Description of a new Late Cretaceous species ofBulimulusLeach, 1814 (Orthalicoidea: Bulimulidae) using geometric morphometric analysis

ABSTRACTIn the Late Cretaceous fossil record of Uruguay, three morphotypes of Bulimulus (Bulimulidae) have been recorded: Bulimulus klappenbachi and two undescribed ones. A geometric morphometric analysis was conducted to show whether the three morphotypes represent one or more species. With this aim, the three fossils were compared with three extant species of the same genus: Bulimulus bonariensis, B. guadalupensis and B. rushi. Variability within and among these three well-known extant species was tested to evaluate differences in the fossil morphotypes. Twenty-eight landmarks were selected (9 permanent landmarks and 19 semi-landmarks) and principal component analysis and canonical variate analysis were performed. Results indicate that only one of the unnamed morphotypes can be described as a new species and that the other is a variant of B. klappenbachi. The latter fossil species is described as Bulimulus frenguellii n. sp.

Capture of conspecific planktonic larvae by the suspension-feeding gastropod Crepipatella peruviana: association between adult and larval size

ABSTRACT Free-living, planktonic larvae can be vulnerable to capture and ingestion by adult suspension-feeders. This is particularly the case for larvae that settle gregariously in benthic environments where suspension-feeders occur at high densities. Larvae of gregarious suspension-feeding species are at particularly high risk, as adults of their own species often serve as cues for metamorphosis. We conducted laboratory experiments to assess the extent to which adults of the suspension-feeding caenogastropod Crepipatella peruviana would capture and ingest their own larvae. Experiments were conducted with adults of different sizes, with larvae of different ages and sizes, and in the presence or absence of phytoplankton. Adults captured larvae in all experiments. The presence of microalgae in the water did not influence the extent of larval capture. On average, 39% of larvae were captured during the 3-h feeding periods, regardless of adult size. However, up to 34% of the larvae that were captured on the gill were later discarded as pseudofaeces; the other 64% were ingested. The extent of capture by adults was not related to adult size, or to larval size and, thus, to larval age. Our results suggest that the filtration of congeneric larvae by adult C. peruviana is a result of accidental capture rather than a deliberate feeding preference. Such ingestion could, however, still be an important source of larval mortality, especially when the advanced larvae of this species are searching for a suitable substrate for metamorphosis.