Glyptoxanthus vermiculatus Lamarck 1818

Glyptoxanthus vermiculatus (Lamarck, 1818)

(Figs. 9 C–F, 10H)

Cancer vermiculatus Lamarck, 1818: 271 (type locality: most probably Caribbean Sea, see Guinot 1979: 66). Xantho vermiculatus, H. Milne Edwards 1834: 391. —Desbonne in Desbonne & Schramm 1867: 27. — A. Milne-Edwards 1868: 49.

Glyptoxanthus vermiculatus, A. Milne-Edwards 1879: 255, pl. 43 fig. 2. — Rathbun 1900: 288; 1930: 266, pl. 108 fig. 4, pl. 109. — Guinot 1971: 1073; 1979: 66, fig. 18F. — Tavares & Albuquerque 1990: 67, fig. 2. — Melo 1996: 355, 1 fig. — Cobo et al. 2002: 156, fig. 1D. — Almeida & Coelho 2008: 202. —Ng et al. 2008: 199 (list). ? Glyptoxanthus vermiculatus, Guinot 1967: 556.

Material examined. Caribbean Sea: Lectotype, male, 41.8 × 28.6 mm, paralectotype, female, 34.2 × 24.2 mm (MNHN-B3016), locality written as “? Floride” on label, no other data.

Curaçao: 1 female, 32.3 × 21.2 mm (USNM 7589), coll. Albatross, 10–18 Feb. 1884.

Suriname: 1 male, 38.0 × 25.4 mm (RMNH-D12181), off the coast, between mouths of Coppename & Suriname rivers, coll. Coquette, 19–22 Jul. 1957.

Diagnosis. Carapace transversely ovate, width-to-length ratio 1.4–1.5; carapace regions more-or-less defined, cervical furrow slightly wider than other furrows; 2M nearly completely divided longitudinally except anterior part which is fused with 1M; posterior part of 3M fused to inner branch of 2M; 4M bridging 3M and 1P; 2L, 3L, 4L distinct, 5L and 6L fused; 1P with 2 parallel transverse furrows; 2P X-shaped, somewhat subdivided into smaller lobules; vermiculations moderately thick, convoluted, generally smooth, with traces of fused granules. Front quadrilobate. Anterolateral margins arcuate, divided into 4 distinct, subtriangular lobes. Male thoracic sternum eroded, with near-symmetric pattern of ridges and cavities. External surfaces of pereopods with similar sculpturing as dorsal carapace surface. Abdomen with transverse bars. G1 long, slender, distal end studded with spiniform granules, apex blunt, aperture large, unobstructed, ventral margin with 2 short, simple setae; G2 one-fourth length of G1

Remarks. Lamarck (1818) described Cancer vermiculatus from two specimens purportedly collected from the “Antilles” (= Caribbean). Subsequently, other workers treated it as a species of Xantho, and reported additional specimens from the Caribbean region (H. Milne Edwards 1834; Desbonne, in Desbonne & Schramm 1867; A. Milne-Edwards 1868). A. Milne-Edwards (1879) eventually established a new genus, Glyptoxanthus, to accommodate this and five other species. Some confusion had arisen from several reports of G. vermiculatus from outside the Caribbean (i.e., Cape Verde Islands, western coast of Africa, Red Sea) which were actually of different species of Glyptoxanthus, and/or from the poorly substantiated synonymization of related species (see previous Remarks for other Glyptoxanthus spp.; see also Osorio 1897, 1898, 1907; Odhner 1925; Rathbun 1930). Guinot (1977, 1979) stabilized the taxonomy of this species by selecting the male specimen (of the two syntypes originally studied by Lamarck) as the lectotype, and by highlighting the morphological distinctive characters. She expressed some doubt on the provenance of Lamarck’s type specimens (which were said to have come from “? Floride”, as written on the label), and went on to confirm the presence of this species in the Caribbean Sea based on her examination of specimens collected and reported by earlier workers from that region.

Glyptoxanthus vermiculatus is superficially similar in morphology to two Atlantic species, G. erosus from the western Atlantic including the Caribbean and the Gulf of Mexico, and G. angolensis from the eastern Atlantic, particularly in the general form and sculpturing of the carapace. However, G. vermiculatus can be distinguished from these two species primarily by the presence of two parallel furrows on the cardiac region (1P) of the carapace (several, separate, small cavities in G. erosus and G. angolensis). The G1s differ significantly among these species (Fig. 10; also Guinot 1979: fig. 18B, D, F). Furthermore, the condition of the gastric regions differs among the three species. In G. vermiculatus, 2M is almost completely divided longitudinally except for the fused anterior part, which also fused to 1M; in G. e ro s u s, the fusion occurs on the posterior part of 2M, and in G. angolensis, 2M is not as clearly divided as either of the two species. Glyptoxanthus vermiculatus is morphologically most similar to G. meandrinus from the Red Sea, particularly in the way the 2M region is divided, in the presence of two parallel transverse furrows on 1P, and in the pronounced subtriangular lobes on the carapace anterolateral margin. However, G. vermiculatus has thicker and more convoluted vermiculations, narrower intervening furrows, and no oblongate cavity on 5L; whereas G. meandrinus has narrower, less convoluted vermiculations coupled with wider furrows, as well as a clear oblongate cavity on 5L. There is some uncertainty as to whether G. vermiculatus and G. meandrinus are distinct species. In fact, Odhner (1925) considered the two to be conspecific, choosing to believe that the true type locality of G. vermiculatus was probably in the Indo-West Pacific rather than in the Caribbean. It is also possible that the small size of the holotype of G. meandrinus means that it is a juvenile, and, therefore, the observed differences in carapace morphology are age-related and intra-specific. In the absence of additional specimens from the Red Sea, however, and in light of the confirmed presence of G. vermiculatus in the Caribbean and the western Atlantic, we consider the two species to be distinct.

Ecology and geographical distribution. This species has been obtained at depths of approximately 10 m, and has been observed to be associated with coral heads (Cobo et al. 2002). Thus far, there have been no reports of G. vermiculatus from Florida or anywhere north of the Caribbean region (e.g., Rathbun 1930; Williams 1965, 1984), although this species has been found on the South American coast as far south as southeastern Brazil (Melo 1996; Cobo et al. 2002; Almeida & Coelho 2008). Therefore, we consider the northern limit of G. vermiculatus ’ range as within the Caribbean Sea, for the moment.