal surface without median groove, with two pairs of strong dorsal spines, situated at some distance from lateral margins, anterior and posterior to telson mid-length, respectively ( Figs. 1 Q, 2V); posterior margin almost straight ( Fig. 1 Q) to slightly convex (Fig. 2V), with two pairs of posterolateral spines, mesial being three times longer than lateral; anal tubercles well developed. Gill formula typical for Alpheus .

Color pattern.—Background color pale grey to cream whitish; carapace with two broad transverse brown bands, one band at about mid-length, extending anteriorly on mid-dorsal line, and one more posterior band, extending anteriorly dorsolaterally (Fig. 3A); both bands abruptly changing direction on carapace flanks (Fig. 3D); two small short brown bands present anterolaterally, ventrally and posteroventrally to orbital hoods (Fig. 3D); rostral area also brownish, in particular rostral carina; inner organs visible through carapace dorsally as large brownish patch; abdomen with six broad (except first) straight transverse brown bands extending to ventral margin of pleurae, abruptly changing direction laterally (towards posterior); second abdominal band bifurcating laterally, reverse V-shaped (Fig. 3D); sixth abdominal somite almost completely brown; white bands between bands with sparse but quite large spots of egg-yellow chromatophores (Fig. 3A, C); tail fan mostly purple-brown, with large white areas and bright egg-yellow spots, proximal portion of telson and uropods whitish, with egg-yellow spots, dorsal spines yellowish or whitish; distolateral spine black; walking legs and second pereiopods appearing pinkish semitransparent speckled with minute red chromatophores except on articulations; cheliped merus and carpus brown laterally; mesial face of palm of major chela mostly pale brown with white areas and brown patches and fairly large dark brown spots on distal half (Fig. 3B, D), most proximal portion of palm white; pollex brown with whitish tip; dactylus brown-white with dark spots proximally, pink distally (Fig. 3B); palm of minor chela brown-orange, with white areas and brown spots; fingers dark brown, white towards tip (Fig. 3B, D); antennular peduncles brown distally, whitish proximally; basicerite and scaphocerite mostly whitish, with occasional brown-orange spots, lateral margin and distolateral tooth of scaphocerite brown-orange; antennular and antennal flagella pale brown; corneas grey-brown (Fig. 3A–D); juveniles similar, but with more contrasting pattern on chelae and narrower bands on abdomen (Fig. 4A).

Size.—The two largest examined specimens are a male from Isla Grande, Panama, with CL 9.5 mm and TL 25.3 mm, and the aberrant female from Atol das Rocas, Brazil with CL 9.5 mm and TL 30 mm.

Ecology.—Intertidal and shallow subtidal, probably to about 10 m, in coral and rock crevices on sand and coral-sand bottoms.

Type locality.—Florida Keys, Florida, USA.

Distribution.—Western Atlantic: southeastern USA: Florida Keys ( Kingsley 1880); Bahamas: New Providence ( Rankin 1898); eastern Mexico: Quintana Roo (Bahía de la Ascensión, Bahía del Espíritu Santo) and Cozumel ( Chace 1972; Hernández Aguilera et al. 1996; McClure 2005); Honduras: Utila (present study); Cuba: Batabano Gulf ( Martínez-Iglesias et al. 1997); Dominican Republic: Bayahibe; Panama: Bocas del Toro, Isla Grande, Colón ( Cubit & Williams 1983; present study); Venezuela: Los Roques and Distrito Federal ( Rodríguez 1980); Lesser Antilles: Anguilla, Antigua, Saint Lucia, Tobago ( Chace 1972); Guadeloupe (present study); Barbados ( Schmitt 1924); northeastern Brazil: Fernando do Noronha ( Pocock 1890) and Atol das Rocas (present study). An unpublished record from Alagoas, Brazil ( Souza 2001) needs confirmation; the almost schematic illustrations in this study may actually represent A. thomasi and not A. websteri (A. Anker, pers. obs.).

