Monopisthocotylans of <i>Noturus</i> spp. (Siluriformes: Ictaluridae) in the western portion of the Mississippi River drainage, with comments on influence of environment and phylogeny on prevalence

Monopisthocotylans were examined from the gills of 336 specimens of 12 species of madtoms within the ictalurid catfish genus Noturus from western drainages of the Mississippi River in Arkansas, Kansas, Nebraska, and Oklahoma, U.S.A., as follows: 63 N. flavus of the subgenus Noturus; 39 N. exilis, 28 N. gyrinus, 22 N. lachneri, and 47 N. nocturnus of the subgenus Schilbeodes; and 26 N. albater, 18 N. eleutherus, 40 N. flavater, 2 N. maydeni, 23 N. miurus, 11 N. placidus, and 17 N. taylori of the subgenus Rabida. Ligictaluridus pricei (Mueller, 1936) was found on specimens of four of the 12 (33%) species of madtoms: N. exilis, 13 of 39 (33%); N. gyrinus, two of 28 (7%); N. nocturnus, two of 47 (4%); and N. maydeni, two of 2 (100%). Noturus nocturnus and N. maydeni represent new host records for L. pricei. A contingency table analysis indicated significantly less prevalence of infection (X2 = 12.3, P = 0.0004) of L. pricei on species of Rabida (two of 137 [1%]) than Schilbeodes (18 of 136 [13%]). The common occurrence of un-infested species of Rabida residing among syntopic Ameiurus and Schilbeodes potentially serving as reservoir hosts for L. pricei suggests that genetic susceptibility may be involved in its absence in most species of Rabida compared to Schilbeodes, although factors such as host size and microhabitat may also substantially influence prevalence. A single specimen of Crinocleidus crinicirrus (Kritsky and Leiby 1973), previously found only on the centrarchid Lepomis megalotis, was found on N. flavater. These records from N. maydeni and N. flavater represent the first monopisthocotylans reported from the subgenus Rabida, although N. flavater is probably an accidental host for C. crinicirrus.