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Vol. 51 No. 7, 2012
Phylogenetic Position of Vesicomyid Clams from a Methane Seep
off Central Chile (~36°S) with a Molecular Timescale for the
Diversification of the Vesicomyidae
Francisco Valdés1,*, Javier Sellanes1,2, and Guillermo D’Elía3
1Departamento de Biología Marina, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile
2Centro
de Investigación Oceanográfica en el Pacífico Sur-Oriental (COPAS),
Universidad de Concepción, Casilla 160-C, Concepción, Chile.
E-mail:sellanes@ucn.cl
3Instituto de Ciencias Ambientales y Evolutivas,
Universidad Austral de Chile, campus Isla Teja s/n, Valdivia,
Chile. E-mail:guille.delia@gmail.com
Francisco Valdés, Javier Sellanes, and Guillermo D’Elía (2012) Bivalves
of the family Vesicomyidae are conspicuous inhabitants of sulfide-rich
settings associated with both hydrothermal vents and methane
seeps. The taxonomy of the family has been the subject of recent
reviews, and currently, 2 subfamilies, the Vesicomyinae and
Pliocardiinae, are recognized. Although the family has a
worldwide distribution, material from the Southeast Pacific available
so far for study has been scarce. In the present study, we
consider 2 species from the Concepción Methane Seep Area (CMSA;
36°27.87'S, 73°43.25'W), Calyptogena gallardoi Sellanes and Krylova, 2005 and a larger species, which based in its morphology was tentatively assigned to the genus Archivesica (Archivesica sp. 1). We include new mitochondrial DNA sequences of the cytochrome c
oxidase subunit I (COI) gene of these species, together with previously
available sequences, in a phylogenetic analysis using maximum parsimony
and Bayesian inference. In addition, a relaxed molecular clock
was calibrated to estimate the divergence times of the lineages from
which these species originated. The topologies recovered
generally agree with a recent classificatory scheme of the
family. Calyptogena gallardoi falls within the clade of Calyptogena sensu stricto, corroborating the morphologically based generic assignation. Similarly, Archivesica
sp. 1, as expected from its morphology, falls within the clade
corresponding to the genus Archivesica. According to results of
the molecular clock, lineages leading to both CMSA species date back to
the Miocene: C. gallardoi to ca. 11.2 Mya and Archivesica
sp. 1 to ca. 6.18 Mya. Two independent vesicomyid invasions of
the southeastern Pacific Ocean are proposed to account for the
diversity seen at the CMSA. In general, the chronogram shows that
lineages of pliocardiine vesicomyds have accumulated at a regular pace
since the Eocene with no signs of diversification pulses.
Key words: Methane seep, Pacific Ocean Phylogenetic analysis, Central Chile.
*Correspondence: E-mail:fco.valds@gmail.com
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