Pachygrapsus maurus ( Lucas, 1846 )

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 : 28-31

Pachygrapsus maurus ( Lucas, 1846) ( Figures 8a–e , 14k , 15k )

Grapsus maurus Lucas, 1846: 20 , vol. 4, pl. 2, fig. 5 [type locality: Oran, Algeria]

Leptograpsus maurus —H. Milne Edwards, 1853: 173 ( Algeria).

Pachygrapsus simplex — Stimpson, 1858: 48 [102] (Madeira); 1907: 116 (Madeira).

Pachygrapsus maurus — Heller, 1863: 112 ( Algeria). — Kingsley, 1880: 199 (Key; synonymy). — Rathbun, 1918: 244 (Azores, Canary Is.; synonymy). — Bouvier, 1940: 290, fig. 180 ( Algeria, Madeira, Azores). —Zariquiez Álvarez, 1948: 291, pl. 24, fig. 1­2 ( Spain); 1968: 425, fig. 140b, 141a ( Spain). — Falciai & Minervini, 1992: 234. —d’Udekem d’Acoz, 1994: 36 ( Greece); 1999: 255, unnumbered fig. p. 52 (references, distribution, ecology); 2005 (photographs, reference, distribution). — González Pérez, 1995: 223, photo 164 (Canary Is.).

Type material

Probably not extant. According to Rathbun (1918: 244) the type was at MNHN but the first author was unable to locate it.

Material Examined

Central Atlantic. Azores: São Miguel I., coll. Collette & R. B. Manning, 13 March 1963, 1 M 9.0 x 10.4 mm ( USNM 170343 ). Terceira I., unknown coll., 1 F 6.5 x 7.7 mm ( USNM 18627 ; see remarks) .

East Atlantic. Madeira: Funchal, J. Panousse, 1973, 2 M 8.7 x 10.0, 9.6 x 10.7 mm ( MNHN B12931) . Canar y Is.: Gran Canaria, Guia I., coll. U.S. Fish Commission, September 1894, and unknown coll., September 1994, 3 M 6.7 x 7.9–9.2 x 10.4 mm, 1 ov. F 7.4–8.2 mm, 4 juveniles ( USNM 44529 ) . Mediterranean Sea. France: Banyuls, coll. and det. J. Forest, 1 F 12.7 x 14.3 mm ( MNHN B12933) ; Spain, Cadaqués, coll. and det. J. Forest, July 1955, 4 M 6.9 x 8.4–9.4 x 10.6 mm, 1 ov. F 6.0 x 7.0 mm ( MNHN B12932) .

Diagnosis

Carapace with glabrous striae on gastric, hepatic, branchial regions; mesogastric, cardiac regions with shorter, fainter striae, intestinal region almost smooth; lateral margins weakly convergent posteriorly with tooth behind exorbital angle ( Fig. 8a ). Front 0.6 times exorbital width; anterior margin sinuous ( Fig. 8b ). Infraorbital margin slightly denticulated on inner half, almost smooth on outer half; outer notch deep, obliquely oriented ( Fig. 14k ).

Outer face of palm regularly convex with numerous small pits; distal half with faint stria above lower margin ( Fig. 8c ); dorsal margin of palm rounded with faint oblique lines on inner face; cutting edges of fingers with triangular teeth, tip of fingers corneous, spoonlike, glabrous ( Fig. 8c ). P2–P3 propodi without brush of setae, at most with a denser area of stiff setae on smallest specimens. Lower margin of P5 merus smooth; distoventral angle rounded or feebly indented ( Fig. 8d ).

Abdominal tergites smooth. Sixth somite of abdomen plus telson triangular in male ( Fig. 8e ). G1 bluntly rounded with a low corneous gutter­like process ( Fig. 15k ).

Colour (d’Udekem d’Acoz, pers. comm.): Large round bluish/greyish or pale yellowish spots on a black background. In some specimens the spots are confluent.

Measurements: medium size; carapace of specimens examined ranging from 6.5 x 7.7–12.7 x 14.3 mm, smallest ovigerous female 6.0 x 7.0 mm. D’Udekem d’Acoz (2005) indicates a cw of about 20 mm.

Distribution

West Atlantic and Mediterranean. Azores, Madeira, Canary Is. (common), Mediterranean. Patchy distribution as a result of the rarity of suitable habitats .

Habitat Intertidal on rocks and cliffs with strong wave exposure (d’Udekem d’Acoz, 2005).

Remarks

Pachygrapsus maurus appears more closely related to species of Pachygrapsus that have no brush of setae on the P2 or P3 propodi. This brush of setae was absent on most of the specimens examined, however. It seems to be a juvenile character that disappears in adults because it was found in the three smallest specimens examined: female 6.5 x 7.7 mm, Terceira ( USNM 18627 ), and two males 6.9 x 8.4, 7.4 x 8.4 mm, Cadaqués , Spain ( MNHN B12932) .

Pachygrapsus maurus and P. marmoratus occur sympatrically in the Azores, Madeira, Canary Is., and the Mediterranean. Pachygrapsus maurus is smaller (cw about 20 mm) than P. marmoratus (cw about 40 mm), and it has only one tooth behind the exorbital angle instead of two in P. marmoratus .

Pachygrapsus maurus is morphologically close to P. transversus . but P. transversus is larger than P.maurus . The G1 is clearly distinct, with a petal­like tip in P. transversus ( Fig. 15l ) instead of bluntly rounded with a short corneous process in P. maurus ( Fig. 15k ). Small females of these two species are more difficult to separate on a morphological basis. A small female of P. maurus from the Azores (USNM 18627) showed a brush of setae on the P2 propodi, and was thus very similar to females of P. transversus of similar size. It was identified as P. maurus because the distoventral angles of the P5 merus are rounded, without spines, whereas P. transversus has 3–4 spines.

Figures

FIGURE 8. —Pachygrapsus maurus (Lucas, 1846). a) dorsal view; b) front; c) left chela, outer face, d) right P5, e) male abdomen. a, c, d, female 12.7 x 14.3 mm, Banyuls­sur­Mer, France (MNHN B12933), b, e, male 8.5 x 9.9 mm, Gran Canaria I. (USNM 44529).

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).