Alpheus coetivensis Coutière, 1908

Anker, Arthur, 2010, On two snapping shrimps, Alpheus baccheti n. sp. and A. coetivensis Coutière from the Tuamotu Islands, French Polynesia (Crustacea, Decapoda), Zootaxa 2492, pp. 49-62 : 58-60

Alpheus coetivensis Coutière, 1908

Figs. 6 , 7

Alpheus Coetivensis Coutière 1908: 20 .

Alpheus coetivensis — Coutière 1921: 427, pl. 64, fig. 23; Banner & Banner 1979: 26; Banner & Banner 1983: 23; Banner & Banner 1984: 37; Bruce 1984: 154.

Crangon edmondsoni Banner 1953: 78 , fig. 26.

Alpheus edmondsoni — Banner 1956: 345; Banner 1959: 141; Banner & Banner 1964: 91; Miya 1984: 93.

Material examined.— 1 male (CL 9.3 mm), 2 ovigerous females (CL 10.5 mm, 11.3 mm), FLMNH UF Arthropoda 18560, French Polynesia, Tuamotu Archipelago, Makemo, lagoon, reef flat, 1–3 m, coll. P. Bacchet and J. Letourneaux, April 2009.

Description.—See Coutière (1908, 1921) and Banner (1953), latter as Crangon edmondsoni (but see remarks below).

Colour pattern.—Carapace and abdomen with five red-brown longitudinal bands on opaque whitish background: one narrow mediodorsal band, running within broad white dorsal band from post-rostral area to posterior margin of sixth abdominal somite; two broad dorsolateral (= parasagittal) bands, one on each side, running from rostral margins to posterior margin of sixth abdominal somite; two broad lateral bands, one on each side, running from anterolateral margin of carapace to sixth abdominal somite, latter band gradually fading ventrally, expanding to branchiostegal region on carapace and to ventral margins of pleurae on abdomen, here sometimes forming dark-brown fringe (in females); two additional shorter bands present on flanks of carapace, running each from anterior margin below orbital hoods to about mid-length of carapace; both dorsal white band and dorsolateral red-brown bands speckled with yellow chromatophores; telson whitish with brown bands, patches and yellow chromatophores; uropods brownish with yellow chromatophores; antennular peduncles and antennal bases orange-yellow; antennular and antennal flagella pale-brown; walking legs and second pereiopod reddish or pinkish with white articulations, proximal articles more yellow; chelipeds pale hyaline-yellow proximally (ischium to carpus), chelae bright blue with slight purplish tinge, palm of major chela with pinkish patch on distomesial margin, tip of dactylus pink ( Fig. 7 a, b).

Type locality.—Coëtivy Island, Seychelles.

Distribution.—Known from several localities in the Indo-West Pacific; Indian Ocean: Coëtivy Island, Seychelles ( Coutière 1908, type locality); Salomon Island, Chagos Archipelago ( Coutière 1921); Comoro Islands ( Banner & Banner 1979); Somalia ( Banner & Banner 1983); Pacific Ocean: Saipan, Mariana Archipelago ( Banner 1956, as A. edmondsoni ); Truk (Chuuk), Caroline Islands, Federate States of Micronesia ( Miya 1984, as A. edmondsoni ); Christmas Island, Line Islands ( Banner & Banner 1964, as A. edmondsoni ); Bougainville, Solomon Islands ( Banner & Banner 1984); Oneroa, Cook Islands; Raroia Atoll, Tuamotu- Gambier Archipelago ( Banner 1959, as A. edmondsoni ); Oahu and Maui, Hawaiian Archipelago ( Banner 1953, type locality of A. edmondsoni ).

Ecology.—The Makemo specimens were collected under rocks and coral rubble on a reef flat (0.5 m); the Raroia specimens came from a “high surf energy area from a surge channel, on outer reef beyond Lithothamnion ridge” ( Banner 1959; Banner & Banner 1983); elsewhere reported mostly from reef habitats ( Banner & Banner 1983); most Hawaiian specimens described as A. edmondsoni were collected from coral heads in the intertidal, “mostly in areas that seldom are beset by high waves”, although some came from a depth of 45 m ( Banner 1953; Banner & Banner 1983).

Remarks.— Banner & Banner (1983) examined one of Coutière’s syntypes of A. coetivensis deposited in the MNHN, an adult male, and contrasted it to A. edmondsoni from Hawaii. They concluded that the two nominate species must be regarded as the same species and placed A. edmondsoni in the synonymy of A. coetivensis . The slight differences between A. edmondsoni and A. coetivensis were explained by Coutière’s (1921) inaccuracies in the description of the major cheliped and in the figures of the rostro-orbital region. However, three important features of P3 were not discussed by Banner & Banner (1983): the presence of a movable spiniform seta on the ischium, a distodorsal spiniform seta on the propodus, and two small but distinct dorsal notches on the dactylus. These features were not illustrated by Coutière (1921, pl. 64, fig. 23d), but are present in the Makemo specimens ( Fig. 6 a–c), as well as in A. edmondsoni from Hawaii ( Banner 1953, fig. 26m, n). At the author’s request, Régis Cleva (MNHN) examined P3–4 of the largest syntype of A. coetivensis and confirmed that a spiniform seta is indeed present on the ischium and two distodorsal spiniform setae are present on the propodus; however, the dactylus does not seem to be notched dorsally. The subtle difference in the dactylus of P3–4 alone is probably not significant enough to warrant a separation of A. edmondsoni from A. coetivensis . With the present morphological evidence, it seems to be more reasonable to accept the synonymy proposed by Banner & Banner (1983) and report all Pacific specimens as A. coetivensis . However, collection of fresh material in the western Indian Ocean (to document the colour pattern of the Indian Ocean form) and comparative DNA analyses will be necessary to readdress the taxonomic status of A. edmondsoni .

(FLMNH UF Arthropoda 18560): a, shrimp shortly after capture; b, shrimp in situ. Photographs by Philippe Bacchet.

Figures

FIGURE 6. Alpheus coetivensis Coutière, 1908, ovigerous female (CL 11.3 mm) from Makemo, Tuamotu Islands (FLMNH UF Arthropoda 18560): a, third pereiopod, lateral; b, same, detail of distal propodus and dactylus; c, same, detail of distal portion of dactylus.

FIGURE 7. Alpheus coetivensis Coutière, 1908, ovigerous female (CL 11.3 mm) from Makemo, Tuamotu Islands