The genus filopaludina (prosobranchia : Gastropoda) of Thailand : morphology, anatomy, allozymes and systematic relationships

• Main Author: Pairat Tarbsripair
• Other Authors: Suchart Upatham
• Language: English
• Published: Mahidol University. Mahidol University Library and Knowledge Center 2023
• Subjects: Electrophoresis; Enzymes > Analysis; Filopaludina > Classification
• Online Access: https://repository.li.mahidol.ac.th/handle/123456789/88428
• Institution: Mahidol University

Filopaludina, the edible freshwater gastropods, which serve as intermediate hosts for human echinostomiasis, were collected from twenty provinces throughout Thailand, in order to study their comparative morphology, anatomy, and biochemistry. Conchological study revealed that the shell size is medium (10-30 mm) to large (> 30 mm), dextral shell with a corneous operculum. The shell is sub-globose, ovate-conic and sculptured with spiral, transverse lines, and color bands on the surface. Seven variables of shell measurements were used to discriminate the group of viviparid snails. The results from discriminant analysis showing the effective variables with order by size of correlation within function were degree of angle spire, shell width/shell height, body whorl height/shell height, aperture height/shell height, body whorl width/body whorl height, aperture width/shell width, and aperture width/aperture height. Multivariate cluster analysis of the seven variables did not sort the 30 taxonomic samples into two groups associated with Brandts sub-genera The multiple samples of each taxon cluster close to one another suggesting there are species or subspecies-specific differences in mean size and shape and that inter-taxon variation is greater than intra-taxon variation The overall similarity of these shells dose not, however, permit unambiguous assignment of an individual shell to a specific taxon. The basic plan of gross comparative anatomy features in pallial organs, digestive and reproductive systems revealed no significant differences between these organ systems in all populations. Female is ovoviviparous; male with the right tentacle transformed into a male copulatory organ. Biochemical study was performed using the technique of horizontal starch gel electrophoresis. Eleven enzymes used to detect genetic variations were aspartate aminotransferase, esterase, isocitrate dehydrogenase, leucine aminopeptidase, malate dehydrogenase, peptidase (A and B), phosphoglucomutase, 6-phosphogluconate dehydrogenase, xanthine dehydrogenase, and xanthine oxidase Based on the data obtained for 20 allozyme loci, the allele frequencies were determined. The genetic diversity and genetic differences were estimated from allele frequency. The genetic diversity: the mean heterozygosities, mean allele numbers per locus, and the percentage of loci polymorphic were 0.111, 1.25, and 25, respectively. According to the Neis genetic distances, indices of the pairwise comparison between two populations in this study ranged from 0.136 to 0.655. The genetic distances among 30 populations, by grouping according to species and sub-species, were generally extremely high over a large range of snails, while similarities between congeneric species were much lower. The genetic distance of the pairwise comparison between two sub-genera, Filopaludina and Siamopaludina, ranged from 0.180 to 0.374, indicating overlap between the intra-subgeneric and inter-subgeneric distances. The two sub genera should therefore be grouped into one genus Filopaludina. Based on genetical criteria, coupled with morphological characters, it is concluded that a major taxonomic revision of the Filopaludina is now required. Although their reproductive systems are similar, the genus Filopaludina systematic revision should be recognized as 10 species, as follows: Filopaludina doliaris, F. filosa, F. peninsularis, F. polygramma, F. speciosa, F. maekoki, F. continentalis, F. cambodijensis, F. martensi, and F. munensis.