World Congress of Malacology Antwerp ... - Unitas Malacologica

authors disagree about the classification of the taxa included inside these subfamilies mostly because
its taxonomy is based on shell morphology and the anatomy of the reproductive system, both aspects
subjected to very different interpretations resulting in conflicting taxonomic systems. In this work we
present the first comprehensive molecular phylogeny of the group based on DNA sequenciation of
two mitochondrial (16S rDNA, COI) and one nuclear (ITS-I) loci. The work has been carried out on
42 specimens of the following genera: Helicodonta, Atenia, Trissexodon, Caracollina, Oestophora,
Hatumia, Mastigophallus, Oestophorella, Gasullia, Suboestophora, Gasulliella and Gittenbergeria.
The new sequences have been compared with those previously published by other auhtors for several
Helicoidean taxa (Steinke et al., 2004; Manganelli et al., 2005), including Lindholmiola.
Phylogenetic relationships were inferred using maximum parsimony, neighbour joining, maximum
likelihood and Bayesian methods. The reconstructed phylogenies showed high values of support for
more recent branches and confirmed the monophyletic status of all the genera of the two subfamilies
here considered.
This work has been financed by the Basque Country University (Projects: 1/UPV 0076.125-E-
15911/2004 and GIU06/09), by the Regional Ministry of the Environment, Junta of Andalusia
(“Program for conservation and sustainable snail exploitation in Andalusia) and by the Ministerio de
Educación y Ciencia (Project CGL2005-01966).
New evidence for old names: On the systematics of Neotropical freshwater gastropods
(Caenogastropoda: Cerithioidea: Pachychilidae, Thiaridae)
Gomez, Maria 1 ; von Rintelen, Thomas 1 ; Glaubrecht, Matthias 1 ; Strong, Ellen E. 2 ; Köhler,
Frank 1
1. Museum of Natural History, Humboldt University Berlin, Invalidenstrasse 43,
10115 Berlin, Germany,
Email: maria.lopez@museum.hu-berlin.de
2. Smithsonian Institution, National Museum of Natural History, Department of
Invertebrate Zoology, P.O. Box 37012, MRC 163, Washington DC, 20013-7012,
Email: StrongE@si.edu
Understanding of the phylogenetic relationships of Central and South American freshwater
cerithioidean gastropods is incomplete. Hence, current classifications mainly reflect taxonomic
concepts of the late 19th century and are in urgent need of revision. We here present new molecular
and morphological data that provide novel insights into the relationships of several Neotropical
cerithioidean species. The results demonstrate the inadequacy of earlier classifications and will form
the basis for a revised systematization. Accordingly, the once so-called ‘melanians’ can be affiliated
with either one of two distinct lineages: the Pachychilidae and the Thiaridae. Each family comprises
at least two Neotropical genera which possess distinctive characteristics of the operculum, radula and
stomach that can be used as diagnostic criteria to revise the placement of already established genera.
However, the precise limits and taxonomic status of several supraspecific taxa such as Hemisinus,
Aylacostoma, and Cubaedomus within the Thiaridae and Pachychilus and Doryssa within the
Pachychilidae remain to be clarified.
Pachychilid taxa were variously allocated to other cerithioidean families such as Thiaridae or
Pleuroceridae. However, Pachychilus occurring from Mexico to northern South America and
Doryssa replacing the former in Guyana and Brazil, together with a number of African, Malagasy
and Asian taxa form a distinct monophyletic group separate from other cerithioidean freshwater
lineages. In contrast, two other Neotropical freshwater gastropods, Hemisinus and Aylacostoma,
possess morphological features typical for the Thiaridae (e.g. radula, mantle papillae). In particular,
the viviparous Hemisinus exhibits characteristics consistent with a basal position within the family,
including a glandular oviduct with a spermatophore bursa in the lateral lamina, a midgut with a
crescentic ridge that does not enter the caecum, and numerous statoconia. Implications of these
results for the evolution and biogeography of Neotropical freshwater Cerithioidea will be discussed.
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