Aedes (Ochlerotatus) pulcritarsis (Rondani)

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 : 39-42

Aedes (Ochlerotatus) pulcritarsis (Rondani)

subspecies asiaticus Edwards, 1926b —original combination: Aedes (Ochlerotatus) pulchritarsis [sic] var. asiaticus (subspecific status by Monchadskii 1951). Distribution: Bangladesh, India, Nepal, Pakistan, People’s Republic of China, Sri Lanka ( Wilkerson et al. 2021).

subspecies pulcritarsis ( Rondani, 1872) —original combination: Culex pulcritarsis . Distribution: Albania, Afghanistan, Azerbaijan, Bulgaria, Crimean Peninsula, Croatia, Cyprus, Czech Republic, France (includes Corsica), Georgia, Greece, Hungary, India, Iran, Israel ( Gaza Strip and West Bank), Italy (includes Sicily), Kazakhstan, Kosovo, Lebanon, Macedonia, Moldova, Morocco, Pakistan, Portugal, Romania, Russia (Southern Districts), Serbia, Slovakia, Spain (includes Balearic Islands), Tunisia, Turkey, Ukraine, Uzbekistan ( Wilkerson et al. 2021).

The taxonomic history of Aedes pulcritarsis involves eight nominal forms: Culex pulcritarsis Rondani, 1872 ; Culex leucacanthus Loew, 1873 ; Aedes berlandi Séguy, 1921 ; Aedes praeteritus Séguy, 1923 ; Finlaya versicolor Barraud, 1924 ; Aedes pulchritarsis [sic] var. asiaticus Edwards, 1926b ; Aedes pulchritarsis [sic] var. stegomyina Stackelberg & Monchadskii, 1926 (in Montchadsky 1926); and Aedes simici Baranoff, 1927 .

In his treatment of the subgenus Ochlerotatus, Edwards (1932a) listed leucacanthus and simici as synonyms of pulcritarsis (as pulchritarsis ), recognized asiaticus , berlandi , praeteritus and versicolor as varieties of pulcritarsis , and listed stegomyina as a synonym of variety asiaticus . Monchadskii (1951) raised asiaticus to subspecific status, recognized stegomyina and versicolor as its synonyms, and retained berlandi , praeteritus and simici as synonyms of pulcritarsis . Aedes berlandi was restored to specific status by Rioux & Arnold (1955), with praeteritus as a synonym. Much later, Danilov (1978) removed versicolor from synonymy with asiaticus and recognized it as a valid species of the subgenus Finlaya . Aedes versicolor is currently regarded as a species of Aedes without subgeneric placement ( Reinert et al. 2009; Harbach 2018; Wilkerson et al. 2021). As a result of these taxonomic actions, Ae. pulcritarsis is currently recognized as consisting of two subspecies, the nominotypical subspecies with two synonyms ( leucacanthus and simici ) and subspecies asiaticus with a single synonym (stegomyina).

Aedes pulcritarsis was apparently described from a single damaged female collected at an undisclosed locality in Italy ( Rondani 1872; Theobald 1901c). Edwards (1926b) briefly described subspecies asiaticus from an undisclosed number of adult mosquitoes without explicitly mentioning where they were collected. The holotype female in the Natural History Museum, London was collected in “ Pakistan: Chitral, Drosh” ( Townsend 1990). Drosh is a city located at an elevation of 1,359 m in the Chitral District of Khyber Pakhtunkhwa Province.

Seventy-six mtDNA COI sequences derived from specimens identified as Ae. pulcritarsis are available in GenBank. Three are from specimens collected in Austria, one is apparently from a specimen collected in Greece and the remaining 72 (also available in the BOLD database) are from specimens collected in Pakistan. The similarities between all of the sequences is greater than 97.8%, mostly greater than 99%.

