Leptoconops (Leptoconops) carteri Hoffman, 1926

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 : 26-27

Leptoconops (Leptoconops) carteri Hoffman

( Fig. 12 , 16–19 )

Leptoconops carteri Hoffman, 1926: 133 (female; fig. antenna, palpus, spermathecae, abdomen; California).

Leptoconops (Leptoconops) carteri: Wirth and Atchley 1973: 22 (resurrected from L. torrens synonymy; key; female, male; fig. female head, wing, palpus, abdomen, subgenital plate, spermathecae, eye, male genitalia, antenna; larva comparison to Kerteszi group [as L. kerteszi , p. 9]; biology). Atchley 1974: 467 (female; distinction from L. torrens [Townsend]).

Leptoconops torrens , misidentified: Freeborn and Zimmerman 1934: 258 (demoted L. carteri to junior synonym; male; fig. male wing, genitalia, female wing; Yolo County, California). Smith and Lowe 1948: 167 (egg, larva, female, male; biology; fig. larva habitus, last segment, internal head morphology; Sacramento, Santa Clara, and San Joaquin Valleys, California). Wirth 1952a: 110 (in part; key; female; male genitalia; fig. female wing, abdomen, palpus, male genitalia). Fox 1955: 263 (in part; key; taxonomy). Fontaine et al. 1957 (biology). Whitsel and Schoeppner 1965 (biology). Whitsel and Schoeppner 1966 (biology). Whitsel and Schoeppner 1970 (in part; biology).

Diagnosis. ( Table 13) Entirely dark brown to black; stigma brown (as in Fig. 5 L . torrens); eyes with sparse minute interommatidial pubescence on lower portion; clypeus with eight or more setae; palpal segment 3 sensilla in superficial excavation wider than deep; hind tibial comb with four spines; claw with basal bristle, without basal tooth. Female: antenna with 12 flagellomeres; mandible with 16–18 prominent teeth; hind tarsomeres 3 and 5 subequal; two ovoid spermathecae usually ~1.4× longer than wide, third absent; cerci>3× longer than wide (as in Fig. 6 L . torrens). Male: flagellomere 13 ~1.5× longer than 12; tergite 9 evenly tapering to base of thin widely separated apicolateral processes, which are ~8× longer than wide and separated by a distance about equal to their length; aedeagal sclerites apically fused, blunt; distal sclerite of paramere ~2× longer than wide, apical portion flat, not bent.

Distribution. Central Valley of California.

Biology. Northern and central California references to L. torrens from 1934 to 1973 refer wholly or in part to L. carteri .

Larval ecology. Leptoconops carteri (as L. torrens ) larvae have been found 0.4–1.0 m deep in alkaline soils with>40% expanding clay that crack on drying, which allow adult egress for dispersal and access for oviposition ( Smith and Lowe 1948; Fontaine et al. 1957, as L. torrens ). Normal larval development time was 2 years, but could be 1–5 years, depending on precipitation; inadequate soil moisture-initiated diapause; and pupal development took <5 d ( Whitsel and Schoeppner 1966, as L. torrens ).

Experiments have shown that inter-ommatidial pubescence helps protect insect eyes by reducing impact and deposition of airborne particles onto ommatidia ( Amador et al. 2015). Similarly, L. carteri ’s eye hairs may prevent soil particles from lodging between or damaging ommatidia and facilitate adult egress from the soil larval habitat.

Life cycle. Unlike L. torrens , L. carteri does not form mating swarms ( Smith and Lowe 1948, as L. torrens ). In the laboratory at 24 °C, Whitsel and Schoeppner (1970, as L. torrens ) found females laid an average of 19 eggs, of which 43% were viable. Furthermore, Schmidtmann and Washino (1982) found that Sacramento Valley, California, populations had high rates of autogeny and that some of the anautogenous females survived in the wild long enough to take a second blood meal, contrary to previous studies ( Smith and Lowe 1948, Whitsel and Schoeppner 1970) that suggested this species was extremely short-lived.

Adult behavior. Leptoconops carteri is a locally seasonal severe biting pest of humans, other mammals, and birds ( Smith and Lowe 1948; Fontaine et al. 1957, as L. torrens ). Whitsel and Schoeppner (1965, as L. torrens ) found it a strictly diurnal biter, peaking between 1100 and 1500, when air temperature was 21–38 °C, relative humidity was 18% to 62%, and wind speed was <13 km /h. Laboratory observations ( Whitsel and Schoeppner 1970, as, L. torrens ) found L. carteri took from 2 minutes 20 seconds to 8 minutes 15 seconds, averaging 3 minutes 45 seconds, to blood-engorge on humans. In contrast with L. torrens , L. carteri tend to bite humans on the lower extremities rather than around the head and arms ( Wirth and Atchley 1973).

Incandescent light traps have been ineffective at collecting this species ( Fontaine et al. 1957, as L. torrens ), likely because it is diurnal. However, CO 2 -baited sticky traps were highly effective ( Whitsel and Schoeppner 1965, as L. torrens ), and males comprised nearly 2% of the collections, suggesting that males mate with females near their hosts ( Wirth and Atchley 1973).

Remarks. Of the eight specimens selected and slide-mounted from a Yolo County, California, collection from Dave Woodward, one female, identified as L. carteri based on having pubescent eyes, had spermathecae ( Fig. 17 ) like those described and illustrated by Wirth and Atchley (1973) for L. torrens . In addition, of seven L. torrens specimens examined from Utah and Arizona identified by having bare eyes, four had the elongate spermathecae normal for L. torrens (as in Fig. 17 ), two had an elongate and an ovoid spermatheca, and one had two ovoid spermathecae like those described for L. carteri (as in Fig. 16 ), further suggesting that spermathecal shape is not a reliable diagnostic characteristic for distinguishing these species. However, statistical comparison of spermathecal length in combination with the lengths of palpal segments 3 and 4 and flagellomeres 10 and 11 and ventral head width reliably distinguished the species consistent with their eye pubescence and biological differences ( Atchley 1974).

Figures

Figures 9–15. 9) Leptoconops americanus female clypeus, setae (s). 10) L. knowltoni female clypeus. 11) L. knowltoni female palpal segment 3. 12) L. carteri female palpal segment 3 (Yolo County, CA). 13) L. werneri female tarsomeres 4–5 and claw (paratype, Imperial County, CA [UCRC]). 14) L. werneri male genitalia, ventral view, tergite 9 apicolateral processes (T9alp), meso-posterior lobe setae (s) (Riverside County, CA [UCRC]). 15) L. belkini male genitalia, ventral view, tergite 9 sclerotized lobe (L) (Riverside County, CA [UCRC]).

Figures 16–19. Leptoconops carteri (Yolo County, CA). 16) Female terminalia with normal spermathecae. 17) Variant with spermathecae similar to those more typical of L. torrens. 18) Lateral view of lower portion of eye showing interommatidial pubescence.19) Male genitalia, ventral view, proximal sclerites and distal shieldlike fusion of the aedeagus (A), proximal and distal sclerites of a paramere (P), tergite 9 apicolateral processes (T9alp).

Figures 3–8. Female wings with cells (lower case) and veins (upper case) labeled. 3) Culicoides stonei. 4) C. atchleyi (Bonneville County, ID). 5) Leptoconops torrens. Female abdomen, ventral view. 6) L. torrens. 7) C. stonei. 8) L. californiensis, dorsal habitus (in alcohol, Yuma County, AZ [Carl Olson, with permission]).