Metopograpsus messor ( Forskål, 1775 ), Forskal, 1775

Naderloo, Reza, 2011, Grapsoid crabs (Decapoda: Brachyura: Thoracotremata) of the Persian Gulf and the Gulf of Oman, Zootaxa 3048, pp. 1-43 : 8-11

Metopograpsus messor ( Forskål, 1775)

( Figs. 3 a–g, 5e)

Cancer messor Forskål, 1775: 88 .

Metopograpsus messor — Nobili 1906a: 155. — Stephensen 1945: 195, figs. 59 E–G. — Crosnier 1965: 23, figs. 19, 26. — Evans et al. 1973: 276. — Basson et al. 1977: 228, 235. — Titgen 1982: 144, 254 (list). — Jones 1986a: 160, pl. 47. — Vousden 1987: 32, 36, tab. 4, 5, 7. — Hogarth 1989: 104. — Apel 1994a: 43, 1996: 329, 2001: 118. — Al-Khayat & Jones 1996: 797, 800, 803, 812, figs. 3–4, 1999: 58, 61. — Al-Ghais & Cooper 1996: 411, fig. 2. — Cooper 1997: 165. — Hornby 1997: 14. — Apel & Türkay 1999: 132. —Ng et al. 2008: 217 (list). — Hosseini 2009: 39, 41.

Type locality. Red Sea

Material examined. PERSIAN GULF, Iran: 1 male, 1 female ( ZUTC Brach1141), rocky/sandy, Golestan village, Bushehr, 27º 14'N, 51º 16'E, coll. R. Naderloo, 13.04.2006; 1 male ( ZUTC Brach1142), sandy mud-flat, Khor, Bandar-Rig, Bushehr, 29º 28'N, 50º 37'E, coll. R. Naderloo, 13.04.2006; 5 males, 4 females, 1 juv. ( ZUTC Brach1143), sandy shore with patchy stones, Bandargah, Bushehr, 28º 49'N, 50º 54'E, coll. R. Naderloo, 13.04.2006; 2 females ( ZUTC Brach1144), sandy mud-flat, Shah Abdollah, Khuzestan, 30º 10'N, 50º 05'E, coll. R. Naderloo, 14.04.2006; 4 males, 1 female ( ZUTC Brach1145), sandy shore with patchy stones, Bandargah, Bushehr, 28º 49'N, 50º 54'E, coll. R. Naderloo, 13.04.2006; 3 males, 1 female ( ZUTC Brach1155), rocky/cobble, Bustaneh, Bandar-Lengeh, Hormozgan, 29º 30'N, 54º 39'E, coll. R. Naderloo, 02.06.2006; 2 males, 1 female ( ZUTC Brach1156), rocky shore, 20 km E. of Bandar-Kong, Hormozgan, coll. R. Naderloo, 02.06.2006; 2 males, 4 females, 21 juv. ( ZUTC Brach1158), mangroves, Khalij-Nayband, Bushehr, 27º 38'N, 52º 65'E, coll. R. Naderloo, 05.06.2005; 1 male ( ZUTC Brach1159), mangroves, Bandar-Khamir, Hormozgan, 26º 28'N, 55º 35'E,coll. 31.12.2005, R. Naderloo; 3 males, 3 females, 2 juv. ( ZUTC Brach1196), sandy/rocky, Chah-Shur, Bushehr, 29º 40'N, 50º 23'E, coll. 14.04.2006, R. Naderloo; 1 male, 1 female, 3 juv. ( ZUTC Brach1197), rocky bed with dead coral covered with algae, Bandar-Dayyer, Bushehr, 27º 14'N, 51º 16'E, coll. R. Naderloo, 12.04.2006; 1 female ( ZUTC Brach1198), sandy beach, Bandar-Mogham, Hormozgan, 26º 58'N, 53º 28'E, coll. R. Naderloo, 11.04.2006; 1 male ( ZUTC Brach1199), sandy beach, under the stones of the stone-wall jetty, Bandar-Deylam, Bushehr, 30º 03'N, 49º 46'E, coll. R. Naderloo, 15.04.2006; 1 male, 1 female ( ZUTC Brach1202), muddy-sand, Bordekhon-Kohne, Bushehr, 27º 59'N, 51º 22'E, coll. R. Naderloo, 11.04.2006; 3 males, 3 females ( SMF 38455), mangroves behind airport, Bandar-Abbas, 27º 11'N, 56º 24'E, coll. R. Naderloo, 0 7.01.2008. Saudi Arabia: 1 female ( SNMNH 162), rocky shore, Marine Wildlife Sanctuary, N. of Al-Jubail, Jubail, 27º 25'N, 49º 13'E, coll. M. Apel, 14.03.1993; 3 males, 1 female ( SNMHN 165), Ash Sharqiyah, 27º 43'N, 49º 49'E, coll. M. Apel, 19.11.1991; 5 males, 2 females ( SMF 37418), Ash Sharqiyah, N. of Jubail, coll. M. Apel, 28.11. 1991. UAE: 6 males, 5 females ( SMF 37387), mangroves, SE. of the city, Abu Dhabi, 24º 26'N, 54º 25'E, coll. M. Apel, 19.06.1995; 4 males, 3 females, 2 juv. ( SMF 37386), mangroves, southern head of Merawwah, Abu Dhabi, 24º 16'N, 53º 18'E, coll. M. Apel, 19.06.1995.

