Culiseta (Culicella) ochroptera (Peus)

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 : 106-108

Culiseta (Culicella) ochroptera (Peus)

subspecies amurensis Maslov, 1964 —original combination: Culiseta silvestris amurensis (status as subspecies of ochroptera by Berlov & Kuberskaya 2023). Distribution: Central Amur region, Ussuri Basin, Southern Maritime Province, Northeast China ( Maslov 1964); Primorye (Primorsky Krai, far East Region), Russia ( Maslov 1964).

subspecies minnesotae Barr, 1957 —original combination: Culiseta minnesotae (status as subspecies of ochroptera by Berlov & Kuberskaya 2023). Distribution: Canada, United States (Alaska, continental) ( Wilkerson et al. 2021).

subspecies nipponica La Casse & Yamaguti, 1950 —original combination: Culiseta (Culicella) nipponica (status as subspecies of ochroptera by Berlov & Kuberskaya 2023). Distribution: Japan, South Korea ( Wilkerson et al. 2021).

subspecies ochroptera ( Peus, 1935) —original combination: Theobaldia (Culicella) ochroptera . Distribution: Belarus, Belgium, Czech Republic, Estonia, Finland, Germany, Hungary, Lithuania, Netherlands, People’s Republic of China, Poland, Romania, Russia, Slovakia, Sweden, Ukraine ( Wilkerson et al. 2021).

Soon after submission of this monograph for review, Berlov & Kuberskaya (2023) published a paper titled “Additions and corrections to the catalog of blood-sucking mosquitoes of the world ( Insecta: Diptera , Culicidae ) by Wilkerson et al. (2021) ” [verbatim translation from the Russian]. The authors inferred that Culiseta amurensis Maslov, 1964 , Cs. minnesotae Barr, 1957 , Cs. nipponica LaCasse & Yamaguti, 1950 and Cs. ochroptera ( Peus, 1935) were incorrectly listed in the catalog as valid species. They pointed out that Maslov (1964, 1967, 1989) classified them as subspecies of Cs. silvestris Shingarev, 1928 . However, because Cs. silvestris has been treated as a doubtful species since Dahl & White (1978) listed it, without explanation, as a nomen dubium in a footnote to a table of European mosquito species, Berlov & Kuberskaya proposed that amurensis , minnesotae and nipponica should be recognized as subspecies of ochroptera , the oldest of the four nominal taxa. To gain a better understanding of this taxonomic conundrum, we examined Maslov’s (1964) treatment of Cs. silvestris . The reasoning behind his recognition of Cs. silvestris and its purported subspecies is revealed in the following passages (translated from the Russian).

… C. silvestris Sching. ‒ was described very unsuccessfully, too fragmentary and general, so much so that it was difficult to extract anything significant from the description ( Shingarev, 1928). Not surprisingly, Peus (1935) later described the same species under the name C. ochroptera Peus. It is under this name that he [Peus] now appears in the literature. Unfortunately, the holotype and allotype of C. silvestris have not been preserved, but in the year of description (1928) N. I. Shingarev [the author of silvestris ] gave me one male, one female, and them as paratypes. Later from the Moscow region, in the area where C. silvestris was first found, I also managed to obtain larvae of this species. Thus, at present, it seems to me necessary in the revision of the Eurasian representatives of the subgenus Culicella to establish the following taxonomic divisions: the species name C. silvestris with three subspecies 1 C. silvestris silvestris Sching. ‒ Eastern Europe, the Urals, Western Siberia; C. silvestris ochroptera Peus ‒ Central Europe and the Baltics; C. silvestris amurensis Masl. (subsp. n.) (Maslov, 1949, 1963) ‒ the extreme east of the species range ‒ Piamurye and Primorye. Below is a redescription of the species with a differential diagnosis of all subspecies and a description of C. silvestris amurensis , subsp. n.

1 It is possible that when analyzing more extensive European material, the first two forms [ silvestris sensu stricto and ochroptera ] will turn out to be one and the same subtype.

In Japan, another species was described (La Casse а. Yamaguti, 1950), assigned by the authors to the subgenus Culicella , C. nipponica . Unfortunately, adult females and males of this species remain unknown; as for the larva of the 4th stage, then differentiating C. nipponica from C. silvestris amurensis n. is not possible (Maslov, 1963). It is probable that there are not two species here, even sub-indigenous, but one form, and then the Far Eastern C. silvestris amurensis n. would prove to be synonymous with Japanese C. nipponica , which would need to be considered as a subspecies, C. silvestris nipponica . However, at the present time, due to the lack of descriptions of the male and female already indicated, both forms have to be preserved.

