Culicoides riethi Kieffer

Shults, Phillip & Borkent, Art, 2018, Pupae of the Nearctic species of Culicoides Latreille subgenus Monoculicoides Khalaf (Diptera: Ceratopogonidae), Zootaxa 4504 (4), pp. 451-472 : 463

Culicoides riethi Kieffer

( Figs. 1 , 3B , 6B , 8A )

Diagnosis. The only species of C. ( Monoculicoides ) with anterior portion of segment 9 greatly swollen ( Fig. 8A ).

Description. Male. Total length = 3.30–3.70 (3.5, 0.283 SD, n=2) mm. Medium brown coloration throughout ( Fig. 1 ). Head: Dorsal apotome (DA) roughly 90% covered in uniform spicules ( Fig. 3B ). DA length = 0.32–0.33 (0.325, 0.007 SD, n=2) mm; DA width = 0.21–0.22 (0.215, 0.007 SD, n=2) mm; DAW/DAL= 0.636–0.688 (0.662, 0.036 SD, n=2). DA–1–H apex extending past ventral margin of DA. CL–1–H about twice length of CL–2–H, CL– 3–H campaniform sensilla medial. Thorax: Cephalothorax length = 1.00–1.13 (1.08, 0.057 SD, n =2) mm. Respiratory organ (RO) elongate, slender, 1–2 subbasal pores, RO length = 0.21–0.26 (0.23, 0.016 SD, n=2) mm; RO width = 0.03–0.035 (0.030, 0.001 SD, n=2) mm; ROW/ROL = 0.1 1–0.15 (0.13, 0.01 SD, n=2), D–5–T short. 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 ( Fig. 6C ) 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 elongated 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, with lateral shagreen. Segments 5–7 with similar chaetotaxy, shagreen to that of segment 4. Segment 8 slightly swollen, with seven sensilla, with lateral shagreen. Segment 9 with anterior shagreen, anterior margin greatly swollen.

Female. S imilar to male other than sexual differences on segment 9 and the following: total length = 3.50–3.94 (3.66, 0.241 SD, n=3) mm, DA length = 0.31–0.34 (0.32, 0.017 SD, n=3) mm, DA width = 0.21–0.23 (0.22, 0.01 SD, n=3) mm, DAW/DAL = 0.65–0.74 (0.689, 0.048 SD, n=3), Cephalothorax length = 1.35–1.40 (1.38, 0.025 SD, n=3) mm, RO length = 0.37–0.41 (0.387, 0.021 SD, n=3) mm, RO width = 0.05–0.06 (0.057, 0.006 SD, n=3) mm, ROW/ROL = 0.13–0.16 (0.147, 0.015 SD, n=3).

Taxonomic discussion. Pupae of C. riethi are medium brown in coloration ( Fig. 1 ), similar to that of C. shemanchuki , but have much more lateral shagreen than that species. The density of the spines on the DA ( Fig. 3B ), abundance of lateral shagreen on all abdominal segments, and the swollen anterior most region of segment 9 ( Fig. 8A ) make this the most distinctive species of C. ( Monoculicoides ). Like C. occidentalis , this species has an additional clypeal seta not seen in other members of the subgenus, although no specimen has been observed with a CL–4–H. The pupa of C. riethi has been redescribed by many authors since its original description by Kieffer (1914) ( Rieth 1915, Thienemann 1928, Mayer 1934, Kettle & Lawson 1952, Dzhafarov 1964, Damian-Georgescu & Spătaru 1971, and Glukhova 1989) and we found no contradictions in those papers to our description.

This species is Holarctic in distribution. In North America it ranges from Alaska to Manitoba, south to British Columbia, Wyoming and Nebraska ( Borkent & Grogan 2009 (as C. gigas ), Grogan & Lysyk 2015).

Material examined: 2 males, 3 females, (1 female TAMU, voucher series #732; 2 males, 2 females CNCI), Canada, B.C., White Lake , 5 km SW Okanagan Falls, 49°18’27.51"N, 119°138’00.23"W, 4.V.2014, A. Borkent.

Figures

FIGURE 1. Habitus of the pupae of Culicoides occidentalis (left) and C. riethi (right) in dorsal view.

FIGURE 3. Female, dorsal apotomes, in anterior view. (A) Culicoides occidentalis. (B) C. riethi. (C) C. sonorensis. (D) C. variipennis.

FIGURE 6. Male, lateral and ventral tubercles of abdominal segments 4, in dorsal view (A) Culicoides occidentalis. (B) C. riethi.

FIGURE 8. Female abdominal segments 8–9, in dorsal view. (A) Culicoides riethi. (B) C. occidentalis.