Scirtes adustus Boheman, 1858

Ruta, Rafał & Libonatti, María Laura, 2016, Redescriptions of Scirtidae (Coleoptera: Scirtoidea) described by Carl Henrik Boheman (1796 – 1868) with notes on Scirtes adustus diversenotatus Pic, 1930, Zootaxa 4072 (2), pp. 203-216 : 209-211

Scirtes adustus Boheman, 1858

( Figs 1 E–F, 7, 8, 9)

Scirtes adustus Boheman, 1858: 72 (type locality: Montevideo)

Type material (2 specimens, NHRS). Lectotype (present designation), male. “Monte- \ video”; “Kinb.”; “ Type ”; “Sc. ad. ♂ \ T” [handwritten by T. Nyholm]; “ Type ” [red label]; “NHRS-VKBS \ 000000415”. [genitalia dissected and photographed]. Paralectotype (present designation), female. “Monte- \ video”; “Swedish Museum \ of Natural History \ Stockholm \ NHRS ”.

Additional material studied. 6 specimens ( MACN): 1 ♂, “Riachuelo \ Colonia Uru \ A. Stévenin” [white label, printed]; 1 ♂ and 1 ♀, “S. Fernando”, “ Scirtes \ sp.” [both white labels, handwritten]; 1 ♀, “ ARGENTINA \ S. Fernando \ BS AIRES ” [white label, printed except “S. Fernando”, which is handwritten], “35815” [white label with red edge, handwritten]; 1 ♂, “ ARGENTINA \ M Garcia \ BS AIRES ” [white label, printed except “M Garcia”, which is handwritten]; 1 ♂ ( MLLC): Ciudad Autónoma de Buenos Aires, Reserva Ecológica Costanera Sur, Laguna de los Patos, 10.xi.2014, S. A. Mazzucconi.

Redescription. Lectotype, male. Body oval, depressed, shining, covered with yellowish setae, which are easily broken and present in the studied specimen only on head and sides of elytra. Head brownish, pronotum with brownish central portion and yellowish sides, elytra yellowish. Antennomeres 1–5 yellowish, remaining brown, legs yellowish with darker femora.

Head moderately convex, covered with punctures which are separated by ca. 1.0–1.5 diameters; clypeus moderately long, transversely rectangular, front margin shallowly arcuate. Eyes moderately large, HW/IS 1.7. Antennae filiform. Pronotum slightly convex, punctures a bit shallower than on head; antero-lateral angles subtriangular, slightly projecting anteriorly; postero-lateral angles almost right-angled, somewhat projecting posteriorly; posterior margin subtly bisinuate; PW/PL 2.2. Scutellar shield finely punctate, equilateral-triangular. Elytra oblong-oval, sides rounded, punctures distinctly stronger than on head and pronotum, separated by ca. 1.0 diameter; humeri elevated; EL/EW 1.3; EL/PL 4.0; EW/PW 1.4; TL/EW 1.6. Hind tibial spurs slightly curved, dorsal one ca. 0.6 X as long as tarsomere 1, ventral one 0.5 X as long as dorsal one.

Penis long and narrow (L 1.31 mm, W 0.15 mm), asymmetrical, with serrate margin and large apical hook-like projection; tegmen (L 1.27 mm, W 0.40 mm) symmetrical, with single basal apodeme and short parameres which are widened before apices; sternite 8 absent; sternite 9 membranous, bilobed; tergite 8 (L 0.92 mm, W 0.51 mm) with subtrapezoidal apical plate and moderately long apodemes, apical margin with large median projection (better visible in fresh specimens than in type specimen); tergite 9 (L 0.77 mm, W 0.32 mm) smaller, with long apodemes and short apical plate.

Female. TL 3.25 mm, body brownish. Prehensor (L 0.60 mm) subrectangular, membranous and lightly sclerotized; bursal sclerite (L 0.23 mm, W 0.18 mm) subrectangular, with three spines.

Sexually dimorphic characters. Apical part of elytra with longer setae in females (absent in males). Tergite 7 with medial posterior area devoid of microtrichia (completely covered with microtrichia in males), with posterior margin parabolic (rounded in males). Ventrite 5 with a pair of foveae (absent in males).

Measurements. Male, n = 1. TL 3.3 mm, PL 0.65 mm, PW 1.5 mm, EL 2.7 mm, EW 2.15 mm. Female, n = 1. TL 3.4 mm, PL 0.68 mm, PW 1.5 mm, EL 2.65 mm, EW 2.15 mm.

Variability. TL in additional studied specimens: males (n = 4): 2.94–3.40 (mean 3.14) mm; females (n = 2): 3.30–3.74 (mean 3.52) mm. Males vary in the degree of dark colouration on elytra and in the extent of the brownish central area on pronotum.

Distribution. Uruguay: Montevideo (according to Persson (1971), excursions were made in the vicinity of Colonia and the Cerro hill at Montevideo between 29.12.1851 – 16.01.1852); Argentina. This species is distributed in the coastal area surrounding the Río de la Plata estuary, including the Martín García Island.

Remarks. In the original description, a range of measurements is given, therefore it is certain that the description was based on at least two specimens. It seems highly plausible that the female with no type label belonged to the original type series. The male specimen is designated here as the lectotype in order to preserve the stability of nomenclature by selecting one specimen as the sole, name-bearing type of the taxon.

Figures

FIGURE 1. Labels of type specimens. A) Brachycyphon marginipennis, male, lectotype; B) Brachycyphon marginipennis, male, paralectotype; C) Brachycyphon marginipennis, female, paralectotype; D) Contacyphon caffer, holotype; E) Scirtes adustus, male, lectotype; F) Scirtes adustus, female, paralectotype.