Grammia eureka, 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 : 42-44

Grammia eureka New Species

( Figs. 1 h, 7)

Diagnosis. Males of G. eureka resemble those of G. b o w m a n i, n. sp. (the female of bowmani unknown) but have a reduced, elliptical eye and a larger, more exposed gena; the reduced eyes suggest that both sexes are diurnal, which may help explain why so few have been collected. The longest antennal branches are shorter than those of both bowmani and nevadensis : 2–2.5 times the intersegmental length in eureka compared to 3– 3.5 and 4–4.5 for bowmani and nevadensis , respectively. The black spots of the hindwing are mainly clustered toward the outer margin as in bowmani and some forms of G. nevadensis , but the hindwing ground colour is a more orange­tinted shade, not the pink to deep salmon pink of bowmani . Although somewhat faded from age, the male and female hindwings of eureka appear to be coloured alike (not as in G. nevadensis , in which female hindwing colouring is much more saturated). Also, surprisingly for a Grammia species of this group, the male genitalia appear to be distinctive (only one specimen was dissected), in that the apex of the valve is blunt and squared off, not elongate and rounded as in other members of the group ( Fig. 6 ). Collection dates indicate a much earlier flight period than G. nevadensis , with records from April to May, compared to August through September for G. n. nevadensis . G. e u re k a and G. nevadensis are sympatric at Eureka , Utah, with numerous nevadensis specimens known from Eureka (T. Spalding; CNC, USNM) and nearby localities (D.F. Hardwick; CNC).

Description. MALE. Head: Eyes reduced to little more than half the size seen in most species of Grammia , including G. nevadensis , behrii , and bowmani , and having the appearance of being directed forward. The eye reduction leaves an exposed gena, which bears a few brown scales, more in one male than the other. Upper edge of eye set well apart from base of antenna, whereas it almost touches base of antenna in species with larger eyes. Compound eye roughly equals one­fourth of a sphere; that of nevadensis , bowmani , and most others of the group is one­half a sphere or close. Antennae bipectinate with relatively short branches, the longest 2–2.5X longer than intersegmental distance; antenna brown, the branches tending to be slightly clavate, the shaft and branches fully scaled above, setose beneath in the usual way; palpi appearing long but probably only because of their long vestiture and more conspicuous appearance relative to the reduced eye. Front and tips of palpi white at sides, otherwise dark brown or blackish. Thorax: Vertex with tuft of long, black scales; each patagium black with border of whitish vestiture along both sides; tegula black with whitish border along each side; dorsum of thorax otherwise whitish with wide mid­dorsal black band. Thorax beneath mostly with shaggy black vestiture (with some small white patches), except for legs, which are largely white, especially the tibiae. Abdomen: Abdomen with medium­width black mid­dorsal band, reddish at sides, pale ventrally except for a segmental series of vertical bars in zone between pink and pale areas. Forewing ( Fig. 1 h) dorsally with an almost complete set of whitish bands, except that the basal and antemedial bands may be fragmentary as in bowmani and many specimens of nevadensis . General pattern as in other members of group except that medial band is nearly straight, as in bowmani ; not as strongly convex as in nevadensis . Postmedial band curved or bent basad near costa, but not as strongly so as in most members of the nevadensis complex ( bowmani differs in having this band nearly straight as in williamsii ); cubital band well developed. Wing length: holotype, 16.5 mm; paratype male, 17 mm. Length to width ratio = 2.25 (n = 2). Hindwing ( Fig. 1 h) dorsally orange red, not pink to salmon coloured as in bowmani , or bright red as in many nevadensis ; submarginal dark spots with tendency to be concentrated as a border on outer margin much as in bowmani . Ventrally with pattern very similar to upper side, but with colour less intense. Abdomen: Male genitalia ( Fig. 6 ) with valves relatively distinctive for this genus, with the distal part of the valve wide and spatulate, appearing squared­off not tapered and rounded. Inner median ridge and median process of valve moderately developed; Juxta wide with broad, shallow dorsal notch; basal 1/4 of uncus with pronounced constriction, smoothly tapering to apex with slight constriction 2/3 of distance to apex. Aedeagus with strong dorsad curve at 2/3 distance beyond base. Vesica apparently indistinguishable from G. nevadensis , coarsely and extensively scobinate but not much more so than in related species. Largest (apical) chamber of vesica more elongate like nevadensis in comparison to the short, broad vesica of G. williamsii ( Fig. 6 ) and G. bowmani ( Fig. 8 ). The genitalia of only one male was examined so that the other could be kept intact for future reference and illustration, since the abdominal markings are sometimes important in Grammia .

FEMALE. Head: palpus with or without pale tip. Eye reduced as in male; gena large, partly scaled; antenna somewhat laminate, appearing serrate at sides, black. Thorax: Legs black with cream­coloured markings as in male; tibiae characteristically pale outwardly (laterally), blackish inwardly (proximally). Markings of both wings much like those of male, except that basal and antemedial bands of forewing tend to be further reduced; basal band essentially absent; antemedial band wide and prominent, although broken in the middle in the Utah female, absent except for a trace at costa in the Idaho female. It should be emphasized that in most members of the nevadensis complex and other species of Grammia , the hindwings are more intensely coloured than those of the male, but G. eureka differs in having the sexes coloured alike. Length of forewing: 18 mm; length­width ratio = 2.25 (n = 2). Abdomen: Generally similar to male but larger, and nearly all black ventrally. Genitalia not examined.

Holotype: Male. UTAH, [Juab County], Eureka , 16 May 1909, Tom Spalding ( Fig. 1 h). (illustrated in Barnes & McDunnough (1912) pl. 3, fig. 1).

Paratypes: 1 male, 2 females. Male, same locality and collector as holotype, 9 May 1910, USNM Slide No. 56401; female, same locality and collector, 20 April 1910 (illustrated in Barnes & McDunnough (1912) pl. 3, fig. 8); female, IDAHO, Ada Co., Boise, Jim Manning [no date, and locality not certain ­ see Remarks below].

All types deposited in USNM. The female dated 20 April 1910 has slightly crumpled wings as though it had been reared or perhaps collected before the wings had fully hardened.

Distribution. Eastern and northern edges of the Great Basin in Utah and Idaho, insofar as known.

Flight period. 20 April–16 May.

Remarks. Grammia eureka is based on three old specimens from the Barnes collection in the USNM, collected in Utah by Tom Spalding almost a century ago, and a female paratype thought to have been collected near Boise, Idaho (see below). The three Utah specimens collected in 1909 and 1910 were acquired by Barnes and McDunnough for the Barnes Collection, the largest privately held North American Lepidoptera collection of its day. Spalding was one of several field collectors from whom Barnes purchased western material or paid to collect for him, and the Barnes collection was later purchased by the U.S. Dept. of Agriculture for the National Collection. Barnes and McDunnough (1912: p. 10, pl. 3, figs. 1, 8) published photographs of the specimen here designated as holotype of G. e u re k a and the female from Utah as examples of what "is probably the true blakei .” This determination was wrong, as McDunnough must later have realized, but no one pursued the matter further. These specimens remained intact just as McDunnough (Barnes’ curator) had left them. Their specific identity has remained somewhat of a puzzle without additional specimens coming to light, with the exception of the paratype female; this specimen was received in the 1950s by the senior author from Jim Manning, a butterfly collector of Boise, Idaho. Received as a papered specimen, it bore no data and it is merely assumed that the collection locality was at or near Boise. That region, like Eureka , Utah, is near the edge of the Great Basin, which may provide a clue to the species’ habitat.

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).