STUDI SULLE LARVE DEI COLEOTTERI DITISCIDI l. Note morfologiche sulle larve mature di sei specie del genere Agabus Leach

Abstract

The author relares about the main morphological differences and similarities found comparing che following species: A. bipustulatus L., A. conspersus Marsh., A. nebulosus Forst., A. melanocornis Zimm., A. dydimus Ol., A. brunneus F.

In the first part of this paper, a morphological description of A. bipustulatus L. is given, more in detail for those parts which have different characters at least in one of the other five species. A. bipustu/atus L. was appointed as comparison species because it is a very common one.

In the second part, the distinctive characters and the morphological similarities are reported for each of the other five species.

Finally, it is noticed that the present subdivision of the genus Agabus in different subgenera, made by GUIGNOT (1959) for the imagos, is validated by the third stage larvae characters (maxillae characters particularly); a preceding subdivision (GuiGNOT 1931-33), concerning melanocornis, is also justified: this species (whose third stage larva has peculiar characters) was separated from the others one in a third subgenus.

A key to  the larvae treated here is proposed.

Several specimens of each species, gathered in distant water bodies of Southern Italy, were examined. The specific identification of the single larvae was verified by imagos reared from some specimens of them.

Dopo una dettagliata trattazione della morfologia esterna della larva matura dell'Agabus bipustulatus L., vengono annotati, per ognuna delle altre cinque specie, i caratteri distintivi e le affinità morfologiche riscontrate nell'esame comparativo. Vengono infine fatte alcune considerazioni sulla distribuzione in sottogeneri delle sei specie trattate, alla luce dei caratteri delle loro larve mature. I caratteri distintivi sono riassunti in una tavola dicotomica.