Achelous tumidulus Stimpson, 1871a

TAVARES, MARCOS & MENDONÇA, JOEL BRAGA DE JR., 2022, Brachyuran crabs (Crustacea, Decapoda) from the remote oceanic Archipelago Trindade and Martin Vaz, South Atlantic Ocean, Zootaxa 5146 (1), pp. 1-129 : 52-53

Achelous tumidulus Stimpson, 1871a

( Fig. 27B, E )

Acheloüs tumidulus Stimpson, 1871a: 149 [Type locality: West of Tortugas and off Conch Reef, Florida].

Trindade and Martin Vaz specimens. 1 juvenile ( MZUSP 40252 ), Brazil , off Espírito Santo , Trindade Island, Praia da Calheta, 20°30’29.5”S, 29°18’37.0”W, D. Abatte et al. coll., 23.vii.2011 . 1 juvenile ( MZUSP 40182 ), ibidem, 20°30’24.04”S, 29°20’47.86”W, Thiony-Lucas coll., 30.i.2012, rocks, 32 m . 1 ovigerous female ( MZUSP 41419 ), Trindade Island , R/V “Marion Dufresne”, TAAF MD55/ Brésil Expedition, stn 36 DC61, 20°29.2’S, 29°18.2’W, 22.v.1987, 63 m . 1 juvenile female ( MZUSP 40177 ), Martin Vaz Archipelago , 20º30’45.7’’S, 29º18’21.9’’W, J.B. Mendonça coll., 23.vii.2013, 13 m .

Size of largest female: cl 10.5 mm, cw 16 mm.

Comparative material examined. Achelous tumidulus : United States: Florida: 1 male, 1 female ( MZUSP 9402 ), Cape Canaveral, R /V “Combat”, stn 119, 29º52’N, 80º11’W, 16.ix. 1956, 360 m [F.A. Chace det., don., 1957]. Brazil: Espírito Santo: 1 ovigerous female ( MZUSP 21201 ), Vitória – Trindade Seamount Chain, R /V “Marion Dufresne”, TAAF MD55/ Brésil Expedition, Dogaressa Bank, stn 24 DC42, 20º54.67’S, 34º01.35’W, 17.v.1987, 60 m . 1 juvenile ( MZUSP 41466 ), ibidem, Columbia Bank, stn 27 DC47, 20º41’S, 32º12.85’W, 19.v.1987, 94–105 m. São Paulo: 1 male ( MZUSP 8082 ) , Ubatuba, R/V “Veliger II”, Projeto Integrado, stn 23, 23º47’S, 45º13’W, 19.iv.1986, 36 m.

Distribution. Bermuda, South Florida, Gulf of Mexico, Antilles, Caribbean, Guyana and Brazil (Par to Bahia, Espírito Santo, São Paulo, Santa Catarina) ( Rodriguez 1980; Melo 1996; Felder et al 2009). This is the first record of A. tumidulus from the Vitória–Trindade Seamount Chain (Dogaressa and Columbia banks) and the Trindade and Martin Vaz Archipelago.

Ecological notes. Achelous tumidulus inhabits sand, coral and rocky bottoms ( Melo 1996) and vegetated habitats dominated by Thalassia testudinum mixed with Syringodium filiforme , Halimeda opuntia , H. incrassata , Penicillus capitatus and Udotea flabellum ( Rathbun 1930; Park 1969; Heck & Weinstein 1989), between 1 m and 75 m. It is preyed by a number of juvenile fish species ( Heck & Weinstein 1989) and also by the cobia fish Rachycentron canadus (Linnaeus) ( Hamilton et al. 2019).

Remarks. Achelous tumidulus ( Fig. 27B, E ), originally described in Achelous , was later combined to Cronius Stimpson, 1860 by Rathbun (1920). Afterwards, Rathbun (1930) formally synonymized Cronius bispinosus Miers, 1886 (type locality: Bahia, Brazil) with Achelous tumidulus Stimpson, 1871a , while keeping the Stimpson’s species in Cronius . More recently, Mantelatto et al. (2009) returned C. tumidulus to Achelous .

Figures

FIGURE 27. A, D, Achelous ordwayi Stimpson, 1860, male, cl 16.1 mm, cw 28.1 mm (MZUSP 21204). B, E, Achelous tumidulus Stimpson, 1871, ovigerous female, cl 10.5 mm, cw 16.5 mm (MZUSP 41419). C, F, Cronius ruber (Lamarck, 1818), juvenile male, cl 7 mm, cw 10 mm (MZUSP 40173). Note in (B, C) carapace anterolateral teeth unequal, alternating large and small (arrows). Scales: D–F, 0.5 mm.