Macrophthalmus depressus Rüppell, 1830

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 : 11-15

Macrophthalmus depressus Rüppell, 1830

( Figs. 6 a–e, 7a–d, 10c, d)

Macrophthalmus depressus Rüppell 1830: 19 , pl. 4, fig. 6. — Nobili 1906a: 155. — Stephensen 1945: 191, 210, fig. 58A. — Guinot 1967: 282 (in list). — Basson et al. 1977: 56, 228, 235, fig. 37. — Clayton 1986: 87, fig. 3. — Vousden 1987: 35 – 37, tabs. 4, 7. — Hogarth 1989: 117. — Ismail & Ahmed 1993: 158. — Apel 1994: 42 –45, pl. 2; 1996: 331, 337, figs. 1–3. — Al-Ghais & Cooper 1996: 415, fig. 5. — Tirmizi & Ghani 1996: 116, fig. 44. — Cooper 1997: 158. — Hornby 1997: 15. — Al-Khayat & Jones 1999: 58, 61.

Macrophthalmus (Mareotis) depressus — Barnes 1970: 206, 226, fig. 7; 1977: 278 (in key), 279; 2010: 36 (in key). — Pretzmann 1971: 482, pl. 9, fig. 1. — Pretzmann 1974: 440. — Titgen 1982: 148, 253 (in list). — Jones 1986: 159, pl. 47. — Hywel-Davies 1994: 37, 48. — Apel & Türkay 1999: 134. — Apel 2001: 110.

Type locality. Red Sea.

Material examined. Persian Gulf: Iran: 1 male ( SMF 36868), Qeshm I., 3 km E. of Kuweii, 26° 57'N, 56° 00'E, 0 5.05.2008, R. Naderloo & A. Kazemi; 3 males ( ZUTC Brach1218), Bushehr, Khalij-Nayband, 27° 38'N, 52° 65'E, mangroves, 5.06.2006, R. Naderloo; 1 male, 1 juv. ( ZUTC Brach1239) Khuzestan, Shah Abdollah, 30° 10'N, 50° 05'E, sandy mud-flat, 14.04.2006; 1 male ( SMF 36879), Bushehr, Bandar-Rig, 29º 28'N, 50º 37'E, muddy sand flat, R. Naderloo & A. Kazemi.

Bahrain: 5 females (2 ovig.) (NHM 1999: 370-374), Jufair, 18.04.1974, A.L. Rice, det. M. Apel; 15 males, 7 females (3 ovig.) (NHM 1974:414), W. coast of Bahrain, Janabiya, from burrows in clean sand, 0 1.06.1971, A.L. Rice.

