Alpheus percyi Coutière, 1908

Anker, Arthur, 2013, Notes on two rare and little-known Indo-Pacific snapping shrimps, Alpheus percyi Coutière, 1908 and A. pseudopugnax (Banner, 1953) (Decapoda, Alpheidae), Zootaxa 3722 (2), pp. 267-282 : 268-272

Alpheus percyi Coutière, 1908

( Figs. 1–5 , 11 A–D)

Alpheus Percyi Coutière 1908: 211 ; Coutière 1921: 426, pl. 64, fig. 22 (spelled A. percyi ). Alpheus percyi — Banner 1957: 203; Banner & Banner 1968: 288; Banner & Banner 1983: 62; De Grave & Fransen 2011: 388. Alpheus pearcyi (lap. cal.) — Hayashi et al. 1994: 270.

Crangon percyi — Banner 1953: 124, fig. 45.

Material examined. 1 female, lectotype (cl 8.1 mm), MNHN 3188, Seychelles, Amirante Islands, Percy Sladen Trust Expedition sta. E II, no further data; 1 male (cl 4.8 mm), MNHN 3486, Amirante, Percy Sladen Trust Expedition sta. E II; 1 male (cl 6.8 mm), 1 female (cl 6.7 mm), UF 12372, Hawaiian Islands, French Frigate Shoals, Arc Shell Reef, 23.765° -166.169°, depth ~ 10 m; rubble extraction, leg. R. Brainard and B. Zgliczynski, 17 Oct 2006 [fcn FFS-0104]; 1 male (cl 6.1 mm), UF 15237, Hawaiian Islands, Oahu, off Kewalo, 21.289° -157.865°, outer reef slope, settling plates, depth 9–12 m, leg. R. Moffitt, 1 Dec 2008 [fcn BOAHU-177]; 1 female (cl 4.8 mm), UF 16336, French Polynesia, Society Islands, Moorea, west of Cook’s Bay, northwest of Pihaena, outer reef slope, depth 4–7 m, spur and groove zone, in large piece of dead Acropora , leg. S. McKeon, J. Moore, A. Anker, S. Ivanenko, 10 Nov 2008 [fcn BMOO-5260]; 1 male (cl 7.5 mm), MNHN-IU-2011-8936, French Polynesia, Marquesas, bank east of Motane, sta. MQ17-R, 9°59.845' -138°10.716', depth 35–40 m, outside of cave, leg. J. Starmer et al., 19 Jan 2012 [fcn LC193]; 1 female (cl 6.5 mm), UF 10662, Kiribati, Line Islands, Tabuaeran Atoll, S-SW side of atoll, 3.8051° -159.3021°, outer reef slope, depth 10–23 m, in dead Pocillopora heads, leg. G. Paulay and N. Knowlton, 13 Aug 2005 [fcn BTAB-643]; 1 male (cl 5.2 mm), UF 10986, Kiribati, Line Islands, Kiritimati Atoll, South of main reef passage, 1.8913° -157.5448°, outer reef slope, in dead Pocillopora heads, leg. N. Knowlton and G. Paulay, 8 Aug 2005 [fcn BLINX-309]; 1 female (cl 8.2 mm), UF 3120, Mariana Islands, Guam, Orote, northern tip, Harry’s rubble field, under dead coral rubble and boulders, depth 25 m, leg. L. Kirkendale, 20 Jun 2002 [fcn LAK-124]; 1 female (cl 7.1 mm), MNHN-IU-2013-0927, Papua New Guinea, Madang lagoon, off Kranket Island, sta. PB28, depth 10–12.6 m, rubble brushing and basket, leg. B. Faure et al., 24 Nov 2012 [fcn PZD-359F].

