Studies on Monogenetic Trematodes. XXXIII. New Species of Gyrodactylus and a Key to the North American Species

Abstract

Five new species of Gyrodactylus are described: G. colemanensis from Salmo gairdneri Richardson, Coleman National Fish Hatchery, Anderson (Shasto Co.) and Navarro River (Mendocino Co.); G. crysoleucas from Notemigonus crysoleucas (Mitchill), Rooney Pond, 17 miles east of Sacramento (Sacramento Co.) (all) California; G. lacustris from Pimephales promelas Rafinesque, Cottonwood Lake, two miles north of Butte (McHenry Co.), North Dakota; G. perforatus from Clevelandia ios (Jordan & Gilbert), Bodega Lagoon (Sonoma Co.); and G. variabilis from Notemigonus crysoleucas, Rooney Pond, 17 miles east of Sacramento (Sacramento Co.) (both) California. Gyrodactylus hoffmani Wellborn & Rogers, 1967, is recorded from Pimephales promelas, Cottonwood Lake, two miles north of Butte (McHenry Co.), North Dakota. Parasite-host and host-parasite lists, and a key to the North American species of Gyrodactylus are provided. Treatment of fish hosts and methods concerning preparation, observation, measurement, illustration, and description including nomenclature and development of species described herein, were employed as given by Mizelle & Kritsky (1967) and Kritsky & Mizelle (in press). A recent emended diagnosis of Gyrodactylus by these authors (1967) facilitates much shorter descriptions of species in this genus. In each of the following described species (1) a single spicule is present in each cephalic lobe, (2) the rami of the superficial bar are secured under the anchor folds, and (3) the ends of the deep bar insert within the anchor knobs. All primary embryos were oriented as an inverted U. The width of the pharynx is the maximum for this organ. The filamentous hooklet loop is abbreviated FH loop; all measurements are given in microns. Paratypes are in the authors' collections. Gyrodactylus colemanensis n. sp. Figures 1-6 This species is described on the basis of 16 specimens (Holotype, USNM Helm. Coll. 61691) from the steelhead (skin), Salmo gairdneri Richardson, Coleman National Fish Hatchery, Anderson (Shasta Co.) (type locality); and Navarro River, (Mendocino Co.) (both), California. Vitellaria-like spherules infrequently present from cephalic area to haptor. Length 457 (400-552), width 110 (90-121). Cephalic lobes of moderate size. Pharyngeal bulbs subovate, subequal, width 47 (39-52); intestinal crura infrequently with mesial diverticula. Peduncle moderate to broad; haptor subcircular, width 80 (65-94), length 71 (65-85). Hook distribution extrahamular. Super1 The authors are grateful to Mrs. R. P. Dempster, Associate Curator, Department of Ichthyology, California Academy of Sciences, San Francisco, California for aid in the identification of fishes; and to Dr. W. A. Rogers for loan of paratypes of Gyrodactylus hoffmani Wellborn & Rogers, 1967. The following also are gratefully acknowledged for their cooperation in collecting fish hosts: Mr. E. B. Barney, Fishery Biologist, Coleman National Fish Hatchery, Anderson, California; Mr. P. Christman, Sr., of Butte, North Dakota; and Mr. J. W. Crane, graduate student at Sacramento State College, Sacramento, California. 2 The present work was supported by the National Science Foundation (GB 3803). TRANS. AMER. MICROSC. Soc. 86(4): 390-401. 1967. This content downloaded from 207.46.13.179 on Sun, 17 Apr 2016 07:43:45 UTC All use subject to http://about.jstor.org/terms MIZELLE & KRITSKY-MONOGENETIC TREMATODES 391