Pachygrapsus gracilis (de Saussure, 1858 )

Poupin, Joseph, Davie, Peter J. F. & Cexus, Jean-Christophe, 2005, A revision of the genus Pachygrapsus Randall, 1840 (Crustacea: Decapoda: Brachyura, Grapsidae), with special reference to the Southwest Pacific species, Zootaxa 1015 (1), pp. 1-66 : 15-18

Pachygrapsus gracilis (de Saussure, 1858) ( Figures 4a–e , 14h , 15h )

Metopograpsus gracilis de Saussure, 1858: 443 [27], pl. 2, fig. 15 [type locality: St. Thomas, Virgin Is.].

Grapsus (Leptograpsus) rugulosus von Martens, 1872: 108 ( Cuba) , not Leptograpsus rugulosus H. Milne Edwards, 1863 .

Pachygrapsus gracilis — Verrill, 1908: 324, fig. 6a, b, pl. 12, fig. 2 ( Bermuda). — Rathbun, 1918: 249, pl. 60, fig. 3, pl. 61, fig. 1 ( Bahamas, Jamaica, Puerto Rico, Colombia, Brazil, Bermuda; synonymy); 1921: 445, pl. 40, fig. 1 ( Congo); 1933: 89 ( Puerto Rico). — Capart, 1951: 187, fig. 74, pl. 3, fig. 19 (West Africa). — Monod, 1956: 419, fig. 569 (West Africa). — Holthuis, 1959: 239, pl. 10, fig. 3 ( Suriname). — Chace & Hobbs, 1969: 167, fig. 51, 52j (West Indies; references). — Rodríguez, 1980: 380, pl. 59 ( Venezuela). — Manning & Holthuis, 1981: 233 ( Senegal to Angola; references). — Rodrigues & Brossi­Garcia, 1989: 63, fig. 1–5 ( Brazil). — Melo, 1996: 453, fig. 1 ( Brazil); 1998: 499 ( Brazil).

Type material

One dry specimen ( MHNG, frame n° 190, no record number) (P. J. Schwendinger, pers. comm.) .

Material Examined

East Atlantic. Angola: Lobito , intertidal in oysters, 2 M 7.8 x 10.0, 9.4 x 12.0 mm, 1 F 9.2 x 12.0 mm, 4 F ov. 6.4 x 7.9–8.5 x 11.1 mm ( MNHN B12903) .

West Atlantic. Florida: Banana river , Cap Canaveral, on rock rubble and oysters, 1.8 m, coll. R. H. Gore, 10 August 1972, 3 M 11.3 x 14.3–14.9 x 19.5 mm, 2 ov. F 7.2 x 10.0, 12.4 x 16.7 mm, 3 F 10.7 x 14.1–13.5 x 14.3 mm ( USNM 170178 ) . — French Guiana: coll. F. Geay 1906, 1 F 11.5 x 16.0 mm ( MNHN B29570; mixed with specimens of P. transversus under MNHN B16013) .

Diagnosis

Carapace markedly striated on gastric, hepatic, branchial regions; cardiac, intestinal regions smooth or only with short striae; lateral margins strongly convergent posteriorly, with tooth behind exorbital angle ( Fig. 4a ). Front 0.6 times exorbital width; anterior margin straight ( Fig. 4b ). Infraorbital margin almost smooth, at most slightly granulate; without outer notch ( Fig. 14h ).

Outer face of chelae smooth and regularly convex, sometimes with a faint stria near lower margin, becoming more obvious on outer face of fixed finger; dorsal margin of palm with a weak carina and several oblique striae on inner side; dorsal margin of dactyl tuberculated. Cutting edges of fingers widely gaping, with small triangular teeth; tip of fingers spoon shaped, glabrous ( Fig. 4c ).

Ambulatory legs with few scattered long bristles and longitudinal rows of short setae on carpi, propodi; propodi without brush of setae. P5 merus with lower margin marked by several oblique striae on outer face; with a somewhat more noticeable submedian tubercle ( Fig. 4d ).

Abdominal tergites smooth. Male abdomen with sixth somite broader than telson, sixth somite and telson not forming triangle. G1 bluntly rounded at tip, with short corneous process ( Fig. 15h ).

Colour (from photograph): Carapace light green to cream with transverse lines composed of small violet spots. Chelipeds and ambulatory legs pale violet with numerous darker violet spots. The spots retained on the carapace even after several years in preservative ( Fig. 4a ) is a useful character to recognize the species.

Measurements: medium size; carapace of specimens examined ranging from: males 7.8 x 10.0–14.9 x 19.5 mm; females 6.4 x 7.9–13.5 x 14.3 mm; smallest ovigerous female 6.4 x 7.9 mm.

Distribution

West Atlantic. Argentine, Brazil, French Guiana, Caribbean, Texas. East Atlantic. Senegal to Angola.

Habitat

Intertidal. Among mangrove roots and on river banks near the sea ( Chace & Hobbs, 1969).

