Tricotterofauna delle Alpi e Prealpi Centrali

Abstract

A preliminary list of the Trichopteran fauna of the central Alps and pre-Alps has been prepared on the basis of bibliographical references, studies of specimens collected by various researchers and unpublished data from Prof Malicky and Dr. Valle. A faunistic, ecological and chorological analysis is presented. The 373 sampling stations in nine Provinces are located between Col di Ferret in the west and Passo del Brennero in the east. They are in lotic, lentic and hypogean environments at altitudes from 20 to 3000 m a.s.l. The highest number of sampling stations is in the Province of Bergamo. A total number of 1471 samplings were made. The 205 taxa (201 species, 4 subspecies) known up to 2004 belong to 73 genera and 19 families. Of these taxa, 10 species were not included in previous faunistic lists of the central Alps and pre-Alps. The most common genera in running waters are Rhyacophila with 22 species (56{%} of the Italian fauna) and Drusus with 11 species (73{%} of the Italian fauna). The most widespread species in the sampling stations are Rhyacophila vulgaris (65 stations), Philopotamus ludificatus (59), Drusus discolor (41) and the troglophilous Stenophylax permistus (36 caves of the 47 inspected). The altitudinal distribution, based on the harmonic mean of the sampling levels, shows a high number of species at levels between 20 and 600 m a.s.l. The species found between 1800 and 2500 m belong to the genera Drusus (5 species), Limnephilus (2) and to the species Acrophylax zerberus, Rhadicoleptus ucenorum and Lithax niger. Zoogeographical analysis shows a predominance of species with European distribution (68{%}) followed by those with wider distribution and by those with Mediterranean distribution. 8 species and 1 subspecies are endemic to the Italian fauna. These include: Synagapetus padanus endemic to the Lombardia, Trentino Alto'Adige and Veneto, Ecclisopteryx malickyi to Trentino Alto Adige and Veneto, Hydroptila ruffoi, Hydropsyche spiritoi, Helicopsyche crispata to the pre-Alps and Apennines. For all species the similarity index shows a greater affinity between central and eastern Alps (75,8{%}) compared to the central and western Alps (63,80{%}).