Marrying molecules and morphology: first steps towards a reevaluation of solariellid genera (Gastropoda: Trochoidea) in the light of molecular phylogenetic studies

Abstract

ABSTRACT The assignment of species to the vetigastropod genus Solariella Wood, 1842, and therefore the family Solariellidae Powell, 1951, is complicated by the fact that the type species (Solariella maculata Wood, 1842) is a fossil described from the Upper Pliocene. Assignment of species to genera has proved difficult in the past, and the type genus has sometimes acted as a ‘wastebasket’ for species that cannot easily be referred to another genus. In the light of a new systematic framework provided by two recent publications presenting the first molecular phylogenetic data for the group, we reassess the shell characters that are most useful for delimiting genera. Shell characters were previously thought to be of limited taxonomic value above the species level, but this is far from the case. Although overall shell shape is not a reliable character, our work shows that shell characters, along with radular and anatomical characters, are useful for assigning species to genera. Sculpture of the early teleoconch (the region immediately following the protoconch) and the columella are particularly useful characters that have not been used regularly in the past to distinguish genera. However, even with the combination of all morphological characters used in this study (shell, radular and eye), a few species are still difficult to assign to genera and in such cases molecular systematic data are essential. In the present study, we discuss 13 genera—12 of which were recovered as well-supported clades in recent molecular systematic studies—and provide morphological characters to distinguish them. We describe several new taxa: Chonospeira n. gen. (referred to as ‘clade B’ in previous molecular systematic studies), Phragmomphalina n. gen. (Bathymophila in part in molecular systematic studies) and Phragmomphalina vilvensi n. sp. (type species of Phragmomphalina n. gen.). We synonymize Hazuregyra Shikama, 1962 with Minolia A. Adams, 1860, Minolia subangulata Kuroda & Habe, 1952 with Minolia punctata A. Adams, 1860 and M. gemmulata Kuroda & Habe, 1971 with M. shimajiriensis (MacNeil, 1960). We also present the following new combinations: Bathymophila bairdii (Dall, 1889), B. dawsoni (Marshall, 1979), B. regalis (Marshall, 1999), B. wanganellica (Marshall, 1999), B. ziczac (Kuroda & Habe in Kuroda, Habe & Oyama, 1971), Chonospeira nuda (Dall, 1896), C. iridescens (Habe, 1961), C. ostreion (Vilvens, 2009), C. strobilos (Vilvens, 2009), Elaphriella corona (Lee & Wu, 2001), E. diplax (Marshall, 1999), E. meridiana (Marshall, 1999), E. olivaceostrigata (Schepman, 1908), E. opalina (Shikama & Hayashi, 1977), Ilanga norfolkensis (Marshall, 1999), I. ptykte (Vilvens, 2009), I. zaccaloides (Vilvens, 2009), Minolia shimajiriensis (MacNeil, 1960), M. watanabei (Shikama, 1962), Phragmomphalina alabida (Marshall, 1979), P. diadema (Marshall, 1999), P. tenuiseptum (Marshall, 1999), Spectamen euteium (Vilvens, 2009), S. basilicum (Marshall, 1999), S. exiguum (Marshall, 1999) and S. flavidum (Marshall, 1999).