| Summary: | 琵琶湖および近畿地方の諸河川の30箇所から採集したスゴモロコ属(Squalidus) (コイ科魚類)の標本について外部形態を比較し,相互の類似性を検討した。検討はクラスター分析法によった。比較の対象にした外部形態は8形質,すなわち,体高,尾柄高,頭長,頭幅，吻長，上顎長，眼径および口ひげ長である。これら8形質は相互に比較的独立性が高いが，体高と尾柄高，および，頭長と眼径との間には関連性が認められる。標本相互の類似性を列記すれば，デメモロコの異質性が最も高く，以下，ほぼ同じレベルの類似度で，①スゴモロコ，②コウライモロコ1，③コウライモロコ2，そして，④コウライモロコ3の4つのグループに区分される。これら各グループの分布には一部の標本に地域性が認められ，デメモロコは琵琶湖の標本のみに，スゴモロコは琵琶湖と天ヶ瀬ダムの標本に，コウライモロコ2は淀川水系の三川合流付近の標本に，そして，コウライモロコ3は紀伊半島の有田川と日高川の標本に，それぞれ，限られる。 External forms of the thirty samples of the minnows, genus Squalidus from Lake Biwa and from the eight different rivers in Kinki District were compared, and the affinity and the geographical variation among them were examined. Eight characters of the external form of the fish were compared, that is, the body depth, the caudal peduncle depth, the head length, the head width, the snout length, the upper-jaw length, the eye diameter and the barbel length. Although the independency of these characters is relatively high, the body depth and the caudal peduncle depth, and, the head length and the eye diameter change correlatively each other. The cluster analysis for the eight characters suggest that there are two groups in the genus Squalidus, one of which is sub-categeri 3ed into four groups. The difference of the distribution in the samples divided into above five groups suggest that S. japonicus japonicus is found only in Lake Biwa, S. chankaensis biwae in Lake Biwa and River Setagawa down to Amagase dam, the S. chankaensis subsp. group 2 in the neighborhood of the confluence of the three rivers in River Yodogawa, and, those group 3 in River Aridagawa and River Hiki-gawa of Kii Peninsula.
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