Placobdella cryptobranchii is a rarely collected leech of the Ozark hellbender (Cryptobranchus alleganiensis bishopi) in northern Arkansas and southern Missouri, U.S.A. Between October 2002 and August 2005, 58 hellbenders were examined from Eleven Point River (Randolph Co., Arkansas and Oregon Co., Missouri), the north fork of the White River (Ozark Co., Missouri), and the Spring River (Fulton Co., Arkansas). Forty-one of the 58 hellbenders (70.7%) were infested with 1-140 leeches with a mean intensity (+/- SD) of 8.7 (+/- 22.1) and a relative abundance (+/- SD) of 6.3 (+/- 18.9). Contingency table analysis and t-tests revealed no significant differences in prevalence and mean intensity among various years and localities sampled. Leech size did not substantially change over the time period sampled. The dorsal pigmentation of live specimens of P. cryptobranchii is described for the first time.

Twenty-one lotic and lentic environments throughout central and northern Arkansas were surveyed for the presence of leeches during June 2004 and April, July - October 2005. Fourteen species of leeches (Helobdella elongata, Helobdella papillata, Helobdella stagnalis, Placobdella cryptobranchii, Placobdella multilineata, Placobdella ornata, Placobdella papillifera, Placobdella parasitica, Placobdella phalera, Placobdella picta, Haemopis marmorata, Erpobdella fervida, Erpobdella microstoma, and Erpobdella punctata) representing 3 families were collected. Five species (H. elongata, P. cryptobranchii, P. multilineata, H. marmorata, and E. fervida) are reported from Arkansas for the first time. The natural history of the 22 species of leeches now known from Arkansas is reviewed.