Macrophthalmus laevis A. Milne-Edwards, 1867

Naderloo, Reza, Türkay, Michael & Apel, Michael, 2011, Brachyuran crabs of the family Macrophthalmidae Dana, 1851 (Decapoda: Brachyura: Macrophthalmidae) of the Persian Gulf, Zootaxa 2911, pp. 1-42 : 23-25

Macrophthalmus laevis A. Milne-Edwards, 1867

( Figs. 13 a–f, 14a–e, 10e–f)

Macrophthalmus laevis A. Milne-Edwards 1867: 287 . — Barnes 1976: 143, fig. 6a–c. — Titgen 1982: 150.

Macrophthalmus (Macrophthalmus) ressli Pretzmann 1971: 382 , pl. 9 figs. 23.

Macrophthalmus resseli [sic!] — Pretzmann,1974: 441.

Macrophthalmus (Macrophthalmus) laevis — Barnes 1977: 277 (in key), 280 (in list); 2010: 35 (in key), 40. — Tirmizi & Ghani 1988: 253, figs. 1–11. — Tirmizi & Ghani 1996: 109, fig. 41. — Apel & Türkay 1999: 135. — Apel 2001: 109.

Type locality. “ Indian Seas”.

Examined material. Persian Gulf: Iran: 4 males, 4 females, 3 juv. ( SMF 36896), Qeshm I., N. coast, 3 km W. of Kuweii, 26º 57'N, 56º 00'E, muddy sand with rocky patches, 0 6.05.2008, R. Naderloo & A. Kazemi; 1 juv. ( SMF 36870), Qeshm I., Zeyton (olive) park beach, 27º 11'N, 56º 24'E, 0 8.01.2008, R. Naderloo & M. Türkay; 2 juv. ( SMF 36871), Bandar-Khamir, 26º 56'N, 55º 36'E, muddy, 24.04.2008, R. Naderloo, A. Kazemi & A. Keykhosravi; 3 males, 1 female, 2 juv. ( SMF 36872), Qeshm I., Dargahan, 26º 58'N, 56º 04'E, sandy mud, with planted mangroves, 13.01.2008, R. Naderloo & M. Türkay; 1 male, 3 juv. ( SMF 36873) E. Bandar-Kolahi, 27º 02'N, 56º 51'E, muddy sand flat, 22.04.2008, R. Naderloo, A. Kazemi & A. Keykhosravi; 1 female ( SMF 36874), Bandar-Abbas, E. city, 27º 11'N, 56º 21'E, muddy sand flat, 23.04.2008, R. Naderloo, A. Kazemi & A. Keykhosravi; 1 juv. ( SMF 36875), Bandar-Khamir, E. fishery Jetty, 26º 56'N, 55º 36'E, muddy flat, water channel, 24.04.2008; R. Naderloo, A. Kazemi & A. Keykhosravi; 1 juv. ( SMF 36876), Bandar-Khamir, E. city, between mangroves and fisheries jetty, 26º 28'N, 55º 35'E, muddy sand flat, 0 7.06.2006, R. Naderloo & A. Kazemi; 2 females ( SMF 36877), Bandar- Emam, Park Saheli, 30º 28'N, 49º 04'E, muddy (Khor), cobble with stones covered densely with Saccostrea cucullata , 21.05.2008, R. Naderloo, A. Kazemi & H. Salehi; 4 females (2 ovig.), 2 juv. ( SMF 36878), Qeshm I., 2 km E. of desalination centre, 26º 56'N, 55º 47'E, muddy sand with shells, 15.01.2008, R. Naderloo & M. Türkay. 1 male (NHM 1999:71, all appendages missing), Hormoz I., 0 1.1973, coll. G. Polleri, det. M. Apel.

UAE: 16 males, 3 females ( SMF 26293), Ras al Khaimah, inner side of the spit of the south Ras, 25º 50'N, 55º 00'E, supralittoral among Salicornia sp., 11.07.1995, M. Apel.

Macrophthalmus ressli Pretzmann, 1971 . Holotype: male (NHMW 3790), paratype: 1 male (NHMW 3791), Iran, Bandar Abbas, sandy coast (Pretzmann 1970).

