Heterotrissocladius brundini spec. nov. from Norway (Diptera, Chironomidae) By Ole A. Ssether and 0yvind A. Schnell Abstract Heterotrissocladius brundini spec. nov. is described in all stages and both sexes. It apparently form the plesiomor-phic sister species oi H. maeaeri Brundin. Introduction Langton (1984: 88, fig. 28 a) illustrated a pupa oi Heterotrissocladius with imbedded spines on Seg-ments VI -VIII and very large frontal warts. During an investigation of some acidified lakes in the sou-thernmost part of Norway the junior author found all stages of apparently the same species. Later it was found also in western and northwestern Norway. Methods and morphology Morphological nomenclature follows SitTHER (1980) with the exception that the apical spine of the gonostylus is termed the megaseta. The measurements are given as ranges followed by a mean when four or more measurements are made, followed by the number measured in parentheses (n). The type material is kept at the Museum of Zoology, University of Bergen (ZMB). Heterotrissocladius Spärck 1922, emended Imago — Eyes completely naked, with a few microtrichia between marginal ommatids or pubes-cent, i. e. with microtrichia between all ommatids, with reticulation between central ommatids. Otherwise as in Sii;THER (1975: 3). Pupa — Frontal warts weak to strongly developed. Frontal setae on frontal apotome (most species) or onprefrons (atleast/f. latilaminus Sxther). Caudolateralcornersof segments Vl-VIIIoccasionally with inner sclerotization resembling imbedded spines (H. brundini spec. nov), these strong on VII, weaker on VI, and only indicated on VIII. Otherwise as in Sxther (1975: 4). Larva — Anterior parapods with apical claws grading over into basal hair-Hke spines anteriorly and on a common base. Otherwise as in Sxther (1975: 4). 57
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