Anatomical revision of Alopiinae (Gastropoda: Pulmonata: Clausiliidae)
Testing genital characters in clausiliid systematics
The systematics of Alopiinae clausilids is almost exclusively based upon shell features, even if some difference in the genital apparatus is known to partially define each genus. The whole picture is anyway far from being clear, despite of a huge amount of taxonomic literature. All of these papers, if not exclusively focusing on molecular phylogeny, give absolute priority to shell characteristics, considering the morphology of genitalia of little if none importance.
Alopiinae and clausiliids in general show great phenotypic plasticity of the dimensions and features of the shell.
In order to evaluate a possible research path, genital investigations are being performed to test if a taxonomically relevant situation could be detected. The anatomy of representatives of the genera Montenegrina, Delima, Alopia, Medora, Agathylla and Charpentieria s.l. will be investigated.
At genus level the general objective of this project comprises two questions:
1. Can genera (and subgenera) be delimited more precisely with anatomical characters?
2. Which characters are phylogenetically informative at higher taxonomic levels?
Until now, only summary and sometimes incorrect descriptions of the genital arrangements of the different Alopiinae genera are found in the literature. This situation is principally due to the superficial (if not wrong) approach to dissections and the approximate resulting iconography. Nevertheless, the most important factor is the extremely small number of individuals/taxa for every genus investigated until now. Only a large number of observations carried out on large numbers of species/individuals can provide a reliable general anatomical description for each genus.
Phylogenetic investigation aims to identify synapomorphies (vs. homoplasies) to reveal evolutionary relationships.
At species/subspecies level the general objective of the project addresses several questions and subtasks:
- Can species be delimited more precisely with the anatomical characters? If so, which section/structure of genital anatomy better delimits a taxon?
- Are genital characters more stable than shell characters?
- Are there characters that differ among population of one species?
- How do morphological and molecular data relate to each other?
- Re-description of the species by means of this new taxonomical approach.
Preliminary results revealed that every anatomical section can assume a set of different arrangements and thus, the taxa proved to be clearly distinguishable by virtue of the combination of the different sections. Sometimes taxa with remarkably different shells are considered as subspecies of the same species, whereas similar shells are considered as different species, e.g., based on only a small difference in the lenght or a slight change in the position of a single plica. The analysis of the genitalia will significantly increase the morphological traits that can be investigated, providing new insights in intraspecific variability, both regarding shell and genitalia.
A merger of the three taxonomic approaches − shell, genitalia and molecular genetic − will be attempted in order to create a complete integrative approach to the systematics of the Alopiinae.