Pachygrapsus laevimanus Stimpson, 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 : 18-22

Pachygrapsus laevimanus Stimpson, 1858 ( Figures 5a–f , 14b , 15b , 16 )

Pachygrapsus laevimanus Stimpson, 1858: 48 [102] [type locality: Port Jackson, Sydney, Australia] — Stimpson, 1907: 117 (New South Wales). — Holthuis & Gottlieb, 1958: 102 (New South Wales). — Davie, 1998b: 151, photograph (Queensland); 2002: 218 (Queensland, New South Wales, Norfolk I.). — Poore, 2004: 508, fig. 161d, h, 162b (Queensland, New South Wales, Victoria).

Pachygrapsus transversus — Rathbun, 1907: 29 (Easter I.); 1918: 248 (part, only specimens from Sydney and Easter I.). — Garth, 1973: 324 (Easter I). — Báez & Ruiz, 1985: 105 (Easter I.). [Not P. transversus ( Gibbes, 1850) ]

Type material

Male neotype 18.0 x 21.7 mm ( AM P7478), herein designated. Pachygrapsus laevimanus was poorly described by Stimpson (1858) from specimens collected in the vicinity of Sydney. Most of Stimpson’s collections, including the types of P. laevimanus , were lost in the Chicago fire of 1871. As a result, this species has been ignored for many years and often confused with P. transversus ( Gibbes, 1850) , a species widely distributed in the Mediterranean, east and west Atlantic, and east Pacific. Because of this long period of confusion, and because even now there is uncertainty over the identity of specimens from Easter I. (see below), we believe that it is necessary to erect a neotype for P. laevimanus to ensure the future stability of this taxon.

Material Examined

Neotype. Australia. New South Wales: Sydney, 33°52’S, 151°15.5’E, on reef, Rose Bay, Port Jackson , coll. Mel Ward, September 1924, 1 M 18.0 x 21.7 mm ( AM P7478 ).

Other specimens. Australia. New South Wales: Sydney, Manly , leg from AM, 3 M 6.2 x 7.9–8.3 x 10.2 mm, 1 F 6.8 x 8.4 mm ( USNM 43776 ) ; Sydney , November 1926, among small stones in rock crevices, between tides marks, 1 M 10.6 x 12.6 mm, 1 ov. F 8.5 x 10.6 mm, 1 F 8.0 x 10.0 mm ( MNHN B11083; leg from AM P5D07, part) ; Sydney, Balmoral Beach, Mosman , coll. L. B. Holthuis, 23 April 1955, 5 M 7.9 x 9.6–12.0 x 14.7 mm, 5 F 6.3 x 7.9–9.6 x 12.1 mm ( RMNH 10424 ) ; Sydney, Port Jackson , bottle and glass rocks, intertidal under stone and weed, 33°50.9’S, 151°16.2’E, coll. D. J. G. Griffin, 23 October 1968, 1 M 6.7 x 8.4 mm, 1 F 7.0 x 8.7 mm, 1 juv. 3.9 x 4.9 mm, ( AM P17802) ; Sydney, Long Bay Coast, rocky reef, between tide marks, purchase #78 S. Kellner, 3 M 6.3 x 7.4– 7.5 x 9.1 mm, 1 ov. F 5.8 x 7.3 mm ( USNM 98830 ) ; Sydney , ‘ Maulyi’, AM acc. n° 25661, coll. 3 February 1889, 2 M 8.5 x 10.5, 10.5x12.5 ( UNSM 17054 ) ; Twofold Bay, Murrumbulga point, 37°04.7’S, 149°53.1’E, intertidal rock platform, coll. S. Keable, 25 July 1985, 3 M 7.5 x 9.1–11.9 x 14.7 mm, 2 F 8.0 x 10.1, 9.7 x 12.1 mm ( AM P36075) ; mouth of Clarence R., 29°26’S, 153°22’E, coll. A. A. Cameron, 1 ov. F 11.3 x 14.2 mm ( QM W3306 ) . — Lord Howe I.: 31°31’S, 159°04’E, Neds Beach, coll. G. Kelly, 14 September 2003, 5 M 9.6 x 11.7–12.1 x 14.4 mm, 1 ov. F 11.8 x 14.0 mm ( QM W26879) ; 31°31’S, 159°04’E, Neds Beach, coll. G. Kelly, 30 August 2003, 1 M 14.3 x 17.4 mm ( QM W26876) . — Queensland: Caloundra, Kings Headland , 26°48’S, 153°08’E, rocky shore, under rocks, coll. J. W. Short, M. Bavins, October 1996, 3 F 8.5 x 10.4–13.8 x 16.8 mm ( QM W21818) ; Kings Headland , 26°48’S, 153°09’E, rocky shore, under rocks, coll. J. W. Short, 27 September 1996, 1 F 8.7 x 10.5 mm ( QM W21533) ; Kings Headland, N. end, Kings Beach , 26°48’S, 153°08’E, rocky shore, coll. M.S.A. party (Brisbane Shell Club), 13 March 1983, 1 F 7.6 x 9.3 mm ( QM W10457) ; Kings Headland , 26°48’S, 153°08’E, rocky shore, coll. P. Davie, D. Potter, 30 July 1997, 2 M 11.6 x 14.6, 11.3 x 13.3 mm ( QM W23937) ; Moreton Bay , 27°00’S, 153°00’E, 2 M 11.3 x 13.3, 14.7 x 17.9 mm ( QM W12336) . — Tasman Sea. Middleton reef: 29°28.5’S, 159°03.7’E, reef flat near wreck of Runic, rubble, dead coral heads, dead Tridacna , low tide, coll. J. K. Lowry, 4 December 1987, 9 M 3.5 x 4.6–10.3 x 12.9 mm, 7 ov. F 4.5 x 5.8–7.9 x 9.8 mm, 6 F 5.9 x 7.6–8.7 x 11.0 mm ( AM P38221) ; 29°25’S, 159°00’E, near wreck of Runic, coll. J. W. Short, R. J. McKay, 9 May 1987, 1 M 10.6 x 13.2 mm ( QM W13048) , 1 M 7.1 x 9.2 mm ( QM W13050) . — Elizabeth reef, 29°55.4’S, 159°02.7’E, sand cay, north west lagoon entrance, under stone, low tide, coll. J. K. Lowry, 12 December 1987, 12 M 7.9 x 9.8–11.7 x 14.2 mm, 5 ov. F 6.5 x 8.0–8.2 x 10.2 mm, 4 F 8.3 x 9.8–10.0 x 12.7 mm ( AM P38223) ; 29°55’S, 159°00’E, coll. J. W. Short, 6 May 1987, 1 M 12.4 x 14.9 mm ( QM W13051) , 4 May 1987, 4 M 4.8 x 5.9–14.3 x 17.4 mm ( QM W13047) .

