A subfossil record of the presumed larva of Corynocera oliveri Lindeberg from the Lobsigensee (Swiss Plateau). lU ('S Studies in the Late-Quatemary of Lobsigensee 8. UNESIO l (Diptera, Chironomidae) Von Wolfgang Hofmann Max-Planck-Institut für Limnologie, Abt. Allgemeine Limnologie, Plön Abstract Having some morphological features in common with Corynocera ambigua Zetterstedt and occuring simultane-ously with subfossil male hypopygia of C. oliveri Lindeberg, a subfossil Tanytarsini larva from lata glacial Sedi-ments of the Lobsigensee (Swiss Plateau) is presumed to belong to Corynocera oliveri. C. oliveri and C, ambigua coexisted in the Lobsigensee during the Oldest Dryas period until about 13 000 B. P. This is the first record of both species from the alpine region. Introduction The Lobsigensee is a primary reference site in the Swiss contribution to the International Geological Correlation Programme (IGCP) 158 B (Berglund 1979). It is a small (2 ha), shallow (2.5 m) lake about 15 km northwestof Bern (Swiss Plateau, 514 m asl) from which a series of Sediment profiles have been obtained. The lowermost layers were from Oldest Dryas (Amann & Tobolski 1983). In the late glacial layers from the centre of the recent lake (prof ile LQI 120 a), as well as from the litto-ral Zone of an earlier period of lake development (LQI 150 a-i-b), head capsules of Tanytarsini larvae with some distinctive morphological characteristics were found. In the same layers male hypopygia of adult specimens identified as Corynocera oliveri Lindeberg by Dr. Reiss (München) frequently occur-red (Hofmann 1983). Reiss (pers. comm.) also agreed with the Suggestion that the Tanytarsini head capsules in question belong to this species, the larva of which was until now unknown. Description of the subfossil larva and discussion This conclusion is not simply deduced form the co-occurrence of larval and adult remains, but also from the fact that the larva shares some morphological features with the second species of the genus Co-rynocera, C. ambigua Zetterstedt (Hirvenoja 1961). The mentum of the subfossil specimens (Fig. 1) is of the Tanytarsini type, having one middle tooth and five pairs of side teeth and slender mental plates. However, the middle tooth and the first side teeth form a unit as a distal-ventral plate. The second lateral teeth are not beside the first laterals but dorsal to them. Similarly, each of the foUowing lateral teeth is dorsal to its median neighbour. Hence, the men-tum is not piain but the teeth form a bow. This arrangement of the mental teeth corresponds with the 211
A subfossil record of the presumed larva of Corynocera oliveri Lindeberg from the Lobsigensee (Swiss Plateau). Studies in the Late-Quaternary of Lobsigensee 8. (Diptera, Chironomidae)
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