 |
| Etheostoma cyanorum (Moore and Rigney, 1952)
in Matthews & Turner, 2019.
DOI: 10.1643/CI-18-054
|
Abstract
Etheostoma cyanorum, endemic to the Blue River drainage of southern Oklahoma, is redescribed and recognized as a distinct species within the Etheostoma whipplei–Etheostoma radiosum complex, separating it from E. radiosum. Originally described as Poecilichthys radiosus cyanorum, it was one of three putative subspecies of E. radiosum (with E. r. radiosum and E. r. paludosum) considered valid until now, defined in part by drainage-specific allopatry. Two separate mtDNA gene trees show that E. cyanorum forms a distinct and strongly supported lineage. Ten meristic and 16 morphometric traits are reexamined and new information included, confirming traits separating E. cyanorum from E. radiosum, and clarifying ambiguities about “bluntness of the snout” as diagnostic for P. r. cyanorum. Etheostoma cyanorum differs from E. radiosum by lower counts of unpored lateral line scales, higher counts of pored lateral line scales, and greater interorbital width. Large adult E. cyanorum have a deep body and blunt snout per earlier studies, but those traits are not diagnostic due to allometry. Head depth and head width can separate E. cyanorum from most populations of E. radiosum, but they overlap with some populations of E. radiosum in southwest Arkansas. All evidence supports recognition of E. cyanorum as a valid species. A broad geographic, molecular assessment to supplement existing morphological information is needed to assess validity of the two remaining subspecies of E. radiosum.
 |
| Fig. 3 (A) Male Etheostoma cyanorum, 63 mm SL, in nuptial color, from mainstem Blue River, 1.7 km west-northwest of Connerville, OK, 30 March 2018 (WJM 3645; OMNH 86859); (B) female E. cyanorum, 41 mm SL, same collection (OMNH 86860). Location: 34°27.067′ N, 96°39.327′ W. Photographs by N. Lang. (C) Detail of distal color band in nuptial male from same collection, same date (OMNH 86861). Photograph by WJM. |
Etheostoma cyanorum (Moore and Rigney, 1952), elevated to species
Blue River Orangebelly Darter
Holotype.— UMMZ 161366, holotype of Poecilichthys whipplii cyanorum, adult breeding male, 68 mm SL, designated by Moore and Rigney (1952), collected by Moore in 1949 in Blue River at State Hwy 99 north of Connerville, Johnston County, Oklahoma (Fig. 2).
Paratypes.— Paratypes include 329 individuals collected by Moore or students from the Blue River drainage (museum acronyms and catalog numbers, Moore and Rigney, 1952: p. 10).
Diagnosis.— Etheostoma cyanorum differs from E. radiosum by their allopatric distribution, with E. cyanorum known only from Blue River and tributaries, versus E. radiosum occupying tributaries of Washita River west of Blue River and all drainages eastward from the Clear Boggy to the upper Ouachita and Little Missouri in southwest Arkansas. Etheostoma cyanorum differs from E. radiosum in having all assayed mtDNA haplotypes not shared with E. radiosum, lower counts of unpored lateral line scales, higher counts of pored lateral line scales, and a wider interorbital distance. Etheostoma cyanorum can be distinguished by a deeper and wider head from E. radiosum in all Oklahoma drainages, and in most but not all drainages in Arkansas. Nuptial males of Etheostoma cyanorum differ from nuptial E. radiosum in the geographically closest drainages (Washita, Clear Boggy, Muddy Boggy, and Kiamichi) by a solid blue distal band in the spinous dorsal (Fig. 3C), compared to the distal blue band in those populations of E. radiosum (=E. r. paludosum of Moore and Rigney) having an appearance of blue “dots” or “spots” bordered in white, between clear or orange tips of the fin spines.
....
Distribution.— Etheostoma cyanorum is known only from the Blue River drainage in southcentral Oklahoma, a tributary of Red River. It is most abundant in the upper, spring-fed, rocky portions of the drainage, and in some small tributary creeks, but is scarce or absent in lower, muddy portions of the drainage closer to Red River.
Etymology.— The specific name “cyanorum” (=“of the Blues” referring to Blue River) was suggested for the subspecies, on advice from R. M. Bailey (Moore and Rigney, 1952), to reflect restriction of this form to Blue River and its tributaries. Linder (1955) and Echelle et al. (2015) referred to it as the “Blue River Orangebelly Darter,” but Near et al. (2011) called it “Blue Darter.” We follow Linder (1955) and Echelle et al. (2015) and recommend the common name “Blue River Orangebelly Darter,” because E. cyanorum is not predominantly blue in coloration. This common name aligns with the practice of referring to other fishes in Oklahoma in a drainage-specific manner, including Red River Pupfish (Cyprinodon rubrofluviatilis), Red River Shiner (Notropis bairdi), and Arkansas River Shiner (Notropis girardi).
William J. Matthews and Thomas F. Turner. 2019. Redescription and Recognition of Etheostoma cyanorum from Blue River, Oklahoma. Copeia. 107(2); 208-218. DOI: 10.1643/CI-18-054
