Taxonomy and karyotypes of freshwater leeches subfamily Hirudinae in the Northeastern Thailand

Abstract

Taxonomy of freshwater leeches in subfamily Hirudinae from northeastern Thailand was investigated. In total, 435 specimens were collected from 17 localities during April 2012 to February 2014. Three morpholcgical distinct species were classified: (i) the common Hirudinaria manillensis (Lesson, 1842) is the majority found 78.2% from 17 locations, (ii) 20.3% for Hirudinaria javanica (Wahlberg, 1856) from five locations, and (iii) only six samples (1.5%) for an unidentified morphospecies, Hirudinaria sp., from two locations. Three species show distinct diagnostic characters as follows: H. javanica, gonopore separated by seven annuli, 4-5 dorsal sensillae on caudal sucker per radius, atrium short and small, and vaginal ceacum short and ovate; H. manillensis, gonopore separated by five annuli, dorsal sensillae on caudal sucker with 4-5 sensillae per radius, atrium large and relatively elongated, vaginal caecum relatively long and ovate; and Hirudinaria sp., gonoperes separated by five annuli, dorsal sensillae on caudal sucker with two sensillae per radius, atrium moderate and somewhat elongated, and vaginal caecum long and elongated. The karyotypes of three species were also examined. The haploid chromosome numbers were confirmed of 12 (2n=24) for H. manillensis, 13 (2n=26) for H. javanica, and 14 (2n=28) for Hirudinaria sp. The different chromosome number suggested the unknown Hirudinaria sp. is a distinct biological species. Karyotypes of all species were asymmetric with mostly telocentric and difference bi-armed chromosomes in each species. The bi-armed chromosomes were found on the first pair in H. javanica, on pairs 1, 2, 3, and 5 in H. manillensis, and on pairs 3 and 5 in Hirudinaria sp.