Culicoides saundersi Wirth and Blanton

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 : 112-113

Culicoides saundersi Wirth and Blanton

Culicoides saundersi Wirth and Blanton, 1969a: 557 (female, male; fig. female antenna, palpus, wing, eye separation, spermathecae, male genitalia, parameres; Washington). Wirth et al. 1985: 36 (numerical characters; fig. female wing; placement in Chaetophthalmus group). Borkent and Dominiak 2020: 22 (rename Chaetophthalmus group as Saundersi group).

Diagnosis. ( Tables 14, 15) Brown; wing without pattern of pale spots, veins thicker and darker than normal (as in Fig. 4 C . atchleyi); eyes with prominent interommatidial pubescence; mandible with 14–18 teeth; two sclerotized ovoid spermathecae, vestigial third fingerlike; ventro-posterior membrane of male sternite 9 bare; aedeagus Y-shaped, median process simple, moderately slender, blunt, aedeagal ratio ~0.45; parameres fused at base by a narrow bridge, apex simple, slightly curved, extending beyond tip of aedeagus.

Distribution. Alaska, British Columbia, Washington, Montana, Oregon, California.

Adult behavior. This species has been collected while biting humans and from a magpie nest ( Wirth and Blanton 1969a), suggesting it may also feed on birds.

Larval ecology. Culicoides saundersi ’s larval habitat is unknown. However, the eye pubescence suggests a relatively dry soil habitat. See the discussion in the larval ecology section of C. atchleyi .

Remarks. No specimens of C. saundersi were examined.

Subgenus unplaced, Stonei group

Jones and Wirth (1978) state that males of the four recognized western species of the Stonei group ( C. stonei , C. mortivallis , C. owyheensis , and C. werneri ) are morphologically indistinguishable; however, C. werneri seems to be distinguishable—at least in part—by body and leg color and by the shape of the median process of the aedeagus. The females can be distinguished morphologically only by the combination of SCo pattern, antennal, palpal, and proboscis ratios, and mean wing length ( Jones and Wirth 1978). The ranges of these measurements and ratios have considerable overlap between species, with mean values differing by 13% for the antennal ratio, 19% for the palpal ratio, 9% for the proboscis ratio, and 13% for the wing length.

Furthermore, I found 20 different combinations of SCo patterns among 85 Stonei group females ( Table 17). SCo patterns ranged from the 1–12 of C. stonei , to the 1, 5–12 of both C. mortivallis and C. owyheensis , to the 1, 8–12 pattern of C. werneri , with some specimens possessing different SCo patterns on their antennae. Though the seasonal distributions for the mortivallis - owyheensis and unidentified Stonei group collections have peaks in late May (weeks 21, 22) and September (weeks 36, 37) (Table 5), no significant seasonal difference of SCo patterns was evident.

Such variability in SCo patterns and ratios casts doubt over the status of several of these species. In particular, the only way to distinguish C. owyheensis from C. mortivallis in Jones and Wirth’s (1978: 57) key is to compare wing lengths and to compare the ratios of the length of flagellomeres 7+8, the length of palpal segment 3, and the length of the proboscis to the length of flagellomere 9.

I did this with 10 randomly selected Stonei group specimens from Grand County having SCo patterns of 1, 5–12 on both antennae; however, though wing length was tabulated, the final determinations did not use wing length because of its variability depending on food availability and other environmental conditions during larval development ( Akey et al. 1978; Mullens 1987; Mullens and Rodriguez 1988; Smith and Mullens 2003). Using the medians between the published average values of the three ratio variables for the two species ( Jones and Wirth 1978), whereby values less than the median indicate C. mortivallis and values greater indicate C. owyheensis , seven of the specimens met all three criteria for C. mortivallis , one was intermediate within ~1% for all criteria, and one met two criteria and another met all three criteria for C. owyheensis ( Table 18).

Further study is needed to determine the status of species in this group and consider the possibility C. owyheensis and C. mortivallis are synonymous. Incidentally, Grand County, Utah, is ~ 660 km from the Inyo County, California, C. mortivallis type locality and ~ 710 km from the Owyhee County, Idaho, C. owyheensis type locality, and all are arid to semi-arid habitats.

Specimens not so evaluated and with SCo pattern 1, 5–12 are listed in the tables as “ mortivallis - owyheensis ”; and all males and those females of the Stonei group that have not been identified to species or as “ mortivallis - owyheensis ” are listed as “unidentified” in the data tables.

Biology. Records and descriptions of C. stonei prior to Atchley (1967) do not mention SCo pattern, or antennal, palpal, or proboscis ratios and, thus, are conflated with C. mortivallis and C. owyheensis records from California, Idaho, Utah, and western Colorado.

Jones’s (1961a: 741) description of the C. stonei pupa variant from Grand County, Utah, is likely of C. mortivallis . He collected these immatures from the nonvegetated sunlit margin of an alkaline stream near Cisco (47 km north-northeast of Moab), along with immatures of C. jamesi , C. occidentalis or C. sonorensis (as C. variipennis australis ), C. haematopotus (may be C. defoliarti ), C. grandensis (as “n. sp.”), and C. crepuscularis ( Jones 1961b) . I was able to rear C. mortivallis along with C. crepuscularis , C. occidentalis , and C. sonorensis from mud collected from nonvegetated sunlit alkaline pools in the same stream bed on 10 September 2020 in Grand County at 38.96339°N 109.33585°W and 1315 m elevation.

Jones (1961c, as C. stonei ) also collected blood-engorged Stonei group females from a domestic sheep near Grand Junction, Colorado. Based on my Grand County collection data, these specimens are also likely to be C. mortivallis .

One Stonei group female collected in Grand County, identified as intermediate between C. mortivallis and C. owyheensis ( Table 18), has dark starburst infections inside abdominal segments 6–8 (Fig. 290, Table 11).

Figures

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]).