World Congress of Malacology Antwerp ... - Unitas Malacologica

on the first postlarval growth step; they are fully developed from the 3rd or 4th step onward. Pits
become more numerous and occur in radial rows. Reticulation and pits have been previously
described from the periostracum in some recent astartids. Our results now suggest that this ornament
is a property of the underlying shell rather than of the periostracum itself. The pits do apparently not
reflect the sites of periostracal spikes, but short thread-like radial ridges sometimes occur very close
to them. Low energy forms like N. (Trautscholdia) phillis possess a finer reticulation than high
energy forms such as N. (Nicaniella) morini. A similar pattern is observed for species of P.
(Pressastarte) (fine) and P. (Pinguiastarte) (coarse).
Early juvenile right valves of N. (Trautscholdia) and P. (Pressastarte) provide evidence that cardinal
teeth 3a and 3b are indeed connected (so far only assumed). Hinge teeth are stronger and earlier
developed in Nicaniella than in Pressastarte, and the angle between 3a and 3b is significantly larger
(97° vs. 78°). 5b is only present in juvenile Nicaniella. In summary, larval dimensions, microornament
and angles between cardinal teeth provide significant information on larval strategy and
taxonomy, and micro-ornaments appear to be facies dependent.
Sphaerium corneum, Sphaerium nucleus (Bivalvia: Sphaeriidae) and difficulties with
determination and taxonomy of Sphaeriidae
Kořínková, Tereza 1 ; Juřičková, Lucie 1 ; Petrusek, Adam 2
1. Department of Zoology, Charles University, Viničná 7, 128 00 Praha 2, Czech
Republic,
Email: korinko1@natur.cuni.cz
2. Department of Ecology, Charles University, Viničná 7, 128 00 Praha 2, Czech
Republic
The diversity and taxonomical relationships in the family Sphaeriidae are still not completely
understood. There are several groups of hardly distinguishable sibling taxa, the rank of which is a
subject to discuss.
We focused on anatomy, shell morphology, ecology, karyotypes and sequences of selected genes to
compare populations of Sphaerium corneum and S. nucleus from the Czech Republic and Central
Europe. The taxa proved to be good and distinct species, whether the biological or ecological species
concept was adopted. However, none of the traditional anatomical and morphological characters
alone is absolutely reliable for determination. S. corneum and S. nucleus have very similar karyotypes
and differ from the most species of the family in the ploidy - they are probably diploid, whereas
allopolyploidy is otherwise very common in the genus Sphaerium and Pisidium. No evidence for the
occurrence and distinctness of the obscure “S. ovale“ has been found so far. The analogy with other
species complexes (e.g. Pisidium casertanum/globulare) and possible taxonomical and faunistic
consequences are also discussed.
The anatomy and relationships of Troschelia (Buccinidae, Neogastropoda):
evidence of polyphyly for the Buccinidae?
Kosyan, Alisa 1 ; Modica, Maria Vittoria 2 ; Oliverio, Marco 2
1. A. N. Severtsov Institute of Ecology and Evolution. Russian Academy of Sciences, Leninsky
prospect 33, 119071 Moscow, Russia,
Email: kosalisa@rambler.ru
2. Dipartimento di Biologia Animale e dell’Uomo, “La Sapienza” Rome University, Viale
dell’Università 32, I-00185 Roma, Italy,
Email: mariavittoria.modica@uniroma1.it; marco.oliverio@uniroma1.it
Phylogenetic relationships among the 200+ genera and subgenera included in the gastropod family
Buccinidae remain quite ambiguous. The northeastern Atlantic monotypic genus Troschelia Mörch,
1876, has been classified by a number of authors (e.g., G.O. Sars, J. Thiele, A. Graham) in the family
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