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The Taxonomic Status of the Introduced North American Signal Crayfish, Pacifastacus Leniusculus (Dana, 1852) In Japan, and the Source of Specimens in the Newly Reported Population in Fukushima Prefecture

2004; Brill; Volume: 77; Issue: 7 Linguagem: Inglês

10.1163/156854004774248735

1568-5403

Coral and Marine Ecosystems Studies

An alien crayfish, Pacifastacus leniusculus (Dana, 1852), was introduced in Japan from North America, and populations have survived in Hokkaido and Shiga Prefecture. Detailed morphological analyses suggested that the subspecific division in P. leniusculus that was previously proposed in the U.S.A., is not consistent in the Japanese populations, because intermediate and overlapping subspecific diagnostic characters were frequently found. Recently, P. leniusculus was illegally introduced into Fukushima Prefecture, Japan. In order to track down the origin of the new population, the detailed morphology of the P. leniusculus specimens as well as the species composition of their ectosymbiotic crayfish worms (Annelida, Clitellata, Branchiobdellidae) were examined and compared with those in two previously introduced populations in Hokkaido and Shiga Prefecture. Crayfish from Hokkaido and Fukushima Prefecture have a relatively long rostrum that differs from that found on specimens from Shiga Prefecture. In addition, the crayfish worm, Sathodrilus attenuatus Holt, 1981, occurs only in the Hokkaido and Fukushima Prefecture populations, thus suggesting the crayfish in Fukushima were introduced from Hokkaido. The shape of the rostrum and the presence of the crayfish worm can be used as tools for tracing the spreading of introduced P. leniusculus in Japan. Une ecrevisse etrangere, Pacifastacus leniusculus (Dana, 1852) a ete introduite au Japon en provenance de l'Amerique du Nord et des populations ont survecu dans les prefectures d'Hokkaido et de Shiga. Une analyse morphologique detaillee suggere que la division en sous-especes de P. leniusculus, precedemment proposee aux U.S.A., n'est pas justifiee pour les populations du Japon, parce que des caracteres diagnostiques subspecifiques intermediaires y ont ete trouves. Recemment, P. leniusculus a ete illegalement introduite dans la prefecture de Fukushima, au Japon. Afin de retrouver l'origine de cette nouvelle population, la morphogie detaillee des specimens de P. leniusculus ainsi que la composition specifique de leurs ectosymbiotes (Annelida, Clitellata, Branchiobdellidae) ont ete examinees et comparees a ceux des populations precedemment introduites dans les prefectures de Hokkaido et de Shiga. Les ecrevisses d'Hokkaido et de Fukushima ont un rostre relativement long qui differe de celui des ecrevisses de Shiga. De plus, le symbiote Sathodrilus attenuatus Holt, 1981 n'est present que dans les populations d'Hokkaido et de Fukushima, ce qui suggere donc que les ecrevisses de Fukushima proviendraient d'Hokkaido. La forme du rostre et la presence du ver ectosymbiotique ci-dessus signale peuvent etre utilises comme outils pour reperer la propagation des P. leniusculus introduites au Japon.