Taxonomic studies and seasonal variations in density of fresh water leech erpobdella bhatiai (nesemann, 2007) inhabiting torrential hill stream in greater Himalayas

Present study encompasses the taxonomic characteristics of a freshwater predatory leech, Erpobdella bhatiai and variations in its population density in relation to various physico-chemical attributes of habitat. A comparison of its morpho-taxonomic characters with other congeneric species has been done. A detailed and close examination of about 30–35 adult specimens revealed that absence of proboscis, presence of long V-shaped myognaths, multiple testis sacs per somite, and absence of post caeca, accessory male and female pores are genus characters. The length and shape of atrium, atrial horns, 2.5 annuli between gonopores and three post anal annuli are species characters for identification. Highest density value was found in winter (21.6) and lowest in summer (3.3). A strong negative correlation of density with temperature, FCO₂ and positive correlation with chloride ions indicated this species to be tolerant to low temperature and good indicator of chlorides.