Grapsus granulosus H. Milne-Edwards, 1853

Naderloo, Reza, 2011, Grapsoid crabs (Decapoda: Brachyura: Thoracotremata) of the Persian Gulf and the Gulf of Oman, Zootaxa 3048, pp. 1-43 : 5-6

Grapsus granulosus H. Milne-Edwards, 1853

( Figs. 2 a–f, 5b, c)

Grapsus granulosus H. Milne-Edwards, 1853: 169 .

Grapsus granulosus — Crosnier 1965: 13, figs. 9, 12. — Holthuis 1977: 148. — Vannini & Valmori 1981: figs. 1E, 2E, 3E. — Apel 2001: 117. — Zaouali et al. 2007: 2, fig. 1. — Ng et al. 2008: 216 (list), 218.

Type locality. Red Sea.

Material examined. PERSIAN GULF, Iran: 1 male, 2 juv. ( SMF 38442), rocky/boulders with dead corals, Zeytun park beach, Qeshm I., 27º 11'N, 56º 24'E, coll. R. Naderloo & M. Türkay, 08.01.2008; 1 female (ovig.) ( SMF 38443), sandy/cobble, Dustku, Qeshm I., 26º 31'N, 55º 21'E, coll. R. Naderloo & A. Kazemi, 0 7.05.2008. Saudi Arabia: 1 male ( SNMNH 158), Ash Sharghiyah, Karan I., 27º 43'N, 49º 49'E, coll. M. Apel, 20.05.1995; 1 male ( SMF 37392), Ash Sharghiyah, Karan I., 27º 43'N, 49º 49'E, coll. M. Apel, 17.07.1992; 1 male, 1 female ( SMF 37390), Ash Sharghiyah, Karan I., 27º 43'N, 49º 49'E, 20.05.1995. UAE: 1 male ( SMF 37391), Lulayyah Harbour, Sharjah, 25º 23'N, 56º 22'E, coll. M. Apel, 27.06.1995.

GULF OF OMAN, Iran: 1 male ( ZUTC Brach1183), rocky bed, Djod village, Baluchestan, 25º 17'N, 59º 30'E, coll. R. Naderloo & A. Kazemi, 25.10.2006; 2 males ( ZUTC Brach1133), rocky/sandy, Ramin, Baluchestan, 25º 16'N, 60º 44'E, coll. R. Naderloo & A. Kazemi, 18.11.2005. UAE: 2 males, 1 juv. ( SMF 37390), Sandy Beach Hotel, 15 km N. of Khor Fakkan, Fujairah, 25º 30'N, 56º 22'E, coll. M. Apel, 23.06.1995.

Redescription. Carapace nearly quadrate ( Figs. 2 a, 5c), slightly broader than long, weekly convex; regions well defined; lateral regions of carapace with numerous curved ridges, ridges longer posteriorly, short ridges over central regions, one transverse ridge parallel to posterior margin. Lateral margin of carapace smooth, nearly straight, gently converging posteriorly; 2 anterolateral teeth (including exorbital tooth), sharp triangle, separated by relatively wide V-shaped notch; shallow groove extending obliquely from this notch towards cardiac region. Frontal region with 4 granular lobes; frontal region gently flexed downwards; frontal ridge sinuous-shaped, weekly 2- lobed.

Orbits with supraorbital margin smooth, curved medially, V-shaped notch separated inner part from lateral part; one granular elevation behind this notch; inferorbital margin with inner angle elongated triangular; middle portion finely granular, separated from outer angle by deep U-shaped notch; outer angle with elevated granular process on inner surface.

Third maxilliped ( Fig. 2 d) with ischium remarkably longer than merus, about 1.4 times as long as merus; inner margin granular, with large spine, smaller one on proximal portion, concealed with dense setae; merus with small tooth on distal part of inner margin.