Remarks

Pachygrapsus gracilis is morphologically close to P. loveridgei Chace, 1966 and P. transversus ( Gibbes, 1850) , both also Atlantic species of similar size, with only one tooth behind the exorbital angle and with the male abdomen not triangular at the tip. The three species have very distinct G1 that should not be confused ( Fig. 15h, i, l ). Pachygrapsus gracilis is also distinct by the lateral carapace margins being strongly convergent posteriorly, the straight anterior margin of the front, the infraorbital margin being almost smooth and without an outer notch, the upper margin of the dactyl of the chela being tuberculated, the absence of a brush of setae on the propodi of the ambulatory legs, and by its colour pattern, having spots that are retained on the carapace even after several years of preservation.

Figures

FIGURE 4. —Pachygrapsus gracilis (de Saussure, 1858). a) dorsal view; b) front; c) left chela, outer face; d) right P5; e) male abdomen. a, c–e, male 14.9 x 19.5 mm, Florida (USNM 170178); b) ov. female 8.5 x 11 mm, Angola (MNHN B12903).

FIGURE 14. —Infra–orbital margin: a) Pachygrapsus fakaravensis Rathbun (1907), ov. female 15.0 x 16.5 mm, Taiaro, French Polynesia (MNHN B25782); b) Pachygrapsus laevimanus Stimpson, 1858, neotype male 18.0 x 21.7 mm, Sydney, Australia (AM P7478); c) Pachygrapsus minutus A. Milne­Edwards, 1873, male 5.2 x 7.0 mm, Moruroa, French Polynesia (MNHN B29273); d) Pachygrapsus planifrons de Man, 1888, male 7.0 x 9.0 mm, Rangiroa, French Polynesia (UF 1490); e) Pachygrapsus plicatus (H. Milne Edwards, 1837), male 12.1 x 15.3 mm, Taiaro, French Polynesia (MNHN B29279); f) Pachygrapsus corrugatus (von Martens, 1872) ov. female 13.6 x 15.2 mm, Virgin Is. (USNM 72340); g) Pachygrapsus crassipes Randall, 1840, male 31.9 x 36.6 mm, Sagami Bay, Japan (NSMT Cr7516); h) Pachygrapsus gracilis (de Saussure, 1858), ov. female 8.5 x 11 mm, Angola (MNHN B12903); i) Pachygrapsus loveridgei Chace, 1966, male 8.1 x 10 mm, St. Helena I. (MNHN B17836); j) Pachygrapsus marmoratus (Fabricius, 1787), female 12.7 x 14.3 mm, Préfailles, France (MNHN B22654); k) Pachygrapsus maurus (Lucas, 1846), female 12.7 x 14.3 mm, Banyuls, France (MNHN B12933); l) Pachygrapsus transversus (Gibbes, 1850), male 17.0 x 22.5 mm, French Guiana (MNHN B16013). Scale bar 1 mm.

FIGURE 15. —Male gonopods: a) Pachygrapsus fakaravensis Rathbun (1907), holotype 18.0 x 19.4 mm, Fakarava, French Polynesia (USNM 32844), right G1, abdominal face (left) and detail of terminal portion, sternal face (right); b) Pachygrapsus laevimanus Stimpson, 1858, neotype 18.0 x 21.7 mm, Sydney, Australia (AM P7478), left G1, abdominal (left) and sternal face (right), setae omitted; c) Pachygrapsus minutus A. Milne­Edwards, 1873, cl 8.2 mm, Caroline Is., lateral (left) and abdominal face (right), setae omitted; d) Pachygrapsus planifrons de Man, 1888, 9.5 x 11.8 mm, Hawaiian Is. (USNM 29350), right G1, abdominal (left) and sternal face (right); e) Pachygrapsus plicatus (H. Milne Edwards, 1837), cl 11.7 mm, Hawaiian Is., lateral (left) and abdominal face (right); f) Pachygrapsus corrugatus (von Martens, 1872), cl 8.5 mm, Ascension I., left G1 abdominal face (left) and detail of terminal portion, setae omitted (right); g) Pachygrapsus crassipes Randall, 1840, cl 35.6 mm, California, lateral (left) and abdominal face (right) setae omitted; h) Pachygrapsus gracilis (de Saussure, 1858), cl 8.7 mm, Virgin Is., lateral (left) and abdominal face (right), setae omitted; i) Pachygrapsus loveridgei Chace, 1966, holotype 10.3 x 13.1 mm, St. Helena I. (USNM 112457), left G1, abdominal (left) and sternal face (right); j) Pachygrapsus marmoratus (Fabricius, 1787), cl 30.5 mm, Gibraltar, lateral (left) and abdominal face (right), setae omitted; k) Pachygrapsus maurus (Lucas, 1846), cl 8.5 mm, Canary Is., lateral (left) and abdominal face (right) setae omitted; l) Pachygrapsus transversus (Gibbes, 1850), cl 11.1 mm, Key West, Florida, lateral (left) and abdominal face (right), setae omitted. (c, e, g–l, from Chace, 1966, fig. 10–11; f, from Manning & Chace, 1990, fig. 43). Approximate magnification x 6 (x 12 for detail of terminal portion).