GULF OF OMAN, Iran: 6 males, 3 females ( ZUTC Brach1161), mangroves, Khor-Khalasi, Jask, Hormozgan, 25º 35'N, 58º 02'E, coll. R. Naderloo & A. Kazemi, 21.11.2005; 2 males, 1 female, 2 juv. ( ZUTC Brach1165), mud flat behind mangroves, Khor-Khalasi, Jask, Hormozgan, 25º 35'N, 58º 02'E, coll. R. Naderloo, 26.10.2006; 8 males, 4 females, 2 juv. ( ZUTC Brach1166), mangroves, Khor-Khalasi, Jask, Hormozgan, 25º 35'N, 58º 02'E, coll. R. Naderloo & A. Kazemi, 26.10.2006.

Redescription. Carapace ( Figs. 3 a, 4c) about 1.3 times as broad as long, maximum breadth slightly behind exorbital angles, posterior surface nearly flat, slightly convex; carapace regions poorly defined, lineal depression between gastric, cardiac region; cardiac, intestinal regions slightly defined by shallow depression; lateral region with 11 curved ridges, third, last ones longer than others, some short ridges behind frontal lobes; frontal region strongly flexed downwards; 4-lobed, median 2 smaller than lateral 2, moderately granular on anterior margin; frontal edge about 0.62 times as broad as carapace, distinctly longer than posterior edge of carapace, weekly 2-lobed. Supraorbital margin smooth, slightly oblique; infraorbital margin ( Fig. 3 b) with denticles relatively large, irregular on medial portion; outer portion oblique, smooth, separated from exorbital tooth by semicircular notch; inner angle with raised keel.

Lateral margin without tooth (except of exorbital angle), behind exorbital angle straight or slightly convex, slightly divergent posteriorly.

Chelipeds subequal. Ischium of large cheliped with 2 sharp teeth on anterior margin, those of small cheliped with 3 or 4 small denticles. Anterior margin of merus with 3 blunt teeth on proximal and 4 sharp triangular teeth on distal part; posterior surface with transverse, smooth ridges. Carpus with spine-shaped tooth distally on inner margin, with 2 small supplementary tubercles; posterior surface with transverse ridges and scattered granules. Outer surface of manus ( Fig. 3 c) smooth over most part, with microscopic granules, some oblique ridges on lower proximal portion, longitudinal, finely granular ridge along lower portion, scattered granules on upper surface, small tubercles along inferior margin; inner surface with oblique ridges on proximal part. Fingers smooth, curved inwards, some small denticles along upper margin of movable finger, denticles smaller distally; cutting edges with moderate gap in proximal half portion; prominently triangular tooth on median part of cutting edge of unmovable finger.

Walking legs ( Fig. 3 d), flattened, second, third legs longer than first, fourth. Merus with anterior border serrated, with subdistal spine; posterior distal part with 4 spines, becoming smaller distally; posterior surface with transverse ridges, less extensive on merus of last legs. Propodus with black bristles along anterior, posterior borders, 2 large spines on posterior distal part; dactylus with 6 spines along anterior, 4 spines along posterior margin; scattered black bristles along anterior, posterior margins.