Norfolk I.: Cemetery Bay , under stones on intertidal rock platform, coll. D. J. G. Griffin, 30 March 1969, 1 M 5.4 x 7.0 mm, 1 F 6.7 x 8.7 mm ( AM P17329) .

Austral Is.: Rapa I., Haurei Bay , intertidal, RV Marara campaign, coll. J. Poupin, 19 to 21 March 1995, 13 M 6.6 x 7.8–14.0 x 16.8 mm, 4 ov. F 8.0 x 10.0–11.1 x 13.9 mm, 4 F 8.1 x 10.3–13.9 x 17.0 mm ( MNHN B29265) . — BENTHAUS Expedition: Haurei Bay , intertidal, near wharf, among stones and rubbles, coll. J. Poupin, 2 November 2002, 14 M 4.0 x 5.0–14.8 x 17.5 mm, 7 ov. F 6.6 x 8.0–12.8 x 16.0 mm, 7 F 7.1 x 8.6–11.3 x 13.6 mm ( MNHN B29266) ; Haurei Bay , intertidal, coll. A. Warén, 8 November 2002, 2 F 6.3 x 7.7, 6.6 x 7.9 mm ( MNHN B29267) ; 27°37.4'S, 144°18.4’W, north of Anatakuri Bay , 2 m, in sediment under stones, coll. malacologist team, stn 38, 22 November 2002, 1 M 6.3 x 7.6 mm ( MNHN B29268) ; Anarua Bay , 27°36.4’S, 144°22.6’W, intertidal, coll. malacologist team stn 87 (possibly 86), 25 November 2002, 1 juv. 2.6 x 3 mm ( MNHN B29269) .

Easter I.: shore, coll. RV Albatross, 16 December 1904, 1 F 7.6 x 9.5 mm (UNSM 33186; see remarks).

Description

Carapace 1.2–1.3 times broader than long ( Fig. 5a ). Dorsal surface slightly convex on anterior half, covered with strong transverse striae, smooth or with scarce setae. Median postfrontal lobes distinct, striated; mesogastric, cardiac regions with few short striae (sometimes indistinct on cardiac region); intestinal region flat, almost totally smooth. Lateral margins of carapace convex, slightly convergent posteriorly, armed with single conspicuous tooth posterior to exorbital tooth. Front 0.6 times exorbital width ( Fig. 5b ); anterior margin sinuous, granulate, with shallow sinuses. Orbits subrectangular in dorsal view, about one third as wide as front; infraorbital margin minutely dentate, separated by deep notch from outer orbital tooth ( Fig. 14b ).

Chelipeds equal. Merus striated transversely, inner ventrodistal lobe denticulated, with 2–6 distinct teeth. Carpus smooth on upper surface; with blunt tooth at inner distal angle. Chelae robust, height about half length ( Fig. 5c ). Upper margin rounded, with faint oblique striae proximally, on inner side. Outer face smooth, regularly convex; smaller specimens with weak longitudinal line on outer face of fixed finger, near lower margin. Inner surface of palm smooth. Fingers about two third as long as palm, narrowly gaping, tip corneous, spoon­like, glabrous. Cutting margin of fixed finger with 6–7 triangular teeth, larger medially; moveable finger with 3–4 triangular teeth proximally.

