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Shen, 1930

Diagnosis: Body very thick. Carapace strongly convex and nearly smooth. Front usually triangularly notched. Third maxilliped studded with numerous coarse granules, which are more distinct on merus than on ischium. Ischium shorter than merus. Merus of cheliped with an oval tympanum on its outer surface and two on inner. Carpus with its inner margin sharp, rounded and finely serrated. Palm with a strong carina, near its outer ventral margin, extending to immovable finger. Movable finger of male cheliped bearing a prominence near its base. Tympana on ambulatory legs very large. Sixth segment of male abdomen broader than long.

Description: Body very thick. Carapace strongly convex, about one and half times as broad as long. Its depth subequal to its length. Its fronto-orbital breadth much greater than its length. Surface smooth, strongly inflected along antero-lateral margin of carapace. Protogastric region bulging anteriorly to such an extent, that from its dorsal view, the middle portion of dorsal orbital margin is altogether concealed. Its anterior border marked with an oblique granulated ridge. At inner end of this ridge, surface with some scattered granules. Branchial region also bulging upward and its antero-lateral border also granularly ridged. Another granulated ridge above the base of last leg. Some scattered granules in front of this ridge. Cardiac region very large, with its posterior portion deflexed and central portion shallowly depressed. A fine deep groove running posteriorly along its lateral border to a point where the cardiac region attains its greatest breadth, turning laterally and again anteriorly forming a loop on inner portion of branchial region. A small crescent impression in front of this loop. Urogastric region marked with two small pits.
Front narrow, roundish and deflexed. Its breadth between bases of eye-peduncles more than one-fourth breadth of fronto-orbit. Its lateral margin slightly convex and highly elevated, anterior marin slightly produced and triangularly notched at middle, posterior portion faintly marked by transverse grooves. Its surface with a depression, in which there is a roundish elevation.
Orbit large, oblique and shallow. Its dorsal margin markedly sloping posteriorly, smoothly rimmed, broadly triangular and bearing long hairs beneath, and bounded posteriorly by a shallow notch, ventrally by a broad and deep groove extending downward to another fine horizontal one on lateral surface of carapace. Floor of orbit with a short granulated ridge, its outer end meeting middle portion of ventral orbital margin, which is finely denticulated. A transverse groove below ventral orbital margin, and below lateral portion of this groove surface of carapace more or less sculptured.
Lateral margin of carapace behind the notch of outer orbital tooth soon divided into dorsal and ventral margins by a smooth groove. At point of dividing, margin strongly convex. Both dorsal and ventral margins all finely granulated and short hairy. Dorsal one straight, extending posteriorly for a short distance. Ventral one extending posteriorly and ventrally to a point above the base of third leg, with a smooth groove below it. Lateral surface of carapace covered with fine and dense setulose granules and bearing a fine horizontal groove.
Epistome broad but short, with a curved transverse ridge at middle. Anterior margin of buccal cavity finely granulated and triangularly angulated at middle, and distant from the distal margin of merus of third maxilliped, space between these margins occupied by palpus.
Third maxillipeds very large, bulging. Surface coarsely granulated. Granules more distinct on merus than on ischium. Ischium shorter than merus, its distal portion broader than basal, its lateral portion bearing a patch of soft hairs, its inner margin somewhat straight, outer margin concave, antero-outer angle produced antero-laterally. Suture between ischium and merus almost straight medially and concave laterally. Merus broader than long, more than one and half times as long as ischium. Its inner margin straight, outer markedly ridged and laterally convex covering exognath almost completely, antero-inner margin oblique and reflected upward, antero-outer angle usually concealed under antero-lateral angle of buccal cavity. A short, broad ridge running posteriorly from the articulation of palpus.
