Glyptoxanthus angolensis ( Brito Capello, 1866 )

Mendoza, Jose Christopher E. & Guinot, Danièle, 2011, Revision of the genus Glyptoxanthus A. Milne-Edwards, 1879, and establishment of Glyptoxanthinae nov. subfam. (Crustacea: Decapoda: Brachyura: Xanthidae), Zootaxa 3015, pp. 29-51 : 34-35

Glyptoxanthus angolensis ( Brito Capello, 1866)

( Figs. 2 , 10 A)

Actaea angolensis Brito Capello, 1866: 4 , pl. 1, fig. 3; 1867: 4, pl. 1, fig. 3 (type locality: Angola, west Africa). — Capart 1951: 157, fig. 59. — Longhurst 1958: 88. — Gauld 1960: 70.

Xantho vermiculatus, Osorio 1887: 224 ; 1898: 192. Not Cancer vermiculatus Lamarck, 1818 .

Glyptoxanthus vermiculatus, Rathbun 1900: 288 ; 1930: 267 (in part). — Balss 1921: 61. Not Cancer vermiculatus Lamarck, 1818 .

Actaea (Glyptoxanthus) angolensis, Monod 1956: 296 , fig. 361. — Serène 1961: 198 (list).

Glyptoxanthus angolensis, Bouvier 1922: 64 . — Forest & Guinot 1966: 77, fig. 6a, b. — Guinot 1967: 556; 1971: 1073; 1979: 66, fig. 18B, pl. 6 fig. 3. — Manning & Holthuis 1981: 135 —Ng et al. 2008: 199 (list).

Glyptoxanthus sp., Sourie 1954: 112.

Material examined. Equatorial Guinea: 1 male, 24.7 × 17.1 mm (RMNH-D31547), stn 282, 23 m, 01º28’S, 5º36’E, Annobon Is., coll. Pillsbury, 21 May 1965; 1 male, 12.0 × 8.2 mm ( USNM 127170), drag net, 35–55 m, 01º28.5’S, 5º37.5’E, south coast of Annobon Is., coll. F. Poinsard, 16 Jun. 1967; 1 female, 16.5 × 11.3 mm ( USNM 170332), dredge, 16–21 fms (29–38 m), Annobon Is., coll. Pillsbury, 21 May 1965.

Gabon: 1 male, 49.9 × 34.4 mm (MNHN-B8352), Mayumbo Verques, Congo Français, 1899.

Senegal: 1 female, 35.5 25.4 mm (MNHN-B7410), Dakar, anse Bernard, coll. Sourie, det. Th. Monod, 1953; 1 male, 13.8 × 9.6 mm (RMNH-D40257), stn SEN.08, 0.5–6m, boulder beach, near Lido Hotel, southern tip of Cape Verde Peninsula between Cap Manuel & Pointe Bernard, coll. 2 Jun. 1982; 1 male, 26.8 × 18.7 mm (RMNH- D40255), stn SEN.12, snorkelling, 1–5 m, sandy bay between Ile de N’Gor & Plage du Virage, N coast of Cape Verde Peninsula, coll. 23–24 Nov. 1983; 1 male, 16.8 × 11.5 mm, 1 female, 24.0 × 16.5 mm (RMNH-D40256), stn SEN.17, snorkelling, 0-4 m, protected bay with sand, stone & boulders, facing Ile de N’Gor, N coast of Cape Verde Peninsula, La Calao, coll. 28, 30 Nov. —1 Dec. 1983.

Diagnosis. Carapace transversely ovate, width-to-length ratio about 1.4; vermiculations relatively thick and smooth, with traces of fused granules visible under low magnification, some smaller vermiculations resembling “doughnuts” particularly on cardiac and branchial regions; furrows between vermiculations deep, filled with setae; 2M undivided, partially fused with 3M posteriorly; 4M fused with 3M and 1P by narrow, median bridge; 4L distinct; 5L and 6L united; 1P with small, round, separate but regularly arranged cavities; cervical furrow deep, moderately broad. Front quadrilobate, with deep lateral notches. Anterolateral margin with 4 feeble lobes; fourth well separated, subtriangular. External surfaces of thoracic sternum, pereopods and abdomen with similar sculpturing as carapace. Margins of ambulatory legs fringed with long setae. G1 long, slender, bluntly tipped; ventral wall of aperture with 2 short, simple setae; G2 about one-fourth length of G1.

Remarks. Brito Capello (1866, 1867) described Actaea angolensis from Angola, on the southwestern coast of Africa. Some authors ( Osorio 1887; Rathbun 1900; Balss 1921) treated it as conspecific with G. vermiculatus ( Lamarck, 1818) . Capart (1951) and Monod (1956), however, considered these to be two separate species, particularly on the basis of the carapace sculpturing, the live colouration, and the G1 morphology. Glyptoxanthus angolensis is morphologically most similar to G. e ro s u s and to G. vermiculatus in the general shape of the carapace, and the disposition of the carapace regions and vermiculations. However, G. angolensis can be distinguished from these two species by the unique pattern of the carapace vermiculations, particularly in the formation of “doughnut”- shaped lobules especially on the branchial and cardiac regions, and by the G1. Glyptoxanthus angolensis can also be distinguished from G. erosus by its less, and irregularly, eroded anterior thoracic sternum (more eroded, but erosions and ridges forming a regular pattern in G. e ro s u s). Furthermore, G. angolensis differs from G. vermiculatus by its poorly divided 2M region (partially but clearly divided longitudinally in G. vermiculatus ) and the discrete subcircular cavities on the 1P region (two transverse parallel furrows on 1P in G. vermiculatus ).

The type specimen reportedly deposited at the Museu Nacional de História Natural, Lisbon, Portugal, was not examined in this study. However, several specimens presently deposited at MNHN, RMNH and USNM were examined, which agree with descriptions and illustrations of previous workers ( Brito Capello 1866; Capart 1951; Monod 1956; Guinot 1979).

Ecology and geographical distribution. Glyptoxanthus angolensis has been found in shallow to moderate subtidal depths (to 40 m), in sandy-rocky, rocky or coralline substrate. It is known to occur on the western coast of Africa: Ghana, Senegal, Angola, São Tomé, Annobon, Sierra Leone, and Gabon (see Manning & Holthuis 1981). The live colouration of this species has been described as generally red, with lighter patches of yellow ( Brito Capello 1866) or orange-red with lighter patches ( Capart 1951).

Figures

FIGURE 2. Glyptoxanthus angolensis (Brito Capello, 1866), male, 49.9 × 34.4 mm (MNHN-B 8352), Mayumbo Verques, Gabon: A, dorsal view; B, anterior view; C, ventral view; inset, abdomen; D, right chela, external view.

FIGURE 10. Glyptoxanthus spp. gonopods (G 1). A, G. angolensis (Brito Capello, 1866); B, G. cavernosus (A. Milne-Edwards, 1878); C, G. erosus (Stimpson, 1859); E, G. c o r ro s u s (H. Mile Edwards, 1834); E, G. labyrinthicus (Stimpson, 1860), (LACM CR 1935.075.3); F, G. meandricus (Lockington, 1877), neotype (LACM CR 1940.65); G, G. vermiculatus (Lamarck, 1818). (A – C, D, G, after Guinot 1979).