Journal Article 沖縄島から採集された日本初記録のミナミヨコナガモドキ ( 新称) Asthenognathus hexagonum Rathbun, 1909 ( 十脚目: 短尾下目: モクズガニ科)

前之園, 唯史  ,  Maenosono, Tadafumi

40pp.1 - 9 , 2018-01-08 , 琉球大学資料館 (風樹館) , Ryukyu University Museum, Fujukan
琉球列島の沖縄島から採集された標本 に基づき, 日本初記録のミナミヨコナガモド キ ( 新称) Asthenognathus hexagonum Rathbun, 1909 を報告する. 本研究により本種の分布記録 の北限と東限が大きく更新された. 標本が採集 された状況から, 本種がギボシムシ類の巣穴に 生息していることが示唆された. 本稿ではさら に, 本種と同属のヨコナガモドキA. inaequipes Stimpson, 1858 の識別形質についても記述した.
A rarely collected varunid crab, Asthenognathus hexagonum Rathbun, 1909 (Crustacea: Decapoda: Brachyura), is reported from Japan for the first time based on the specimens collected from Shioya Bay, Okinawa Island, Ryukyu Archipelago. The present specimens greatly extend the geographical range of the species to the northeast. The specimens examined in this study were collected from a subtidal zone, with a depth of about 1 m during nearly lowest low water level (N.L.L.W.) with the aid of yabbie pump, where the bottom was very soft knee-deep mud. Eight out of 10 individuals of A. hexagonum were collected together with an unidentified acorn worm species (Enteropneusta), suggesting their symbiotic relationship. The distinguishing characters between A. hexagonum and its western Pacific congener, A. inaequipes Stimpson, 1858, are also documented.

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