Helicana wuana

(Rathbun, 1931)

Diagnosis: Suborbital crest of the male with 15 protuberances, the four innermost of which are finely striated vertically. Carpi and propodi of first three ambulatory legs bear dense fur on their anterior surfaces. The distal part of 1st pleopod elongate and largely curved dorsally; palp small, narrow and slightly protruded distally; genital opening situated apically on the ventral side.

Description: The carapace is broader than long, and its dorsal surface is rather flattened transversely. The mesogastric and protogastric regions are continuous with each other and also flattened. The cervical grooves are barely discernible. The cardiac furrow is distinct. The lateral margins of the carapace are trilobed, the 3rd lateral tooth is rudimentary. The branchial regions present three granulate lines, the 1st one is short, arising from the 2nd lateral tooth, the 2nd is rather long, arising from the rudimentary 3rd lateral tooth, and the 3rd is straight and lies above the 4th ambulatory leg. The postero-lateral margins are straight and slightly divergent posteriorly. The suborbital ridge of the male shows 15 elongate protuberances; the four innermost ones are confluent with one another and finely striated vertically.
The palm of the chelipeds is in males 1.7 times as long as high, its ventral margin is swelling medially. The outer surface is imperceptibly granulate under the binocular. The inner angle of the carpus bears a strong tooth and just below it bears also two strong and 3-4 small teeth.
Carpi and propodi of the 1st and 2nd ambulatory legs bear dense fur on their anterior surfaces, and those of the 3rd only in the upper half of the anterior surface.
The 1st pleopods of the male are slender; the distal part is elongate and curved dorsally. The dorsal surface of the stem is slightly concave and semicalcified in its anterior half. The inner-dorsal margin forms a short narrow palp distally, which is clearly separated from the stem. The longitudinal ditch leads distally to the rounded genital opening situated apically on the ventral side.
Colour in alcohol is almost faded away, however the carapace is largely spotted by obscure maron. (Sakai & Yatsuzuka, 1980)

Type locality: Wenchow, Chekiang, China.
Range: Korea - Zennando and Heinando (Sakai, 1939), Yellow Sea and Korea Strait (Kamita, 1941), Ganghwa Island (Kim, 1970), Bi-geum Island, Seondu Ri, and Seopo Ri (Kim, 1973), Yellow Sea side (Sakai, 1976a); China - Wenchow, Chekiang (Rathbun, 1931), Bo Hai and Shandong Peninsula (Shen, 1932), Dairen (Sakai, 1939), Wenzhou, Zhejiang Province, and Muihwa, Fujian Province (Shen, 1940b), Luta, North China (Sakai, 1976a), Guangdong, Fujian, Shandong, Bohai Bay and Liaodong Peninsula (Dai & Yang, 1991); Taiwan - Saisen (Sakai, 1939), Saisen and Lu-kang (Lin, 1949), west coast (Sakai, 1976a, Sakai K. & Yatsuzuka, 1980); inland sea or estuary.

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