o .eg an Jo of En1tomol0lD' - Norsk entomologisk forening

Chironomidae (Dipt.) from Ekse, Western Norway
GODTFRED A. HALVORSEN, ENDRE WILLASSEN & OLE A. SiETHER
Halvorsen, G.A., Wiliassen, E. & Srether, a.A., 1982. Chironomidae (Dipt.) from Ekse,
Western Norway. Fauna norv. Ser. B. 29, 115 -l2t.
A systematic list of the chironomid fauna from Ekse, Western Norway is given. Thirty-two
genera and 67 species are listed, of which 13 species, including 3 uncertain, are new to region
20 following Limnofauna Europea, and 4 are previously uncertain recordings. Two
species are new to science, while II have a more or less uncertain taxonomic status. Diamesa
ursus Kieffer, 1918, is synonymized with Diamesa hyperborea Holmgren, 1869. Figures
of 2 species of Procladius Skuse are presented.
G.A. Halvorsen, E. Willassen &a.A. Srether, Dept. of Systematic Zoology, Museum of Zoology,
University of Bergen, N-5000 Bergen, Norway.
INTRODUCTION
The following paper is the result of a ftrst attempt
by two of us (G.A.H. & E.W.ho get familiar
with the family Chironomidae, and to obtain
some knowledge of the chironomid fauna
of Western Norway. For this purpose light trap
catches taken from May to mid October 1976 at
Ekse, ROi: Vaksdal were examined. The catches
were part of «The Weir Project». a study of the
,effects of building weirs in the regulated West
Norwegian river Ekso, and collected by various
participants of the project.
The river Ekso is situated about 100 Km north
east of Bergen. The light trap was placed at Ekse
(60°50' N6° 15' E, altitude 580 m a.s.l.) about 20
m from the river bank, just opposite an artificial
weir making a basin with relative slowflowing
water. The vegetation in the study area is described
in Fredriksen (1980), the river being surrounded
by pasture and hayfields, acid bogs and
birchwood. The area lies in the subalpine birchwood
belt. Apart from mosses, no aquatic macrophyte
vegetation was present in the river.
MATERIAL AND METHODS
Most of the material examined consists of the
above mentioned light trap catches from May to
mid October 1976 at Ekse. While revising Eukiefferiella
Thienemann, Tvetenia Kieffer and Diamesa
Meigen several collecting trips were made
to the same area in the summers of 1979 and
1980 in order to rear specimens for these genera.
The larvae were collected mostly from the surfaces
of stones and from submerged mosses in the
river and in tributary brooks, at most 3 km upstreams
from the location ofthe light trap. However,
a few collections were also made in the weir
basin and in the bog pools.
The light trap material represents a vast number
of specimens. No attempt was made to make
a quantitative subsampling or to cover all collecting
dates. The specimens were determined to
subfamily and grouped with a stereomicroscope
and than mounted on slides following the procedure
outlined by Seether (1969). The terminology
used follows Seether (1980). The identified
species are listed in alphabetic order under the
respective subfamilies with collecting dates,
number of identified specimens and systematic
remarks when necessary. According to the faunistic
aspect we do not designate species new to
Norway, but follows the delineation of regions
in Limnofauna Europea (Illies, 1978:
XIII - XVII). This means that Ekse lies in region
20, together with most of Norway. 0stfold is a
part of region 14, Troms north of Troms0 and
Finnmark are included in region 21, while parts
of Sweden are included in region 20.
For identification of the genera Pinder (1978),
Bmndin (1956) and Fittkau (1962) were mostly
used. For many genera such as Procladius Skuse
and Orthocladius van der Wulp no appropriate
keys on Palaearctic species exists. For these genera
works on Nearctic species have been conferred.
The species of the genera Chaetocladius
Kieffer, Limnophyes Eaton, Orthocladius and
Parakiefferiella Thienemann have been identified
mainly by means of the descriptions given
in Bmndin (1947, 1956).
Fauna narY. Ser. B 29 .. 115 - 121. Oslo 1982. 115