Saudi Arabia: 1 juv. ( SMF 36110), Jubail Marine Wildlife Sanctuary, N Al Jubail, 27° 25.41'N, 49° 13.53'E, low intertidal, rocky, in tide pool under stone with macroalgae, 0 7.02.1993, M. Apel; 1 male, 1 female (NHM 1974:382), Abu Ali, J. Birchard; 3 males, 3 females ( SMF 36116), Jubail Marine Wildlife Sanctuary, Al Jubail, S Dauhat ad Dafi, 27° 8.57'N, 49° 23.11'E, mangroves, 0 5.12.1995, M. Apel; 3 males, 2 females ( SMF 36117), Jubail Marine Wildlife Sanctuary, N. Al Jubail, S. Dauhat ad Dafi, 27° 8.57'N, 49° 23.11'E, mangroves, 26.11.1992, M. Apel; 1 male, 1 female ( SMF 36118), Jubail Marine Wildlife Sanctuary N. Al Jubail, S. Dauhat ad Dafi, 27° 8.57'N, 49° 23.11'E, mangroves, 24.06.1992, M. Apel; 3 males, 1 female ( SMF 36119), Jubail Marine Wildlife Sanctuary, N. Al Jubail, S. Dauhat ad Dafi, 27° 8.23'N, 49° 23.41'E, sand, 27.09.1992, M. Apel; 2 males, 1 female, 1 juv. ( SMF 36120), Jubail Marine Wildlife Sanctuary, N. Al Jubail, S. Dauhat, ad Dafi, 27° 8.23'N, 49° 23.41'E, sand, 27.09.1992, M. Apel; 3 males ( SMF 36121), Jubail Marine Wildlife Sanctuary, N. Al Jubail, S. Dauhat ad Dafi, 27° 8.23'N, 49° 23.41'E, sand, 28.09.1992, M. Apel; 5 males, 1 female ( SMF 36122), Jubail Marine Wildlife Sanctuary, N. Al Jubail, SW bank of Dauhat al Musallamiya, 27° 23.33'N, 49° 10.15'E, rock and muddy sand, 0 2.1993, M. Apel; 5 males (1 juv.), 1 female (juv.) ( SMF 36123), Jubail Marine Wildlife Sanctuary, N. Al Jubail, SW bank of Dauhat al Musallamiya, 27° 23.33'N, 49° 10.15'E, rock and muddy sand, 21.03.1993, M. Apel; 4 males, 3 females ( SMF 36124), Jubail Marine Wildlife Sanctuary, N. Al Jubail, S.W. bank of Dauhat al Musallamiya, 27° 23.33'N, 49° 10.15'E, rock and muddy sand, 10.12.1991, M. Apel; 3 males, 3 females ( SMF 36125), Jubail Marine Wildlife Sanctuary, N. Al Jubail, S.W. bank of Dauhat al Musallamiya, 27° 23.33'N, 49° 10.15'E, rock and muddy sand, 0 6.12.1991, M. Apel; 5 males, 1 female ( SMF 36126), south coast of Abu Ali, 27° 19'N, 49° 38'E, sandy/sandy mud, 29.06.1992, M. Apel; 2 males, 4 females (2 ovig.), 2 juv. ( SMF 36127), Abu Ali/Jubail, south coast near the head, 27° 19'N, 49° 38'E, muddy sand, among Salicornia sp., 27.08.1992, M. Apel; 3 males, 1 female (ovig.) ( SMF 36128), Tarut Bay, 29.06.1992, M. Apel; 1 male ( SMF 36129), N. Jubail, 0 9.1992, M. Apel; 1 female (ovig.) ( SMF 36130), Jubail Marine Wildlife Sanctuary, N. Al Jubail, W. Qurma I., 27° 7.09'N, 49° 27.3'E, muddy sand, 24.06.1992, M. Apel; 1 male ( SMF 36131), Jubail Marine Wildlife Sanctuary, N. Al Jubail, S. Dauhat ad Dafi, 27° 8.57'N, 49° 23.11'E, mangroves, 29.05.1992, M. Apel; 1 male, 2 females ( SMF 36133), Jubail Marine Wildlife Sanctuary, N. Al Jubail, S. Dauhat ad Dafi, 27° 8.23'N, 49° 23.41'E, sand, 29.05.1992, M. Apel; 1 male, 1 female ( SMF 36134), Jubail Marine Wildlife Sanctuary, N. Al Jubail, W. bank of Dauhat al Musallamiya, 27° 24.25'N, 49° 7.55'E, muddy substrate, 0 3.05.1993, M. Apel; 1 male ( SMF 36135), Jubail Marine Wildlife Sanctuary, N. Al Jubail, Qurma I., 27° 7.59'N 49° 29.1'E, mangroves, 0 5.08.1992, M. Apel; 1 male ( SMF 36136), Jubail Marine Wildlife Sanctuary, N. Al Jubail, SW bank of Dauhat al Musallamiya, 27° 23.33'N, 49° 10.15'E, rock and muddy sand, 21.03.1993, M. Apel; 6 males, 1 female ( SNMNH 101), Abu Ali, S. side, 27° 19'N, 49° 38'E, muddy/ sandy mud, 29.06.1992, M. Apel; 2 males, 2 females (ovig.) 1 juv ( SNMNH 101), Abu Ali, Jubail, south side near the headland, 27° 19'N, 49° 38'E, muddy sand, among marsh of Salicornia sp., 27.08.1992, M. Apel; 3 males, 1 female (ovig.) ( SNMNH 103), Tarut Bay, sandy mud, among marsh of Salicornia sp., 0 9.06.1992, M. Apel; 3 males, 3 females ( SNMNH 104), Jubail Marine Wildlife Sanctuary, N. Al Jubail, SW. Bank of Dauhat al Musallamiya, 27° 23.33'N, 49° 10.15'E, rock and mudy-sand, 10.12.1991, M. Apel.