All of the COI sequences obtained from specimens collected in Pakistan were submitted by Ashfaq et al. (2014). The authors indicated that the specimens were collected at altitudes of 111– 2,376 m in urban and rural areas of Punjab and Khyber Pakhtunkhwa Provinces in central-eastern and northwestern regions of the country, respectively, and identified retrospectively as Ae. pulcritarsis “through barcodes”. It is also interesting to note that the specimens from Austria which Bakran-Lebl et al. (2022) used to generate COI sequences were identified to species using the morphological keys of Gunay et al. (2018) and Becker et al. (2020), with the identifications subsequently confirmed by comparison “to sequences available in GenBank® and BOLD.” Obviously, the only sequences available in the databases for comparison at the time were those deposited by Ashfaq et al. (2014). Even though the holotype of asiaticus was collected at an altitude intermediate between the altitudes where Ashfaq et al. (2014) collected their alleged specimens of Ae. pulcritarsis (see above), we do not think that the genetic data are sufficient to unambiguously indicate the former is a synonym of the latter. Although the currently available barcode sequences appear to indicate that the same species is present in Austria, Greece and Pakistan, the existence of a complex of species, which may not be distinguished by barcodes, cannot be ruled out.

Edwards (1934) (in Barraud 1934) stated, with reference to Ae. pulcritarsis (as pulchritarsis ) that “The species is usually scarce and still but little known, but appears to be subject to considerable local variation. Two different varieties [ asiaticus and versicolor ] or possibly distinct species, occur within the Indian area and are described below.” As noted above, versicolor is now recognized as a species of the subgenus Finlaya . Edwards gave a brief description of the female of asiaticus and included a description of the larva based on the descriptions of Montchadsky (1926) and Montschadsky (1930). His descriptions of the females of pulcritarsis (as pulchritarsis ) and asiaticus are not entirely comparable. The comparable characters are listed in Table 3 .

Contrary to Edwards, Gutsevich et al. (1971, 1974) indicated that the ornamentation of the legs is more variable in subspecies pulcritarsis (as pulchritarsis ): “Femora and tibiae dark anteriorly, with small spots of dark scales or with scattered light scales, often also completely dark anteriorly, with white apex.” They reported that subspecies asiaticus “differs mainly in the coloration of the mesonotum. Head with white and black scales which form spots. Mesonotum with blackish brown or dark brown sales, with a longitudinal median stripe of white scales and white transverse stripes, stripes on the mesonotum sometimes formed by yellowish scales which are indistinct against the background; lateral margins of mesonotum with white scales.” Oddly, Gutsevich et al. did not mention the head scaling of subspecies pulcritarsis ; however, for comparison, Edwards described the head of this subspecies as having “a median line of long and rather wide white lanceolate scales on vertex, continued forwards between eyes and around eye-margins; white upright scales in centre of nape [occiput]; a large patch of black scales on either side of middle line of vertex.” It is uncertain but the median line of white scales and lateral patches of black scales described by Edwards probably correspond with the white and black spots described by Gutsevich et al. (1971, 1974).

The most recent treatment of Ae. pulcritarsis , the nominate form in Europe, is that of Becker et al. (2020). Those authors merely stated that the female is “Very similar to the females of Ae. berlandi . A slight difference exists in the scutal colouration pattern. Whereas the scutum of Ae. berlandi is distinctly contrasted by dark and pale golden scales, Ae. pulcritarsis exhibits a weaker pattern of pale and dark scales on the scutum and looks rather uniformly golden brownish coloured. However, the median and lateral stripes may be somewhat lighter than the submedian spots.” There is no mention of the median line of white scales on the anterior half of the scutum that is present in subspecies asiaticus .

