Grapsus albolineatus Latreille

Naderloo, Reza, 2011, Grapsoid crabs (Decapoda: Brachyura: Thoracotremata) of the Persian Gulf and the Gulf of Oman, Zootaxa 3048, pp. 1-43 : 2-5

Grapsus albolineatus Latreille in Milbert, 1812

( Figs. 1 a–e, 5a, b)

Grapsus albolineatus Latreille in Milbert, 1812: 274. — Vannini & Valmori 1981: 64, figs. 1D, 2D, 3D, 4D. — Crosnier 1965: 13, figs. 8, 11. — Holthuis 1977: 145. — Titgen 1982: 142, 253 (list). — Tirmizi & Ghani 1996: 138, fig. 53. — Carpenter et al. 1997: 40. — Apel 2001: 116, 124, 134 (list). — Ng et al. 2008: 216 (list).

Grapsus maculatus subsp. tenuicrustatus — Stephensen 1945: 194, 210 (list), figs. 59A–D [not Cancer tenuicrustatus Herbst, 1783 ].

Grapsus tenuicrustatus — Pretzmann 1971: 479. — Basson et al. 1977: 47, 145, 227. — Titgen 1982: 253 (list) [not Cancer tenuicrustatus Herbst, 1783 ].

Type locality. Mauritius

Material examined. PERSIAN GULF, Iran: 1 male ( SMF 38394), Basaeedu, Qeshm I., 26º 36'N, 55º 16'E, coll. R. Naderloo & A. Kazemi, 07.05.2008; 2 males, 1 female ( SMF 38395), Zeytun (olive) park beach, Qeshm I., 27º 11'N, 56º 24'E, coll. A. Sari, M. Türkay & R. Naderloo, 0 8.01.2008. UAE: 3 males ( SMF 37384) Lullayyah Harbour, Sharjah, 25º 23'N, 56º 22'E, coll. M. Apel, 27.06.1995; 1 female ( SMF 37385), N. coast of Ash Sham, Ras Al-Khaymah, 26º 02'N, 55º 02'E, coll. M. Apel, 10.07.1995. Saudi Arabia: 1 male, 1 female ( SNMNH 156), Ash Sharghiyah, Karan I., 27º 43'N, 49º 49'E, coll. M. Apel, 17.07.1992; 1 male, 1 female ( SNMNH 157), Ash Sharghiyah, Karan I., 27º 43'N, 49º 49'E, coll. M. Apel, 20.05.1995; 2 males, 1 female ( SNMNH 158), Ash Sharghiyah, Karan I., 27º 43'N, 49º 49'E, coll. M. Apel, 17.07.1992.

GULF OF OMAN, Iran: 1 female ( ZUTC Brach 1130), rocky shore, Gwadr, Baluchestan, 25° 08'N, 61° 27'E, coll. R. Naderloo & A. Sari, 19.11.2005; 1 male, 1 juv. ( ZUTC Brach 1179), rocky shore, Pasabandar, Baluchestan, 25° 04'N, 61° 24'E, coll. A. Sari & R. Naderloo, 18.11.2005; 1 female ( ZUTC Brach1132), rocky shore, Bandar- Ramin, Baluchestan, 25° 16'N, 60° 44' E, coll. A. Sari & R. Naderloo, 18.11.2005; 2 males ( ZUTC Brach1135), rocky shore, Hotel Lipar, Chabahar, Baluchestan, 25° 19'N, 60° 37' E, coll. A. Sari & R. Naderloo, 17.11.2005; 1 female ( ZUTC Barch1175), rocky/cobble, Portuguese castle, Chabahar, Baluchestan, 25º 16'N, 60º 37'E, coll. R. Naderloo & A. Kazemi, 17.11.2005; 4 males (juv.) ( ZUTC Brach1177), rocky shore, Chabahar, Baluchestan, 25° 16'N, 60° 40'E, coll. A. Sari & R. Naderloo, 17.11.2005; 1 male, 1 female ( ZUTC Brach1133), sandy/rocky, shrimp aquaculture station of Gorgij, Bandar-Jask, Hormozgan, coll. A. Sari & R. Naderloo, 16.11.2005; 2 males ( ZUTC Brach1134), sandy/rocky, fishery jetty, Sorgolm village, Bandar-Jask, Hormozgan, 25º 35'N, 58º 02'E, coll. A. Sari & R. Naderloo, 21.11.2005; 1 male, 1 female, 1 juv. ( ZUTC Brach1157) rocky shore, Yekdar village, Bandar-Jask, Hormozgan, 25° 33'N, 58° 15'E, coll. A. Sari & R. Naderloo, 21.11.2005.

Redescription. Carapace subcircular ( Figs. 1 a, 5a), slightly broader than long, about 1.1 times as broad as long, maximum breadth across middle part of carapace; carapace weakly convex; regions defined with shallow grooves; lateral regions with numerous curved ridges, getting longer posteriorly; transverse ridge along posterior region, parallel to posterior margin; short ridges on anterior half portion of carapace. Lateral margin of carapace remarkably arched (nearly straight in small specimens); 2 anterolateral teeth (including exorbital tooth), sharply triangular, separated by V-shaped notch; shallow groove extending obliquely from this notch towards cardiac region. Frontal region gently flexed downwards; 4-lobed, median 2 slightly larger than lateral 2; large tubercles on lobes, tubercles smaller posteriorly, large tubercles behind lateral lobes, small tubercles between frontal lobes, frontal edge; frontal ridge slightly wider than posterior margin of carapace, finely crenulated, nearly straight, slightly concave medially, with lateral angle rounded.

