Manningis arabicum ( Jones & Clayton, 1983 )

Manningis arabicum ( Jones & Clayton, 1983) View in CoL

( Figs. 1 View FIGURE 1 B, 4)

Paracleistostoma arabicum Jones & Clayton, 1983: 190 View in CoL , fig. 4.

Manningis arabicum View in CoL — Al-Khayat & Jones 1996: 798, 809, fig. 7. – Ng et al. 2008: 233.

Material examined. IRAQ: 1 male (3.5 x 5.3 mm) ( ZRC 2009.1097), Shatt Al-Basrah, 30°24'21.41"N 47°46'43.23"E, coll. M. D. Naser, 2009. KUWAIT: holotype: male (5.4 x 8.9 mm) (NHM 1981.496), sand/ mudflats, Al Kiran, 8 April 1981; paratypes: 2 males (4.4 x 7.0 mm, 4.4 x 7.0 mm), 3 females (4.2 x 6.9 mm, 4.4 x 7.2 mm, 4.6 x 8.1 mm) (NHM 1981.497), sand/mudflats, Al Kiran, 8 April 1981; 2 males, 1 female (NHM 1974.389), no other data.

Type locality. Al Kiran, Kuwait.

Description. Carapace much broader (1.6–1.7 times) than long, glabrous, dorsal surface sloping downwards from posterior to anterior portion, hepatic region immediately posterior to external orbital tooth sunken, epigastric lobes indistinct, posterior branchial region with central group of rounded granules; gastric region moderately convex, anterior, lateral grooves of cardiac region, lateral grooves of intestinal region distinct; anterolateral margin convex, granular, with 2 weak lobes posterior to external orbital tooth, dorsolateral margin defined by row of granules running along anterior half of posterior branchial region; posterolateral margin convex, rounded; posterior carapace margin thickened, broad, straight. Front about as wide as orbital, deflexed, margin thick, weakly bilobed from dorsal view, lateral angles sharp, junction between base of front, supraorbital margin rounded, without distinct notch; frontomedial margin distinctly bilobed. Supraorbital margin sloped posteriorly, sinuous, thick, outer corner with tuft of setae curled over eye; infraorbital margin finely granular, setose, median third with larger granules; inner infraorbital tooth not very distinct from rest of margin, separated by shallow, wide indentation, suborbital ridge moderately developed, sparsely setose, granular along outer third, not visible dorsally.

Pterygostomian region smooth, sparsely setose, with small granules just under outer end of supraorbital margin, anterior region with shallow, transverse, closed sulcus. Anterior half of epistome separated from posterior half by distinct groove, followed posteriorly by transverse ridge. Posterolateral margin separated from anterior pterygostomian margin by open sulcus, posteromedial tooth broadly triangular, posterior margins on either side concave.

Third maxillipeds with thick inner margin; merus slightly shorter than ischium, outer distal angle slightly broad, rounded, outer surface without distinct grooves; ischium with inner distal angle slightly produced; basal segment of palp not excavated to form spatulate structure.

Chelipeds robust in males, well developed; outer surface of merus granular, particularly on dorsal surface; carpus globular from dorsal view, with small tuft of setae on inner surface; palm about as high as long, smooth, with row of setae on inner surface, close to dorsal margin; fingers with setose inner surfaces, tips spatulate, movable finger with large, molariform tooth closer to proximal end, immovable finger with cutting edge curved slightly, forming gape. Female chelipeds slender, setose, tips spatulate.

Ambulatory legs relatively stout, short, sparsely setose; P3 longest, P5 shortest, second, third meri with anterior, dorsal surface granular, never spinular or serrate.

Thoracic sternum swollen, such that portion of sternum, abdomen visible dorsally. Male abdominal somite 1 about as wide as somite 2, somites 2–4 immobile, sutures complete, not as deep as those between somites 1, 2, 5–7, somites 5, 6, telson freely mobile, lateral margins of somite 6 convex, angular. Female abdomen subcircular, with all somites free, telson triangular.

G1 ending in truncate apex, apex covered with strong, short, backward curving spines, row of long, strong comb-shaped spines subapically on one side.

Remarks. The male holotype agrees well with the original descriptions and figures provided by Jones & Clayton (1983: fig. 4a) except that in their figure, the carapace grooves appear deeper than they are on the actual specimen ( Fig. 4 View FIGURE 4 A). Specimens preserved in alcohol were creamy white with deep-red eyes.

Habitat and Biology. Jones & Clayton (1983:192) gave an account of the biology of this species and remarked that "growth of the large chelae seen in adult males again appears to be rapid, and to some extent unrelated to overall crab size". They added that Manningis arabicum and Nasima dotilliformis are found slightly lower intertidally on the mudflats. According to these authors, M. arabicum is a deposit feeder, using its forcep-like chela to pick up sand grains. Together with N. dotilliformis , M. arabicum was found to feed "on the surface of the sand and mudflats as soon as the ebbing tide left their [its] burrows". They also remarked that M. arabicum was not found with Leptochryseus kuwaitense and that it colonised sandy mudflats at Al Kiran and areas of the salt marsh at Doha, Kuwait. In Iraq, the specimens were obtained from soft silty clay on intertidal salt marshes. As has been discussed earlier, because of the many development projects upstream of the major rivers, there is not much freshwater now flowing to the sea and coupled with the strong tidal influence, the area’s salinity averages 32 ‰ despite its distance from the sea (see also habitat notes for Nasima dotilliformis ).

Geographical distribution. Only previously known from Kuwait, and now Iraq.