Recently, another species of Culicella ‒ C. minnesotae Barr , was described in the USA ( Barr, 1957, 1959; Price, 1958). Among the mosquitoes I received from the USA (Wisconsin) from prof. R. Matheson, turned out to be one male matching the description ( Barr, 1957), especially in the structure of the phallus. Comparison of American C. minnesotae with other representatives of the subgenus Culicella confirmed significant differences in all developmental stages from C. morsitans morsitans and C. morsitans dyari . However, an amazing similarity between C. minnesotae and C. silvestris mosquitoes was unexpectedly revealed: the most characteristic imaginal signs of one (spotted wing, the presence of not only basal but also apical bands on the abdominal tergites [terga], etc.) coincided with those of the other. Of particular interest was the similarity in the structure of the phallus [genitalia] of C. minnesotae and C. silvestris silvestris (Fig. 9, A, B). A comparison of the larval morphological structures also does not support the species independence of C. minnesotae Barr. The same is shown by the details of pupal chaetotaxy (Maslov, 1963). Thus, C. minnesotae should not be considered as an independent species, but only as a subspecies ‒ C. silvestris minnesotae Barr.

Following the above, Maslov (1964) distinguished the females, males and fourth-instar larvae of subspecies amurensis , minnesotae , ochroptera and silvestris in separate keys, accompanied by descriptions of silvestris sensu lato and the new subspecies amurensis . Maslov (1967, 1989) incorporated the keys into keys for distinguishing the females, males and fourth-instar larvae of all known species of Culiseta and provided descriptions for silvestris sensu stricto and each of the four subspecies.

Because Maslov (1964) had examined paratypes and topotypic specimens of silvestris , and recognized ochroptera as the same species, we were inclined to consider ochroptera as a synonym of silvestris until we noticed that Gutsevich et al. (1971, 1974) justified the retention of ochroptera : “A. V. Maslov (1964) considered C. ochroptera as a synonym of C. silvestris Shingarev, 1928 , but to judge from Shingarev’s incomplete description, ‘it is certain that the two species are not identical’ (Shtakel’berg, 1937 [ Stackelberg 1937]). The holotype of C. silvestris is lost and Maslov examined only paratypes. Because of the incomplete original description of C. silvestris , it seems advisable to retain the name C. ochroptera [translated from the Russian].” It is important to note here that Stackelberg (1937) treated ochroptera and silvestris as separate species (of Theobaldia Neveu-Lemaire, 1902 ) [the map in Maslov (1967, 1989: fig. 82) indicates they may have allopatric distributions], and distinguished them in a key for the identification of males. It seems likely that Dhal & White (1978) listed silvestris as a nomen dubium based on the explanatory note and recommendation proffered by Gutsevich et al. (1971, 1974). Until the identity of silvestris is resolved, we concur with Dahl & White that it should remain a nomen dubium.

Wood et al. (1979) provided a cogent summary of the silvestris-ochroptera conundrum and decided to continue to recognize minnesotae as a separate species “Until Russian workers concur in choosing between ochroptera and silvestris ”. We agree with this rationale and reaffirm the specific rank of minnesotae established by Wood et al. (1979), and accepted by later workers (e.g. Darsie & Ward 1981, 2005; Belton 1983; Harrison et al. 2016): Culiseta (Culicella) minnesotae Barr, 1957 . Culiseta minnesotae is currently listed as a species in the Encyclopedia of Life.

Berlov & Kuberskaya (2023) incorrectly asserted that Maslov (1967, 1989) had considered nipponica to be a subspecies of silvestris . All prior authors ( Maslov (1964, 1967, 1989; Gutsevich et al. 1971, 1974; Tanaka et al. 1979; Lu et al. 1997) recognized nipponica as a distinct species. As there is no justification or precedence for treating nipponica as a subspecies, the specific rank of this nominal species must be retained: Culiseta (Culicella) nipponica La Casse & Yamaguti, 1950 , as listed in the Encyclopedia of Life.

We have not been able to find a source for the recognition of amurensis as a species; consequently, its listing as a species by Harbach (2018) was apparently in error; it should have been listed as a subspecies of ochroptera . The error was repeated in Wilkerson et al. (2021). Although amurensis is recorded from the extreme northeast of China ( Knight & Stone 1977; Wilkerson et al. 2021), it is not treated or even mentioned by Lu et al. (1997) in their monograph on the culicine mosquitoes of China (however, they do recognize and describe Cs. nipponica ). As noted above, Maslov (1964) thought it “probable” that amurensis was the same as nipponica , in which case the apparent morphological similarity of the two nominal forms may explain why Lu et al. only recognized the presence of nipponica in China. In agreement with Maslov (1964), we also believe amurensis is likely to be synonymous with nipponica ; hence, until proven otherwise, it is herewith consigned to synonymy: amurensis Maslov, 1964 , junior subjective synonym of Culiseta (Culicella) ochroptera ( Peus, 1935) . The nominal subspecies amurensis , which is listed as a species in the Encyclopedia of Life, must be removed from the list of valid species of Culiseta .