Pilumnus spinulus

Shen, 1932

Diagnosis: Carapace with short stiff pairs. Frontal lobe each edged with fifteen to sixteen spinulous denticles. Antero-lateral margin with two small denticles and three spiniform teeth behind the outer orbital tooth. Ventral orbital margin with eleven to twelve denticles. Merus of smaller cheliped with a distal and a subdistal curved spine. Carpus and palm spinulous. Merus of each ambulatory leg more or less denticulous on its anterior margin.

Description: Carapace subquadrilateral rather than transversely oval. Surface strongly convex antero-posteriorly, covered with short stiff hairs and some scattered longer ones and smooth when denuded. Regions indistinct.
Front less than one-third the greatest breadth of carapace, deflexed, cut into two lobes by a V-shaped notch. Its surface marked with granules. Each lobe with its margin slightly oblique and bearing fifteen to sixteen spinulous denticles, of which the one on its outer angle is most prominent and is separated from the small inner orbital denticle by a groove.
Dorsal orbital margin coarsely granulated and with two faint notches. Ventral orbital margin with about twelve denticles, of which the inner one is the most prominent, quite visible from its dorsal aspect. Gap below the outer orbital tooth indistinct. Suborbital region with three denticular tubercles on its inner portion. Subhepatic region with some more denticular tubercles.
Antero-lateral margin of carapace much shorter than postero-lateral, with two small denticles and three spiniform teeth behind the outer orbital tooth. The three spiniform teeth equidistant, each with some spinules at its base and with its tip sharply pointed and slightly curved inward; the two small denticles situated immediately behind the outer orbital tooth. Postero-lateral margin almost straight.
Smaller cheliped bearing long, stiff and pointed hairs. Coxa with its ventral surface smooth, its anterior margin with a distal denticle. Basi-ischium with its ventral surface granulate, its anterior margin bearing five denticles. Merus finely granulated on its outer and ventral surfaces, its dorsal margin with about six denticles, a distal and a subdistal curved spines, its outer ventral margin with about seven denticles at its distal portion and also some denticles on its distal lobe, its inner ventral margin with about four denticles at its basal portion, of which the distal second is the most prominent. Carpus covered with short, stout and sharply pointed spines, its inner distal spine most sharply pronounced. Palm covered with similar spines on its outer surface. The spines becoming longer toward its dorsal margin. Fingers sulcate, not gaping, inner margin sharp and bluntly denticulated. Movable finger with basal poriton of its dorsal surface spinulously denticulated.
Ambulatory legs slender, more or less similar in shape to those of Pilumunopeus makiana. Third pair longest. Merus with its anterior margin bearing some small pointed denticles, which are indistinct on that of the last leg. Three terminal segments bearing numerous long, stiff hairs.
Abdomen of male pubescent, more or less similar in shape to that of the preceeding species, except its seventh segment which is rounded at its apex. First male appendage curved inward, with two lines of short, stout spines on its distal half when viewed from its ventral aspect, its apex blunt and unarmed, more or less spatulate in form. (Shen, 1932: 107)

Type locality: Penglai, Shandong Peninsula, China.
Range: China - Shandong Peninsula (Shen, 1932), Jiaozhou Bay (Shen, 1937); 25-41 m.

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