Review of the Middle Pleistocene molluscan association from La Mancha de la Laja, Tenerife, Spain, with the description of two new species of Napaeus Albers, 1850 (Gastropoda: Enidae)

Abstract

We studied a Middle Pleistocene molluscan association from northern Tenerife. It was composed of 14 species, all found in the TL-1 and TL-2 stratigraphic beds of the middle Pleistocene Unit I. The families present were Helicidae, Enidae with two new species, Pomatiidae, Canariellidae, Vitrinidae and Geomitridae. For the Geometric Morphometrics (GM) analysis, a total of 58 pictures from three localities were analysed, comparing the morphological similarities between Napaeus guanche sp. nov., and some closely related extant species, Pomatias laevigatus and extant and fossil Hemicycla eurythyra based on shell shape. According to the PCA, Napaeus accounted for 77.53% of the variation of the shell shape within the first two components, Hemicycla accounted for 62.62% and Pomatias accounted for 52.79%. The permutational ANOVA showed to be a useful analysis to discriminate between groups, presenting non-significance for Napaeus, and significance for Hemicycla and Pomatias depicting high similarity. Despite this, the dispersion analysis showed a relatively high dispersion of the dataset for Napaeus and Pomatias, related to sample size, while for Hemicycla, the result was significant and congruent with permutational ANOVA. We describe two new species, Napaeus lipauges and Napaeus guanche increasing the known diversity of the genus Napaeus in the Canary Islands.