André KEBOLO BAKU NA NGONDA
Graduate of Advanced Studies in Biology

Thesis presented and defended with a view to obtaining the degree of Doctor of Science
Group: Biology

Thesis Supervisor : Professor PA LATA KABUDI
Co-Promoter : Professor PUNGA KUMANENGE

Summary

The overall objective of this study relates to the morphology associated with molecular phylogeny, ecology and distribution of giant snail ecotypes in Central Africa (Democratic Republic of Congo and Republic of Congo). Snail samples collected in four western provinces of the Democratic Republic of Congo and in 1 site in the south-east of the Republic of Congo were subjected to morphological analyses (shell identification and biometry), examination of genitalia and molecular analyses (mitochondrial DNA cytochrome oxidase gene sequencing). Six species of the genus Achatina and 1 species of the genus Archachatina,
represented by 2 subspecies, belonging to the Achatinidae family, were identified. Achatina weynsi is the only species that presented 6 different forms (ecotypes). On the other hand, the species Achatina bandeirana is distributed in three of the four provinces of the ROC. Analysis of the genitals revealed the presence of the penis sheath in species of the genus Archachatina, while this organ was completely absent (agenesis) in species of the genus Achatina. This distinctive, unprecedented character allowed the determination of the species, and confirms the morphological variability between the genera Achatina and Archachatina. The relationships between the measured variables revealed a correlation between the length, width and weight of the snails. The genetic profile of the snails was determined for the first time in Congolese snail species. It shows genetic variability for samples from Bandundu province, and homogeneity for those from the provinces of Bas-Congo, Equateur, Kinshasa (ROC) and M'Bamou Island (RC). This genetic variability corroborates morphological analyses. Furthermore, the consistency of the number of eggs (3 eggs per clutch) produced in captivity by Archachaiina matginata ovum, is unprecedented, and suggests the modification of the status of this subspecies. It was therefore important to support morphological analyses by examining the genitals and molecular analyses for reliable taxonomic identification. In addition, it is necessary to continue investigations for a better understanding of the diversity and distribution of snails in the DRC.

Keywords: Morphology, Anatomy, Phylogeny, Taxonomy, Polymorphism.