Remarks.—The ovigerous female from Atol das Rocas (MNRJ 20149) (Fig. 2) is remarkable in lacking orbital teeth (Fig. 2A), bearing a short, ascendant rostrum (Fig. 2B) and having no trace of a distomesial tooth on the merus of the major cheliped (Fig. 2J). In all other features of the chelipeds (Fig. 2J–O), second to fifth pereiopods (Fig. 2P–S), tail fan (Fig. 2U, V), third maxilliped (Fig. 2H, I), antennules and antenna (Fig. 2A, B, F), this specimen agrees well with the Caribbean A. websteri specimens.

The more slender minor chela (Fig. 2N, O) and the less stout uropodal spine (Fig. 2U) appear to occur generally in females of A. websteri . Moreover, the color of the uropodal spine in females of A. websteri apparently varies from brown, as in the female from Atol das Rocas (Fig. 2U), to shiny black, as in most Caribbean females ( Fig. 1 P). The shape of the ventromesial carina of the first segment of the antennular peduncle – blunt in the specimen from Atol das Rocas (Fig. 2D) vs. with small subacute tooth in the specimen from Panama ( Fig. 1 C) – may be somewhat variable, as observed in other specimens of A. websteri from the Caribbean, as well as other Alpheus species (A. Anker, pers. obs.). A comparison of the COI gene sequence between the Caribbean specimens and the female from Atol das Rocas resulted in the latter falling within the variation range of the Caribbean samples. Therefore, this single specimen is considered as an aberrant individual of A. websteri . The lack of distinct orbital teeth and distomesial tooth on the chelipeds in large specimens could be due to wearing away from use or from bluntening (polishing) during molting (see also under A. rugimanus ). The abnormal frontal region can also be result of a physical damage (injury). Unfortunately, no other specimens of A. websteri were collected at Atol das Rocas.

In the field, A. websteri may be confused with the sympatric A. thomasi , which ranges from southern Florida to Panama and Brazil ( Hendrix & Gore 1973; Christoffersen 1998; present study). However, the latter species can be easily distinguished from A. websteri by the frontal margin between the rostrum and the orbital hoods being more deeply notched; the slenderer major and minor chelae; the uropod with a distinctly narrower distolateral spine and with a simple distolateral tooth on the diaeresis (doubled in A. websteri ); and several features on the third pereiopod, including the distinctly slenderer merus, a simple dactylus (biunguiculate in A. websteri ), and most importantly, the presence of a ventrolateral spine on the ischium (absent in A. websteri ) (see Hendrix & Gore 1973). Alpheus thomasi can also be distinguished from A. websteri by several details of the color pattern, the most important being the absence of spots on the major chela (compare Figs. 5D, E and 4A–D).

GenBank number.— EU339467 [05-020, MNHN-Na 16362, Dominican Republic], EU339468 [06-500, not deposited, Panama], EU339469 [F119, not deposited, Panama], EU339470 [AA-AC-42, MNRJ 20149, Atol das Rocas, Brazil].

Figures

FIGURE 1. Alpheus websteri Kingsley, 1880, male from Isla Grande, Caribbean coast of Panama (USNM 1109181) (A – Q), male from Guadeloupe (MNHN-Na 16241) (R – T); A, frontal region, dorsal view; B, same, lateral view; C, tooth on ventromesial carina of first segment of antennular peduncle, lateral view; D, third maxilliped, lateral view; E, major cheliped, chela, lateral view; F, same, coxa to carpus, lateral view; G, same, chela, mesial view; H, same, detail of mesioventral margin of merus and carpus, mesial view; I, same, dactylus, lateral view; J, minor cheliped, lateral view; K, same, chela, mesial view; L, second pereiopod, lateral view; M, third pereiopod, lateral view; N, same, distal propodus and dactylus, lateral view; O, second pleopod, appendix masculina and appendix interna, mesial view; P, right uropod, dorsal view; Q, telson, dorsal view; R, frontal region, dorsal view; S, major chela, lateral view; T, minor chela, lateral view. Scale bars: 1 mm.