Pachygrapsus transversus ( Gibbes, 1850 )

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 : 45

Pachygrapsus transversus ( Gibbes, 1850)

( Fig. 20B )

Grapsus transversus Gibbes 1850: 181 [type-locality: Key West , Florida; type probably in USNM].

Leptograpsus rugulosus H. Milne Edwards, 1853: 172 .

Metopograpsus dubius de Saussure, 1858: 445 , pl. 2, fig.16.

Pachygrapsus intermedius Heller, 1862: 521 .

Pachygrapsus transversus . — Rathbun 1897: 29; Hay & Shore 1918: 447, pl. 36, fig. 9; Rathbun 1918: 244, pl. 61, figs. 2–3; 1920: 24; 1921: 77; 1924: 18; 1933: 88; 1936: 387; Monod 1956: 415, figs. 568, 570, 572, 573; Williams 1965: 217, fig. 202; Chace & Hobbs 1969: 169, fig. 52k; Coelho & Ramos 1972: 201; Felder 1973: 79, pl. 11, figs. 5, 10; Powers 1977: 130; Rodríguez 1980: 380; Williams 1984: 459, fig. 368; Keith 1985: 271, fig. 10E; Abele & Kim 1986: 63; Scelzo & Varela 1988: 37; Melo 1996: 454; Boos et al. 2012: 1027; Garcia & Capote 2015: 17, fig. 8f; Poupin 2018: 225, fig. 256; Mantelatto et al. 2020: 21 , fig. 6D; Jarquín-González et al. 2022: 6, tab. 2.

Distribution. Western and Eastern Atlantic and Pacific. Western Atlantic: USA (North Carolina, Florida), Bermuda, Bahamas, Jamaica, Barbados, Brazil, and Uruguay; Eastern Atlantic: Madeira, Angola, and Cape Verde Islands; Eastern Pacific: California, Tahiti, Galapagos Island, Easter Island, Peru, Australia, and New Zealand ( Rathbun 1897; Keith 1985).

Material examined. Barbados, Drill Hall , St. Michael, nearshore rubble, 13°04’36.30”N, 59°36’26.63”W, 1 Ô CW: 9.4 mm ( BLSZ 145 ) . Idem , 1 Ô CW 10.3 mm ( BLSZ 153 ) . Idem , 1 Ô CW: 10.2 mm ( BLSZ 209 ) . Cattlewash, St. Andrew , subtidal, 13°13’21.63”N, 59°031’55.58”W, 4 Ô, 1 ♀, 1 ♀ (ovig.) CW: 12.1, 9.1, 8.3, 6.6, 9.6, 6.1 mm ( BLSZ 149 ) . Jordans, St. James , nearshore rubble, 13°14’48.24”N, 59°38’40.90”W, 1 Ô CW: 10.0 mm ( MZUSP 40895 ) .

Remarks. Specimens of Pachygrapsus transversus were caught by hand in nearshore rubble habitat at low tide, under rock rubble, on the east, south, and west coasts of Barbados. Pachygrapsus transversus is very abundant in Barbados and was observed under the same rubble rock as Amphithrax aculeatus , Amphithrax verrucosus , Mithraculus coryphe , Mithraculus forceps , and Eriphia gonagra in nearshore rubble habitats. Ovigerous females were collected in July 2019 and May 2021. Pachygrapsus transversus was first reported for Barbados by Rathbun (1921: 78) on specimens (one female, USNM 74803; one ovigerous female, USNM 58034; one male, USNM 74800) collected by the Barbados-Antigua Expedition in 1918. Additional specimens (one male, one female, USNM 74988) were also collected by this expedition but were not reported by Rathbun. The Smithsonian-Hartford Expedition in 1937 collected one juvenile specimen of Pachygrapsus tranversus , which was deposited to the USNM (74987). Jones (1968b: 188) reported Pachygrapsus gracilis ( de Saussure, 1857) for Barbados, however, this record is doubtful. Jones’ identification of this species is based on the “greyish-brown” colour of the specimen. In Barbados, there is substantial diversity in the colour of Pachygrapsus transversus . The colour of specimens is based on the type of substrate the crabs inhabit. For example, crabs collected on dark brown or black rocks have a greyish-brown colour, crabs collected on green algae have a greenish-grey colour, and crabs collected from greyish white rocks have a yellow-brown colour (N. Parasram, pers. obs). Chace & Hobbs (1969: 35) reported Pachygrapsus transversus as occurring along rocky shores and along the tide line. However, in Barbados, this species was collected in nearshore rubble and rock platform habitats that are submerged at high tide. Pachygrapsus transversus can be identified by its slender angulated first gonopod, which terminates in a long corneous obliquely T-shaped endpiece ( Chace & Hobbs 1969).

Figures

FIGURE 20. Superfamily Grapsoidea MacLeay, 1838, dorsal habitus: A, Grapsus grapsus (Linnaeus, 1758), female (juv.), cw 26.6 mm (BLSZ 231); B, Pachygrapsus transversus (Gibbes, 1850), male, cw 10.2 mm (BLSZ 209); C, Percnon gibbesi (H. Milne Edwards, 1853), male, 20.8 mm (BLSZ 117); D, Plagusia depressa (Fabricius, 1775), female, cw 10.6 mm (MZUSP 40922). Scale bars = 20 mm.