Culicoides (Silvaticulicoides) vetustus Breidenbaugh and Mullens

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 : 89-90

Culicoides (Silvaticulicoides) vetustus Breidenbaugh and Mullens

( Fig. 96 , 150, 239)

Culicoides vetustus Breidenbaugh and Mullens, 1999b: 156 (egg, larva, pupa, adult female; male genitalia; fig. egg, larval head, mouthparts, caudal segment, pupal respiratory trumpet, operculum, caudal segment, chaetotaxy, female eyes, antenna, palpus, leg, wing, spermathecae, male genitalia; comparison to C. sublettei and C. usingeri ; California).

Culicoides (Silvaticulicoides) vetustus: Borkent and Grogan 2009: 15 (in Nearctic catalog).

Diagnosis. ( Tables 14, 15) Wing pattern reduced; r 2 dark; pale spots at tip of costa, on r-m crossvein, absent from r 3, m 1, m 2, cua 1, anal cell; spermathecae with sclerotized necks about as long as wide; male tergite 9 apicolateral processes large: their length ~0.4 the distance between them; ventral apodeme of gonocoxite tapering thornlike, about as long as dorsal apodeme; entire lateral contour of gonostylus convex; aedeagus Y-shaped, arms U-shaped, median process parallel-sided, blunt; parameres separate, mostly straight, apex with four divergent holly leaflike spines.

Distribution. Southern California.

Adult behavior. Breidenbaugh and Mullens (1999b) report collections of females with CO 2 -baited traps, and the mandibular and lacinial teeth on the female also indicate it feeds on vertebrate blood; however, its hosts are unknown.

Life cycle. Laboratory studies by Breidenbaugh and Mullens (1999b) found that wild-caught C. vetustus laid an average of 86 eggs, of which 67% hatched an average of 7 d later. Average time to pupation was 117 d, with adults emerging ~4 d later at 21 °C, with an overall survivorship of 31%. However, unlike other Culicoides they reared, C. vetustus larvae would not feed on the nematodes provided. Whether this exceptionally long development time was due to nutritional deficiency is unknown.

Remarks. Willis Wirth referred to this species as new species number 122 (Bradley Mullens, personal communication). Breidenbaugh and Mullens (1999b) describe C. vetustus with five spines on the hind tibial comb; however, five of five specimens I examined, including a paratype, had four spines on each. See subgenus Silvaticulicoides discussion.

Subgenus Silvicola Mirzaeva and Isaev

Using morphological cluster analysis, Mirzaeva and Isaev (1990) placed the Palearctic Grisescens and Nearctic Cockerellii groups of subgenus Culicoides into their new subgenus Silvicola Mirzaeva and Isaev , retaining the Holarctic Pulicaris group in the subgenus Culicoides sensu stricto. More recently, Meiswinkel et al. (2004) and Gomulski et al. (2006) supported this taxonomy using genetic analysis. Western North American members of subgenus Silvicola are readily distinguished from subgenus Culicoides sensu stricto by lacking a dark spot in the middle of cua 1 and by having, in the male, the midportion of tergite 9 convex and extending more caudally than the relatively small apicolateral processes. In contrast with North American authors, I am following their taxonomy here.

Wirth and Blanton (1969b: 207) state in their paper on Nearctic species of subgenus Culicoides , “Caution must be exercised in using the key because of variability in many species. A series of specimens is preferred, and the most representative specimens should be selected and keyed. Confirmation by reference to the table of numerical characters, to the illustrations, and finally to the descriptions, is nearly always necessary.” Furthermore, Meiswinkel et al. (2004) and Gomulski et al. (2006) reported many Palearctic specimens of this group could not be reliably identified morphologically using published keys.

In his seminal work on subgenus Selfia, Atchley (1970) was the first author to use the presence or absence of apical hind tarsal spines as a diagnostic character. Likewise, the presence or absence of spines on the fore and hind tarsomeres seems to clearly separate the southwestern species of Silvicola into three groups: those with spines on both fore and hind tarsomeres include C. cockerellii , C. neomontanus , and C. sierrensis ; those with spines on only the fore tarsomeres include C. freeborni ; and, those without spines on either include C. lahontan , C. neofagineus , and C. saltonensis ( C. tristriatulus Hoffman was not characterized because no specimens were examined). This characteristic is reliable for all the specimens examined; however, further identification of the species relies on the fairly variable characteristics of eye separation, palpal segment 3 sensorial arrangement, and antennal SCo pattern in females, genitalia details in males, and leg-banding and wing pattern. This is especially difficult with the C. cockerellii subgroup where there are a considerable number of intermediate forms of the three species collected from similar habitats—suggesting that there is considerable interbreeding or the possibility that C. cockerellii is a highly variable species to include the currently recognized C. neomontanus and C. sierrensis . The three specimens of Silvicola representing possible species D and E further complicate this. See also the specific remarks in the following species accounts.

Figures

Figures 94–99. Male genitalia of Culicoides, ventral view. Ventral apodeme of gonocoxite and apex of paramere circled on Fig. 94–96. 94) C. sublettei (Gillespie County, TX [FSCA]). 95) C. usingeri. 96) C. vetustus (San Bernardino County, CA [BM]). 97) C. posoensis (paratype, Kern County, CA [FSCA]). 98) C. kibunensis. 99) C. travisi (VA [FSCA]).