Anthrax argentatus (Cole 1919)

Anthrax argentatus (Cole)

Spongostylum argentatum Cole.—Cole and Lovett, 1919, p. 227 [Spogostylum].—Cole and Lovett, 1921, p. 244 [Spogostylum].

Anthrax argentatus.—Maughan, 1935, p. 32 [argentatum].

MALE.—Integument generally black; brown to gray pruinose; tibiae, proximal tarsal segments, and genitalia reddish. Front covered with coarse black setae and linear black scales; a few white scales usually present ventrolaterally. Face bare just below antennae, with coarse black setae and a few linear white scales on lower two-thirds; oral margin with linear and lanceolate yellowish-white scales laterally. Occiput with sparse, short black setae and sparse, linear black scales. Fringe of pile on posterior margin of occiput black. Second antennal segment rounded or with a sharp ridge apically; base of third segment hemispherical, slightly flattened; styliform portion and style slightly shorter than first two segments (Figure 102).

Scales on mesonotum linear, mostly black; some curly, white or yellowish-brown scales laterally and on humeral and postalar calli. Scales on pleura black, a few yellow and white scales sometimes on sternopleuron; scales on coxae black, yellow, and white. Postalar tuft of pile and that on prosternum, propleuron, and anterior margin of mesonotum black; a few white hairs intermixed, especially on mesonotum. Scutellum with linear and lanceolate, mostly black scales; white scales on posterior margin and laterally on anterior margin.

Wing (Plate 3f) translucent brown basally, hyaline apically, the color filling cell C, all except the apex of Sc, the basal half of R, the extreme bases of R2+3 and R5, the basal third of 1M2, the extreme base of 2M2 and Cu1 and all but the extreme apices of 1A and 2A. Stigmatic area anterodistally in cell 2M not pigmented. Calypter not pigmented, fringe of pile black. Alula well developed, posterior margin rounded.

Scales on femora lanceolate and ovate-truncate, black; a few white ones sometimes posteriorly on fore and middle pairs; scales on tibiae linear, black. Middle and hind femora with four to six setae anteroventrally.

Pile on lateral margins of first abdominal tergum white, a few brown or black hairs posteriorly; lateral margins of second, third, fourth, and fifth segments with dense black hairs, setae and erect linear scales. Terga two, three, four, and anterior half of five with linear and lanceolate black scales except for small submedial patches of lanceolate white scales and large lateral patches of ovate-truncate, silvery-white scales on posterior margins of two and three; posterior half of fifth, and sixth and seventh sloping ventrally on each side of meson at a 45° angle, covered with dense, overlapping, elongate-truncate, laterally projecting silver scales except for a few lanceolate black scales and black setae medially on six and seven, and on medial half of five. Abdominal sterna with lanceolate scales except for some lanceolate-truncate, white or yellow scales along posterior margins.

MALE GENITALIA (Figure 50).—Gonocoxites short and broad, upper margin rounding to lower margin apically in lateral view; apices rounded and slightly emarginate medially in ventral view, with sparse, evenly distributed setae extending two-thirds of way to base. Basal segment of gonostylus convex dorsally, extending to base of distal segment; distal segment with a flat footlike part slightly emarginate apically, from which a curved, styliform part arises dorsomedially; footlike part with fine setae. Apex of epiphallus with a triangular, acuminate dorsal process extending slightly basad; apically rounded ventrolateral parts. Dorsal bands of epiphallus joined medially, without setae. Base of aedeagus large, bulbous, tapering to junction with ventral bands slightly before junction of dorsal bands.

FEMALE.—Similar to male. Only a few white scales laterally on six and seventh abdominal terga. Middle and hind femora sometimes with only three macrochaetae anteroventrally. Fore and middle tibiae with white scales posteriorly.

FEMALE GENITALIA (Figure 84).—Tenth tergum with 10 spines on each side. Ventral arm of ninth tergum narrow, slightly expanded and unequally bilobed apically. Dorsomedial angle of sclerite on each side of gonopore not greatly produced, bent interiorly; lateral arm formed in same plane as dorsomedial angle, slightly bent upward and truncate apically; ventral arm narrow, parallel sided and bent sharply mesad ventrally. Spermathecal ducts about two-thirds as long as bulbs, strongly contorted just before joining bulbs; middle section about twice as long as basal section, slightly shorter than apical section before contortions; bulbs of spermathecae elongate, tubular, tapering at base, slightly narrowed to apical “nipples” which are one-fifth as long as base.

DISTRIBUTION.—Anthrax argentatus occurs in mountainous areas from southern California north into British Columbia and south in the Rocky Mountains into Colorado (Map 11). It is generally allopatric to A. nitidus Marston in southern California, although the two species were collected together at Surprise Canyon in the Panamint Mountains, Inyo Co., California.

MAP 11.—Distribution of Anthrax argentatus (horizontal lines) and A. nitidus (vertical lines).

TYPES.—The holotype and allotype are in the collection of the California Academy of Sciences. The type-locality is Hood River, Oregon. Two paratypes have been seen by the author.