World Congress of Malacology Antwerp ... - Unitas Malacologica

and alimentary system. The analysis of morphological diversity suggests the following general trends
within the family: increasing of body size, elongation of shell, reduction of the outer demibranch and
simplification of alimentary system. Increasing of body size in vesicomyids is correlated with
elongation of shell. Extremely elongated shell has evolved independently within the family at least in
two different groups – species with single demibranch and ones with two demibranchs.
Skeneimorph gastropods in Neomphalida and Vetigastropoda
Kunze, Thomas; Beck, Friedericke; Brückner, Martin; Heß, Martin; Ruthensteiner, Bernhard;
Haszprunar, Gerhard
Department Biology I, Ludwig-Maximilians-Universität München, BioZentrum Martinsried,
Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany,
Email: ThomasKunze1@gmx.de; haszi@zsm.mwn.de
Until recently the classification of the members of the Skeneidae (type species Skenea serpuloides
Clark 1851) has been solely based on shell characters, radula details und external morphology.
Accordingly, this vetigastropod group is suspected to represent a polyphyletic, “skeneimorph”
assemblage. Recent methodological progress including serial semithin sectioning combined with
computer-aided (software AMIRA) 3D-reconstruction enables the detailed anatomical investigation
of such small (max. 3 mm), helicoid gastropods. Indeed, already preliminary anatomical data shed
some light on the skeneimorph question:
True Skeneidae (exemplified by Skenea serpuloides) doubtless belong to the Vetigastropoda and
probably rests within the Trochoidea/Turbinoidea. Apomorphies of Skenea and related genera include
a penis formed by the right propodium.
Cyclostremiscus ornatus, Bathyxylophila excelsa and Ventsia tricarinata also have papillate cephalic
and epipodial tentacles, a single monopectinate ctenidium with skeletal rods and bursicles, a papillary
left and a right excretory organ, and statocysts with several statoconia. All these characters suggest a
position of these species inside the Vetigastropoda. However, the distinct appearance of epipodial
tentacles and the lack of a combined epipodial sense organ argues against an inclusion into the
Trochoidea/Turbinoidea and Skeneidae, where combined epipodial tentacles are always present. At
present, these species cannot be classified in any known vetigastropod subclade.
Leptogyra, Xyleptogyra and Leptogyropsis species are characterized as follows: Smooth cephalic and
epipodial tentacles, a single, left excretory organ, a monotocardian heart bypassed by the rectum, and
statocysts with one statolith. These anatomical data clearly contradict inclusion in the Vetigastropoda,
but strongly suggest a systematic position in the likewise rhipidoglossate Neomphalida.
It is likely that microanatomical studies on the more than 40 remaining “skeneimorph” genera will
greatly influence our understanding of the evolution of Vetigastropoda and related gastropod clades.
The microanatomy of Bathyxylophila excelsa Marshall, 1988, and Ventsia tricarinata Warén &
Bouchet, 1993, two skeneimorph vetigastropods from Pacific deep sea habitats
(Vetigastropoda)
Kunze, Thomas; Heß, Martin; Haszprunar, Gerhard
Department Biology I, Ludwig-Maximilians-Universität München, BioZentrum Martinsried,
Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany
Email: ThomasKunze1@gmx.de, hess@zi.biologie.uni-muenchen.de, haszi@zsm.mwn.de
The family Skeneidae (Vetigastropoda, Trochoidea/Turbinoidea?) is currently regarded as a
polyphyletic lumping pot for small (max. 3 mm), rhipidoglossate gastropods (“skeneimorphs”)
showing signs of internal fertilisation. Recent methodological progress including serial semithin
sectioning combined with computer-aided (software AMIRA) 3D-reconstruction enables the detailed
anatomical investigation of such small, helicoid gastropods. Here we describe the microanatomy of
the small (max. 1.5 mm) Bathyxylophila excelsa Marshall, 1988, found on sunken wood (800 m
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