Chelipeds nearly equal, relatively small compared to walking legs. Ischium with 3 or 4 spines on anterior margin. Merus with spine-shaped teeth on anterior margin; lower posterior margin granular, granules tooth-shaped distally; upper posterior margin serrate; outer surface with transverse ridges. Carpus with strong spine on inner margin; outer surface with dispersed low granules. Manus ( Fig. 2 c) with 2 long ridges on lower portion of outer surface, lower one longer, extending from tip of immovable finger to near articulation with carpus; large granules on upper margin, distal one longest, tooth-shaped; lower margin with long transverse ridges; inner surface with transverse ridges. Movable finger with large tubercles proximally on upper surface; cutting edges of fingers proximally with large gap between them; teeth of different sizes on movable finger; cutting edge of immovable finger with 2 large teeth on middle part; short setae along inner surface of teeth; brown tip of fingers not spoon-shaped.

Walking legs relatively long, with third leg longest ( Fig. 2 b). Merus large, anterior margin slightly serrate, with subdistal spine, distal portion notched, small spine between subdistal spine, distal notch; posterior margin smooth, 4 spines on posterodistal lobe, smaller distally; posterior surface with transverse ridges. Carpus with 2 carinae on posterior surface, anterior one more prominent, posterior one with fine, plumose setae along it. Propodus of third leg ( Fig. 2 b) about 3.3 times as long as broad, slightly longer than carpus; posterior margin with distal spine, distal lobe with small spiniform tooth on posterior portion; row of plumose setae along posterior surface near anterior margin, in fourth walking legs near posterior margin. Dactylus with 2 rows of 6 spines along anterior margin, 2 rows of 4 or 5 spines on posterior margin; dactylus ending with large spine.

Male abdomen ( Fig. 2 e) broadly triangular, fifth somite longest, about 2.8 times as broad as long; sixth converging distally, telson relatively elongately triangular, longer than sixth somite.

G1 stout ( Fig. 2 f), relatively straight, flatted proximally, getting swollen distally; short setae densely on apical portion; apical chitinous process ( Fig. 2 g) small, flat, triangular, directed outward.

Remarks. Grapsus granulosus H. Milne-Edwards, 1853 , has often been considered to be a junior synonym of Grapsus albolineatus (e.g., Alcock 1900; Banerjee 1960; Davie 2002), but Crosnier (1965), Vannini & Valmori (1981), Zaouali et al. (2007) and Ng et al. (2008) have argued that it is a distinct species. This species is distinguishable from its closely related congener, G. albolineatus , by using a combination of characters (see Table 1 ).

Biology. Grapsus granulosus is a medium-size species (largest male CL = 19.71 mm, CB = 21.49 mm, largest female CL = 21.11 mm, CB = 23.49 mm). It is essentially a rocky shore species found in mid-intertidal. Grapsus granulosus is not as common as the G. albolineatus .

Colour. The upper surface of carapace and legs has a background of light greenish grey mottled with brown spots, which are dark brown on the frontal region of the carapace. The walking legs have dark and thick transverse bands. The ventral surface of the carapace is white with light reddish brown patches on the anterior part. The cheliped in frontal view is white, with pale violet on the proximal and upper surface of the palm.

Regional records. PERSIAN GULF: Saudi Arabia ( Apel 2001), UAE ( Apel 2001), Iran (present study); GULF OF OMAN: UAE ( Apel2001), Iran (present study).

Geographical distribution. Western Indian Ocean: Red Sea, Gulf of Aden, Persian Gulf, Gulf of Oman, and recently entered south Mediterranean Sea from Red Sea through Suez Canal ( Zaouali et al. 2007).

Figures

FIGURE 2. Grapsus granulosus H. Milne Edwards, 1853, male (ZUTC Brach 1183). a, posterior surface of carapace; b, third walking leg of male (left); c, cheliped of male, outer surface; d, third maxilliped (right); e, male abdomen; f, G 1, lateral surface (right); g, apical part of the same G 1.