Uranotaenia (Pseudoficalbia) anhydor Dyar

Harbach, Ralph E. & Wilkerson, Richard C., 2023, The insupportable validity of mosquito subspecies (Diptera: Culicidae) and their exclusion from culicid classification, Zootaxa 5303 (1), pp. 1-184 : 131-132

Uranotaenia (Pseudoficalbia) anhydor Dyar

subspecies anhydor Dyar, 1907 —original combination: Uranotaenia anhydor . Distribution: Mexico (Baja California), United States (Arizona, southern California, Nevada) ( Carpenter & LaCasse 1955; Belkin & McDonald 1956).

subspecies syntheta Dyar & Shannon, 1924 —original combination: Uranotaenia syntheta (subspecific status by Belkin & McDonald 1956). Distribution: Mexico (eastern and central), United States (New Mexico, Oklahoma, Texas) ( Dampf 1943; Carpenter & LaCasse 1955; Belkin & McDonald 1956).

Uranotaenia anhydor and Ur. syntheta were both originally described as distinct species, the former from a single larva taken from a swamp at Sweetwater Junction near San Diego, California and the latter from an adult female collected at Mission, Texas. The authors of the latter species ( Dyar & Shannon 1924), prior to describing syntheta , noted that anhydor was “not yet known outside of southern California ”. The two nominal forms continued to be recognized as separate species by Dyar (1928), Edwards (1932a), Dampf (1943), Yamaguti & LaCasse (1951), Brookman & Reeves (1953), Galindo et al. (1954) and Carpenter & LaCasse (1955); however, the authors of the last three articles observed that the two forms are so similar morphologically that they may constitute two subspecies or a single species.

The two forms remained as separate species until Belkin & McDonald (1956) formally treated syntheta as a subspecies of anhydor based on comparisons of all life stages of specimens from a population sampled at Saratoga Springs in Death Valley (San Bernardino County, California) with populations of “ anhydor from San Diego County, Baja California and Arizona, and syntheta from several localities in Texas.” They noted “…that the Saratoga Springs population is distinct from both anhydor and syntheta and that it is in no way intermediate between the two.” Despite these findings, they concluded “that all these populations are so close morphologically that they should be considered to form one species…. The populations in the United States east of the Continental Divide, and in all probability those in eastern and central Mexico, constitute the subspecies syntheta , easily recognizable only in the adult stage by the thoracic ornamentation. The Saratoga Springs population cannot be considered to be in any way intermediate between the typical anhydor from San Diego Co. and syntheta but rather an extreme development of the former. It is suggested that the Saratoga Springs population, which is quite distinct morphologically and ecologically from the other western populations, has been isolated in the Amargosa drainage of the Death Valley System since late Pleistocene times… and that it may represent a third subspecies in the anhydor complex.” This concept subsequently has been accepted in all later works ( Bohart & Washino 1978; Darsie & Ward 1981, 2005; Nava & Debboun 2016).

All published treatments of anhydor and syntheta agree that the adults of the two forms are reliably distinguished by the development of a line (single row) of iridescent blue scales along the lateral margins of the scutum. In syntheta , this line is distinct (conspicuous) from the scutal fossa to the base of the wing, with a narrow gap at mid-length, whereas in anhydor the line is faint or obsolete (indistinct) with a wide gap in the middle ( Dyar & Shannon 1924; Dyar 1928; Galindo et al. 1954; Yamaguti & LaCasse 1951; Carpenter & LaCasse 1955; Belkin & McDonald 1956). In contrast, the Saratoga Springs form has an elongate patch of several rows of iridescent light blue scales on each side of the scutum ( Belkin & McDonald 1956). Based on the morphological distinction and lack of evidence for gene flow across the Continental Divide, we believe molecular data will show that anhydor and syntheta are separate species, and for that reason we hereby restore syntheta to its original specific rank: Uranotaenia (Pseudoficalbia) syntheta Dyar & Shannon, 1924 . Uranotaenia syntheta is currently listed as a species in the Encyclopedia of Life. Contrary to Belkin & McDonald (1956), we believe the morphological and ecological distinctions of the Saratoga Springs form are a clear indication that it is a genetically distinct species, i.e. it is an unnamed species pending formal taxonomic validation.