Metaplax indica H. Milne-Edwards, 1852

Naderloo, Reza, 2011, Grapsoid crabs (Decapoda: Brachyura: Thoracotremata) of the Persian Gulf and the Gulf of Oman, Zootaxa 3048, pp. 1-43 : 31-34

Metaplax indica H. Milne-Edwards, 1852

( Figs. 15 a–e, 18c–d)

Metaplax indicus H. Milne-Edwards, 1852: 161, 1854: 165 , pl. 11, figs. 2. — Alcock 1900: 431. — Apel 1994a: 43, pl. 3, 1996: 330, 2001: 117, 118. — Apel & Türkay 1999: 133.

Metaplax indica — Clayton 1986: 87, fig. 3. — Jones 1986: 161, pl. 47. — Tirmizi & Ghani 1996: 161, fig. 62. — Al-Khayat & Jones 1999: 58, 61. — Ng et al. 2008: 226 (list).

Metaplax indicus occidentalis — Pretzmann 1971: 478, pls. 1–3, figs. 1–4. — Titgen 1982: 254 (list).

Type locality. Indian Ocean (exact locality not known).

Material examined. PERSIAN GULF, Iran: 4 males, 1 female (ovig.), 2 juv. ( ZUTC Brach1160) sandy mudflat, Shah Abdollah, Bushehr, 30º 10'N, 50º 05'E, coll. R. Naderloo & A. Kazemi, 14.04.2006; 1 male, 5 females, 1 juv. ( ZUTC Brach1206), mangroves and muddy sand-flat, Bandar-Khamir, Hormozgan, 26º 28'N, 55º 35'E, coll. R. Naderloo & A. Kazemi, 31.12.2005; 3 males, 1 female ( ZUTC Brach1207), mangroves and muddy sand-flat, Bandar-Khamir, Hormozgan, 26º 28'N, 55º 35'E, coll. R. Naderloo, 31.04.2005; 7 males, 1 female ( ZUTC Brach1209), mud flat, 15 km E. of city, Hendijan, Khuzestan, 30º 06'N, 49º 46'E, coll. R. Naderloo & A. Kazemi, 16.04.2006; 1 male, 2 females ( SMF 38130), muddy flat, Bandar-Khamir, Hormozgan, 26º 56'N, 55º 36'E, coll. R. Naderloo & A. Kazemi, 24.04.2008; 1 male ( SMF 38131), muddy sand-flat with shells, E. of city, Bandar-Abbas, 27º 08'N, 56º 20'E, coll. R. Naderloo, A. Kazemi & A. Keykhosravi, 23.04.2008; 1 male, 1 female ( SMF 38132), muddy flat, Bandar-Khamir, Hormozgan, 26º 56'N, 55º 36'E, coll. R. Naderloo & A. Kazemi, 24.04.2008; 1 male, 2 females ( SMF 38133), muddy flat, Bandar-Khamir, Hormozgan, 26º 56'N, 55º 36'E, coll. R. Naderloo & A. Kazemi, 24.04.2008; 6 males, 1 female ( SMF 38134), muddy flat, Bandar-Khamir, Hormozgan, 26º 56'N, 55º 36'E, coll. R. Naderloo & A. Kazemi, 24.04.2008; 1 juv. ( SMF 38135), muddy sand-flat with shells, E. of city, Bandar- Abbas, 27º 08'N, 56º 20'E, coll. R. Naderloo, A. Kazemi & A. Keykhosravi, 23.04.2008; 1 female, 3 juv. ( SMF 38136), sandy-mud, Bandar-Kolahi, Hormozgan, coll. R. Naderloo, A. Kazemi & A. Keykhosravi, 21.04.2008; 2 males ( SMF 38137), muddy-sand, Bandar-Tiab, Hormozgan, 27º 09'N, 56º 37'E, coll. R. Naderloo & A. Kazemi, 07.01.2008; 1 female ( SMF 38138), Kuweii, Qeshm I., 26º 57'N, 56º 00'E, coll. R. Naderloo & A. Kazemi, 13.01.2008; 1 juv. ( SMF 38139), sandy-mud in planted mangroves, Dargahan, Qeshm I., 26º 58'N, 56º 04'E, coll. R. Naderloo & A. Kazemi, 13.01.2008; 1 juv. ( SMF 38140), muddy-sand with rocky patches, 3 km W. of Kuweii, Qeshm I., 26º 57'N, 56º 00'E, coll. R. Naderloo & A. Kazemi, 06.05.2008; 2 males, 1 juv. ( SMF 38141), mangroves, Bandar-Khamir, 26º 56'N, 55º 36'E, coll. R. Naderloo & A. Kazemi, 24.04.2008; 1 male, 2 females, 1 juv. ( SMF 38141) muddy-sand with shells, 2 km E. of desalination center, Qeshm I., 26º 56'N, 55º 47'E, coll. R. Naderloo & M. Türkay, 15.01.2008; 1 female ( SMF 38143), sandy-mud, Bandar-Kolahi, coll. R. Naderloo, A. Kazemi & A. Keykhosravi, 21.04.2008; 1 female ( SMF 38144), muddy sand-flat with shell fragments, E. of the city, Bandar- Abbas, 27º 11'N, 56º 21'E, coll. R. Naderloo, A. Kazemi & A. Keykhosravi, 23.04.2008; 2 juv. ( SMF 38145), muddy-sand, Tula, Qeshm I., 26º 59'N, 56º 12'E, coll. R. Naderloo & M. Türkay, 13.02.2008.

