Glyptoxanthus vermiculatus

Glyptoxanthus vermiculatus (Lamarck, 1818)

(Figs. 33A–H)

Cancer vermiculatus Lamarck, 1818: 271 [Type locality: Antilles from the original description. Note, however, that the lectotype and paralectotype are labeled? Floride].

Trindade specimens. 1 juvenile female (MZUSP 41024), Trindade Island, Enseada da Cachoeira, Farrilhões, 20º31’29.8’’S, 29º19’52.0”W, J.B. Mendonça coll., 6.viii.2018, 10.4 m. 1 female (MZUSP 40931), 1 female (MZUSP 41027), ibidem, J.B. Mendonça coll., 10.viii.2018, 10.9 m. 1 female (MZUSP 40938), ibidem, Praia da Cachoeira, 20º30’59.56”S, 29º20’11.86”W, J.B. Mendonça coll., 29.xi.2017, 11.2 m. 1 male (MZUSP 33832), ibidem, Ponta da Cachoeira, 20º30’31.1”S, 29º20’39.5”W, J.B. Mendonça coll., 21.vii.2015, 19.1 m. 1 male (MZUSP 41056), ibidem, Ilha da Racha, 20º30’26.5”S, 29º20’48.0”W, J.B. Mendonça coll., 30.vii.2018, 23 m. 1 male (MZUSP 41263), Ponta da Calheta, 20º30’18.72”S, 29º18’31.6”W, J.B. Mendonça coll., 24.xi.2017, 17 m. 1 ovigerous female (MZUSP 41264), ibidem, Enseada das Orelhas, 20º29’40.2”S, 29º20’32.9”W, J.B. Mendonça coll., 22.xi.2014, 14.3 m.

Size of largest male: cl 19 mm, cw 23 mm; largest female: cl 36 mm, cw 52 mm.

Comparative material examined. Glyptoxanthus angolensis (Brito Capello, 1866): West Africa: 1 female (USNM 170332), Gulf of Guinea, Annobon Island, R/V “Pilsbury”, stn 282, 22.v.1965, 29.2–38.4 m. 1 male (USNM 127170), Annobon Island, 01º28.5’S, 53º7.5’E, F. Poinsard coll., 16.vi.1967, 35–55 m. Glyptoxanthus labyrinthicus (Stimpson, 1860): Panama: 1 male (MZUSP 33961), Las Perlas, small rocky island, off NE Saboga, A. Anker coll. 21.iv.2015, rocky sandy bottom and rocky wall, 0–1.5 m. Glyptoxanthus vermiculatus: Curaçao: 1 female (USNM 7589), U.S. Fish Commission R /V “ Albatross ”, 1884, 10–18.ii.1884. Brazil: Espírito Santo: 1 female (MZUSP 9059), Vitória–Trindade Seamount Chain, R/V “ Marion Dufresne ”, TAAF MD55/Brésil Expedition, Vitória Bank, stn 11 CP25, 20º35.8’S, 37º27.4’W, 14.v.1987, 65 m. São Paulo: 1 male (MZUSP 13478), Ubatuba, Praia Cedro, A. Fransozo coll., iv.2000.

Distribution. Gulf of Mexico, Antilles, Venezuela, Suriname and Brazil (Bahia, Espírito Santo, São Paulo) (Holthuis 1959; Rodriguez 1980; Tavares & Albuquerque 1990; Cobo et al. 2002; Almeida & Coelho 2008; Felder et al. 2009; Diez García 2014). This is the first record of G. vermiculatus from Trindade. The species also occurs in the Vitória–Trindade Seamount Chain (Vitória and Dogaressa banks) (Tavares & Albuquerque 1990; Serejo et al. 2006).

Ecological notes. This species has been recorded from shell and rubble bottoms, rocky bottoms and reefs, between 1 and 65 m. The color pattern is variable (Fig. 33A–F). The highly vermiculated pattern of the body and mottled coloration allow for the crab to conceal its body by matching the rocky, coralline background (Fig. 33G, H).

Remarks. In G. vermiculatus the afferent opening at the base of the cheliped is protected by dense setae (Fig. 33B, F), so that the water entering the branchial chamber via the afferent aperture is “filtered” and freed from excess of particles in suspension and propagules of fouling organisms.

The pleonal-holding system (Guinot & Bouchard 1998), well-developed in young females, is preserved in mature females (both press-button and socket), even though folding of the pleon beneath the thorax is made impossible by the egg-mass carried by the ovigerous female of G. vermiculatus.

Generally, the pleonal and thoracic sternal margins closely fit each other in males, so much that the outline of the pleon is not always clearly distinguishable. The male locking system is well-developed and effective but only releases the distal half of the pleon when disengaged. The press-button system is complemented by a sterno-pleonal locking system (very rare in Eubrachyura, v. Guinot & Bouchard 1998). The sterno-pleonal cavity is protruded into an edge at the level of the sternite 7 that overhangs the corresponding margin of the pleonal somite 3, whose role is preventing the pleon from being lifted.Additionally, the margin of the pleonal somite 3 is provided with a hollowed, curved forward spur that closely fits the rounded posterior edge of the thoracic sternite 7 from behind and beneath. Both systems work together to prevent the proximal half of the pleon from being lifted. The proximal half of the pleon is released only when moved backwards and then upwards.

No mention has been made in the literature of the presence of sound producing apparatus in G. vermiculatus. However, stridulation is obtained by rubbing the heavily granulated mesial lower surface of the P1 propodi against the also heavily granulated mesial surface of P1 meri, which can be considered the pars stridens. Sound production as a result of friction of the cheliped against itself has been reported in a few numbers of crab species (Guinot-Dumortier & Dumortier 1960, and references therein).