Ambulatory legs robust. Meri with faint transverse ridges on outer surfaces; upper margins with few moveable spines on distal half; P2–P4 with strong dorsodistal tooth, dorsodistal angle of P5 rounded or only with small tooth; lower margins unarmed except for 2–3 spines at distal angles. Dactyli slightly curved, armed with several long moveable spines, terminating in strong corneous claw. P2 propodus with row of setae on dorsal margin. P3 propodus with conspicuous brush of setae on dorsal margin ( Fig. 5d ); on some specimens this brush may be poorly developed or even missing. Lower margin of P5 merus slightly denticulate, usually without sub­median tubercle ( Fig. 5e ), except on few of smallest specimens (less than 8 x 10 mm).

Abdominal tergites and thoracic sternites smooth ( Fig. 5f ). Sixth somite of abdomen plus telson triangular in male. G1 ( Fig. 15b ) stout with distal process horn­like, strongly curved.

Colour: live colour is dark brown to black, slightly paler along transverse striations, often with paler cardiac and intestinal regions and a few small paler patches surrounding the metagastric region; chelae with inner face becoming lighter in colour ventrally and distally with tips of fingers pale.

Measurements: medium size; carapace of specimens examined ranging from: males 3.5 x 4.6–18.0 x 21.7 mm; females 4.5 x 5.8–13.9 x 17.0 mm; smallest ovigerous female was 4.5 x 5.8 mm.

Distribution

Eastern Australia (New South Wales, southern Queensland, Victoria); Tasman Sea (Middleton and Elizabeth Reefs), Norfolk and Lord Howe islands ; French Polynesia, Austral Is. (Rapa I.);? Easter I. Between latitude 26– 37°S, longitude 149°E – 144°W ( Fig. 16 ) .

Habitat

Found in the intertidal zone among small rocks and stones, dead coral, rubble, and seaweeds.

Remarks

Pachygrapsus laevimanus is morphologically close to P. transversus ( Gibbes, 1850) of similar size, especially in the shape of the carapace and chelae. The setation of the ambulatory legs, however, differs conspicuously between the two species. There is a brush of setae on the P2 propodus in P. transversus (obvious in females only), whereas it is located on P 3 in P. laevimanus . The shape of the G1 is also very different between the two species, with the tip slender and petal­like in P. transversus instead of stout and horn­like in P. laevimanus ( Fig. 15b, l ).

Pachygrapsus laevimanus was poorly described by Stimpson (1858) from specimens collected in the vicinity of Sydney. As a result, this species was ignored for many years and often confused with P. transversus ( Gibbes, 1850) , a species with a wide distribution in the Mediterranean, east and west Atlantic, and east Pacific. Holthuis & Gottlieb (1958) were the first to point out the existence of P. laevimanus from specimens collected near Sydney in 1955. Davie (2002) correctly listed P. laevimanus , giving its distribution as New South Wales, Queensland, and Norfolk I. The specimens collected from Rapa I. greatly extend eastward the distribution of P. laevimanus . In French Polynesia at least, the species seems to be confined to subtropical latitudes. It is one of the commonest intertidal crabs in Haurei Bay, Rapa I. (28°S) but it has never been observed in the Austral Is., which are situated at more northern latitudes (Raevavae I., 24°S; Tubuai I., 23°S).

Pachygrapsus laevimanus may also be present much further east on Easter I. at the same latitude as Rapa I. Similarities between the decapods of the two islands have been shown by Poupin (2003). A Pachygrapsus female collected in 1904 on Easter I. ( USNM 33186) and attributed to P. transversus by Rathbun (1907) shows that although very similar to P. transversus of the same size and sex from the Atlantic, it differs slightly in the setation of the ambulatory legs. Females of P. transversus from the Atlantic have a slight brush of setae on the P2 propodus and no setae on the P3 propodus, whereas on the Easter I. female there is no brush on P2 and a faint one on P3, a characteristic of P. laevimanus . Unfortunately, no male specimen of P. transversus was available from Easter I. to confirm this identification. Garth (1973) confirmed the presence of P. transversus on Easter I. but did not mention the shape of the G1 and did not compare his specimens with P. laevi­ manus. Garth’s Easter I. specimens have not been located in several collections ( CAS, LCMN, SIO, USNM). Other specimens from Easter I. attributed to P. transversus by Báez & Ruiz (1985), and deposited in the MNHNS collections, were not available for this study. While the morphology of the G1 should confirm the identification, it seems most likely that P. laevimanus , not P. transversus , is found in Easter I.

Figures

FIGURE 5. —Pachygrapsus laevimanus Stimpson, 1858. Neotype male 18.0 x 21.7 mm (AM P7478): a) dorsal view; b) front; c) left chela, outer face; d) right P3; e) right P5; f) abdomen.

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).

FIGURE 16. —Geographic distribution of: a) Pachygrapsus crassipes Randall, 1840 (Stars); b) Pachygrapsus transversus (Gibbes, 1850) (full dots); and c) P. laevimanus Stimpson, 1858 (empty dots). a–b, mostly from literature; c) from collections examined during this study. Occurrence of P. laevimanus at Easter I. uncertain (?) and must be confirmed by examination of G1 (see text).