Description. Small-sized species of Alpheus (cl range 4.8–8.1 mm). Carapace with small post-rostral tubercle on mid-dorsal line, at about 0.25 carapace length, separating more or less descendant frontal area from horizontal or slightly domed posterior area; post-rostral tubercle continued by low, sometimes barely discernable, mid-dorsal crest flattening completely before reaching posterior margin of carapace ( Figs. 1 A, B, 3A, B). Rostrum welldeveloped, dorsally flattened, abruptly rising above deep orbito-rostral furrows, forming narrowly triangular, posteriorly more or less broadening plate, latter without median carina; lateral margins of rostral plate overhanging orbito-rostral furrows; rostral tip not reaching distal margin of first article of antennular peduncle, slightly descendant ( Figs. 1 A, B, 3A, B). Orbital hoods unarmed, rounded anteriorly ( Figs. 1 A, 3A). Pterygostomial angle broadly rounded ( Figs. 1 B, 3B). Telson moderately broad, tapering distally; dorsal spiniform setae stout, inserted far from lateral margins; posterior margin broadly rounded, with two pairs of distolateral spiniform setae, mesial much longer than lateral, and row of smaller spiniform setae ( Figs. 1 I, J, 3I, J). Antennular peduncle with slender stylocerite, its acute tip overreaching distal margin of first article; second article about 1.5-1.6 times as long as wide ( Figs. 1 A, 3A). Antenna with stout basicerite armed with strong, sharp distoventral tooth; carpocerite not exceeding scaphocerite; scaphocerite with broadly concave lateral margin, strong distolateral tooth reaching well past end of antennular peduncle, blade moderately broad ( Figs. 1 A, B, 3A, B). Third maxilliped with antepenultimate article not expanded; penultimate article slightly more than twice as long as wide ( Fig. 3 C). Minor cheliped significantly smaller and more slender than major cheliped; merus with dorsal margin ending in stout distodorsal tooth, mesial margin armed with widely spaced spiniform setae and ending in small, sharp distomesial tooth; carpus cup-shaped; chela with palm subcylindrical, rounded in cross-section, smooth, with strong sharp distomesial and distolateral teeth on each side of dactylar articulation; fingers slightly shorter than palm, conical, non-gaping, dactylus with more or less developed ridge bearing row of balaeniceps setae in males, simple in females ( Figs. 2 A-C, 4A-C). Major cheliped with short, stout merus; dorsal margin of merus ending in strong, curved distodorsal tooth; mesial margin of merus rugose, with widely spaced, stout spiniform setae, ending in strong, sharp distomesial tooth; carpus very short, bowl-shaped; chela with palm ovoid, rounded in cross-section, smooth except for deep transverse groove on distodorsal surface; fingers less than half-length of palm, dactylus with very short, truncate plunger ( Figs. 2 D-F, 4D-G). Second pereiopod with first carpal article 1.0-1.4 times as long as second ( Figs. 1 C, 3D). Third and fourth pereiopods similar, slender; ischium with spiniform seta; merus ~4.5 times as long as wide, with stout, sharp distoventral tooth; carpus with sharp distoventral tooth; propodus with row of slender spiniform setae on ventral margin (some inserted in pairs), as well as one pair of distoventral and one distodorsal spiniform setae; dactylus simple, conical, slightly curving, about 0.3 length of propodus ( Figs. 1 D, E, 3E, F). Fifth pereiopod more slender than third and fourth pereiopods; ischium with small spiniform seta; propodus with row of slender spiniform setae on ventral margin, cleaning brush poorly developed. Male second pleopod with appendix masculina reaching far beyond appendix interna ( Fig. 1 F). Uropod with exopod slightly longer than endopod; protopod with lateral lobe ending in strong, sharp tooth; exopod with diaeresis sinuous, ending in strong sublateral tooth, distolateral tooth strong; distolateral spiniform seta long, slender; endopod with row of slender spiniform setae on distal margin ( Fig. 1 G, H, 3G, H). See also description and illustrations in Coutière (1908, 1921) and Banner (1953).

Colour pattern. Body brown to reddish-orange background covered with whitish patches and spots of various sizes and shapes, mostly rounded on carapace, often interconnecting and forming more complex transverse pattern on dorsal surface of each somite; posterior area of carapace and first abdominal somite mostly white, resulting in broad, white transverse band conspicuously interrupting main red-orange pattern; second to fourth abdominal somites each with bright white area dorsally; first somite with three aligned, dark orange to brown-red, dorsal spots, median most conspicuous; third somite with two conspicuous dark-orange to brown-red dorsolateral spots; fifth somite with one dark-orange to brown-red dorsal (median) spot; antennular and antennal peduncles pale orange with white areas, flagella pale yellowish orange; minor chela bright orange-reddish with small white spots on mesial surface; major chela orange-red with abundance of conspicuous white spots and blotches on mesial surface, dactylus bright purple, especially proximally, purple colour fading to almost white distally; second pereiopods and walking legs reddish-orange interrupted by broad white transverse bands; tail fan reddish-orange distally (except for small white area near distolateral spine), whitish mixed with some orange patches proximally ( Fig. 5 A–F); young female from Moorea with generally similar, although darker, more contrasting red-brown pattern, and in addition, with proportionally more white areas on major chela and wider white bands on abdomen; third abdominal somite with two characteristic dark spots; dactylus distinctively pale purple ( Fig. 5 G).