Redescription. Carapace ( Figs. 10 e, 13a) wider than long (CB/CL = 1.7); posterior surface relatively convex, small granules evenly distributed on posterior surface, glabrous on central regions, slightly larger ones irregularly distributed on branchial regions, without longitudinal row of granules; short setae very sparsely on posterior surface, extensive patch of setae near posterolateral margin, long setae on lateral margin. Regions well defined; furrows defining gastric, epibranchial regions are remarkably deep. Frontal region smooth, deflexed downwards; two frontal ridges low, smooth; front narrow, about 0.14 times as wide as carapace; anterior edge smooth, slightly concave, nearly bi-lobed, frontal furrow faint.

Lateral margin ( Fig. 13 a) with three teeth including exorbital angle; exorbital angle subquadrate, directed forwards, slightly smaller than second, separated from second by wide V-shaped notch; second one largest, broadly triangular, directed forwards; third one very small, but usually discernible; posterolateral margin nearly straight, very slightly converging posteriorly, with small granules, besets with long setae.

Eyestalks ( Fig. 13 a) narrow, short, never reaching to end of exorbital angle ( Fig. 13 a); upper orbital margin moderately convex, regularly granular, granules very small, directed outwards; lower margin granular, granules relatively large, getting larger in middle, directed inwards.

Third maxilliped large, ischium about 2.6 times as long as merus; inner margin of ischium, merus bearing long setae, outer margins without setae; outer surface smooth, with short row of setae on outer proximal part of ischium.

Chelipeds nearly equal (in one case unequal); merus ( Fig. 13 b) with upper surface smooth, inner, upper margins sparsely beset with long setae, row of long setae near inner margin, some long setae on distal portion; 12–13 long tooth-shaped tubercles on distal two thirds of inner upper margin; outer margin with very small granules; inner lower margin tuberculate, 4–5 tubercles on distal portion large, tooth-shaped. Carpus smooth with large spineshaped tooth medially on upper inner margin, small one behind it, two spine-shaped teeth on inner proximal margin, of various size; upper surface smooth; outer margin finely serrated. Palm ( Fig. 13 c) relatively long, about 1.6 times as long as high in proximal portion, outer surface ( Fig. 13 c) smooth, with microscopic granules on proximal portion; lower, upper margins with very small granules; inner surface ( Fig. 13 d) smooth, without setae, large spineshaped tooth on proximal portion, 2–4 large granules before large tooth; lower proximal portion covered with large granules, distal lower portion depressed. Movable finger long, curved inward distally; upper margin smooth; cutting edge with differentiated subproximal tooth, large, subquadrate, low, small denticles distal to large one along cutting edge. Immovable finger short, with median tooth, large, extending proximally, small denticles on cutting edge, even on large tooth.

Walking legs narrow, long, anterior margin of segments bearing long setae. Merus with small subdistal tooth on anterior margin, that of second, third legs large, last leg usually lacking this subdistal tooth; posterior margin of merus minutely denticulate; merus of third leg about 3 times as long as wide; second leg with dense patch of plumose setae along proximal two thirds of anterior margin. Propodus slightly longer than dactylus, that of last leg as long as dactylus; last leg very small, unarmed, with long setae on posterior, anterior margins.

Posteromedian margin of epistome strongly convex, anterior part of buccal cavity smooth.

Male abdomen ( Fig. 13 e) oblongly triangular; segments 3, 4 of same length, segment 5 slightly longer; segment 6 longest with lateral margins swollen proximally ( Figs. 13 e, f), gently converging distally; telson slightly shorter than segment 6, with margins clearly converging distally, rounded distally.

Male G1 ( Fig. 14 a) curved outward medially; apical chitinous process short ( Fig. 14 b), nearly subdistal, directed laterally at 45° ( Fig. 14 b); distal opening prominent ( Fig. 14 c), located apically; long setae around apical part, long plumose setae sparsely set along lateral, ventral surfaces.

Female gonopore ( Fig. 14 e) nearly triangular; operculum small, located at inner side, roundish, directed outwards; lateral margins elevated.

