Ephemeroptera: Heptageniidae of Gunnison County, ColoradoEcdyonurus (Nixe) criddlei(McDunnough 1927)Updated 20250520
TSN 100693 NotesThis species was moved into the genus Ecdyonurus by McCafferty in 2004. Scientific papers and fishing literature from the late 1900s refer to this species as Nixe criddlei.ReferencesColletti,PJ; Blinn,DW; Pickart,A and Wagner,VT 1987 Influence of different densities of the mayfly grazer Heptagenia criddlei on lotic diatom communities. Journal of the North American Benthological Society 6(4):270-280. PDFEdmunds Jr,GF and McCafferty,WP 1988 The mayfly subimago. Annual review of entomology, 33(1)509-527. PDF Quote from page 515: "It appears that structural expansion is variously apportioned to the sub- imaginal and adult molts in mayflies. Nixe criddlei tarsi are 1.83 times longer than those of the larva in the subimagoand 2.61 times longer than those of the larva in the adult; " Quote from page 519: "Complete underwater emergence has been observed in certain species within seven genera in four families (21, 27, 28, 30, 31, 49), including Nixe (G. F. Edmunds, Jr., unpublished). Underwater emergence behavior varies among species, with the subimago emerging at different depths and either crawling or floating to the surface. Kimmins (31) found that individuals would alternatively emerge at the surface if larvae lost their underwater foothold. We expect that underwater emergence probably occurs in other mayflies, especially night emergers. Also, it is feasible that some mayflies that have been reported as surface emergers might actually emerge just below the surface, as is common in some caddisflies (39)." Quote from page 522: "The speed with which subimagos were able to right themselves after being placed on their side with wings contacting water varied immensely among subimagos of different genera observed (G. F. Edmunds,Jr. and T. J. Fink, unpublished). The results could be based on differences in hydrofuge capacity, differences in behavioral response among mayflies, or both. Siphlonurids (Siphlonurus, Ameletus, Parameletus) were slow to respond, and most of the individuals, especially of Siphlonurus, were entrapped on the surface. Heptageniids (Stenacron, Nixe, Heptagenia) righted themselves faster than the siphlonurids and almost always escaped successfully. Leptophlebiids (Paraleptophlebia) and ephemerellids (Ephemerella, Drunella) responded rapidly and escaped so fast that sometimes it was impossible to see if they righted themselves before taking flight" Flowers,RW 1980 Two new genera of Nearctic Heptageniidae (Ephemeroptera). Florida Entomologist 63:296-307. PDF Splits and describes the new genera Leucrocuta and Nixe from Heptagenia. McCafferty,WP 2001 Status of some historically unfamiliar American mayflies (Ephemeroptera). Pan Pacific Entomologist, 77(3), pp.210-218. PDF Quote from page 213: "NIXE OTJOSA (MCDUNNOUGH) This species (as Heptagenia Walsh) was based on a single male adult taken at Maupin, Oregon in 1934 (McDunnough 1935). Traver (1935) realized that it was very similar to the relatively common western species Nixe criddlei (McDunnough), for example, with respect to the presence of short foretarsi associated with males. The genitalia are fundamentally similar, and the supposed differences in tint or degree of brown coloration in the two is of little consequence because of variability witnessed in populations of N. criddlei from throughout the West held in the Purdue Entomological Research Collection (PERC hereafter). The only possible differences that might support the validity of N. otiosa are differences that may seem to be present in genitalia based on figures assigned to each. However, if one compares the figures of the ventral genitalia labeled as "n. sp. McD." (= McDunnough's single specimen of N. otiosa) and "criddlei" in Traver's (1935) figure 98, it is apparent that the genitalia of N. otiosa are simply a distortion of those drawn for N. criddlei. This was likely due in part to the genitalia of N. otiosa being drawn from a dry specimen rather than from fluid preserved genitalia that were then slide mounted, as was probably the case in all of the other species represented in figure 98 and elsewhere in Traver (1935). Medial spines appear high on the penes in N. otiosa (compared with all other drawings of related species, where the medial spines are shown in their natural basomedial position); and the spine that appears mediodistally on the ventral face of the penes in N. criddlei was incorrectly interpreted by Traver to be an additional and unique apical spine, as seen on the distorted penes drawn for N. otiosa. Another classic case of penes distortion in North American heptageniid mayflies was discussed and illustrated in detail with respect to Anepeorus McDunnough species by McCafferty and Provonsha (1985). Although Traver (1935) indicated that there was some genitalic difference between N. otiosa and N. criddlei, Edmunds (in Bednarik and Edmunds 1980) stated that Traver had told him on several occasions that she believed N. otiosa was a synonym of N. criddlei. Nixe otiosa is here placed as a subjective junior synonym of N. criddlei, NEW SYNONYM" McCafferty,WP 2004 Contribution to the systematics of Leucrocuta, Nixe, and related genera (Ephemeroptera: Heptageniidae). Transactions of the American Entomological Society 130(1): 1-9. PDF The author moves Nixe criddlei into the genus Ecdyonurus because it has all the features of the Ecdyonurus simplicioides species group. Quote from page 3: "For the purposes of recognizing Ecdyonurus in North America, i.e., the simplicioides species group of Ecdyonurus, especially from the closely related genera Leucrocuta and Nixe, it may be diagnosed as having generally plesiotypic larvae with well-developed male eyes, an unmodified pronotum, a gill tuft with two or more filaments present at base of gill lamellae 6 (usually well-developed), and the three caudal filaments with well-developed interfacing setae; and in adults, as having proximate male eyes in addition to having penes (e.g., Fig 98 [Traver 1935], Fig. 4g [Demoulin 1964], Figs 103, 106 ;Jensen 1966]) with divergent lobes that have spines present ventrally, a medially extended lateral sclerite dorsally, narrowly attenuate titillators, and that lack developed dorsolateral spines." He notes that the genera Ecdyonurus, Leucrocuta and Nixe are very similar. McCafferty,WP; Durfee,RS and Kondratieff,BC 1993 Colorado mayflies (Ephemeroptera): an annotated inventory. Southwestern Naturalist 38 3, 252-274. PDF Discusses this species as Nixe criddlei. Quote from page 261: "It is likely that some of the Heptagenia spp. reported from the upper Gunnison River drainage system by Argyle and Edmunds (1962) are referable to this species." McDunnough,J 1927 A new Heptagenia from the Yellowstone Region (Ephemeroptera). Canadian Entomologist 59:261. Described as Heptagenia criddlei.  Zuellig,RE; Heinold,BD; Kondratieff,BC and Ruiter,DE 2012 Diversity and Distribution of Mayflies (Ephemeroptera), Stoneflies (Plecoptera), and Caddisflies (Trichoptera) of the South Platte River Basin, Colorado, Nebraska, and Wyoming, 1873-2010.U.S. Geological Survey Data Series 606, 257 p. PDF - caution 46MB Quote from page 30: "Remarks: This species is common in small streams in the foothills of the SPRB. McCafferty (2004) transferred Nixe criddlei into the genus Ecdyonurus." Zuellig,RE; Kondratieff,BC and Rhodes,HA 2002 Benthos recovery after an episodic sediment release into a Colorado Rocky Mountain river. Western North American Naturalist 62(1) 59-72. Discusses this species as Nixe criddlei. |