中国海倒颚蟹属(甲壳动物亚门:十足目:豆蟹科)两新记录种

NEW RECORD OF TWO SPECIES OF GENUS ASTHENOGNATHUS (CRUSTACEA:DECAPODA:PINNOTHERIDAE)FROM CHINA SEAS

长期以来,中国海倒颚蟹属仅记录一种,即渤、黄、东海底栖动物常见种异足倒颚蟹AsthenognathusinaequipesStimpson,1858。作者对中国科学院海洋生物标本馆收藏的采自中国海的全部倒颚蟹属标本进行系统研究后共发现除该种外还有以下2种,为中国海的新记录:宽身倒颚蟹AsthenognathusgallardoiSer埁neandSoh,1976和六角倒颚蟹AsthenognathushexagonumRath-bun,1909,均采自南海北部。异足倒颚蟹为中国北方和东部海域常见种,但未见于南海。六角倒颚蟹与异足倒颚蟹形态上较相似。两者差异在于六角倒颚蟹头胸甲六角形,后缘约与额-眼眶缘等宽,背面有2对凹陷,后侧缘有2条颗粒脊,而异足倒颚蟹头胸甲后缘约为额-眼眶缘宽的1.5倍,背面仅有浅横沟。宽身倒颚蟹与其他两种形态差异较大,头胸甲宽约为长的1.9倍。

This paper reports the species of Genus Asthenognathus Stimpson from China seas based on the crab collections deposited in the Marine Biological Museum of Chinese Academy of Sciences, Qingdao. In addition to Asthenognathus inaequipes Stimpson, 1858,commonly found in northern and eastern China seas,Asthenognathus hexagonum Rathbun,1909 and Asthenognathus gallardoi Serene and Soh, 1976, are recorded here for the first time from China. Diagnoses of the species are given and comparisons between the two closely related species are made. 1 Asthenognathus gallardoi Serene and Soh, 1976 （ Fig.1） Asthenognathus gallardoi Serene ＆ Soh, 1976：27, fig 28A,B,pl. 8 fig. A,B.-Ghani ＆ Tirmizi,1991 ：100, text-fig. 1A-G Material K54-390. 1 male（cl4.9mm,cw 9.2mm）,2 female（cl6. Smm,cw 12.8mm;cl 3.4mm,cw 6.6mm）. Weizhou Island（21°02＇N, 109°06＇E ） , Tonkin Gulf, northern South China Sea,27 December 1954. J. Y. Liu collected. The main characteristics of the male and females agree with the descriptions by Serene and Soh 1976 and those by Ghani and Tirmizi 1991. Diagnosis Carapace 1.9 times as broad as long, regions ill defined. Fronto-orbital margin and posterior margin sub-equal in width, with two obscure parallel transverse ridges on dorsal surface, the anterior one is at the level of base of chelipeds and the posterior one at the level of the contact between the 2nd and 3rd ambulatory legs,and a wide M-shaped depression is found in the meta-gastric region between the two ridges. An oblique granular carina extends postero-mesially from the middle of lateral margin. The third maxilliped stout and broad, the suture between ischium and merus oblique;segments of palp broad and short. Chelipeds symmetric, stronger in male. Propodus slightly bulgy, with a distinct carina on outer surface extending to tip of fixed finger. One obtuse tooth on inner margin of movable finger in the male, while 2 in the female. Lateral margin of the fused 4-6th abdominal somites （R segment）with a protrude （lateral lobe）at the distal third（ Fig. 1 e） ;telson obtuse triangular in shape. Female gonopore on 6th thoracic sternum circled by 3 carinae,and with a soft round cover. Ambulatory legs flat,2nd pair the longest,4th pair much slender in male. Outer margin of the male first gonopod fringed with short plumose setae, both dorsal and ventral sides of distal end covered with thick thorn-like setae. Tip of it corneous and flat, bending slightly inwards. Habitat Lives in burrows on sandy beaches or sandy parts of rocky shores. Type locality Andaman Sea. Distribution Tropical Indo-west Pacific from the South China Sea（ China：Weizhou Island,Tonkin Gulf, Vietnam：Nhatrang Bay） ,western to the Andaman Sea,and further to northern Arabian Sea. The species is recorded from China for the first time. 2 Asthenognathus hexagonum Rathbun, 1909 （ Fig. 2） Asthenognathus hexagonum Rathbun, 1909 ： 111 ; 1910 ： 339, fig. 24, pl. 2 fig. 14. -Serene ＆ Soh, 1976 ： 27 ,fig. 28C. Material ＊ NCOS 186B-23,1 female（ cl 8.4mm, cw 11.5mm）. Northern South China Sea off Naozhou Island（20°45＇N, 110°45＇E）, depth 26m, bottom muddy, 10 April 1960. J. Y. Liu collected. Daignosis Carapace hexagonal, 1.4 times as broad as long. Front marked with an obscure median groove. Mesogastric region with a pair of short transverse grooves, and a pair of U-shaped depressions bellow them. Lateral parts of intestinal region with a triangular dotted area （depression）close to posterior margin. Posterior margin of carapace subequal to fronto-orbital margin in width. 2 oblique granular carinae on postero-lateral margin. Third maxilliped slender,ischium subequal to merus,suture between ischium and merus tranverse. Dactylus of palp thin and slender,with long plumose setae. Female chelipeds slender,fingers not gapped,propodus almost 3 times as long as broad. The second ambulatory legs are the longest and the forth pair the shortest. Last three pairs of ambulatory legs with transverse rows of small pits, and covered with thick short setae. Habitat Lives in muddy bottom,12 to 26m deep . Type locality Gulf of Thailand . Distribution Tropical Western Pacific from the China coast, northern South China Sea , to Manila Bay and Gulf of Thailand. The species is recorded for the first time from the China seas. 3 Aethenognathus inaequipes Stimpson, 1858 （ Fig. 3 ） Asthenognathus inaequipes Stimpson, 1858 ： 107 ; 1907 ： 140, pl. 14, fig. 1. -Sakai, 1935 ： 206, fig. 110 ; 1939：601, text-fig. 86a, b; 1976：587. -Shen et Liu, 1963 ： 144. Material examined： Bohai Sea：5 ♂♂ and 9 ♀♀ Depth 6-16m. Yellow Sea, Jiaozhou Bay ： 12 ♂♂,27 2 2 ♀♀ Depth 0-50m. East China Sea ：4 ♂♂ , 1 ♀. Depth 6-26m. This species resembles Asthenognathus hexagonum Rathbun, 1909, but differs from it in the following aspects ： Asthenognathus hexagonum Rathbun, 1909 Asthenognathus inaequipes Stimpson, 1858 Carapace hexagonal ; carapace trapezoid ; Carapace with paired U-shaped depressions and triangular dotted area on dorsal surface;With an obscure transverse groove only on dorsal surface;Carpace with posterior margin sub-equal to frontoorbital margin in width;posterior margin 1.5 times as wide as fronto-orbital margin;Fingers of cheliped not gapped in female ; fingers narrowly gapped in female （ Fig. 3 ） Distribution This species is a Sino-Japanese faunal element commonly found in shallow waters of the Bohai Sea, Yellow Sea and East China Sea ; as well as the Pacific coast of Japan, but has never been found in the South China Sea.