Rheocricotopus (s. str.) costai sp. n. AND R. (s. str.) pyrenaeus sp. n., TWO RELICT SPECIES FROM GLACIAL RHEOCRENES AND STREAMS IN CORSICA AND THE EASTERN PYRENEES (DIPTERA: CHIRONOMIDAE, ORTHOCLADIINAE)

Abstract

Two new species of the genus Rheocricotopus subgenus Rheocricotopus (R. costai sp. n. and R. pyrenaeus sp. n.) are diagnosed and described, based on material collected in some glacial rheocrenes and streams located in the high mountains of Corsica and the Eastern Pyrenees. Rheocricotopus costai sp. n. is described as male and pupal exuviae, while R. pyrenaeus sp. n. is described as male and female adults and pupal exuviae. Rheocricotopus costai sp. n. is known from both western Corsica and the Eastern Pyrenees, while the geographical distribution of R. pyrenaeus sp. n. is restricted to the protected area of the Mantet Nature Reserve (Eastern Pyrenees). Larvae of both R. costai sp. n. and R. pyrenaeus sp. n. are exclusively rheophilic being confined to lotic habitats located at high altitude (crenal and rhithral). Apart from the presence of an additional median circular small patch of spinules on tergite III of the exuviae, R. costai sp. n. directly keys into the effusus-group on the basis of several specific characters found in the male adult. Nevertheless, R. pyrenaeus sp. n. keys near both of R. reduncus Sæther & Schnell, 1988 (known from Finland, Norway and Russian Far East) and R. tchernovskii Makarchenko & Makarchenko, 2005 (known from Russian Far East), based in particular, on the unusual shape of the superior volsella which is inwardly markedly turned over distally. The genus Rheocricotopus is currently represented by 10 species in continental France and by 8 species in Corsica (Moubayed-Breil 2016). Consequently, the description of R. costai sp. n. and R. pyrenaeus sp. n. increases the total number in the genus to 12 for continental France and to 9 for Corsica. Taxonomic remarks, discussion and comments on the ecology and geographical distribution of the two new species are given.