Abstract
We describe Catadiscus marielaosornae Cajiao-Mora and Bullard n. sp. (Diplodiscidae) from the intestine of Peters' thin-toed frog, Leptodactylus petersii (Steindachner) (Anura: Leptodactylidae) from the Yahuarcaca Lake System, Colombia. We assigned our specimens to Catadiscus Cohn, 1904 because they have a smooth-surfaced, pyriform body, centrally-constricted ventro-terminal acetabulum that lacks an accessory sucker, pharynx with extramural sacs, oesophageal bulb, and single testis. The new species differs from all but Catadiscus rodriguezi Caballero, 1955, Catadiscus marinholutzi Freitas and Lent, 1939, and Catadiscus propinquus Freitas and Dobbin, 1956 by having a vitellarium that is confluent anteriorly (vs. two non-confluent fields). It differs from the aforenamed congeners by having a ventral common genital pore that opens anterodextral to the oesophageal bifurcation, round vitelline follicles that become confluent anterior to the testis, and a 1: 2-3 ratio of acetabulum: testis width. Our 28S phylogenetic analysis recovered the new species sister to C. marinholutzi, and Diplodiscidae as paraphyletic, with Catadiscus sister to a clade comprising a sequence ascribed to Chiorchis fabaceus (Diesing, 1838) Fischoeder, 1901 (Cladorchiidae), and sequences of three species of Diplodiscus Diesing, 1836. The species description herein includes several features pertaining to the acetabulum, female genitalia, and excretory system that could comprise useful character states with which to more readily classify and diagnose diplodiscid species and genera. To our knowledge, this is the first record of a digenean infecting Peters' thin-toed frog, and it is also the first record of any parasite infecting any ditch frog (Leptodactylus spp.) from Colombia.