Tanytarsus occultus Brundin, 1949

Giłka, Wojciech & Gadawski, Piotr, 2022, Tanytarsini (Diptera: Chironomidae) collected during Polish expeditions to North Korea, Zootaxa 5214 (2), pp. 151-175 : 161

Tanytarsus occultus Brundin, 1949

Tanytarsus holochlorus Edw. : Brundin 1947: 67 (male, fig. 100; Sweden).

Tanytarsus occultus Brundin, 1949: 847 (male, Sweden); Reiss & Fittkau 1971: 89, 123 (male, fig. 35a–c, in key); Ekrem et al. 2003: 315 (male, pupa, figs 248–250; Europe, North America); Ekrem 2004: 137 (pupa, figs 183–187); Giłka & Paasivirta 2007: 107– 110 (male, figs 2–4, 13, 16; Fennoscandia); Giłka et al. 2018: 573–576 (male, diagnostics, barcoding, phylogeny).

Material examined. Phjŏngjang, 13 June 1981, 2 males; Sokam, 8 July 1981, 3 males; leg. W. Krzemiński.

Remarks. A diagnostic character of the Tanytarsus occultus male is the hypopygial anal point, usually with a square or concave apex, which the shape, however, may be affected by strong intraspecific variations. T. occultus was described on the basis of a males’ series by Brundin (1949), who referred the description to his illustration of a specimen’s hypopygium presented two years earlier [ Brundin 1947, originally erroneously as Tanytarsus holochlorus (= T. mendax Kieffer, 1925 )]. The illustration was apparently based on a specimen with a hypopygial anal point of a structure rarely observed in T. occultus . That choice could lead to confusion until Reiss & Fittkau (1971) redescribed the male on the basis of Brundin’s series, indicating variations in the shape of the anal point, thus stabilizing the status of the species. Recently, one more close species was described, Tanytarsus latens Giłka, Paasivirta, Gadawski et Grabowski, 2018 , in which the anal point is similar or nearly identical (variable) to that illustrated from the atypical specimen of T. occultus by Brundin (1947). In case of these two species, the anal point structure can be thus critically misleading in their delimitation. The characters best separating males of the two species is the shape/length of the superior volsella and the digitus, and the arrangement of anal tergite bands (cf. Giłka et al. 2018). T. occultus is one of the best-defined species in the genus in term of morphological variability and diagnostics supported by molecular analyses ( Reiss & Fittkau 1971; Ekrem et al. 2003, Ekrem 2004; Giłka & Paasivirta 2007, Giłka et al. 2018). Only now recorded from North Korea.