World Congress of Malacology Antwerp ... - Unitas Malacologica

Cytogenetics of bivalves: a review with some comments on phylogeny
Martínez-Lage, Andrés; Francisco, Marta; Vierna, Joaquín; Da Rocha, Bibiana; Seoane,
David; González-Tizón, Ana
Departamento de Biología Celular y Molecular, Universidade da Coruña, A Zapateira s/n, E-15071
La Coruña, España,
Email: andres@udc.es; hakuna@udc.es
Bivalvia, the second largest class of molluscs, are scarcely investigated at chromosome level. Studies
have determined chromosome number for eight Protobranchia species, 111 Pteriomorphia, 28
Palaeoheterodonta, 62 Heterodonta and one Anomalodesmata. Analysis of chromosome morphology
and karyotype is even more limited, these numbers being 8, 91, 11, 41 and 1, respectively.
For chromosome number, Protobranchia species display diploid modal values of 22, 24 and 38
chromosomes. Subclass Pteriomorphia shows high variability, as chromosome number ranges from
2n = 12 (for some species of the genus Anomia), 2n = 20 (most frequent number in oyster species),
2n = 28 (for mussels) and 2n = 38 (for pectinids). Species included in the Palaeoheterodonta subclass
show, mainly, 2n = 38, except in the case of Mutela rostata, which displays 20 chromosomes.
Subclass Heterodonta exhibits a tendency to 2n = 38 (most Heterodonta present this chromosome
number); however, the only species showing polyploid chromosome numbers belong to this subclass
are included in genera Lasaea and Corbicula. Finally, chromosome number for subclass
Anomalodesmata species was only determined for Laternula elliptica, which shows a diploid number
of 40 chromosomes.
The aim of this work was to review the cytogenetic status of bivalve species to follow the karyotying
of this group of animals and to comment on their phylogeny based on chromosome data.
Revision of the taxonomy of the Ibero-Balearic populations of Tudorella (Caenogastropoda,
Pomatiidae) by molecular and morphological analyses
Martínez-Ortí, Alberto 1 ; Elejalde, Miren Arantzazu 2 ; Madeira, María José 2 ; Gómez-Moliner,
Benjamín 2
1. Museu Valencià d’Història Natural, Passeig de la Petxina 15, E-46008 Valencia, Spain,
Email: alberto.martinez@uv.es
2. Departamento de Zoología y Biología Celular Animal, Facultad de Farmacia, Universidad del País
Vasco, Paseo de la Universidad 7, E-01006 Vitoria, Álava, Spain,
Email: benjamin.gomez@ehu.es
We have realized molecular and morpho-anatomical studies of two Spanish populations from
Alicante and Granada provinces, both fossil and recent forms traditionally assigned in the Iberian
Peninsula to Tudorella sulcata sulcata. They have been compared with other populations from
Marseille (France) (Type locality), Sardinia and Sicily (Italy), Malta, NW Algeria and S Portugal, as
well as with T. ferruginea from Balearic Islands and T. mauretanica from NE Morocco.
DNA sequences of two mitochondrial genes, COI and 16S rRNA were used to know the phylogenetic
relationships, using Leonia mamillaris as outgroup. The individual and combined analyses of these
genes show three main genetically unique lineages which were considered as different species: T.
ferruginea, T. mauretanica and T. sulcata. The study of the shell size and shape, including
microsculpture of protoconch and teleoconch, together with anatomical studies of the reproductive
system allow us to characterize the morphology of the main phylogroups obtained. There is a great
congruence between morphology and phylogeny. Besides, the validity of the subspecies T. sulcata
melitense and T. s. sulcata is also evaluated on the basis of their genetic divergences and
morphology.
We conclude that both Spanish populations from Alicante and Granada provinces, should be
reassigned to T. mauretanica, that inhabits also in North Africa between Oran (Algeria) and NE
Morocco. After this study, we consider that Tudorella populations from SE France, Sardinia, Sicily,
Algeria and Portugal correspond to T. sulcata sulcata. Malta specimens are considered a valid
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