RESUMO
Morphological and chromosomal characteristics of a number of unionid freshwater mussels were studied from northeastern Thailand. Karyotypes of eight species from seven genera (Chamberlainia, Ensidens, Hyriopsis, Physunio, Pseudodon, Scabies and Trapezoideus) were examined. Six species possess 2n = 38 karyotypes, whereas Scabiescrispata and an unidentified Scabies sp. lack three small chromosome pairs, giving a diploid number of 32. Moreover, the karyotypes of the unidentified Scabies differ from Scabiescrispata as it exhibits a telocentric chromosome pair (6m + 7sm + 2st + 1t). Most of the conchological characters also differ between the two species - adult size, colour pattern, muscle scars, pseudocardinal and lateral teeth. The name Scabiessongkramensis sp. n. is proposed for the unidentified species, and its description is included in this paper. Interestingly, seven species contain mostly bi-armed chromosomes, but only the mud-dweller in stagnant water, Ensidensingallsianus, contains predominantly five telocentric pairs. In addition, the marker chromosome characteristics of an unbalanced long arm, twisted centromere, a wider angle 180° arrangement, a twisted arm and telomeric end union reported in this study are described for the first time for unionid mussels.
RESUMO
In total, 435 specimens of the Southeast Asian freshwater leech species within the Hirudinidae family were collected from 17 locations of various types of aquatic habitats in northeastern Thailand. They were all morphologically placed within the genus Hirudinaria Whitman, 1886 and there were three distinct species: the common Hirudinariamanillensis, 78.2% of all collected specimens and at all 17 locations, Hirudinariajavanica at 20.3% of collected samples and from five locations and a rarer unidentified morphospecies (Hirudinaria sp.) with six samples from only two locations. The karyotypes of these three species were examined across their range in this study area for 38, 11 and 6 adult specimens of Hirudinariamanillensis, Hirudinariajavanica and Hirudinaria sp., respectively. This revealed different chromosome numbers among all three species, with Hirudinariajavanica having n = 13, 2n = 26, Hirudinariamanillensis lacked one small chromosome pair with n = 12, 2n = 24, and the unknown Hirudinaria sp. differed from any known Hirudinaria karyotypes in exhibiting a higher chromosome number (n = 14, 2n = 28) and a gradual change in size from large to small chromosomes. This suggests that the unknown Hirudinaria sp. is a new biological species. However, phylogenetic analysis based upon a 658 bp fragment of the cytochrome oxidase subunit I gene placed this unknown morphospecies within the Hirudinariamanillensis clade, perhaps then suggesting a recent sympatric speciation, although this requires further confirmation. Regardless, the chromosomes of all three species were asymmetric, most with telocentric elements. A distinct bi-armed chromosome marker was present on the first chromosome pair in Hirudinariajavanica, whilst it was on pairs 1, 2, 3 and 5 in Hirudinariamanillensis, and on pairs 3 and 5 for the unknown Hirudinaria sp.
RESUMO
The status of species currently assigned to the Southeast Asian Elephant Pupinid snail genus Pollicaria Gould, 1856 is reassessed. Shell, radular and reproductive morphology are investigated and analysed with reference to karyotype patterns previously reported and to distribution patterns among the species. Six previously described species are recognised: Pollicaria gravida (Benson, 1856), Pollicaria myersii (Haines, 1855), Pollicaria mouhoti (Pfeiffer, 1862), Pollicaria elephas (Morgan, 1885), Pollicaria crossei (Dautzenberg & d'Hamonville, 1887) and Pollicaria rochebruni (Mabille, 1887). A new subspecies, Pollicaria mouhoti monochroma ssp. n.,is proposed and a dichotomous key to species is provided.
