Omalacantha bicornuta ( Latreille, 1825 )

Parasram, Nadeshinie, Santana, William & Vallès, Henri, 2023, Checklist of the shallow-water marine Brachyura (Crustacea: Decapoda) of Barbados, West Indies, Zootaxa 5314 (1), pp. 1-62 : 27-28

Omalacantha bicornuta ( Latreille, 1825)

( Figs. 11C–D )

Pisa bicornutus Latreille, 1825: 141 [type-locality: ‘Nouvelle Hollande’, erroneous; probably “Antilles” instead; type in MNHN (see Carmona-Suárez & Poupin 2016: 375)].

Pericera bicorna H. Milne Edwards, 1834: 337 .

Pericera bicornis de Saussure, 1857: 501 .

Microphrys bicornutus .—A. Milne-Edwards, 1880: 61; Rathbun 1897: 7; 1924: 21; 1925: 489, pl. 175; Rodríguez 1980: 293; Scelzo & Varela 1988: 37; Melo 1996: 224, unnumbered fig.; Lira et al. 2013: 54, tab. 1; Carmona-Suárez & Poupin 2016: 375, fig. 8E.

Omalacantha bicornuta . — Assugeni et al. 2017: 1630, tab. 1; Poupin 2018: 196–197, fig. 215; Mantelatto et al. 2020: 42, fig. 13F; Jarquín-González et al. 2022: 6, tab. 2.

Distribution. Western Atlantic: USA (North Carolina), St. Thomas, St. Martin, St. Eustatius, Antigua, Guadeloupe, Isla de Aves, Martinique, Barbados, Trinidad, Isla de Blanquilla, Isla de Margarita, Isla de Cubagua, Los Roques, Tortuga, Bonaire, Curaçao, and Venezuela ( Assugeni et al. 2017; Poupin 2018; Mantelatto et al. 2020).

Material examined. Barbados, Drill Hall , St. Michael, nearshore rubble, 13°04’36.30”N, 59°36’26.63”W, 6 Ô, 2 ♀, 1 ♀ (ovig.) CW: 10.7, 14.5, 12.4, 14.8, 7.3, 7.3, 10.1, 7.3, 14.4 mm ( BLSZ 142 ) . Idem , 1 Ô CW: 10.7 mm ( BLSZ 146 ) . Idem , 1 Ô CW: 10.4 mm ( MZUSP 40898 ) . Idem , 1 Ô CW: 15.0 mm ( BLSZ 213 ) . Batts Rock , St. Michael, subtidal, 13°08’4.81”N, 59°38’12.30”W, 1 Ô CW: 20.0 mm ( MZUSP 40901 ) .

Remarks. Specimens of Omalacantha bicornuta were collected by hand at low tide in nearshore rubble habitat and caught in crab traps (~ 4m deep) on sandy bottom. Omalacantha bicornuta is very abundant in nearshore rubble habitat and can sometimes be found under the same rubble rock as Mithraculus coryphe , Mithraculus forceps , Eriphia gonagra , and Pachygrapsus transversus . Omalacantha bicornuta camouflages by attaching Caulerpa sertularioides (S. G. Gmelin) M. Howe, 1905 , algae to the hooked setae on its carapace ( Fig. 10D ). One ovigerous female was collected in July 2019. First reported for Barbados by Rathbun (1892: 254) as Omalacantha bicornuta on specimens collected by the U.S. Eclipse Expedition to West Africa in 1890; these specimens are stored at USNM (14883). Rathbun (1921: 85) also reported specimens of Omalacantha bicornuta (three ovigerous females, one juvenile, USNM 72071; one juvenile female, USNM 71761; two males, USNM 58016; one male, USNM 71759; four males, two ovigerous females, USNM 58015). Additional specimens were also collected by this expedition but were not reported by Rathbun (one female USNM 71762; one ovigerous female, USNM 71764; one male, USNM 72074). One juvenile female specimen was collected in 1924 by G. S. Miller, who deposited this specimen at the USNM (71697). The Smithsonian-Hartford Expedition (1937) also collected specimens of Omalacantha bicornuta (two females, two ovigerous females, seven juveniles, USNM 75098; three ovigerous females, USNM 73302). Rathbun (1925: 494) reported two males and one female specimens of Omalacantha bicornuta , which were collected during the U.S. Eclipse Expedition. These specimens are stored at the USNM (one male, one female, USNM 14883; one male, USNM 26409). Windsor & Felder (2014: 158) resurrected the genus Omalacantha Streets, 1871 and assigned Microphrys bicornutus to this genus.

Genus Pitho Bell, 1835

Figures

FIGURE 10. Superfamily Majoidea Samouelle, 1819, dorsal habitus:A, Mithraculus coryphe (Herbst, 1801), male, cw 8.2 mm (BLSZ 121); B, Mithraculus forceps A. Milne-Edwards, 1875, female, cw 15.4 mm (BLSZ 208); C, Mithrax hispidus (Herbst, 1790), male (juv.), cw 11.2 mm (BLSZ 029). Scale bars: A, B: 20 mm; C = 10 mm.

FIGURE 11. Superfamily Majoidea Samouelle, 1819, dorsal habitus: A, Nemausa acuticornis (Stimpson, 1871), male, cw 4.8 mm (BLSZ 057); B, Nemausa cornuta (de Saussure, 1857), male, cw 8.3 mm (BLSZ 210); C, D, Omalacantha bicornuta (Latreille, 1825), male, cw 10.4 mm (MZUSP 40898); male, cw 15.0 mm (BLSZ 213). Scale bars: A, B = 5 mm; C, D = 20 mm.