Chelipeds symmetrical, larger in male than in female. Coxa with its ventral distal margin finely granulated. Basi-ischium with its anterior margin granulated. Merus trigonal, its margins sharp and finely serrated, its outer surface granulated with a well defined oval tympanum on basal half, below tympanum a granulated ridge almost parallel to basal portion of its outer ventral margin. Above distal portion of its outer ventral margin, smoothly depressed. Its inner surface smooth and shiny, with two elongate oval tympana separated by a longitudinal hairy and granulated ridge, dorsal one longer than ventral. Its ventral surface slightly convex, with a short granulated ridge almost parallel to basal portion of its inner ventral margin. Carpus longer than broad, its outer surface closely covered with granules, scarcely on ventral. Its inner portion compressed and rounded, inner margin sharp and granulated. Palm convex on its outer and inner surfaces, both entirely covered with conspicuous granules. Granules on inner surface coarser and fewer in number than on outer. Its dorsal margin rounded. Its outer and inner margins with granular ridges, which all extend nearly to the tip of the immovable finger. Its ventral surface slightly convex. Palm with its distal portion much higher than basal, its height nearly as great a its length. Fingers longer than palm, their tips horny, very sharply pointed and inwardly curved. Movable finger with granulated ridges, two on its outer, inner as well as dorsal surface. Its inner margin conspicuously serrated, with a triangular denticulated prominence near its base, which is absent in the female but only slightly broadened at that region. Immovable finger with a granulated ridge on its outer, inner as well as vetral surface. Fingers widely gaping in male but narrowly in female.
Ambulatory legs granulated and bearing short bristles. A hairy branchial orifice situated between first and second legs. First and second legs subequal in length. Coxa of first leg with its ventral surface smooth, ventral distal margin finely granulated. Basi-ischium of first leg also granulated on its ventral distal portion. Merus of each leg compressed, its size increasing posteriorly, so also with tympanum which is greatly expanded posteriorly. Tympanum smooth, occupying entire breadth of the merus and about three-fourths the length of the latter. Carpus of each of first two legs with a granulated ridge on its dorsal surface. Propodus of each of first two legs with a granulated ridge on its ventral surface. Carpus and propodus of third leg without ridges, of fourth leg even scarcely granulated on its dorsal and ventral surfaces. Dactylus sharply pointed, longer than propodus, compressed and grooved, grooves all bear bristles. Dactylus of first as well as second leg more or less serrate on its anterior and posterior margins.
Sternum and abdomen smooth and shining. Abdomen of male with first segment much broader than second, its lateral portions angulated. Second with its lateral margins straight. Third and fourth subequal in length, the former slightly broader than the latter, its lateral margins slightly convex. Fourth with its lateral margins converging distally, distal margin slightly convex. Fifth broader than long and shorter than that of Scopimera globosa de Haan, its basal portion less constricted but much narrower than distal. Sixth quadrate, broader than long, its distal margin broader than basal, the former concave and the latter straight, its lateral margins with its posterior portion sometimes concave, surface with two deep parallel channels as on fifth. Seventh semicircular in outline. Of female, abdomen large and subcircular in shape, not covering whole surface of sternum. First segment broader than second. Second with its lateral margins straight. Third and fourth similar in shape, the latter broader than the former, its lateral margins oblique. Fifth broadest, its basal margin convex and distal concave at middle, lateral margins slightly convex. Sixth with its basal margin convex at middle and distal broadly concave, lateral obliquely convex but with a concavity at its middle. Seventh small, broadly triangular in shape. (Shen, 1932: 262)

Type locality: Beidaihe, Bo Hai, China.
Range: China - Beidaihe, Qinhuangdao and Yanghokow (Shen, 1930), Bo Hai and south of Shandong Peninsula (Shen, 1932), Hainan Island, Fujian, Jiangsu, Shandong and Bohai Bay (Dai & Yang, 1991), Hong Kong (Davie, 1992); Korea - Daecheon (Kamita, 1941), Bi-geum Island, Daehang Ri, and Daecheon (Kim, 1973); Taiwan - Tan-shui (Sakai, 1939, Lin, 1949), Wu Creek, Taichung County (Huang et al., 1992); sand muddy flats, at low water mark.

Scopimera bitympana