Trainee: André Sartori, Universidade de São Paulo (Brazil) and University of Cambridge (U. K.), and Cheewarat Printrakoon, Mahidol University (Bangkok), Thai Bivalve Workshop Trainees, 2005.

Despite their remarkable ecological and economic importance, there is a surprising scarcity of anatomical data on species of Veneridae, with only about 50 species having at least some detailed information published on soft-part morphology. In an extensive morphology- and multiple gene-based phylogeny of the superfamily Veneroidea by the PIs and PEET participants, morphological characters were highly homoplastic and few in number, illustrating the general anatomical uniformity of the family and providing an explanation for its historically controversial taxonomy. The siphons, which play important functional roles in nutrition, reproduction, and defense proved particularly challenging to study and interpret in preserved specimens due to varying degrees of contraction upon fixation. During the 2005 Second International Marine Bivalve Workshop, an opportunity was taken to compare the siphonal morphology in living specimens of 15 venerid species, belonging to seven nominal subfamilies. Examination revealed that only the innermost mantle folds are involved in forming venerid siphons (Yonge’s Type A fusion), contrary to most published opinions that also include the second innermost fold (Yonge’s Type B). When mapped on a previously published recent phylogeny, no phylogenetic patterns emerge, suggesting that siphonal characters are highly homoplastic.

Publications: Sartori, A. F., C. Printrakoon, P. M. Mikkelsen, and R. Bieler. In press. Siphonal structure in the Veneridae (Bivalvia: Heterodonta) with an assessment of its phylogenetic application and a review of venerids of the Gulf of Thailand. In: Molluscs of Eastern Thailand: Proceedings of the International Marine Bivalve Workshop, Chanthaburi, Thailand, August-September 2005, with contributions on other molluscan groups, Rüdiger Bieler, Kashane Chalermwat, Paula M. Mikkelsen, Tan Koh Siang and Fred E. Wells, eds. Raffles Bulletin of Zoology.