Nasusina vallis Ferris 2004, New Species

Nasusina vallis New Species

(Figs. 3–7, 14–20)

Diagnosis. The forewings of N. vallis are light smoky gray as opposed to the light smoky brown of inferior, and there is only a very slight suggestion of the discal dot that is prominent in inferior. The ventral plate in males of vallis, often visible without dissection by brushing away the abdominal scales, displays flared tips and an expanded base, as opposed to pointed tips and gently tapered base in inferior. The two tips are smooth, and not strongly chitonized and formed into needles as in E. annulata Hulst.

Description. MALES (Fig. 1): Forewing length (base to apex): 9–10 mm, mean = 9.3 mm; holotype = 9 mm. Head (Fig. 5): Nasusina – type; frons vertically truncate, clothed with appressed scales, mostly very pale gray with speckling of brownish­gray; short, bushy, brownish­gray labial palpus approximately as long as eye width (Fig.6); antennae weakly and evenly ciliate, with alternately brown and pale gray segments. Body: Thorax, abdomen, and legs covered with mixture of pale gray and brownish scales. Ventral surface of the abdomen paler than the dorsal surface, with suggestion of dark band on segment II. Upper hind tibial pair of spurs slightly reduced in size over the lower pair (Fig. 7), consistent with the genus. Wings: Forewing light smoky gray, moderately narrow with pointed apex with only very slight suggestion of discal dot. Numerous fine cross lines, slightly curved below the costa, thence extending oblique inwardly and essentially parallel to the outer margin until they intersect the inner margin. Narrow pale band, whose width varies across individuals, just distad from the poorly defined pm. line, extending from apex to inner margin and essentially parallel to the outer margin. In very fresh specimens, color of latter band pale brownish or tawny because of overlying diffuse pale brown scales, which apparently slough off during the flight period. Same coloration basally and in central areas of wing where maculation is reduced. In most individuals, a very narrow, pale, and weakly defined st. line. Fringes pale­tipped and inwardly peppered with mixture of white and dark scales that produces a weak checkered aspect. Hindwings slightly paler than forewings only because more lightly maculated; marked by numerous darker lines and bands of varying widths without discal dark spot. Fringes as in the forewings, but less peppered with dark scales (Fig. 3). Wings ventrally uniformly gray with very slight suggestion of forewing discal spot and slight repetition of darker dorsal striations. Male genitalia (Figs. 14– 19) [6 specimens dissected; the holotype was not dissected, but only checked to verify species by lightly brushing the eighth sternite]: Hair pencils on abdominal segment IX poorly developed (not illustrated); eighth sternite partially bifurcated distally, tapering from base to apex; apically the two tines are expanded, but no more sclerotized than other portions (Fig.18); uncus short, bifid, with lower tine slightly broader and more rounded apically than upper tine (Fig. 19); valva (length 2.6 X width) medially broad, with smooth ventral margin, tapering to rounded apex (Fig. 14); saccus rounded; transitilla typical of other members of the genus; aedoeagus about 90% the valve length and 30% as wide as long. Vesica armed with seven sclerites (Figs.15–17): three roughly oval dentate pieces; one larger elongate ovoid dentate piece; a small, smooth, curved piece; a smooth shovel­like plate; a smooth disc. N. vallis is immediately recognized by the chitonized disc located in the aedoeagus at the entrance of the ductus ejaculatorius (arrows Figs. 15, 17). A small curved sclerite lies just above the disc.

FEMALES (Fig. 4): Forewing length (base to apex): 8.5–10 mm, mean = 9.2 mm. Maculation of wings and characters of head, thorax, body, and legs generally as in male; antenna slightly setose (as in N. inferior). Female genitalia (Fig. 20) [5 specimens dissected]: Ovipositor lobes broad, rounded, moderately setose; anterior apophyses very long and moderately wide; posterior apophyses of normal length; caudal spur short, terminating on the laterocephalic edge of the ventral plate; ventral plate very lightly shagreened centrally; ostium bursae a broad irregularly shaped membranous funnel and very finely shagreened dorsally; ductus bursae short, terminating in a well developed and rounded colliculum. Corpus bursae: nearly globular; encircled by a narrow band of moderately robust spines at the base of the ductus bursae; most of remaining surface covered by spines with open areas below the upper narrow band and on right and left sides; spines long and well developed proximally, while toward the fundus, they become more diffuse and directed inwardly, producing star­like patterns on membrane surface. Ductus seminalis arises proximally, as a broad membranous tube, on right side and curves clockwise over the front of corpus bursae, as in N. inferior.

Type material. Holotype male and paratype female to be deposited in USNM. Additional paratypes (15♂, 40♀) to be deposited in other public museums and in the collection of the author. All specimens from the type locality, John Brown Canyon, S. of Gateway, Mesa Co., Colorado; GPS: 38° 39.16’N, 108° 58.99’W, 1515 m, 23 May 2003.

Biology. Unknown. The type locality is located in an arid region of mesas and canyons. Fig. 22 is a general view of the type locality habitat on 23 May, 2003, and Fig. 23 shows the intermittent stream that lies behind and below the trees shown in Fig. 22. Vegetation includes Acer negundo L., Juniperus sp., Pinus edulis Engelmann, Populus sp., Quercus gambelii Nuttall, Artemisia sp., Ericameria sp., Lupinus sp., Ribes sp., Yucca sp., various other woody and herbaceous plants, and grasses.

Flight period. Probably mid to late May; perhaps variable on an annual basis subject to environmental conditions. Considering the worn condition of the males and preponderance of females, the first appearance of males was projected to be about 15 May, 2003.

Distribution. Presently known only from the type locality.

Etymology. The epithet vallis is derived from the Latin feminine noun meaning valley to reflect the narrow canyon habitat of this species. There is no Latin word for canyon.

Variation. In addition to the variation in forewing length, the forewing dorsal discal spot varies from absent to a small point consisting of from six to twelve black scales (typically); otherwise there is little discernible variation in habitus.

Discussion. As has been noted previously by McDunnough (1949), the separation of Nasusina into a genus distinct from Eupithecia is tenuous and based upon very weak characters: reduction in size of the upper pair of hind tibial spurs; frons bulging, usually truncate vertically, and clothed in closely appressed scales. Within the genus Eupithecia (s.s.) there is some variation in size of the hind tibial spurs. The range of variation within Nasusina is extensive as is shown in Figs. 8 (vaporata) and 9 (inferior). In many specimens of N. minuta (Hulst) (not illustrated), the upper pair of spurs is often vestigial at best. McDunnough recognized four species of Nasusina, and the most recent catalog of the World Geometridae by Scoble (1999) lists the same four species (page 622). I have elected to place vallis in Nasusina because of the similarity to other members of the genus in the general form of the genitalia in both sexes and the habitus of the adults. The habitat is also consistent with other Nasusina species.