A revision of the genus Pachygrapsus Randall, 1840 (Crustacea: Decapoda: Brachyura, Grapsidae), with special reference to the Southwest Pacific species
Author
Poupin, Joseph
Institut de Recherche de l'Ecole Navale, IRENav BP 600, 29240 BREST NAVAL France (poupin @ ecolenavale. fr; cexus @ ecole-navale. fr) Queensland Museum, P. O. Box 3300, South Brisbane, Queensland, Australia (peter. davie @ qm. qld. gov)
poupin@ecolenavale.fr
Author
Davie, Peter J. F.
Author
Cexus, Jean-Christophe
Institut de Recherche de l'Ecole Navale, IRENav BP 600, 29240 BREST NAVAL France (poupin @ ecolenavale. fr; cexus @ ecole-navale. fr) Queensland Museum, P. O. Box 3300, South Brisbane, Queensland, Australia (peter. davie @ qm. qld. gov)
poupin@ecolenavale.fr
text
Zootaxa
2005
2005-07-05
1015
1
1
66
https://biotaxa.org/Zootaxa/article/view/zootaxa.1015.1.1
journal article
10.11646/zootaxa.1015.1.1
11755334
5049232
67DBD7AA-FA11-4F32-811B-0A9EFF4C668F
Pachygrapsus fakaravensis
Rathbun, 1907
(
Figures 3a–f
;
14a
;
15a
)
Pachygrapsus fakaravensis
Rathbun, 1907: 29
, pl. 5, fig. 1, pl. 9, fig. 6, 6a [
type
locality: Fakarava Atoll, Tuamotu Archip.,
French Polynesia
].
—
Tesch, 1918: 76
(Key). —
Sakai, 1976: 636
, pl. 218, fig. 3 (
Japan
). —
Hwang & Yu, 1980: 153
, pl. 112 (Taiwan). —
Monteforte, 1984: 172
, annex I, tab. a (Tuamotu Archip.). —
Poupin, 1994: 62
, fig. 58, pl. 7e (Tuamotu Archip.). —
Davie, 1998a: 63
(Hawaiian Is.). —
DeFelice
et al
., 2001: 45
(Hawaiian Is.). —
Ng
et al
., 2001: 40
, fig. 8e (Hawaiian Is.,
Taiwan
; references).
Type material
Male
holotype
, 18.0 x
19.4 mm
(
USNM 32844
)
.
Material Examined
French Polynesia
.
Tuamotu Archip.
:
Fakarava Atoll
, outer reef, coll. USS
Albatross
,
12 October 1899
, M
holotype
18.0 x
19.5 mm
(
USNM 32844
);
Taiaro Atoll
, outer reef, low tide at night, on big coral rocks,
Taiaro Expedition
, coll.
J. Poupin
,
12–20 February 1994
, 1 ov. F 15.0 x
16.5 mm
(
MNHN
B25782)
. —
Hawaiian
I.
:
Milolii
, intertidal on rocks at night, coll.
G. Paulay
,
31 October 1997
, 1 ov. F. 12.9 x
15.1 mm
(
UF 2255
; erroneously labelled
P. plicatus
)
.
Diagnosis
Carapace subquadrate; lateral margins almost parallel with no tooth behind exorbital angle (
Fig. 3a
). Dorsal surface weakly convex with strong transverse striae with setae. Front 0.5 times carapace width at exorbital angles; anterior margin sinuous (
Fig. 3b
). Infraorbital margin dentate along entire length, separated from outer orbital tooth by deep notch (
Fig. 14a
).
Chelipeds equal. Merus with deep transverse striae with setae; dorsal, anterior margins with few mobile spines, inner ventrodistal lobe with 3–4 teeth. Carpus with few granules, short striae with setae; inner spine stout, blunt. Outer face of chela with several longitudinal striae formed by rounded tubercles with setae on lower half; upper half with rounded granules surrounded by setae (
Fig. 3c
).
Tips
of fingers spoonlike, glabrous.
Meri of ambulatory legs with deep transverse to oblique ridges with setae; lower margin of P5 meri without submedian tubercle (
Fig. 3d
). Carpi, propodi with two longitudinal striae with setae. Dactyli ending in strong corneous claw; dorsal, ventral margins with rows of strong, moveable spines.
Male with numerous short setiferous striae on abdominal tergites, thoracic sternites; sixth somite of abdomen plus telson triangular (
Fig. 3e
). Female with several short setiferous striae on abdominal tergites (
Fig. 3f
). G1 with long, hornlike process with minute spinule medially (
Fig. 15a
).
Colour: overall brown to dark brown with violet hues and paler areas on ambulatory legs.
Measurements: carapace of specimens examined ranging from 12.9 x 15.1 to 15.0 x
16.5 mm
.
Distribution
West and Central Pacific
.
Japan
;
Taiwan
, Hawaiian Is.,
French Polynesia
(Tuamotu Archip.: Fakarava, Makatea, Mataiva, Taiaro, Takapoto).
Habitat
Collected at upper level of reefs at night; uncommon.
Remarks
FIGURE 3.
—
Pachygrapsus fakaravensis
Rathbun (1907)
. a) dorsal view; b) front; c) left chela, outer face; d) right P5; e) male abdomen; f) female abdomen. a, b, d, f, ov. female 15.0 x 16.5 mm (MNHN B25782); c, e, holotype male 18.0 x 19.4 mm (USNM 32844).
Pachygrapsus fakaravensis
is uncommon, rarely reported in the literature. It is morphologically close to the IndoWest Pacific
P. plicatus
(H.
Milne Edwards, 1837
)
, which has similar coarse striations on the carapace and the same longitudinal striae on the outer face of the chelae. The two species have been collected together in
French Polynesia
. They can be separated by the shape of the lateral carapace margins (subparallel in
P. fakaravensis
, posteriorly convergent in
P. plicatus
), the presence of setae on the longitudinal striae of the outer face of the chelae of
P. fakaravensis
, and by the abdominal tergites having short striae in
P. fakaravensis
but being smooth in
P. plicatus
. The shape of the G1, figured here for the first time for
P. fakaravensis
, also separates the two species (
Fig. 15a, e
).
After examining
P. corrugatus
(von
Martens, 1872
)
from the west and central Atlantic (
USNM
72340, 122786, 252325), it is clear that
P. fakaravensis
is morphologically close to the latter and may thus be considered a sibling species. It is surprising that neither
Rathbun (1907)
in her description of
P. fakaravensis
, nor
Manning & Chace (1990)
in recording and illustrating a male of
P. corrugatus
from
Ascension
I., mentioned this sharp similarity. Both species share a subrectangular carapace, with almost parallel lateral margins; coarse and hairy striae on the carapace; several longitudinal striae furnished with setae on the outer face of the chelae; abdominal tergites with short transverse striae; similarly shaped infraorbital margins, with a small protrusion distally followed by a deep indentation; and similar G1 (
Fig. 15a, f
). The two species can, however, easily separated using the relative striation of the abdominal tergites, which is more pronounced in
P. fakaravensis
than in
P. corrugatus
. This difference is especially obvious in males. Striae are also present on the thoracic sternites of
P. fakaravensis
but absent in
P. corrugatus
(
Fig. 3e
,
1d
).
Davie (1998a)
suggested that it was likely that
P. fakaravensis
had only recently become established or possibly introduced in the Hawaiian Is. because it was unusual that such a relatively large and distinctive intertidal crab, living in a major harbour on the island of Oahu, had not been previously noticed, especially given the large collections reported by
Rathbun (1906)
and the extensive collections made by
Edmondson (1959)
.