Distribution. Indo-West Pacific from southwestern Indian Ocean to Hawaii and French Polynesia. Indian Ocean: Cargados Carajos Shoals 300 km northwest of Mauritius; Amirante and Coëtivy Islands, Seychelles (Coutière 1908, 1921). Pacific Ocean: Arno and Rongerik Atolls, Marshall Islands (Banner 1957; Banner & Banner 1968); Asuncion Island and Guam, Mariana Islands (Hayashi et al. 1994; present study); Ifaluk Atoll, Caroline Islands (Banner & Banner 1968); Kiritimati Atoll, Line Islands; Madang, Papua New Guinea; Motane, Marquesas Islands; Moorea, Society Islands (present study); Oahu, Hawaii and French Frigate Shoals, Hawaiian Islands (Banner 1953; present study).

Ecology. Coral reef and associated habitats, in dead coral heads and in or under coral rubble; depth range: 5–91 m [e.g., 46–91 m (Cargados Carajos, Amirante), 25 m ( Guam), 35–40 m (Marquesas), 12–20 m (Moorea), 10–12 m ( Papua New Guinea), 5–13 m (Hawaii)].

Remarks. Three of the four original syntypes of A. percyi in Coutière (1908), viz. one large male and one large female from Cargados Carajos Shoals, and one small male from Coëtivy, remain untraceable. The Muséum National d’Histoire Naturelle in Paris (MNHN) currently has only two specimens labeled as A. percyi , a larger female and a smaller male; both are from Amirante sta. E II of the Percy Sladen Expedition. The female was labeled as “co-type” = syntype (MNHN 3188) and therefore is here designated as lectotype of A. percyi . It matches well the original description in Coutière (1908) and illustrations in Coutière (1921), with a few exceptions (see below). The vial containing the smaller male (MNHN 3486) has no mentioning of it being a syntype; instead it has an additional label with H. Coutière’s writing: “n. sp. proche à [A.] lanceloti ” = new species close to A. lanceloti Coutière, 1908 , a species not closely related to A. percyi (see description and figures in Coutière 1905 for comparison).

The non-type male from Amirante (MNHN 3486) and the young female from Moorea (UF 16336) were tentatively assigned to Alpheus percyi , because they differ in several aspects from the other, more typical specimens of this species. The most important difference of these specimens is the considerably narrower postrostral plate, its anterior portion being almost as narrow as a typical rostral carina (compare Figs. 1 A, 11A–C and Figs. 3 A, 11D). It appears that the postrostral plate is generally variable in A. percyi , being more slender in younger individuals ( Fig. 11 A–D). Another important difference is the ratio of the carpal articles of the second pereiopod (female lectotype: 3.0/2.2/1.0/1.0/1.6, male from Amirante: 2.3/2.3/1.0/1.0/1.3; see also Figs. 1 C, 3D). Coutière (1921) noted that the first and second carpal articles of the second pereiopod are subequal in length. He also provided two illustrations, one showing the first article noticeably longer than the second (Coutière 1921, fig. 22) and the other showing the first and second article being of almost the same length (idem., fig. 22c). This suggests that the length proportions of the first two carpal articles of the second pereiopod in A. percyi are also variable. The female from Moorea also differs from the more typical A. percyi in the relative length of the second article of the antennular peduncle (compare Fig. 1 A and Fig. 3 A). On the other hand, the colour pattern of the female from Moorea ( Fig. 5 G) appears to be a juvenile pattern of A. percyi ( Fig. 5 A–F), not only in its general aspects, but also in some important diagnostic details, such as the purple dactylus of the major chela and the presence of two dark spots on the third abdominal somite. In the absence of molecular data (no COI sequences could be obtained from the Moorea specimen), the male from Amirante and the female from Moorea are treated as young specimens of A. percyi .