UAE: 1 female (ovig.) ( SMF 36111), Abu Dhabi, West of southern head of Merawwah, 24° 16.4'N, 53° 18.7'E, mangroves, and sandy mud, 10.06.1995. M. Apel; 5 males, 4 females (2 ovig.) ( SMF 36112), Fujairah, mangroves of Khor Kalba, 25° 01'N, 56° 21'E, mangroves, intertidal, sandy mud, 0 1.07.1995, M. Apel; 1 male ( SMF 36113), Umm al Qaiwain, Khor al Beidah, 25° 35'N, 55° 34'E, sandy mud, 0 9.07.1995, M. Apel; 1 female (ovig.) ( SMF 36114), Umm al Qaiwain, Khor al Beidah, 25° 35'N, 55° 34'E, sandy mud, 0 9.07.1995, M. Apel; 1 male, 1 female (juv.) ( SMF 36115), Ras al Khaymah, Inside of landhead of S. Rams, 25° 50'N, 55° 00'E, sandy flat, upper intertidal with Salicornia sp., 11.07.1995, M. Apel; 1 male (NHM 1963:10:2:8), Abu Dhabi, Dr. Kinsman.

Redescription. Carapace ( Fig. 6 a) moderately wider than long (CB/CL = 1.5); posterior surface moderately convex, small granules covering entire carapace, except of median gastric, postfrontal portions; epibranchial region without longitudinal granules, sometimes with rows of very small granules on lateral region; short setae scarcely spread over carapace, becoming dense in posterior furrow of gastric, epibranchial region. Regions well defined; furrows defining gastric region deep. Frontal region, with small granules, deflexed; front narrow, about 0.12 times as wide as carapace, moderately constricted medially; anterior edge minutely granular, slightly concave, nearly bilobed, frontal furrow distinct, quite deep.

Lateral margin ( Fig. 6 a) with three distinct teeth including exorbital angle; first tooth subquadrate, second largest, higher than first; greatest width of carapace between second lateral teeth; third faint, indicated just with some granules; postrolateral margin nearly straight, slightly converging posteriorly, with small granules, besets with long setae; posterior margin with small, low granules.

Eyestalks ( Fig. 6 a) narrow, short, not reaching to exorbital angle; upper orbital margin fairly convex, regularly granular, granules small; lower margin with relatively large granules, granules wide-based, quite high, apically round.

Third maxilliped with ischium slightly more than twice as long as merus, inner margin of ischium, merus with long setae, outer margins with short setae, outer margin of merus distinctly concave, that of ischium straight; outer surface well decorated, covered with short setae.

Chelipeds nearly equal. Merus smooth, margins without tubercles, densely covered with setae. Carpus smooth on outer, inner surface, dense setae on inner surface. Palm ( Fig. 6 b) slightly more than 1.5 times as long as high in proximal portion, outer surface ( Fig. 6 b) smooth to naked eye, small microscopic granules on it, without longitudinal ridge; inner surface ( Fig. 6 d) fully covered with patch of dense setae, surface smooth underneath setae patch; upper margin with large granules, some very small granules on outer surface of this row of granules. Movable finger relatively narrow, slightly curved inward distally, upper margin smooth, inner surface with dense setae; cutting edge with subproximal differentiated tooth, small teeth distally. Immovable finger slightly shorter than movable finger, with relatively large teeth on cutting edge, sometimes medially elevated ( Fig. 6 c), inner surface with dense setae.

