Endohelminths of Fishes from the Upper San Marcos River, Texas

Abstract

A total of 1837 fish representing 22 species were collected between September, 1978 and August, 1980 from the Upper San Marcos River, Hays County, Texas. Thirty-four species of endohelminth parasites were recovered from 1770 infected fish. Those endohelminths recovered represented 11 species of adult digenetic trematodes, 3 trematode metacercariae, 3 adult cestodes, 2 cestode plerocercoids, 6 adult nematodes, 5 larval nematodes, and 4 species of acanthocepha- lans. Strict host-species specificity was observed for only three species of endohelminths: Creptotrematina aguirrepequenoi, Lissorchis hypentelii, and Corallobothrium fimbriatum. Other endohelminth species infected as many as 12 host species with varying intensities. Mean intensity of infection ranged from 1.0 worm per infested host (Proterometra macrostoma in Ambloplites rupestris) to 101.9 worms per infected host for Caecincola latostoma in Micropterus salmoides. The Upper San Marcos River, Hays County, Texas is a clear, cool (yearly range 19.0-22.5°C) river which exhibits relatively constant physicochemical conditions and supports a diverse biota including several introduced plant and animal species (Longley, 1975). Previous studies on the helminth fauna of this river have been confined to trematode infections of gastropods (Lindholm and Huffman, 1979) and to the helminths of Gambusia spp. (Davis and Huffman, 1975; 1978) and Notropis spp. (Martin, 1976). The present study is a survey of endohelminths from other fish species in this river.