Toxorhynchites (Toxorhynchites) manicatus (Edwards)

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 : 126-127

Toxorhynchites (Toxorhynchites) manicatus (Edwards)

subspecies manicatus ( Edwards, 1921a) —original combination: Megarhinus manicatus . Distribution: Japan, Taiwan ( Wilkerson et al. 2021).

subspecies yamadai ( Ôuchi, 1939) —original combination: Megarhinus yamadai (subspecific status by Tanaka et al. 1979). Distribution: Japan (Amami Ôshima, Ryukyu Archipelago) ( Ôuchi 1939).

subspecies yaeyamae Bohart, 1956 —original combination: Toxorhynchites yaeyamae (subspecific status by Tanaka et al. 1979). Distribution: Japan (Ryukyu-Retto) ( Bohart 1956).

These three nominal forms were originally described as separate species: manicatus from Taiwan and yaeyamae and yamadai from islands of the Ryukyu Archipelago (see below). Tanaka (1971a, b) and Tanaka et al. (1975) recognized yaeyamae as a subspecies of yamadai based on examination of all life stages of the former from Iriomote (provenance of the type locality) and Ishigaki Islands and the latter from Amami Ōshima (provenance of the type locality), stating that the adults and larvae are identical with the exception that the postpronotal lobes of the adults have a broad dark-scaled dorsal area in yamadai and a narrow dark-scaled dorsal margin in yaeyamae . The subspecific status of yamadai and yaeyamae was established by Tanaka et al. (1979), who provided the following explanation.

The characteristics differentiating yamadai , yaeyamae and manicatus do not appear sufficient to consider them as 3 distinct species. However, they may be recognized as 3 subspecies, because of the existence of rather distinct and not clinal local variations and their definite allopatricity. The posterior pronotal lobe is covered with dark metallic purple or indigo-blue scales on upper 0.5–0.6 in yamadai and manicatus , and the upper 0.25 or less in yaeyamae . White scaling on the tarsi is most developed in manicatus , least in yamadai and intermediate in yaeyamae ; this may be clinal. Transverse bands of white scales on female abdominal terga are most developed in yamadai , least in yaeyamae and intermediate in manicatus , but these are also highly variable within each subspecies. Lateral bristles [setae] of abdominal terga VI–VIII are most developed in manicatus , the bristles are stiffer and denser than in the other 2 subspecies, though not so conspicuous as in the towadensis group; these bristles are nearly equal to those on anterior terga in yaeyamae , while in yamadai , they are more developed than in yaeyamae and less so than in manicatus . Purple scaling on the median line of the abdominal sterna is most developed in manicatus, IV is usually golden only in narrow lateral margins or small lateroapical patches, VII has a broad median line of purple scales, II, V and VI usually have complete, narrow to moderately broad median lines, II often has an incomplete one. The purple scaling is least developed in yaeyamae and intermediate in yamadai . Male tergum IX is broad, parallel-sided, with the apical margin straight, having 21,22 bristles on each side in one specimen of yamadai . In yaeyamae and manicatus , it is fairly variable, but usually more or less apically narrowed, or having the more strongly rounded lateroapical angle, and the apical margin slightly to deeply concave; the setae are 12–16 (6) in yaeyamae , 10–14 (2) in manicatus . The claspette is 0.96–1.09 (1) as wide as long in yamadai , while it is 1.10–l.40 (7) in the other 2. The shape of tergum IX is usually quite variable in this genus. At present, we have only 1 male specimen of yamadai , and consider its 9th tergite [tergum IX] as a case of individual variation which is rather more remarkable than other variable characters of this species.

As mentioned above for Culex hayashii Yamada, 1917 , the islands of the Ryukyu Archipelago are separated from Palaearctic Japan and Taiwan by two large gaps, and the flora and fauna of the Archipelago tend to be very different from the flora and fauna on the northern and southern sides of those gaps, respectively. We noted above that Toma et al. (2019) had elevated Tripteroides bambusa yaeyamensis Tanaka, Mizusawa & Saugstad, 1979 , which is found in the central and southern regions of the archipelago, to specific status based on molecular and genetic distinctions from Tp. bambusa ( Yamada, 1917) in the northern Palaearctic region of Japan. What we neglected to mention is that Tp. bambusa , which like Tx. manicatus develops in plant cavities, is actually three species: Tp. bambusa in the Palaearctic region of Japan north of the northern gap; Tp. yaeyamensis Tanaka, Mizusawa & Saugstad, 1979 , originally described as a subspecies of Tp. bambusa , in the central and southern regions of the archipelago; and an undescribed bambusa -like species in Taiwan. Considering (1) the morphological comparisons of Tanaka et al. (1979), (2) the parallel distributions of manicatus sensu stricto (Taiwan) and yaeyamae with the bambusa -like species (Taiwan) and Tp. yaeyamensis (Yaeyama Islands) , respectively, (3) the allopatric occurrence of yaeyamae and yamadai in the southern and central regions of the Ryukyu Archipelago, respectively, and (4) because island species are known to evolve independently from species on other islands, we believe that molecular data, once available, will show that manicatus , yaeyamae and yamadai are separate species (a COI sequence is currently available for yaeyamae, GenBank accession LC441028, Toma et al. 2019). For these reasons, we hereby restore yaeyamae and yamadai to their original specific status: Toxorhynchites (Toxorhynchites) yaeyamae Bohart, 1956 and Toxorhynchites (Toxorhynchites) yamadai ( Ôuchi, 1939) . Toxorhynchites yaeyamae and Tx. yamadai are both currently listed as species in the Encyclopedia of Life.