XIIIth International Symposium on Chironomidae - Fribourg, September 5th-9th, 1997.

Oral presentation : First inventory and faunistic originality of the Chironomidae (Diptera) from a 6th order section of the river Loire (France). Garcia XF, Laville H.


The chironomid populations of a 30 km section of the middle River Loire (Tours region) are presented. Six collections of pupal exuviae were made from April to November 1994 in the main bed at three sites of this potamal zone.

99 species or taxa were identified among 9000 sorted exuviae. 16 are new records for continental France, in particular Polypedilum acifer, a dominant species. A new species Cladotanytarsus n.sp. will be described later.

A comparison of the chironomid fauna of the Loire with those of the potamal zones of five European rivers - Rhine (Germany), Meuse (Belgium), Pô (Italy), Garonne and Rhône (France) - shows the largest biodiversity and the originality of the Loire populations. Two among the four dominant species (>10%), Saetheria reissi, Cladotanytarsus vanderwulpi, and two of the nine frequent ones (>1%), Robackia demeijeri, Cladotanytarsus n.sp., are typical of the middle Loire population. The ecological and functional characteristics of the Loire system may explain this faunistic originality and diversity :

· morphological complexity and heterogeneity of the bed,

· mainly sandy nature of substratum,

· annual and inter-annual variations of flow,

· moderate influence on the lower valley of the river.