Cheliped of females small, outer surface of palm smooth, longitudinal ridge close to lower margin, curved upward distally; upper, lower margins with long setae, upper margin with small granules, lower margin smooth; fingers long, slightly longer than palm, narrow gap between, denticulate on cutting edge, long setae on inner surface.

Walking legs medium-size. Merus of third about 3.2 times as long as wide, merus of second, third walking legs with subdistal tooth on anterior margin; merus, carpus, propodus fully covered with dense setae ( Fig. 6 e); dactylus long, about as long as propodus, row of short setae along anterior, posterior margins.

Posteromedian margin of epistome distinctly concave, bearing long longitudinal ridge on anterior part of buccal cavity.

Male abdomen ( Fig. 6 f) elongatedly triangular, segments 3, 4 of same length, shorter than segment 5; segment 6 as long as segment 5, lateral margins gently converging distally; telson about as long as segment 6, semicircular.

Female abdomen ( Fig. 6 g) with small telson, nearly as long as segment 6, but half as wide.

Male G1( Fig. 7 a) moderately stout, slightly curved outward medially; apical chitinous process ( Fig. 7 c) remarkably long, curved outward at about 60°, its distal margin nearly straight, slightly emarginate ventrally; lateral surface with depression along ventral portion ( Fig. 7 b). Distal opening distinct, large, located distally on dorsal portion of apical process. Long plumose setae densely set along lateral margin, long setae around apical process, but not completely concealing it.

Female gonopore ( Fig. 7 d) situated at outer wall of depression, directed mesially, with large operculum; upper margin convex.

Remarks. Macrophthalmus depressus is a well defined species and has been assigned to the subgenus Mareotis Barnes, 1967 . It has been frequently recorded from different parts of the Persian Gulf: Stephensen (1945) and Pretzmann (1971) from Iran, Basson et al. (1977), Apel (1994) and Apel (1996) from Saudi Arabia, Clayton (1986), Jones (1986) and Al-Khayat & Jones (1999) from Kuwait, Vousden (1987) from Bahrain, Al-Ghais & Cooper (1996), Cooper (1997) and Hornby (1997) from the UAE.

Biology. This medium-size species (largest male CL = 20.94, CB = 30.89 mm, largest female CL = 19.85, CB = 27.51 mm) is common, and the only one of this genus in the lower intertidal of muddy and sandy mud habitats in the Persian Gulf ( Apel & Türkay 1999). This zone is densely populated by the species with 40– 75 specimens per m 2 in Tarut Bay on the Saudi Arabian coast, whereas juveniles mainly occur in the mid intertidal zone ( Apel 1994). The lower intertidal zone of the mud flats in the Persian Gulf could therefore be called M. depressus zone. Apel (1996) mentioned that M. depressus has a long breeding period. In a study carried out along the Saudi Arabian coast he recorded ovigerous females of this species over most of the year and only during the coldest season from November to January no ovigerous females were observed. According to Litulo et al. (2005), females of this species reach maturity at a size smaller than males. Females and males reach sexual maturity at carapace widths of 13.4 and 13.6 mm, respectively ( Litulo et al. 2005).

Geographical distribution. Indian Ocean: South Africa, Madagascar, East Africa, Gulf of Aden, Red Sea, Dhofar (South Oman), Gulf of Oman, Persian Gulf, Pakistan, west coast of India.

Figures

FIGURE 6. Macrophthalmus depressus Rüppell, 1830: a, b, d, e, f, male (SMF 36868); c, male (SMF 36119); g, female (SMF 36116). a, Posterior surface of carapace, left; b, cheliped of male, outer surface; c, immovable finger of male cheliped, outer surface; d, cheliped of male, inner surface; e, third walking leg of male, outer surface (right); f, male abdomen; g, female abdomen.

FIGURE 7. Macrophthalmus depressus Rüppell, 1830: a – c, male (SMF 36868); d, female (SMF 36116). a, G 1 of male, ventral surface (right); b, apical part of the same G 1, lateral surface; c, apical part of the same G 1, dorsal surface; d, female gonopore.