Association of Leeches with the Endangered Houston Toad

Lawrence G. Bassett^1,*, Ferris E. Zughaiyir¹, Dennis J. Richardson², Charlotte I. Hammond², Chris T. McAllister³, and Michael R.J. Forstner¹

¹Department of Biology, Texas State University, San Marcos, TX 78666. ²Department of Biological Sciences, Quinnipiac University, Hamden, CT 06518. ³Science and Mathematics Division, Eastern Oklahoma State College, Idabel, OK 74745. *Corresponding author.

Southeastern Naturalist, Volume 21, Issue 1 (2022): 51–62

Abstract
The prevalence of leech attachment on anuran taxa is largely uncharacterized. When parasitic, such relationships may regulate amphibian populations and function as an obstacle to the recovery of imperiled species. We evaluated the prevalence of leech attachment in a population of endangered Bufo (= Anaxyrus) houstonensis (Houston Toad) in Bastrop County, TX, during the spring of 2021. Of 191 toads examined, 2 (1%) were each infested with a single leech. Molecular analysis of the cytochrome c oxidase subunit I gene identified 1 of those leeches as Helobdella austinensis. This constitutes the first reported association of H. austinensis with a vertebrate host and extends the known range of H. austinensis ~50 km eastward. Leech attachment in this Houston Toad population is rare and the nature of the association remains unclear.

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