The colour pattern of A. percyi is remarkably similar to that of A. roseodigitalis Nomura & Anker, 2005 , a species from the A. gracilipes Stimpson, 1860 species complex recently revised by Nomura & Anker (2005). Both A. percyi and A. roseodigitalis are characterised by an intricate banding on the abdomen, similarly disposed dark spots on the first and third abdominal somites, major and minor chela covered with numerous spots and blotches, and major chela dactylus conspicuously purple or purplish pink (see Nomura & Anker 2005, fig. 14, D–F). This colour pattern is very different from the red-banded colour pattern of A. pseudopugnax (see below). However, the latter species is morphologically closer to A. percyi by the presence of a distoventral tooth on the meri of the third and fourth pereiopods, which is lacking in A. roseodigitalis and all other species assigned to the A. gracilipes species complex by Nomura & Anker (2005). This discrepancy between morphology and colour pattern is interesting and needs to be explored further by molecular analyses.

Figures

FIGURE 1. Alpheus percyi Coutière, 1908, male from French Frigate Shoals, Hawaiian Archipelago (UF 12372): A—frontal region, dorsal view; B—same, lateral view; C—second pereiopod, lateral view; D—third pereiopod, lateral view; E—same, distal carpus, propodus and dactylus, lateral view; F—second pleopod, appendices masculina and interna, mesial view; Guropod, dorsal view; H—same, spiniform setae on distal margin of endopod, dorsal view; I—telson, dorsal view; J—same, posterior margin, dorsal view.

FIGURE 2. Alpheus percyi Coutière, 1908, male from French Frigate Shoals, Hawaiian Archipelago (UF 12372): A—minor cheliped, lateral view; B—same, carpus and chela, mesial view; C—same, ischium, merus and carpus, mesial view; D—major cheliped, lateral view; E—major chela, mesial view; F—major chela, lateral view.

FIGURE 3. Alpheus percyi Coutière, 1908, young female from Moorea, French Polynesia (UF 16336): A—frontal region, dorsal view; B—same, lateral view; C—third maxilliped, lateral view; D—second pereiopod, lateral view; E—third pereiopod, lateral view; F—same, distal carpus, propodus and dactylus, lateral view; G—uropod, dorsal view; H—same, spiniform setae on distal margin of endopod, dorsal view; I—telson, dorsal view; J, same, posterior margin, dorsal view.

FIGURE 4. Alpheus percyi Coutière, 1908, young female from Moorea, French Polynesia, UF 16336: A—minor cheliped, lateral view; B—same, carpus and chela, mesial view; C—same, ischium, merus and carpus, mesial view; D—major cheliped, lateral view; E—major chela, lateral view; F—major chela, mesial view; G—distal major chela, fingers opened, lateral view.

FIGURE 5. Alpheus percyi Coutière, 1908: A—female from Tabuaeran Atoll, Line Islands, UF 10662; B— male from Kiritimati Atoll, Line Islands, UF 10986; C—male from Oahu, Hawaiian Archipelago, UF 15237; D—male from the Marquesas Islands, French Polynesia, MNHN-IU- 2011 - 8936; E—female from Moorea, French Polynesia, not deposited; Fsame, close-up of major chela fingers; G—young female from Moorea, French Polynesia, UF 16336. Photographers: Gustav Paulay (A, B, C); Joseph Poupin (D); Matthieu Leray (E, F); Arthur Anker (G).

FIGURE 11. Variation in the shape of the postrostral region in Alpheus percyi Coutière, 1908 (A – D) and Alpheus pseudopugnax (Banner, 1953) (E – G): A—holotype female from Amirante, MNHN 3188; B—female from Tabuaeran, Line Islands, UF 10662; C—male from Oahu, Hawaiian Archipelago, UF 15237; D—non-type male of Alpheus percyi (?) from Amirante, MNHN 3486; E—holotype female from Maui, Hawaiian Archipelago, USNM 93513; F—ovigerous female from Reunion Island (La Réunion), UF 12880; G—female from Palmyra Atoll, Line Islands, UF 10622.