Metalpheus rostratipes (Pocock, 1890)

(Fig. 11 A, B)

Alpheus rostratipes Pocock 1890: 522; Crosnier & Forest 1966: 246, figs. 12–14; Coelho & Ramos 1972: 149; Fausto Filho 1975: 79; Fausto Filho 1980: 113.

Alpheus ? rostratipes— Fausto Filho 1974: 5.

Crangon rostratipes — Schmitt 1924: 65.

Metalpheus rostratipes— Chace 1972: 78; Banner & Banner 1982: 285, fig. 87; Abele & Kim 1986: 19, 194, 228, 229, figs. c-f; Manning & Chace, 1990: 16; Hayashi 1996: 382, figs. 307d–f, 308c–f; Christoffersen 1998: 361; Coelho et al. 2006: 52; Alves et al. 2008: 49; Souza et al. 2011: 47.

Metalpheus cf. rostratipes — Anker et al. 2006: 2510, fig. 1l.

[for more complete synonymy see De Grave & Fransen (2011)]

Material examined. Brazil: 3 males, 5 females, MZUSP 30228, Trindade Island, Parcel / Praia das Tartarugas, 20°31’01.3”S – 29°17’56.9”W, depth: 9.5 m, coll. J.B. Mendonça, 26.vi.2012; 2 males, MZUSP 31107, Trindade Island, Parcel / Praia das Tartarugas, 20°31’01.3”S – 29°17’56.9”W, depth: 14.5 m, coll. J.B. Mendonça, 11.vii.2012; 5 males, 7 (2 ovig.) females, MZUSP 30259, Trindade Island, Enseada da Cachoeira, Praia do M, 20°30’55.6”S – 29°20’21.7”W, depth: 12.0 m, coll. J.B. Mendonça, 12.vii.2012; 1 male, 3 females, MZUSP 30055, Trindade Island, Enseada dos Portugueses, in front of SECON, 20°30’20.9”S – 29°18’43.7”W, depth: 11.6 m, coll. J.B. Mendonça, 18.vii.2012; 2 males, MZUSP 31021, Trindade Island, Enseada dos Portugueses, in front of ECIT, 20°30’19.5”S – 29°18’47.3”W, depth: 14.4 m, coll. J.B. Mendonça, 26.vi.2012; 1 female, MZUSP 31079, Trindade Island, Crista do Galo, 20°29’22.1”S – 29°20’03.1”W, large tidal pool among rocks, depth: 2 m, coll. J.B. Mendonça, 12.vi.2012; 1 ovig. female, MZUSP 33293, Trindade Island, between Ponta da Crista do Galo and Ponta Norte, 20°29’14.8”S – 29°20’13.9”W, depth: 15 m, coll. J.B. Mendonça, 21.v.2014; 1 male, MZUSP 30269, Trindade Island, Praia do Andrada, 20°30’45.7”S – 29°18’21.9”W, tide pool, depth: 0.5 m, coll. J.B. Mendonça, 05.vii.2013; 1 ovig. female, MZUSP 30982, Trindade Island, Praia do Lixo, 20°31’29.8”S – 29°19’43.9”W, depth: 17 m, coll. J.B. Mendonça, 15.vii.2013; 3 females, MZUSP 30255, Trindade Island, Ponta do Monumento, 20°30’10.3”S – 29°20’36.1”W, depth: 12.1 m, coll. J.B. Mendonça, 16.vi.2012; 1 male, MZUSP 30350, Trindade Island, Ponta do Monumento, 20°30’10.3”S – 29°20’36.1”W, depth: 19.5 m, coll. J.B. Mendonça, 30.vi.2013; 1 ovig. female, MZUSP 33282, Trindade Island, Praia dos Cabritos, 20°29’32.0”S – 29°19’46.5”W, depth: 9.2 m, coll. J.B. Mendonça, 28.iv.2014; 2 males, 1 ovig. female, MZUSP 34140, Trindade Island, Enseada do Príncipe, Ilha Sul, 20°31’34.3”S – 29°19’27.9”W, depth: 17.6 m, coll. J.B. Mendonça, 06.xi.2014; 1 female, MZUSP 30357, Martin Vaz Island, 20°28’26.9”S – 28°51’20.9”W, depth: 13 m, coll. J.B. Mendonça, 23.vii.2013; 6 males, 4 females, MZUSP 30265, Martin Vaz Island, 20°28’26.9”S – 28°51’20.9”W, depth: 12.3 m, coll. J.B. Mendonça, 24.vii.2013. Size of largest male: cl 3.8 mm (MZUSP 30228); largest female: cl 4.6 mm (MZUSP 31021). Numerous additional specimens (not listed above) are deposited in MZUSP.

Additional (extra-limital) material examined. São Tomé & Príncipe: 1 male, OUMNH.ZC. 2011.03.0 76, São Tomé Island, Praia do Inferno, rocky intertidal exoposed at low tide, in crevices of rocks, coll. A. Anker & N. Knowlton, 29.i.2006. Kiribati: 2 males, OUMNH.ZC. 2016.02.0 36, Line Islands, Millenium Island, Black Reef, depth: 7 m, coll. M. Leray et al., 06.xi.2013.

Description. See Pocock (1890) for original description (diagnosis), and Crosnier & Forest (1966), Banner & Banner (1982) and Abele & Kim (1986) for illustrations, and Anker et al. (2006) for a colour photograph (see also Fig. 11 A, B).

Distribution. Pantropical (but see below). Amphi-Atlantic: São Tomé & Príncipe; Equatorial Guinea: Annobon Island; Ascension Island; throughout Caribbean Sea; Florida; Brazil: Fernando de Noronha, Atol das Rocas, Trindade & Martin Vaz Archipelago (Christoffersen 1998 and references therein; present study). Indo- Pacific: Madagascar to Hawaii, French Polynesia and Clipperton Island (Banner & Banner 1982).

Ecology. Coral reefs and rocky reefs with abundance of dead corals and coralline algae; dwelling deep in crevices of coral rocks and clumps of coralline algae; intertidal to about 30 m.

Remarks. Metalpheus rostratipes is a crevice-dwelling snapping shrimp found mainly in rock-algal and coralrock substrates on offshore reefs and oceanic islands. The species was previously known from Brazil based on records from Fernando de Noronha and is now recorded from two other oceanic islands, Atol das Rocas and Trindade Island. It is presently not known from the Brazilian continental coast.

Metalpheus rostratipes is currently regarded as a widely distributed pantropical species (Crosnier & Forest 1966; Banner & Banner 1982). A comparison of several male specimens from Trindade Island (western Atlantic), São Tomé Island (eastern Atlantic) and Line Islands (western Pacific) did not yield any substantial morphological differences. Their colour patterns are also very similar or nearly identical (A. Anker, pers. obs.). As for other pantropical species or species complexes, a comprehensive genetic analysis (COI or 16S genes) is desirable for M. rostratipes, in order to evaluate the genetic differences between the Atlantic and Indo-West Pacific populations.

Anker et al. (2006) showed, after performing a cladistics analysis of all alpheid genera known at that time, that Metalpheus may be nested (together with two other genera) within Alpheus, thus making the latter genus paraphyletic. However, generic rearrangements in Alpheus and related genera (including Metalpheus) must await a more comprehensive phylogenetic analysis, including molecular datasets.