Male abdomen ( Fig. 3 e) with second somite remarkably narrow, third slightly longer than fourth; fifth, sixth about in same length; lateral margin of sixth somite evenly convergent distally, telson about 1.7 times as long as sixth somite.

G1 ( Fig. 3 f) stout, sperm canal spiral; apical chitinous process short, curved sharply outwards; long setae around apical portion, completely covered apical process; long setae over posterior proximal surface, in particular on lateral margin.

Female gonopore ( Fig. 3 g) on anterior edge of fifth sternite; with operculum remarkably elevated, wide in proximal part, becoming sharply narrower distally.

Remarks. This species had long been regarded as widely distributed in the Indo-West Pacific ( Holthuis 1977). Tweedie (1949) examined it from different regions and found that they belong to several different species. He identified records from the Western Indian Ocean including Red Sea (type locality), east African Coast, Madagascar, Persian Gulf and Andamans to M. messor . Tweedie (1949), Banerjee (1960), Forest & Guinot (1961), Crosnier (1965) and Holthuis (1977) have since provided detailed descriptions and illustrations of the species. Holthuis (1977) discussed at length the identity of the type material of M. messor and noted that Forskål (1775) in his original description of the species most probably included another species, Grapsus granulosus H. Milne-Edwards, 1853 , which may have caused confusion for subsequent workers. Since Forskål’s (1775) material is lost, in order to resolve this problem, Holthuis (1977) selected a neotype male from the Sinai Peninsula in the northern Red Sea, which is deposited in the National Museum of Natural History, Leiden (Crust D.30637). Castro (2011) mentioned that the records of this species from the Hawaiian Islands belong to M. thukuhar . Metopograpsus messor restricted to the Western Indian Ocean Castro (2011).

Biology. Metopograpsus messor is a medium-size species (largest male CL = 25.45 mm, CB = 32.74 mm, largest female CL = 23.77 mm, CB = 30.08 mm) that is common in the Persian Gulf, occurring in a variety of habitats including muddy substrates, rocky shores and mangroves. It is found in the high-intertidal zone on rocky shores, where it is sympatric with G. albolineatus at its highest limit, and it extends normally downward to the mid-intertidal zone. This herbivorous species prefers mainly rocks covered with thin layer of filamentous algae and it is always seen foraging on algae. Individuals disappear into the rock crevices if disturbed. It is also common amongst stones of any rocky structure in the intertidal region, such as stony jetties found in most coastal cities along the Iranian coast of the Persian Gulf. Metopograpsus messor is typical of mangroves in the Persian Gulf and Gulf of Oman, where it is usually sympatric with Parasesarma persicum . Adults mainly occur amongst trees, while juveniles usually predominate in the pneumatophores zone. Sudha & Anikumar (1996) studied the growth and reproduction rate of M. messor in the Muzhupilangad estuary in south India. According to their findings, the smallest female adults measured up to 13 mm of CB. Three different phases were identified by Sudha & Anikumar (1996): growth-reproductive period (January-May), inactive period (June-July), which is the monsoon period in that part of the Indian Ocean, and reproductive period (August-December).

Colour. Posterior surface of the carapace greenish gray mottled with dark brown spots and small dots. In some specimens, anterior third of the carapace is fully covered with dark sports. Walking legs are dark gray with scattered small brownish spots. The chelipeds are brownish red in outer surface, inner surface is bright gray. Tip of the fingers is light. A more detailed description was provided by Holthuis (1977).

Regional records. PERSIAN GULF: UAE ( Titgen 1982; Al-Ghais & Cooper 1996; Cooper 1997; Hornby 1997), Bahrain ( Nobili 1906a; Stephensen 1945; Vousden 1987), Qatar ( Al-Khayat & Jones 1999), Saudi Arabia ( Basson et al. 1977; Apel 1994a, 1996), Kuwait (Jones 1986), Iran ( Stephensen 1945; Hosseini 2009). GULF OF OMAN: UAE ( Apel 2001), Iran (present study).

Geographical distribution. Indian Ocean: Madagascar, East Africa, Red Sea, Persian Gulf, Gulf of Oman, Pakistan, Arabian Sea coast of India, Andaman Islands.

Figures

FIGURE 3. Metopograpsus messor (Forskål, 1775), male (ZUTC Brach 1305), a – f; female (ZUTC Brach 1305): 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).