Pachygrapsus gracilis
Creators: name: Poupin, Joseph
name: Davie, Peter J. F.
name: Cexus, Jean-Christophe
Publisher: name: Zenodo
Year: 2005
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Grapsidae
Pachygrapsus
Pachygrapsus gracilis

description: 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.
description: Published as part of 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, pp. 1-66 in Zootaxa 1015 (1) on pages 15-18, DOI: 10.11646/zootaxa.1015.1.1, http://zenodo.org/record/5049232