As far as we know, the male genitalia and larva of subspecies pulcritarsis were first described and illustrated by Martini (1930). Montchadsky (1926) described and illustrated the four larval instars of subspecies asiaticus (as var. stegomyina ). Martini included a brief description of var. stegomyina and reproduced the terminal abdominal segments of the second and third-instar larvae (his fig. 359) that were illustrated for this variety in Montchadsky (1926: figs 4 and 3, respectively). The head and terminal abdominal segments of pulcritarsis sensu stricto were illustrated by Martini (1930). The only other illustration of the larva of pulcritarsis sensu stricto known to us is the drawing of the terminal abdominal segments found in Becker et al. (2020: fig. 10.69), which, except for the larger anal papillae, agrees with the illustration of Martini (1930). Monchadskii (1951) and Gutsevich et al. reproduced Montchadsky’s (1926) illustrations of the head and terminal abdominal segments of var. stegomyina for their descriptions of subspecies asiaticus . It is interesting to note that the largest seta of the basal mesal lobe of the male genitalia illustrated for pulcritarsis by Martini (1930: fig. 358) differs significantly from the largest seta of the basal mesal lobe illustrated for pulcritarsis by Gutsevich et al. (1971, 1974: fig. 111) and Becker et al. (2020: fig. 10.68).

Even though the adults and larvae of asiaticus and pulcritarsis have not been described in detail, and the pupae are unknown, the known morphological differences listed in Table 4 provide a clear indication that the two forms are quite distinct.

The distributions of the two subspecies listed in Wilkerson et al. (2021) require some adjustments. Firstly, India and Pakistan should be removed from the distribution of subspecies pulcritarsis for the reason explained for other taxa treated herein. Secondly, Tajikistan, Turkmenistan and Uzbekistan (includes the type locality of stegomyina) should be added to the distribution of subspecies asiaticus (see Gutsevich et al. 1971, 1974). By association, the distribution of asiaticus should include Afghanistan and probably most of Iran and Kazakhstan. Afghanistan and Uzbekistan should be removed from the distribution of subspecies pulcritarsis , and Iran (far northwest) and Kazakhstan (far western region) questionably retained. In agreement with Gutsevich et al. (1971, 1974) and Becker et al. (2020), the distribution of pulcritarsis sensu stricto extends eastward from the Mediterranean region to southwestern Russia and Caucasia; the distribution of asiaticus lies east and southeast of those areas, essentially from areas northeast to southeast of the Caspian Sea.

We suspect that integrated morphological and molecular studies conducted on specimens collected throughout the ranges of the two forms are likely to show that Ae. pulcritarsis is a complex of species. For that reason, based on currently available morphological and distributional information, we believe a prudent course of action is to recognize asiaticus as a separate species until proven otherwise: Aedes (Ochlerotatus) asiaticus Edwards, 1926b . Aedes asiaticus is currently listed as a species in the Encyclopedia of Life.

There is no doubt that var. stegomyina Stackelberg & Monchadskii, 1926 is synonymous with Ae. asiaticus based on its morphology and type locality.As the type localities of leucacanthus Loew, 1873 (Kasan in southwestern Russia) and simici Baranoff, 1927 ( Macedonia) lie within the distribution of Ae. pulcritarsis , we accept that they should be retained as synonyms of this species.

Tables

TABLE 3. Comparable differences between the adult females of the subspecies of Aedes pulcritarsis observed by Edwards

Females	asiaticus	pulcritarsis
Thorax	“Mesonotum mainly dark brown, with a double	“Mesonotum with a variable amount of golden
	median line of white scales on anterior ½, narrowly	scales toward front in middle; pale scales along
	bordered externally with yellow scales; on each side of	margins and over wing-roots, remainder dark
	the posterior end of this stripe a rather large patch of	brown.”
whitish scales.”
Legs	Apparently differing as follows: “Femora and tibiae	kneewith fairly numerous scattered white scales; hindfemur	…“mostly black, with conspicuous white kneewith fairly numerous scattered white scales; hindfemur spots and shite rings on tarsi marrow on front	spots and shite rings on tarsi marrow on front
	kneewith fairly numerous scattered white scales; hindfemur	spots and shite rings on tarsi marrow on front
	(except for this speckling) dark on nearly the whole	and middle pairs, broader on hand pair; 5th tarsal
	outer surface.”	segment of all legs white.”
Abdomen	“White basal bands on tergites [terga] II–VI complete,	…“black, with white basal bands on tergites
	that on VI very narrow.”	II–VI, sternites [sterna] similarly coloured.”