Chironomus samoensis Edwards 1928Although this species does not occur in the Oriental Region, the description is included to indicate why the supposed records of this species in other regions, such as the Oriental rregion, are based on mis-identification. Original Description of C. samoensis: Insects of Samoa Part VI. Fasc. 2, Nematocera."59. Chironomus (s. str.) samoensis, sp. n. Male Female Head ochreous, palpi and antennal flagellum rather darker; plumes of male antennae pale. Frontal tubercles present, of moderate size. Last segment of m antennae quite three times as long as 2-11 together. Thorax greenish; scutum with three reddish-orange stripes, the areas between the stripes dusted with silvery-grey. Postnotum not darker than the scutal stripes. Pronotum slightly emarginate in middle. Abdomen of male (when not discoloured) green, tergites 2-4 each with a more or less diamond-shaped brown spot near base, 5 brownish, 6-8 darker brown, hypopygium pale. Seen very obliquely from in front the segments are rather distinctly silvery-grey at the base; seen obliquely from behind the silvery dusting is on the posterior margins of 2-5 and nearly the whoile of 6-7. Hypopygium with anal point moderately long and slender; claspers slender, not much enlarged at base; upper basal appendage rather small with a downward curved point; the structure almost as figured by Kieffer for Ch. imberbis. Abdomen of female without distinct markings. Legs greenish-yellow; tarsi a little darker, first two segments narrowly and rather indistinctly brown at tip. No darkening on femora, nor on front tibiae. First segment of front tarsi about 1.8 times as long as tibiae. No tarsal beard. Wings hyaline; r-m slightly darkened; venation as in other members of the dorsalis group. Halteres pale. Length of body (male) 4.5-5 mm.; wing 3-3.5 mm. Further description from specimens from American Samoa: Relative length of leg segments (micron) (4 specimens) Tokunaga's (1964) description of the upper basal appendage (SVo), and the list of species to which this species is compared, is important here - all of these species have a D-type SVo of Strenzke (1959), whereas Tokunaga (1964) (although noting the hypopygium is of the "dorsalis" type) illustrates it with a triangular apex which can be misinterpreted as an S-type. The specimens described by Tokunaga from Micronesia are probably C. samoensis, and the illustration is presumably intended to depict the somewhat beaked SVo seen in some specimens. The misinterpretation of this illustration may be partly responsible for the identification of 'C. samoensis' in other locations, which have an S-type SV. However, they also differ in other characters and are misidentifications. Found: Type localities - Apia, Western Samoa; Faratogo, Tutuila (now American Samoa); Tonga.American Samoa – Mapusaga, Tutuila. Micronesia – (Tokunaga 1964) Specimens from other areas (Australia, Japan, and India) are related species, but not C. samoensis. This is further indicated where the immatures and cytology have been studied. |