Grammia bowmani, Ferguson, Douglas C. & Schmidt, Christian, 2007

Ferguson, Douglas C. & Schmidt, Christian, 2007, Taxonomic review of the Grammia nevadensis species group (Lepidoptera: Arctiidae) with descriptions of`two new species, Zootaxa 1405, pp. 39-49 : 44-45

Grammia bowmani New Species

( Figs. 1 i, 8)

Diagnosis. The size, wing pattern, and colouration of bowmani are somewhat similar to those of G. e u re k a (see Diagnosis under that species), and in this respect it is intermediate between G. nevadensis superba and G. williamsii . It can be distinguished from G. nevadensis by the shorter antennal branches (longest branches 3– 3.5 x intersegmental distance versus 4–4.5 x), smaller male juxta (1mm wide or less, versus greater than 1 mm), and shorter, wider male vesica. The forewing median and postmedian bands tend to be straight or nearly so, not distally convex as in nevadensis . Wing fringes are entirely or predominantly black, not predominantly white as in nevadensis . Vestiture of the forecoxae is pale brown to dull yellow, bright yellow in nevadensis . Compared to G. williamsii , bowmani has longer antennal branches (3–3.5 x intersegmental distance versus 2.5 x), and the median and/or postmedian lines extend beyond the postcubital band, very rarely (<5%) so in williamsii . The vestiture of the legs and thorax underside are dark brown, with a buff area restricted to the forecoxae, compared to extensive buff thorax underside in williamsii .

Description. MALE. Head: Head, antennae, and palpi almost entirely black, palpi and frons occasionally with a few pale scales. Antennae prominently bipectinate, length of pectinations 3–3.5 x intersegmental distance. Thorax: Legs and patagia almost entirely black, or patagia with light border typical of the genus. The thorax exhibits two colour forms, an all­brown/black form and the typical striped form (not seen in the Colorado specimens). Both G. nevadensis and G. williamsii tooele (Barnes & McDunnough) also show these two colour forms, while G. behrii exhibits only the dark form. Light­coloured vestiture of and between forecoxae that is normally bright yellow and often extended to adjoining ventral areas of thorax in most members of the nevadensis complex generally reduced or even absent in bowmani , and, when present, it is pale buff to dull whitish, only rarely yellow. Forewing dorsally with typical buff­whitish Grammia pattern on nearly black background, most similar to G. nevadensis superba but with bands more reduced; antemedial band incomplete or absent, although a fragment of the antemedial or postmedial or both may extend toward inner margin beyond postcubital band, but usually not reaching inner margin (for nomenclature of forewing pattern in Arctiini see Ferguson, 1985: 194, 252–253). An especially significant feature of the forewing pattern is that the medial and postmedial bands have a tendency to be nearly straight, as in G. williamsii , rather than convex or curved basad before reaching costa as in nevadensis . Fringes entirely or predominantly black. Length 13–17 mm, average 14.8 mm (n = 49). Hindwing bright­rose to pale pink, with the submarginal dark spots most often concentrated toward outer margin, resembling williamsii in this respect, especially subspecies tooele from the Great Basin region of Utah. Fringes black, often buff along anal angle. Ventral fore­ and hindwing markings identical to dorsal pattern, with a more washed­out colour. Abdomen: Pink dorso­laterally, with a mid­dorsal black band or series of spots as in nevadensis and most Grammia species; black ventrally with thin, transverse, intersegmental stripes of pale brown. Genitalia ( Fig. 8 ) with distal half of valve narrower than that of most nevadensis , but this is variable in both species; the large, membrane­covered cavity on the inner face of the valve, extending from the base to the middle of valve surrounded or enclosed by elevated sclerotic ridges or folds. This whole structure is larger, deeper, and more highly developed or exaggerated in bowmani than in nevadensis . Juxta relatively narrow for members of this group, about 2/3 as wide as that of nevadensis ; the fully everted vesica is only about 2/3 as large as that of nevadensis , and the scobinate zone tends to cover a smaller area, although with many of the individual spinules larger, at least those well toward distal end. Vesica divided by constrictions into several chambers, the largest, distal chamber much larger in nevadensis than in bowmani , closely resembling williamsii .

FEMALE. Unknown.

Holotype. Male. COLORADO, Mesa Co., Coal Mine Pt., Black Ridge, 7,000 ft., 16 May 1987, D.E. Bowman. Deposited in USNM.

Paratypes. 51 males. COLORADO: 9 males, same locality and collector, 16 May 1987 (5), 18 May 1985 (1), 26 July 1975 (3); 11 males, Upper Red Canyon, Colorado National Monument, Mesa Co., 31 May 1997, B. Rodgers family; 1 male, West Entrance, 4,700 ft., Colorado National Monument, Mesa Co., 1 June 1996, B. Rodgers family; 3 males, Upper No Thoroughfare Canyon, 6,200 ft., Colorado National Monument, Mesa Co., 18 June 1996, B. Rodgers family; 20 males, same locality and collectors, 12 July 1997. 1 male, Mesa Co., Colorado National Monument, Upper Ute Canyon, 7 June 2000, Opler & Slossen; 1 male, Mesa Co., Colorado National Monument, head of Red Canyon, 3­4 July 2000, J. Moore. Others taken in Mesa County, 27 May 1988 by T.S. Dickel are not included because full locality data is not at present available. UTAH: 5 males, San Juan Co., Blanding, 1 July 1970, R. Carcasson.; 1 male, San Juan Co., Monticello, 7 June 1960, N. McFarland.

Paratypes are deposited in USNM, DEB, CSU, AMNH, CNC, CU, EME, LACM and RBCM.

Distribution. The species is known only from the localities indicated in Mesa County, western Colorado and from the vicinity of Blanding, southeastern Utah. It may be common where found, as in the Colorado National Monument. For Colorado, Grammia bowmani would have to be considered a relatively low­elevation species.

Flight period. Dates of capture span a period from mid­May to late July. The female likely does not come to light, as in G. nevadensis and G. williamsii .

Early stages. Unknown.

Remarks. Grammia bowmani is remarkably similar in appearance to some individuals of G. nevadensis superba and G. williamsii , and appears to be most closely related to williamsii . The differences in male genitalia, antennal morphology, and wing markings (see Diagnosis), however, show that it is distinct from other species of this group.

Etymology. We are pleased to name this species after Donald E. Bowman of Pueblo West, Colorado, an indefatigable collector of North American arctiids and the person who first brought this species to light.

Figures

FIGURE 1. Adult males of the Grammia nevadensis species group, a) G. n. nevadensis (Winnemuca, Humboldt Co., NV); b) G. n. superba (Victoria, Vancouver Is., BC); c) G. n. geneura (Estes Park, Larimer Co., CO); d) G. n. gibsoni (Burstall dunes, SK); e) G. behrii (Eight Dollar Mtn., Josephine Co., OR); f) G. i n c o r r u p t a (Comanche Natl. Grassland, Baca Co., CO); g) G. williamsii (Jenner, AB); h) G. eureka (HOLOTYPE, Eureka, Juab Co., UT); i) G. bowmani (PARATYPE, Black Ridge, Mesa Co., CO).

FIGURES 3 – 8. Male genitalia Grammia nevadensis group species; caudoventral aspect of genital capsule (a) and aedeagus with vesica everted, right lateral aspect. 3) G. nevadensis superba (Oliver, BC), 4) G. behrii (Kern Co., CA), 5) G. incorrupta (Pima Co., AZ), 6) G. williamsii (Jenner, AB), 7) G. eureka (PARATYPE, Eureka, UT), 8) G. bowmani (PARATYPE, Mesa Co., CO).