Culicoides unicolor (Coquillett)

Phillips, Robert A., 2022, Culicoides Latreille and Leptoconops Skuse biting midges of the southwestern United States with emphasis on the Canyonlands of southeastern Utah (Diptera: Ceratopogonidae), Insecta Mundi 2022 (907), pp. 1-214 : 109-110

Culicoides unicolor (Coquillett)

(Fig. 227, 279)

Ceratopogon unicolor Coquillett, 1905: 65 (key; female, male; California).

Culicoides unicolor (Coquillett) : Hoffman 1925: 279 (combination; key; female; fig. wing, mesonotum). Root and Hoffman 1937: 152 (key). Wirth 1951: 85 (in part; keys; fig. male genitalia from California type). Wirth 1952a: 185 (in part as “poorly marked coastal phase”; female, male genitalia [all figures, larval and pupal descriptions, and larval habitats are for C. cavaticus as the “well-marked tree hole phase”]).

Culicoides (Oecacta) unicolor: Khalaf 1954: 36 (assignment to subgenus Oecacta ). Fox 1955: 258 (in part; keys). Jones 1956: 26 (misidentified). Wirth and Jones 1956: 167 (misidentified in key). Wirth and Hubert 1962: 193 (the eastern C. unicolor of Wirth and Jones [1956] is actually C. denticulatus ). Cochrane 1974: 128 ( C. franclemonti is part of C. denticulatus , thus part of eastern C. unicolor ). Wirth et al. 1985: 24 (numerical characters; fig. female wing).

Diagnosis. ( Tables 14, 15) Wing pattern greatly reduced and faint; r 2 dark; pale spots at tip of costa, on r-m crossvein extending to CuA fork, absent from midportions of M 1 and M 2, distal portions of r 3, m 1, m 2, cua 1, anal cell; eyes contiguous; flagellomeres 9–10 normal, each larger than 8; SCo pattern 1, 11–13; palpus with deep sensory pit ~0.4 diameter of segment; 11 mandibular teeth; apex of labrum with small distinct median lightly sclerotized grayish tonguelike projection; scutellum with nine setae on female; hind tibial comb with five spines; fore tarsomeres without apical spines; legs without pale banding; spermathecae subequal, with tapering sclerotized necks shorter than wide; sclerotized ring on spermathecal duct; male tergite 9 posterior margin concave, with distinct apicolateral processes extending beyond medial portion; ventral apodeme of gonocoxite broad with two short widely divergent processes, stoutly footlike; aedeagus Y-shaped, heavily sclerotized basal arms without submedian fingerlike lobes, median process simple, pointed, aedeagal ratio ~0.6; parameres separate, with fringe of spines on apical third, without submedian lobe.

Distribution. Alaska (USNM), British Columbia, Washington, Oregon, Idaho (Bonneville County, new state record), California, Colorado. One female was collected with UVLT on 14 July 2019 at 43.52974°N 111.18504°W and 2002 m elevation in the Snake River Range, Idaho.

Adult behavior. The mandibular and lacinial teeth on the female indicate it feeds on vertebrate blood; and though its hosts are unknown, it is a member of the Piliferus group, generally considered ornithophilic ( Wirth and Hubert 1962).

Remarks. My Idaho specimen matches the Wirth et al. (1985) data and the above diagnosis, which is a composite from the specimen and relevant items from Wirth 1951 (male genitalia figure from a type) and 1952a (items related to “poorly marked coastal phase”). Furthermore, despite being unable to see an entire wing (Fig. 227), the projection at the tip of the labrum (Fig. 279) is distinctive.

Culicoides unicolor originally encompassed the currently recognized species C. unicolor sensu stricto, C. cavaticus , C. denticulatus , and C. franclemonti . I have been unable to find descriptions of C. unicolor sensu stricto newer than that of the portions from Wirth (1951, 1952a).

In addition, the keys of Jones (1956), Wirth and Jones (1956), Grodhaus (no date), and Kramer and Wirth (no date) that say C. unicolor has 4–6 mandibular teeth seem to be conflating C. unicolor sensu stricto with C. denticulatus and the more recently described C. franclemonti , which are closely related eastern Piliferus group species with 3–6 teeth. Indeed, Wirth and Hubert (1962: 194) state in their discussion of C. denticulatus , “the remarkable reduction of the mandibular teeth, from whence comes the name denticulatus , is so far unique in these groups”, implying that C. unicolor sensu stricto has the greater number of teeth more normal for the Piliferus group.