Macrophthalmus graeffei A. Milne-Edwards, 1873

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 : 19-23

Macrophthalmus graeffei A. Milne-Edwards, 1873

( Figs. 11 a–e, 12a–d, 17a, b)

Macrophthalmus graeffei A. Milne-Edwards 1873: 257 , pl. 2, fig. 5. — Titgen 1982: 253 (in list).

Macrophthalmus (Macrophthalmus) graeffei — Barnes 1970: 225; 1971: 13, 36 (in key), fig. 3; 1977: 276 (in key), 279 (in list); 2010: 34 (in key), 39. — Apel 2001: 108.

Macrophthalmus ( convexus Stimpson ?) — Stephensen 1945: 191. [not Macrophthalmus convexus Stimpson, 1858 ]. Macrophthalmus convexus — Guinot 1967: 282 (in list; partly). [not Macrophthalmus convexus Stimpson, 1858 ].

Type locality. Upolu ( Samoa).

Examined material. Persian Gulf: Iran: 1 male (CL = 14.8, CB = 8.4 mm), 1 male (juv.) ( ZMUC CRU- 1782), DSII St. 26, O, Kharg I., sand and shells, 18 m deep, 15.03.1937, G. Thorson, identified as Macrophthalmus ( convexus Stimpson ?) by Stephensen (1945).

Comparative material. Red Sea: 3 females (NHM 1934: 1:17: 133–135, appendages are broken), Sudan, Mersa Marja in Shab-ul-Shumur, coll. C. Crossland, det. R. D. Laurie.

Redescription. Carapace ( Fig. 17a ) distinctly wider than long (CB/CL = 1.84), moderately convex, posterior surface smooth; lump of small granules on epibranchial region, granules round; scarce granules on lateral regions. Regions relatively well defined; furrows delimiting gastric region remarkably deep, transverse furrow of epibranchial region nearly shallow depression. Front deflexed, narrow, about 0.12 times as wide as carapace, constricted medially; anterior edge smooth, very slightly concave, faintly bi-lobed, frontal furrow faint.

Lateral margin with three distinct teeth including exorbital angle; first tooth remarkably long, longer than second, elongatedly triangular, directed outwards, slightly directed forwards, its posterior margin smooth; second tooth about half as long as first one, triangular, directed outwards, separated from former by long V-shaped notch; third smallest, broadly triangular, directed outwards; posterolateral margin nearly straight, very slightly converging posteriorly, serrated with pointed granules, granules larger posteriorly; posterior ridge smooth.

Eyestalk narrow ( Figs. 11 a, 17a, b), long, extending slightly less than half of cornea beyond exorbital angle, distal part of cornea with remarkably narrow bulge ( Fig. 11 a); upper orbital margin slightly convex, gently sloping outward, regularly granular, granules very small, low blunt, smaller laterally; lower margin with granules, relatively large, pointed, of various size, smaller laterally.

Third maxilliped large, ischium about twice as long as merus, inner margin of ischium with long setae, outer margin nearly straight, without setae, outer surface smooth; merus subquadrate, wide, about 1.7 times as wide as long, inner margin with long setae, outer margin proximally swollen, distally strongly converging, finely dentate, without setae, outer surface smooth.

Chelipeds ( Figs. 11 c, d) nearly equal. Merus ( Fig. 11 b) with outer margin bearing large denticles along entire length, denticles slightly larger medially; inner upper margin with few small granules, with long setae, continuing to inner surface; inner lower margin with small granules; distal margin with very small granules. Carpus outer surface with small granules, getting dense towards upper, lower surfaces, medially smooth; inner distal margin serrated with small granules. Palm relatively long, about 1.6 times as long as high in distal portion; outer surface ( Fig. 11 c) with small granules except in lower distal portion at base of immovable finger, granules continuous to upper, lower margins, granules on upper margin slightly larger than those of lower margin; longitudinal ridge on lower portion, nearly straight, parallel to lower margin, running from proximal part to near end of immovable finger, finely granular, granules small; inner surface ( Figs. 11 d, 17b) without patch of setae, small granules on lower proximal portion, continuous medially to near base of fingers. Movable finger relatively long, curved strongly inward, upper margin with large denticles along proximal two thirds, larger distally, small granules proximally; cutting edge with small differentiated tooth subproximally, teeth along cutting edge small, round, long setae along inner lower surface in movable finger. Immovable finger short, cutting edge elevated medially, large teeth along it, long setae along inner surface; tip of cutting edge of both fingers remarkably narrowed.

