鳥取県岩美町の山陰海岸海浜におけるウスバカゲロウ類の分布

鳥取県岩美町の7つの砂浜と鳥取砂丘東端の海岸砂丘でウスバカゲロウ幼虫（アリジゴク）の分布を調査した。鳥取砂丘でみられる 種（ハマベウスガカゲロウ，クロコウスバカゲロウ，オオウスバカゲロウ，コカスリウスバカゲロウ）のうち，岩美町ではハマベウスガカゲロウをのぞく3種が出現した。小礫～中礫の礫浜または極粗砂の砂浜である鴨ヶ磯と城原海岸ではいずれの種も確認できなかった。鳥取砂丘と岩美町内の海浜の間に砂浜の粒径には大きな差はなく，岩美町内の砂浜でハマベウスバカゲロウがみられない理由は粒径では説明できない。ハマベウスバカゲロウの既知生息地との比較から，海浜の規模が小さいことと，砂丘の形成が弱いことがハマベウスバカゲロウを欠く理由と推測された。 We surveyed distribution of antlions (larvae of Myrmeleontidae) in 14 sites from 7 sandy beaches in Iwami-cho, easternmost town of Tottori Prefecture and Tottori Sand Dunes. Of the four species (Myrmeleon solers, M. bore, Heoclisis japonica, Distoleon contubernalis) known from Tottori Sand Dunes, three species excluding a pit-building species M. solers were found to occur in the Iwami-cho. No species were found in Kamogaiso Beach and Shirawara Beach that are pebble to cobble or very coarse sandy beaches. Absence of M. solers in beaches in Iwami-cho cannot be explained by sand grain size because there were no significant differences between Tottori Sand Dunes and beaches in Iwami-cho. Comparison with beaches where occurrence of M. solers has been reported and beaches in Iwami-cho suggested shorter coast lines and lower development of sand dunes behind beaches in Iwami-cho may explain the absence of the species in Iwami-cho.