Dactylogyrids from North American Cyprinids of the Genus Nocomis. The Bellicus Group

Abstract

A second dactylogyrid (Monogenea) morphologically similar group, the bellicus, parasitizing the North American cyprinid fish genus Nocomis is reported. Eight new species are described: Dactylogyrus ancylostylus from N. leptocephalus interocularis; D. asper from N. asper; D. aviunguis and D. latirictus from N. biguttatus; D. leptostylus from N. 1. leptocephalus and N. 1. interocularis; D. megastylus from N. 1. leptocephalus; D. millieae from N. effusus; and D. mississippiensis from N. 1. bellicus. Geographic distribution and phylogeny of the parasites are discussed. A study of 6,051 dactylogyrid parasites taken from 2,176 cyprinid fish of the genus Nocomis showed that these parasites could be grouped into five distinctly morphological groups. The first group, reciprocus, was discussed previously (Chien, 1971). The present study discusses the bellicus group, including Dactylogyrus bellicus (sic D. bellicae) Rogers and Mizelle, 1966, and eight new species. A total of 1,541 host fish were examined and 2,024 parasites were mounted for systematic analyses. Host species are those discussed by Lachner and Jenkins (1967, 1971a, b) and Lachner and Wiley (1971). Methods are those used by Chien (1971). Measurements are in microns. The average is followed by the range in parentheses. Hosts were collected from museums in many cases and the following codes used: USNM-United States National Museum, TU-Tulane University Ichthyological Collection, BM(NH)-British Museum (Natural History), R.-River, dr.-drainage, sys.-system. Numerals following the drainage designation denote the number of localities where fish were collected. DESCRIPTIONS OF DACTYLOGYRUS Diagnosis for the bellicus group Terminal cephalic lobes confluent with lateral at base. Eyespots subequal. Peduncle absent or indistinct. Cirrus curved and tapered; accessory piece main fork with or without lateral process. Received for publication 7 March 1974. * Supported by the Southeastern Cooperative Fish Disease Project, Rockefeller Foundation RF 65061, and Alabama Cooperative Fishery Unit, Auburn University. t Present address: NUS Corporation, C. W. Rice Division, Manor Oak 2, 1910 Cochran Road, Pittsburgh, Pennsylvania 15220. Haptor broadly rounded or bell-shaped. Ventral bar much smaller than dorsal. Anchor superficial root more than 3 times as long as deep root; shaft constricted in midlength, inflated distally, length subequal to point. Anchor wings arise, insert at proximal half of shaft but loop at distal half. Hooks (except 4A much smaller) different from reciprocus group, with small base and slender shaft; those close to median region of haptor smaller than those on margin. Dactylogyrus ancylostylus sp. n.