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The tardigrade Hebesuncus conjungens (Thulin... (2002)
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200i.

Entomol. Mitt-Mus. Hamburg

14 (166): 83-94

Hamburg, 15. Oktober 2002
ISSN 0044-5223

The tardigrade Hebesuncus conjungens (Thulin, 1911)
in the Alps, with notes on morphology and distribution

(Tardigrada)

Hieronymus Dastych and Konrad Thaler
(With 18 figures)

Abstract

The arctic-alpine tardigrade Hebesuncus conjungens (Thulin, 1911) is re-
described, based on type material and specimens from the ötztal Alps (Nordtirol).
The study focuses on the morphology of the buccal apparatus, claws and eggs,
including SEM analysis. Some aspects of the biology and distribution of the species
are discussed. The species is new for Austria.

Introduction

Members of the genus Hebesuncus Pilato, 1987 belong to cold-dwel-
ling, widely distributed but relatively rarely recorded tardigrades, occurring
in polar regions and various mountain ranges worldwide. Three species of
Hebesuncus have been described: H. conjungens (Thulin, 1911), H. schu-
steri (Dastych, 1984) and H. ryani (Dastych & Harris, 1994). The latter two
taxa are known only from the Antarctic, while H. conjungens has been re-
ported from both the northern and southern hemisphere.

Several specimens and eggs of H. conjungens were found in bryophy-
tes and lichens from the subnival zone of Mt. Festkogel (the ötztal Alps,
Nordtirol, Austria). As the knowledge of the morphology of this species still
has many gaps, it was considered to revise the Information on some of its
poorly known or undescribed characters. Finally, several aspects of the
biology and distribution of the taxon are discussed.

Material and methods

Bryophyte and liehen samples were collected in paper envelopes and air-dried,
the tardigrades and their eggs then being extracted by the method described by
Dastych (1985). The specimens are mounted on six microslides in Faure's medium
or polyvinyl-lactophenol and have been deposited in the Zoologisches Museum Ham¬
burg (ZMH Acc. No A26/02). Photomicrographs were taken with a ZEISS "Photo¬
mikroskop IM", SEM micrographs with LEO 1525. For SEM examination specimens
were washed, transferred to hot Bouin's medium, dehydrated in ethanol, critical-
point-dried and gold-coated.