Culicoides (Monoculicoides) shemanchuki Grogan and Lysyk, 2015

William L. Grogan, Jr. & Lysyk, Timothy J., 2015, A revision of the biting midges in the Culicoides (Monoculicoides) nubeculosus-stigma complex in North America with the description of a new species (Diptera: Ceratopogonidae), Insecta Mundi 2015 (441), pp. 1-24 : 3-6

Culicoides (Monoculicoides) shemanchuki Grogan and Lysyk , new species ( Fig. 1–8 )

Culicoides n. sp. ( C. nubeculosus group): Downes 1958a: 431 (Alberta; figs. male, female antenna; descriptions of larval habitat, autogeny, mating behavior); Downes 1971: 238 (photos of female head, palpus, mouthparts; comments on reduction in size of proboscis, mandible, and numbers or total loss of teeth).

Diagnosis. A medium to large species of the C. nubeculosus - stigma complex most closely resembling C. riethi , but differing from that and other Nearctic species in this complex by the following combination of characters: male wing length 1.22–1.39 mm, female wing length 1.57–1.97 mm; wing membrane and veins dusky brown with indistinct pale spots just beyond apex of costa and over r-m crossvein, and pale streaks in mid portion of cell m 2 and posterior to base of vein CuA 1; femora, tibiae usually without distinct pale bands, fore tibia with poorly developed subapical pale band in some specimens. Male: gonocoxite and gonostylus very short; tergite 9 greatly tapered distally with elongate, conical, divergent apicolateral processes; aedeagus with broad distal portion and rounded apex; parameres fused proximally with bifurcate distal portion. Female: mandible usually with 2–7 small teeth on inner margin (a few specimens without teeth); lacinia without teeth; palpal segment 3 very short (palpal ratio 1.46–2.17); spermatheca elongate with numerous tiny hyaline punctations and a broad opening.

Male. Head: ( Fig. 1 ) Brown. Eyes widely separated by diameter of 4–5 ommatidia, with sparse minute inter-ommatidial spicules. Antennal flagellum with flagellomeres 1, 11–13 separate, 2–10 completely or partially fused; flagellomeres 11–13 considerably longer than 2–10; all flagellomeres covered with short, fine setae; flagellomeres 1, 5–8 with single apical sensilla coeloconica (rarely on 5 or 9; one specimen with 2 sensilla on 8); flagellomere 1 with 2 rows, 2–13 with single row of sensilla chaetica, those on 1–10 comprising the moderately long, sparse plume; combined total lengths of flagellomeres 0.707 (0.666 –0.747, n=14) mm; antennal ratio 0.65 (0.62–0.69, n=14). Palpus similar to female; segment 3 very short, moderately swollen, with well-developed shallow mesoapical pit bearing numerous long capitate sensilla that extend well beyond pit opening; palpal ratio 1.75 (1.46–2.00, n=14). Proboscis short, mandible and lacinia vestigial, without teeth. Thorax: ( Fig. 2 ) Dark brown to golden brown; scutellum paler with 2 marginal, 3–4 centrally located large setae. Legs brown, similar to female; claws smaller, gently curved with bent, deeply bifid tips. Wing ( Fig. 3 ) shorter, narrower than female; wing membrane covered with dense, coarse microtrichia; macrotrichia restricted to costa, radius, moderately dense on anterior margin of cell r 3, few or absent on central portions of cells m 1, m 2, sparse along apical margins of m 1, m 2; veins infuscated brown, distal portion of costa, 2 nd radial cell darker; indistinct pale spots just beyond apex of costa and over r-m crossvein, pale streaks in cells m 1, m 2; wing length 1.31 (1.22–1.39, n=18) mm; costal ratio 0.55 (0.52–0.57, n=17). Halter pale brown. Abdomen: Dark brown to medium brown. Genitalia ( Fig. 4 ) dark brown. Tergite 9 abruptly tapering distally to narrow, rounded apex with narrow, deep, V-shaped median notch; apicolateral process elongate, conical, tapered distally with single short apical seta, apices divergent; cercus large, setose, extending to mid-length of apicolateral process. Sternite 9 nearly 3 x broader than long, anterior margin slightly curved, posterior margin with moderately deep V- or U-shaped excavation. Gonocoxite nearly straight, stout, slightly longer than broad with well-developed, heavily sclerotized mesobasal tubercle, apex broad; dorsal root heavily sclerotized, extending to or near base of parameres. Gonostylus as long as gonocoxite; stout proximally, curved, tapering at mid-length to moderately slender apex, tip pointed. Parameres Y-shaped, heavily sclerotized, fused basally; basal arm stout, broad, slightly curved; extreme base tapered, apex slightly pointed; distal portion deeply bifurcate, each half slender, well separated with narrow sharply pointed apex that extends below level of apex of aedeagus. Aedeagus heavily sclerotized on basal arm and mid portion; basal arm stout, recurved nearly 90 ◦, apex rounded; basal arch U-shaped, extending 0.35–0.40 of total length; distal portion more lightly sclerotized, heaviest on margins, expanded distally to broadly rounded apex, tips of margins ventrally directed and extend just beyond apex.

