Acta Parasitologica, Vol. 52, No. 1, 2007, 51-57. DOI: 10.2478/s11686-006-0049-x František Moravec (1)* and Patrick Muzzall (2) - Redescription of Rhabdochona cotti (Nematoda,
Rhabdochonidae) from Cottus caeruleomentum (Teleostei, Cottidae) in Maryland, USA, with remarks on the taxonomy of North American Rhabdochona spp.
(1) Institute of Parasitology, Biology Centre, Academy of Sciences of the Czech Republic, Branišovská 31, 370 05 České Budìjovice, Czech
Republic; (2) Department of Zoology, Michigan State University, 203 Natural Science Building, East Lansing, MI 48824, USA
*Corresponding author: moravec@paru.cas.cz
ABSTRACT
The nematode Rhabdochona cotti Gustafson, 1949 is redescribed from specimens collected from the intestine of the blue ridge
sculpin Cottus caeruleomentum (a new host record), a recently described fish species, from Little Fishing Creek in Maryland,
USA. The measurements of these specimens, collected in November 2005, are generally smaller than those reported in the original
description of R. cotti, this being probably associated with the nematode's seasonal maturation cycle or the different host
species. As revealed by SEM, the deirids of R. cotti are simple (not bifurcate), in which this species differs from almost all North
American congeners. Of these, simple deirids, filamented eggs and a rounded tail tip in females occur only in Rhabdochona longleyi,
but it distinctly differs from R. cotti in the smaller number of anterior prostomal teeth (6 vs. 14). Rhabdochona rotundicaudatum
is considered a junior synonym of Rhabdochona cascadilla; numerous specimens of the latter were collected from
Semotilus atromaculatus, Luxilus cornutus and Notropis rubellus from the type locality (Eramosa River, Ontario, Canada)
(unpublished). Rhabdochona paxmani and Rhabdochona salmonis are synonymized with Rhabdochona kisutchi, whereas
Rhabdochona californiensis is considered a junior synonym of R. cascadilla. The need of a taxonomic revision of North
American species of Rhabdochona is stressed.
KEY WORDS: Parasitic nematode, Rhabdochona, morphology, freshwater fish, Cottus, Maryland, USA