Anatomy and systematic affinity ofStanleya neritinoides(Smith, 1880), an enigmatic member of the thalassoid gastropod species flock in Lake Tanganyika, East Africa (Cerithioidea, Paludomidae)

Abstract

AbstractThe radiation of gastropods in Lake Tanganyika is an ideal system for testing competing hypotheses of species flock formation. Yet, much of the basic biology of these species remains unknown. In an ongoing effort to understand the evolution of Tanganyikan gastropods, we here describeStanleya neritinoides. Alcohol‐preserved material of the soft parts is rare, consequently, the systematic position of the species, and a repeated suggested affinity toTanganyicia rufofilosa, have been based primarily on features of the shell. However, features of the radula and operculum are unique and do not suggest an affinity to any other Tanganyikan species. Thus,S. neritinoideshas remained a particularly poorly known and enigmatic member of the species flock. This investigation confirmed that several aspects of internal and external anatomy are shared betweenS. neritinoides,T. rufofilosa, and other Tanganyikan gastropods, but thatS. neritinoidesis unique in features of the radula and seminal receptacle. Moreover,S. neritinoidesdiffers fromT. rufofilosain features of the foregut, midgut, hindgut, kidney, nervous system, reproductive system and reproductive strategy. These new data are inconsistent with an interpretation of identity ofStanleyaandTanganyicia.In addition, given the pervasive differences between the two, a sister‐group relationship between the two is unlikely. More precise systematic placement ofS. neritinoidesawaits the establishment of a phylogenetic framework for all Tanganyikan gastropods.