GULF OF OMAN, Iran: 1 male ( ZUTC Brach1205), mangroves, Khor-Khalasi, Jask, Hormozgan, 25º 35'N, 58º 02'E, coll. R. Naderloo & A. Kazemi, 21.11.2005; 2 males ( ZUTC Brach1208), mangroves, Gwadr, Baluchestan, 25º 08'N, 61º 27'E, coll. R. Naderloo, 19.11.2005.

Redescription. Carapace rectangular ( Figs. 15 a, 18c), distinctly wider than long (CB/CL = 1.4), maximum breadth between posterior part of second anterolateral teeth or anterior part of third teeth; posterior surface moderately convex, nearly smooth, some microscopic granules and setae sparsely on branchial regions. Carapace regions distinct; 2 inconspicuous postfrontal lobes; 2 finely granular, transverse edges on cardiac region; 2 shorter ones laterally on front of cardiac ridges; 2 granular ridges on posterolateral region, first one begins at anterior end of third anterolateral tooth, second one from near base of second walking leg. Front short, about one-quarter maximum carapace breadth, gently deflexed; frontal edge finely granular, 2-lobed with distinct notch between them. Supraorbital margin sinuous-shaped, evenly granular; infraorbital margin of males ( Fig. 15 c) irregularly serrate in inner half, following by 2 long lobes, 5–7 tubercles lateral to these lobes, first 4 ones prominent, nearly rounded. Infraorbital margin of females regularly serrated. Anterolateral margin of carapace with 4 teeth (including exorbital tooth), smaller posteriorly; first, second nearly with same shape, nearly subquadrate; first largest, slightly lower than second; fourth very small, attached to former. Posterolateral margin convergent posteriorly.

Chelipeds nearly equal; comparing to carapace, walking legs large. Merus long, anterior margin finely serrated, with chitinous brown crest proximally on anterior margin; posterior margin with very small granules. Carpus with one large, some small teeth on inner angle. Manus ( Fig. 15 d) large, robust, slightly higher distally; outer surface smooth; lower margin with scarce denticles; upper margin with very small granules. Fingers curved downwards, curved slightly inwards posteriorly, point-ended; cutting edges with tubercular teeth; movable finger with 3 or 4 large teeth at proximal half. Female chelipeds very small, without chitinous crest on anterior margin of merus.

Walking legs long, flattened, with second, third longer than first, fourth. Merus long, about as long as carapace, anterior margin slightly serrated; long setae densely on anterior margin, upper surface of proximal part of merus, distal part of carpus, whole propodus; last leg with more sparse setae; dactylus with sparse setae.

Male abdomen ( Fig. 15 b) with somites 3–5 fused, sutures only visible on lateral part; sixth somite longest, becoming wider distally; telson longer than broad.

G1 ( Fig. 15 e) moderately stout, gently curved outwards; sperm canal nearly straight; apical chitinous process ( Fig. 15 f) slightly bending outwards, apical end concave, long setae densely surrounding apical process.

Remarks. The genus otherwise contains 11 species (Davie & Xuan 2003; Ng et al. 2008), all occurring in the tropical and subtropical intertidal regions. Metaplax indica is the only species of the genus in the region. Pretzmann (1971) described a subspecies, Metaplax indicus occidentalis Pretzmann, 1971 , from Bandar-Abbas on the Iranian coast of the Persian Gulf. The subspecies supposedly differed from M. indica as described by H. Milne-Edwards (1852), with Pretzmann citing three features characteristic of the new taxon. Ng et al. (2008) retained the name as a valid species of Metaplax . All three characters used by Pretzmann (1971: 478) for M. occidentalis , however, are similar to what have been observed in the present specimens and are identical as well to the original description and illustrations provided by H. Milne-Edwards (1852). The subspecies is therefore synonymized with M. indica . The second species of this genus, which has been recorded from the northern Arabian Sea in Pakistani waters, is M. distincta H. Milne-Edwards, 1952 , ( Tirmizi & Ghani 1996), but as yet, there is still no record of this species further west in Gulf of Oman and the Persian Gulf.

Biology. Metaplax indica is a relatively medium-size species (largest male CL = 16.70 mm, CB = 24.97 mm, largest female CL = 11.55 mm, CB = 16.50 mm) that is found on mud flats and mangroves, normally digging borrows in the low-intertidal zone. The cheliped of the males shows a higher growth rate than that of the carapace, and in the large specimens (CB> 13 mm) the length of the cheliped palm (including finger) is about as long or even slightly longer as CB.

Colour. Posterior surface of the carapace is dark gray, with a few irregular white sports, Ventral surface bright sometimes with irregular violet spots. The margins of carapace and appendages are bright violet. The merus of the chelipeds is dark gray on the posterior surface and completely violet on the anterior surface, while the palm is light and the fingers violet. The walking legs are dark gray on the posterior surface, anterior surface bright and the margins bright violet. Small specimens, however, show a gray colour pattern on the carapace and appendages, with bright violet fingers.

Regional records. PERSIAN GULF: Kuwait ( Clayton 1986; Jones 1986a), Saudi Arabia ( Apel 1996), Qatar ( Al-Khayat & Jones 1999), Iran ( Pretzmann 1971). GULF OF OMAN: Iran (present study).

Geographical distribution. Northwestern Indian Ocean: Persian Gulf, Gulf of Oman, Pakistan, Arabian Sea coast of India.

Figures

FIGURE 15. Metaplax indica H. Milne-Edwards, 1852, male (ZUTC Brach 1160): a, posterior view of whole crab, male; b, male abdomen; c, lower orbital margin of male; d, cheliped of male, outer surface; e, G 1, dorsal surface (right); f, apical part of the same G 1.