Female. Head: ( Fig. 5 ) Brown. Eyes moderately separated by diameter of 3–4 ommatidia; with sparse fine inter-ommatidial spicules. Antennal flagellum with flagellomeres 9–13 slightly to considerably longer than 2–8, 13 longest; flagellomeres 1, 6–8 (rarely 5–8 or 6–9) with single apical sensilla coeloconica, rarely with 2 sensilla, sensilla rarely absent on 6 or 7; flagellomeres covered with short, fine setae and single whorl of moderately long sensilla chaetica; total combined lengths of flagellomeres 0.640 (0.594 –0.699, n=17) mm; antennal ratio 0.85 (0.80–0.91, n=17). Palpus 5-segmented; segment 3 very short, swollen, with large shallow subapical pit bearing numerous long capitate sensilla that extend well beyond pit opening; palpal ratio 1.79 (1.46–2.17, n=17). Proboscis short, proboscis/head ratio 0.65 (0.60–0.70, n=12); mandible with 2–7 small apical teeth on inner margin, rarely without teeth; lacinia vestigial, without teeth. Thorax: ( Fig. 6 ) Mesonotum with scutum medium dark brown to golden brown with 2 narrow to moderately broad submarginal golden stripes; humerus, lateral margins golden; scutellum light brown or golden with 7–13 large setae arranged more or less linearly along mid-line; postscutellum medium brown to golden brown; pleural regions light brown to golden; katepisternum medium brown. Legs medium to light brown; femora, tibiae generally without distinct pale bands, fore tibia with poorly developed subapical pale band in some specimens; femorotibial joints dark brown; femora, tibiae with sparse coarse setae, most numerous dorsally; tarsomeres 1–3 with 2 apical spines; hind tibial comb with 6 spines, 2 nd longest, slightly longer than 3 rd, spur massive, bifurcate; claws small, curved distally, tips pointed, entire. Wing ( Fig. 7 ) membrane covered with dense, coarse microtrichia; macrotrichia sparse, longest on costa, radius, much shorter macrotrichia on distal portions of vein M 1, present or absent on M 2, CuA 1, CuA 2, also present on distal half of cell m 1, in a few more or less linear rows or absent in cells m 2, cua 1; radial cells well developed but narrow, or reduced to sutures or completely coalesced, distal portion of costa, 2 nd radial cell dark, posterior veins paler; membrane infuscated with indistinct pale spots in cell r 3 just beyond end of costa and over r-m crossvein, a pale streak in mid portion of cell m 1, m 2 and posterior to base of vein CuA 1, poorly defined pale areas may also be present in cell CuA 1 and anal cell; wing length 1.74 (1.57–1.97, n=18) mm; costal ratio 0.58 (0.55–0.62, n=18). Halter stem pale to light brown; knob whitish, but may appear blackish in some slide mounted specimens. Abdomen: ( Fig. 8 ) Brown, light brown or golden in gravid specimens; segments 7–10 brown to medium dark brown; tergite 8 with short anterior, heavily sclerotized, crescent-shaped band, sternite 8 with wrinkled posterior margin; segment 9 a continuous band without well-defined pleurae; sternite 10 broadly triangular with 2 pairs of large ventral setae. Spermatheca elongate, ovoid to egg-shaped; heavily sclerotized with numerous tiny hyaline punctations; distal portion may be narrowed or constricted, with broad opening; neck and duct non-sclerotized but readily visible; total length 0.088 (0.077 –0.102, n=18) mm.

Distribution. Southern and central Alberta and North Dakota, however, it may also occur in other northern Great Plains states in the United States and in Saskatchewan and Manitoba, Canada (see Bionomics).

Etymology. The specific epithet is a patronym in honor of Joseph A. Shemanchuk, mentor of TJL at Lethbridge Research Centre, and in recognition of his pioneering work on Culicoides in Alberta.

Type material. Holotype male, CANADA, Alberta, Fort Macleod , 20.VI.1955, (J. A. D. 194/6/14); allotype female, same data, (J. A. D. 194/8/5); paratypes, 15 males, 18 females, same locality data except J. A. Downes, 10.VI.1955 (males, J.A.D. 184/1/351; females, J.A.D. 184/1/15-19, 352) and 20.VI.1955 (males, J.A.D. 194/8/4, 17-24, 32-35, 194/11/4; females, J.A.D. 194/5/5, 194/6/24,37, 194/8/25-31, 194/11/1- 3) . Holotype, allotype and paratypes deposited in CNCI. Other paratypes: UNITED STATES, North Dakota, Pierce Co., Pleasant Lake, June 1969, W. W. Wirth, alkali lake, 11 males, 9 females with associated pupal exuviae.

Other material examined. Additional pinned specimens, probably the same species, but are not designated paratypes, with same locality data as holotype and allotype: 10.VI.1955 (28 females, J.A.D 184/1/321-343), 20.VI.1955 (8 males, J. A. D. 194/7/4,15,17-22; 10 males, J.A.D. 194/7/2, 5-13), and 22.VII.1955 (17 males J. A. D. 220/5/52,53,55,57,59,62,65,66,86; 220/1/45-48,50,51,53; 221/4/108; 13 females, J.A.D. 220/5/54,56,58,60,63,64; 220/1/42-44,49,52,54; 221/4/72) .

