Culicoides (Borkent, 2014)

Shults, Phillip & Borkent, Art, 2018, Pupae of the Nearctic species of Culicoides Latreille subgenus Monoculicoides Khalaf (Diptera: Ceratopogonidae), Zootaxa 4504 (4), pp. 451-472 : 465-466

Culicoides stigma Meigen

( Fig. 4A )

Diagnosis. The only species of C. ( Monoculicoides ) with short respiratory organ (± 0.26 mm in length) ( Fig. 9 ) and short uniform spicules on the dorsal apotome ( Fig. 4A ).

Description. Male. Total length = 2.05–2.60 (2.39, 0.137 SD, n=17) mm. Light brown coloration throughout. Head: Dorsal apotome (DA) roughly 90% covered in short, uniform spicules ( Fig. 4A ), DA length = 0.28–0.32 (0.299, 0.014 SD, n=17) mm; DA width = 0.17–0.19 (0.179, 0.004 SD, n=17) mm; DAW/DAL= 0.58–0.64 (0.601, 0.024 SD, n=17). Thorax: Cephalothorax length = 1.00–1.13 (1.08, 0.057 SD, n =17) mm. Respiratory organ (RO) slender, 1–2 subbasal pores, RO length = 0.21–0.26 (0.23, 0.016 SD, n=17) mm; RO width = 0.03 0–0.035 (0.03, 0.001 SD, n=17) mm; ROW/ROL = 0.11–0.15 (0.13, 0.01 SD, n=17). Abdomen: Tergite 1 with long D– 3–I, short D– 2–I, D– 7–I anterior, short D– 4–I, and long, thin D– 9–I separated medially by campaniform D– 8–I on short tubercle posteriorly, L– 2–I, L– 3–I short separated medially by long, thin L– 1–I on lateral margin. Chaetotaxy, shagreen of tergite 2 similar to tergite 4, without elongate tubercles, minute L– 2–II, L– 4–II separated medially by long, thin L– 3–II on anterolateral margin. Chaetotaxy, shagreen of segment 3 similar to that of segment 4. Tergite 4 with short D– 2–IV on short tubercle, thin D– 3–IV on elongate, pointed tubercle, D– 5–IV, D– 4–IV, D– 7–IV, D– 8– IV, D– 9–IV in transverse row, arranged medially to laterally, minute D– 5–IV on slightly formed tubercle, D– 4–IV on small tubercle, D– 7–IV on small rounded tubercle, D– 8–IV, D– 9–IV each long on pointed tubercle, D– 8–IV seta thicker than D– 9–IV; lateral tubercles with short, blunt apices, L– 1–IV thick seta on small bifurcate tubercle, L– 2–IV, L– 4–IV thick setae, each on elongate, bifurcate tubercle, separated by thin L– 3–IV on elongate, bifurcate tubercle; sternite 4 with minute V– 5–IV on small rounded tubercle, V– 6–IV thin on pointed tubercle, small V– 7– IV on pointed tubercle, ventral setae in transverse row, shagreen along anterior margins, lateral shagreen reduced or absent. Segments 5–7 with similar chaetotaxy, shagreen to that of segment 4. Segment 8 chaetotaxy with seven sensilla, without lateral shagreen. Segment 9 with anterior shagreen, anterior margin not strongly modified.

Female. Similar to male other than sexual differences on segment 9 and the following: total length = 1.94–2.86 (2.04, 0.248 SD, n=15) mm, DA–1–H apex extending past ventral margin of DA, DA length = 0.23–0.3 (0.267, 0.018 SD, n=15) mm, DA width = 0.17–0.215 (0.197, 0.016 SD, n=15) mm, DAW/DAL = 0.65–0.79 (0.737, 0.035 SD, n=15), Cephalothorax length = 1.00–1.15 (1.07, 0.059 SD, n=15) mm, RO length = 0.21–0.26 (0.237, 0.015 SD, n=15) mm, RO width = 0.03–0.035 (0.031, 0.003 SD, n=15) mm, ROW/ROL = 0.11–0.15 (0.133, 0.019 SD, n=15).

Taxonomic discussion. This species is one of the smaller members of C. ( Monoculicoides ), along with C. sonorensis and C. grandensis , but has a proportionally smaller respiratory organ ( Fig. 9 ) in comparison to its body size. The total range of the ratio of respiratory organ length to cephalothorax length of all other C. ( Monoculicoides ) examined was 0.27–0.31 (n=54), whereas in C. stigma, it is significantly lower 0.19–0.22 (n=32).

This species is Holarctic. However, in North America it is currently known only from central Alberta. The pupa of this species was originally described by Kettle & Lawson (1952) and redescribed in two other studies ( Dzhafarov 1964; Spătaru 1971), and our study did not find any contradictions with these studies. Although this species is reported as Holarctic, our description of the pupa is based solely on Palearctic material. It is possible that there are morphological differences between populations from the two regions.

Material examined: 12 males, 7 females ( ZIN), Russia, Kaliningrad Province, Rybachii village, Curonian Spit National Park [at the Baltic Sea coast], 16– 17.07.1989 , Glukhova. 1 female ( ZIN), Russia, Leningrad Province, Luga district , forest ditch with water, 27.07.1979 , Brodskaya. 1 female ( ZIN), Russia, Leningrad Province, environs of Luga town , ditch with moss, 13.08.1979 , Brodskaya. 1 female ( ZIN), Russia, Leningrad Province, Luga district, floodplain of river Obla, 24.08.197, Brodskaya . 3 males, 3 females ( ZIN), Luga district , in ditch, 12–14.VIII.1979 . 1 male, 1 female ( ZIN), Russia, Republic of Karelia, 1966 . 1 male, 1 female ( ZIN), Russia, Republic of Karelia, 2–4.VII.54 .

Figures

FIGURE 4. Female, dorsal apotomes, in anterior view. (A) Culicoides stigma. (B) C. grandensis. (C) Female mouthparts, in anterior view of C. occidentalis.

FIGURE 9. Box plots of measurements of the length of respiratory organs by species. Species ordered by ascending values.