Remarks. Pretzmann (1971) described M. ressli as a new species from Bandar-Abbas, on the Iranian coast near the Straits of Hormuz. Barnes (1976) reluctantly synonymised M. ressli with M. laevis and was the first to provide a detailed description for M. laevis based on paratype material of M. ressli (NHMW 3791). We have also examined Pretzmann’s specimens, which clearly belong to M. laevis . Further records of this species from the Persian Gulf are those by Titgen (1982) from Dubai and Apel (2001) from Ras al Khaimah ( UAE). We found this species throughout the Iranian coast of the Persian Gulf from Bandar-Emam in the north to Bandar Abbas and Qeshm I. in the southeast.

This species is taxonomically well known and belongs to the subgenus Macrophthalmus Desmarest, 1823 . In a recent revision of the subgenus, Barnes (2010) placed this species together with some others (e.g. M. sulcatus and M. grandidieri ) in what he calls the Macrophthalmus brevis -group. He cited some main characters for this group including, 1)-cornea is not extending beyond exorbital angle, 2)- carapace very broad (CB/CL more than 2), 3)- exorbital angle small and pointed, 4)- front narrow, 5)- male cheliped with spines near carpal joint, 6)- fingers long and usually downflexed. Macrophthalmus laevis shares several characters with other species of this group, but regarding some other morphological characters it seems to be isolated within the group. Macrophthalmus laevis does not have a very broad carapace, the CB/CL ratio being distinctly less than 2, averaging at about 1.7, whereas this ratio in other species of this group (e.g. M. sulcatus and M. grandidieri ) is 2.3 and 2.1 respectively. The exorbital angle of M. laevis is relatively large and distinctly subrectangular rather than small and pointed as in other members of the group. The fingers of the male cheliped (see Figs. 13 c, d) in M. laevis are not remarkably long and downflexed as described by Barnes (2010) for the group. Regarding the presence of spines on the carpal joints of the male cheliped and the convex posteromedian margin of the epistome, M. laevis is related to this group. As is seen here, the new subdivision proposed by Barnes (2010), is not very satisfactory, at least concerning to position of some species (e.g. M. laevis and M. boscii ). Thus, a sound phylogenetic study using genetics as well as morphological characters would be necessary in order to establish a definitive subgeneric system for the genus Macrophthalmus .

Biology. Macrophthalmus laevis is a medium-size species (largest male CL = 12.26, CB = 25.52 mm, largest female CL = 13, 79, CB = 23.76 mm). It occurs mainly in the mid littoral of intertidal flats with sediments ranging from sandy mud to muddy sand. Tirmizi & Ghani (1988, 1996) recorded the deposit-feeding species buried in muddy substrates associated with mangroves. We found M. laevis mainly in the upper mid eulittoral zone on muddy sand, always mixed with shell fragments. Macropthalmus laevis appears not to be a burrow-building species, just burying in sedimentary substrates. It is found sympatric with M. sulcatus in some habitats with muddy sand with a low percentage of shells (e.g. in Iranian coast of the Persian Gulf: Qeshm I., Kuweii and Bandar- Abbas).

Geographical distribution. North-western Indian Ocean: Persian Gulf, Gulf of Oman, Pakistan.

Figures

FIGURE 13. Macrophthalmus laevis A. Milne-Edwards, 1867: a – e, male (SMF 26293); f, male (MHMW 3791, paratype of Macrophthalmus ressli Pretzmann, 1971). a, posterior surface of carapace, left side; b, merus of male cheliped, lower surface; c, cheliped of male, outer surface; d, cheliped of male, inner surface; e, male abdomen; f, male abdomen, penultimate segment and telson.

FIGURE 14. Macrophthalmus laevis A. Milne-Edwards, 1867: a – c, male (SMF 26293); d, e, female (SMF 36896). a, G of male, ventral surface (right); b, apical part of G 1, ventral surface; c, apical part of G 1, lateral surface; d, female abdomen, penultimate segment and telson; e, female gonopore.

FIGURE 10. a, b: Macrophthalmus dentipes Lucas, 1836, male (SMF 26095) a, posterior surface; b, ventral surface; c, d: Macrophthalmus depressus Rüppell, 1830, male (SMF 36101), c, posterior surface; d, ventral surface; e, f: Macrophthalmus laevis A. Milne-Edwards, 1867, male (SMF 36869), e, posterior surface; f, ventral surface.