Orbits deep, U-shaped notch on supraorbital margin, separating inner from lateral part; granular elevation behind notch; outer part slightly granular. Infraorbital margin with inner angle acutely triangular; middle portion finely granular, with relatively large denticles on outer part, separated from outer angle by deep U-shaped notch; outer angle triangle with relatively large tooth on inner surface. Eyestalks short, proximal part wide, with granules on anterior face. Antennae remarkably short, flagellum not reaching to cornea.

Third maxilliped ( Fig. 1 c) with ischium slightly longer than merus, 2 large spines on proximal part of inner margin of ischium, concealed by dense setae.

Chelipeds subequal, in comparison to walking legs relatively small, ischium with 3 or 4 spine-shaped teeth on anterior margin. Merus with spine-shaped teeth on anterior margin, normally larger distally; lower posterior margin granulate, granules dentiform distally; upper posterior margin serrate; outer surface with transverse ridges. Carpus with strong tooth on inner margin, granular on outer surface. Manus ( Fig. 1 b) with 2 long ridges on lower portion of outer surface; lower one longer, extending from tip of immovable finger to near articulation with carpus; upper margin with large granules, distal one long, tooth-shaped; lower margin with long ridges, becoming round tubercles distally to base of immovable finger; inner surface smooth in middle, transverse ridges on upper part, tubercles proximally on lower portion. Movable finger with large tubercles proximally on upper margin; cutting edge with remarkably large, round tooth on proximal part; cutting edge of immovable finger with 3 similar teeth on proximal part, short setae along inner surface of teeth; black tip of fingers not spoon-shaped.

Walking legs relatively strong, flattened. Merus relatively large; posterior surface with transverse ridges; anterior margin serrated, with subdistal spine; small spine between subdistal spines, distal notch of merus in third walking leg; 4 spines on posterodistal lobe, becoming smaller distally. Carpus with 2 carinae on posterior surface, anterior carina more prominent, short plumose setae along posterior one; anterior surface with inconspicuous carina. Propodus with strong, retractile bristle along anterior, posterior margins; plumose setae on posterior surface; one posterodistal spine; distal lobe with supplementary tooth. Dactylus with 2 rows of 6 spines along anterior margin; 2 rows of 4 or 5 spines along posterior margin; dactylus ending with large spine.

Male abdomen ( Fig. 1 d) triangular; fifth somite longest, about 2.3 times as broad as long, sixth with lateral margin converging distally; telson clearly triangular.

G1 ( Fig. 1 e) remarkably stout, nearly straight; outer margin concave; inner margin convex, posterior surface proximally elevated in middle part; apical chitinous process ( Fig. 1 f) small, directed outwards; gonopore terminal; long setae around apical part, obscuring chitinous process.

Female gonopore ( Fig. 1 g) with elevated finger-like operculum, directed obliquely forward.

Remarks. Grapsus albolineatus has been referred to Lamarck (1818), but Ng et al. (2008) noted that the correct authority should be Latreille, in Milbert (1812). Holthuis (1977) has discussed the validity of this name in detail.

Biology. Grapsus albolineatus is a relatively large-size species (largest male CL = 50.27 mm, CB = 54.77 mm, largest female CL = 59.14 mm, CB = 63.80 mm) and is the most common species on exposed rocky shores in the Gulf of Oman and the Persian Gulf, where it is present in large populations on the high rocky intertidal. This species is sympatric with Metopograpsus messor in sheltered rocky shores in the Persian Gulf and in some locations it is replaced by the latter. Grapsus albolineatus is typical of exposed rocky shores and is normally seen foraging on algae, disappearing into crevices if disturbed.

Colour. Brownish red ( Fig. 4 a), sometimes bluish carapace, walking legs light red or orange, ventral side light, mottled with reddish orange, anterior surface of the palms light. The colour pattern was described in detail by Banerjee (1960).

Regional records. PERSIAN GULF: UAE [ Titgen (1982) from Dubai; Apel (2001) from Abu Dhabi and Ras al-Khaimah], Saudi Arabia ( Apel 2001), Iran [ Stephensen (1945) as Grapsus maculatus subsp. tenuicrustatus ; Pretzmann (1971) as Grapsus tenuicrustatus ; present study]. GULF OF OMAN: Iran [ Stephensen (1945) as Grapsus maculatus subsp. tenuicrustatus ; present study], UAE ( Apel 2001).

Geographical distribution. Indo-West Pacific: Mauritius, Somalia, Red Sea, Gulf of Aden, Socotra, Oman, Persian Gulf, Gulf of Oman, Pakistan, Arabian Sea coast of India, Sri Lanka, Bay of Bengal, Andaman Islands, Nicobar Islands, Mergui Archipelago, Indonesia, Singapore, China, Japan, Australia, Hawaii.

Figures

FIGURE 1. Grapsus albolineatus Latreille in Milbert, 1812, male (ZUTC Brach 1175): a – e; female (ZUTC Brach 1175): g. a, posterior surface of carapace; b, cheliped of male, outer surface; c, third maxilliped (right); d, male abdomen; e, G 1, lateral surface (right): f, apical part of the same G 1; g, female gonopore (right).

FIGURE 4. Metopograpsus thukuhar (Owen, 1839), male (ZUTC Brach 1162), a – f; female (ZUTC Brach 1162): g. a, posterior surface of carapace; b, lower orbital margin of male; c, cheliped of male, outer surface; d, third walking leg of male (left); e, male abdomen; f, G 1, lateral surface (right); g, female gonopore (right).