Discussion. This new species most closely resembles C. riethi , which differs from C. shemanchuki by its darker wing with numerous light and dark maculations, and a longer, more slender palpal segment 3. Males of C. riethi differ from males of C. shemanchuki in being larger (wing length 1.46–1.74 mm; vs. 1.22–1.39 mm for males of C. shemanchuki ), with overall longer genitalia, an aedeagus with bifurcate distal portion, a longer gonostylus that is abruptly curved at midlength with a very slender distal half, and a much broader tergite 9 with more widely spaced apicolateral processes. Females of C. riethi further differ from females of this new species in having a mandible with 9–14 larger teeth, a lacinia with 18–25 large teeth, and a broader spermatheca.

Bionomics. In his article on assembly and mating in biting nematocerous Diptera, Downes (1958a) provided details of the unusual mating behavior in the related Palearctic species, C. nubeculosus (Meigen) in a section entitled “Some Examples of Other Patterns of Mating” that include “A number of species which depart widely and conspicuously from the normal are now to be considered. It is a remarkable fact that these species, differing so markedly in certain aspects of their behavior, economy and structure, are nevertheless closely related to normal species and frequently fall within the same sub-genus” [ Monoculicoides ].

Downes (1958a) continued with “This section can best be introduced by a further account of Culicoides nubeculosus , a blood-sucking and anatomically normal species that can exhibit the whole of the typical behavior of swarming and mating in flight. Unlike most others, however, it is also able to mate in an entirely different manner, in a confined space, without flight, and with antennal setae decumbent and thus without an auditory response to the female. When a male, not in flight, encounters and touches a female, there is an immediate response and normal mating takes place. The female may be crawling, or at rest, or in the act of blood-sucking. She is not recognized at a distance, and direct contact, probably by the legs of the male, is necessary. This mating response is not specific; it is elicited not only by females but also by other males and by the females of other species of Culicoides . It may perhaps be supposed that it represents the final stage of the process of mating during the swarming flight, when the male has moved towards the female and the first contact occurs.”

“This second manner of mating in C. nubeculosus has been studied only in the laboratory, but it may occur in nature also since the species breeds at high densities in restricted environments (farms, sewage plants, etc.) and the adults would have a certain chance of encountering each other on the surface of the larval habitat. In Russia, however, it has been recorded that the males are attracted to the host of the females, cattle, and so encounter them as they are feeding.” Similar behavior was noted in the primary vector of bluetongue in the Nearctic region, C. sonorensis by Gerry and Mullens (1998), who observed males swarming near cattle, and then landing and mating with females while they fed upon cattle in southern California.

In his next paragraph, Downes (1958a) describes details of “…a new species of Culicoides , belonging to the nubeculosus group, from southern Alberta.” This species is C. shemanchuki , new species, about which Downes wrote “The larval habitat is very localised, being confined to the zone of damp mud that often surrounds alkaline prairie sloughs, and the larvae occur at very high densities. It is not a blood-sucking species–the mouthparts of the female are reduced–and the ovaries develop within two or three days of emergence from the pupa at the expense of internal reserves. These characteristics, by eliminating the need for dispersal and searching, probably determine its ability to maintain the high level of population.”

“Both sexes fly in the immediate neighbourhood of the larval habitat, although probably to an unusually small extent; male swarms have not been detected. Both sexes also, however, have the habit, not recorded in any other species of Culicoides , of running about rapidly in a random exploratory manner on the surface of the mud; and since the surface is flat and unencumbered by vegetation it provides optimum conditions for accidental meeting. Mating occurs on contact exactly as in the second manner described for C. nubeculosus ; it does not depend on the flight of the female or the erection of the antennal setae of the male and contact occurs only by chance; the claspers of the male, moreover, are somewhat enlarged and heavily sclerotized, and presumably unusually efficient. The mating response is elicited by females and males.”

Finally, Downes (1958a: fig. 5) included a photo of the antenna of a male C. shemanchuki (as C. n. sp.), in which the plume is “…much reduced, and the pedicel, which contains the vibration-sensitive sensilla, is much smaller than usual. Both features suggest that the antenna has become non-functional as an auditory organ, in relation to the novel habits of this species.” In a subsequent article, Downes (1971) provided photographs of the head and mouthparts of a female C. shemanchuki , that he referred to as “…an autogenous biting midge ( Culicoides sp. nov.) closely related to C. variipennis .” He also wrote, “Note the shortened proboscis and other changes in head structure and the feebly sclerotized mandibles, lacinia, and labrum, with armature vestigial or absent.”

Figures

Figures 1–4. Culicoides shemanchuki n. sp., male, from Warner, Alberta, Canada. 1) Head. 2) Thorax. 3) Wing. 4) Genitalia.

Figures 5–8. Culicoides shemanchuki n. sp., female, from Warner, Alberta, Canada. 5) Head. 6) Thorax. 7) Wing. 8) Distal portion of abdomen and spermatheca.