Walking legs medium-size, relatively narrow; merus of third walking leg about 3.4 times as long as wide; merus of second, third with large subdistal tooth; anterior, posterior margins serrated; margins of carpus, dactylus smooth; dactylus of third walking leg about as long as propodus; margins of segments scarcely beset with long setae.

Posteromedian margin of epistome moderately convex, anterior part of buccal cavity distinctly swollen, without ridge.

Male abdomen ( Figs. 11 e, 17b) with segments 5, 6 of same length; lateral margin of segment 6 proximally remarkably swollen, distally very gently converging; telson semicircular, about as long as segment 6.

Male G1 ( Figs. 12 a–d) relatively long, narrow, slightly curving outward medially; apical chitinous process short, narrow, directed outwards at 90°; distal opening ( Fig. 12 d) on tip of chitinous process; dorsal palp remarkably large; long setae scarcely on apical portion, not concealing apical process.

Remarks. Stephensen (1945) recorded one male and one juvenile from the east coast of Kharg I. of Iran in the Persian Gulf which he tentatively identified as M. ( convexus Stimpson ?). Barnes (1971) cited this record in the synonymy of M. graeffei . Apel (2001) examined this specimen and found that it is identical with the M. graeffei sensu Barnes. Barnes (1971) , however, did not examine the type specimens of M. graeffei , which had been described by A. Milne-Edwards (1873) from Samoa. Barnes (1971) record of this species is based on two males collected at the eastern Indian Ocean in South Indonesia (Timor Archipelago), and all following authors used his description for defining M. graeffei . Therefore, the taxonomic position of M. graeffei is still not at all certain, and its identity needs to be established. The present material agrees fully with the description given by Barnes (1971), and thus it is tentatively assigned to this species.

Macrophthalmus graeffei belongs to the subgenus Macrophthalmus Desmarest, 1823 , which recently has been divided into four different subgroups ( Barnes 2010). Barnes (2010) placed M. graeffei in the M. telescopicus - group, which is mainly characterized by long eyestalks with the cornea extended beyond the lateral carapace margin, the carapace being moderately broad with three lateral teeth, the front being relatively broad, the carpus of the male cheliped lacking spines on the distal margin, the fingers being short and the immovable finger not being deflexed. Most species of this group including M. graeffei are sublittoral.

The only record of this species from the Persian Gulf is the two males (one juvenile) from Kharg I. collected by the Danish Scientific expedition ( Stephensen 1945). Apel (2001) furthermore recorded one specimen from Oman (“Djaraman, Mer d’Oman, Côte d’Arabie”) deposited in MNHN Paris. The type material of M. graeffei had been deposited in the Godeffroy Museum of Hamburg (1861–1885), Germany. In 1885, however, the zoological specimens of this museum were sold to different museums, and no information is available regarding the type material of that species.

Biology. Macrophthalmus graeffei is a relatively small-size species. The male specimen from the Persian Gulf is the largest specimen (CL = 14.8, CB = 8.4 mm) that has so far been collected. The species is one of the rarest of the genus, even though the lack of material could be particularly due to its subtidal habitat ( Lewinsohn 1977) and the lack of adequate collections carried out. The specimen from Kharg I. was collected from a sandy bottom in 18 m depth ( Stephensen 1945).

Geographical distribution. Wide Indo-West Pacific distribution: Red Sea, Gulf of Oman, Persian Gulf, Indonesia (Timor), Samoa; migrated to the Mediterranean through the Suez Canal.

Figures

FIGURE 11. Macrophthalmus graeffei A. Milne-Edwards 1873, male (ZMUC CRU- 1782): a, Posterior surface of carapace, left side; b, merus of male cheliped, inner surface; c, cheliped of male, outer surface; d, cheliped of male, inner surface; e, male abdomen.

FIGURE 12. Macrophthalmus graeffei A. Milne-Edwards 1873, male (ZMUC CRU- 1782): a, G 1 of male, ventral surface (right); b, apical part of G 1, ventral surface; c, apical part of G 1, dorsal surface; d, apical part of G 1, lateral surface.

FIGURE 17. a, b: Macrophthalmus graeffei A. Milne-Edwards 1873, male (UZM 1782), a, posterior surface; b, ventral surface; c, d: Macrophthalmus serenei Takeda & Komai, 1991, male (SMF 36097), a, posterior surface; b, anterior surface; e, f: Macrophthalmus sinuspersici Naderloo & Türkay, 2010, holotype, male (SMF 3690), e, posterior surface; f, ventral surface.