Xestia perquiritata orca Crabo & Hammond

Crabo, Lars G., Davis, Melanie, Hammond, Paul, Tomas Mustelin, & Jon Shepard,, 2013, Five new species and three new subspecies of Erebidae and Noctuidae (Insecta, Lepidoptera) from Northwestern North America, with notes on Chytolita Grote (Erebidae) and Hydraecia Guenee (Noctuidae), ZooKeys 264, pp. 85-123 : 112-114

Xestia perquiritata orca Crabo & Hammond ssp. n. Figs 30, 44

Type Material.

Holotype Male. [USA], Oregon, [Lincoln County], Newport, 25.VII.1961. CNC. Paratypes 5 Males, 1 Female. USA. Oregon. Lincoln County: Newport, 20.VIII.1968, K. J. Goeden collector, black-lite trap (1 female); [same locality and collector], 1.VIII.1970 (2 males). 5 mi. S. Newport 4 VIII 1968, Ore. Dept. Agric. (2 males); [same locality], 30 VII 1970, Brown and Goeden leg. (1 male). Washington. Clallam County: Neah Bay, 14.VIII.1961, R. E. Miller (1 male); Grays Harbor County: 3 mi. N Copalis Beach, 11.VIII.2010, MV, Gary L. Peters (1 male). WFBM, GPC, LGCC, ODA, OSAC.

Etymology.

The subspecies name is derived from Orcinus orca , the killer whale, and is a noun in apposition. It refers to the moth’s Pacific Coast distribution, large size, and nearly black and white forewing.

Diagnosis.

Subspecies orca is larger than other populations of Xestia perquiritata (Morrison). It is the only subspecies in which the wing is uniform black with unmarked white filling of the lines and spots. The western mountain subspecies Xestia perquiritata partita (McDunnough) (Fig. 31) has occasional melanic specimens. These are smaller than Xestia perquiritata orca (forewing length 16-20 mm for subspecies partita; 21-23 mm for Xestia perquiritata orca ) and differ in having light gray forewing lines and spots as well as darker gray scales in the central reniform spot. These markings are pure white or cream in subspecies orca.

The valve of the male genitalia of Xestia perquiritata orca is more massive than that of subspecies partita, reflecting the larger size of the moth. The female genitalia of Xestia perquiritata orca were not examined but are unlikely to differ significantly from those of other Xestia perquiritata populations illustrated in Lafontaine (1998).

Description.

Head - Antenna of male beadlike with short anterior and posterior fasciculations. Antenna of female filiform. Scape with black and white scales, predominantly black dorsally and white ventrally. Eye rounded, smooth. Labial palp covered in gray and blackish-gray scales, scales short on sides and lengthening to a ventral fringe on first two segments. Frons smooth, covered by thin scales that are white centrally and black on sides of head. Top of head covered by thin black scales with scattered white scales in midline and on posterior aspect. Thorax - Vestiture of weakly spatulate white-tipped black and scattered white scales, appearing black. Prothoracic collar black with pale-gray edge. Tegula covered by black scales. Legs covered by dark-gray scales with a white ring on each distal segment; medial tibia with a loose row of spiniform setae; ventral tarsal segments with three rows of spiniform setae. Wings - Forewing length of males 21-23 mm; females 22 mm. Forewing ground color nearly even brownish black; darkest black in basal area posterior to cubital vein, in fold in medial area, opposite cell and in fold in subterminal area, and between veins in subterminal area; palest whitish gray anterior to cubital vein across antemedial area; slightly mottled with smudged darker veins in terminal area. Basal, antemedial, and postmedial lines similar, black, double, with nearly white pale-cream filling; mostly evident as filling because of dark ground. Basal line pale filling fused to adjacent pale anterior antemedial area. Antemedial line strongly excurved with apex at base of claviform spot, drawn toward base on veins. Medial line absent. Postmedial line toothed on veins; sharply displaced toward base on costa to top of reniform spot, nearly straight from below costa to M3, then angled toward base and slightly curved to meet posterior margin at nearly a right angle. Subterminal line pale gray near costa and evident elsewhere as a transition between black in subterminal area and slightly lighter terminal area. Terminal line a series of black spots between veins. Orbicular and reniform spots completely filled with light cream, often fused. Orbicular spot irregularly ovoid. Reniform spot sideways heart shaped with a deep lateral indentation. Fringe dark gray, weakly scalloped with black. Dorsal hindwing sooty dark gray, faintly brown tinted in some specimens, with faintly darker thin discal spot, postmedial line, veins, and thin terminal line. Hindwing fringe light gray with darker base. Abdomen - Blackish gray, slightly lighter than thorax. Male genitalia - Uncus strap-like, dorso-ventrally flattened with a spatulate tip. Tegumen with weak penicillus lobes. Juxta broad, 1.8 × as wide as long, with straight transverse ventral margin and bilobed dorsal margin with a slight notch at base of aedeagus. Valve elongate, 4.5 × as long as wide, with slightly undulating costal and ventral margins, tapering to a point distal point with additional small projection from subapical ventral margin and an elongate pollex typical of genus Xestia ( Lafontaine 1998). Sacculus moderate, expanded to reach costal margin at base of valve and tapering distally to end at mid-valve. Clasper shark-fin shaped, oriented slightly mesially at origin and curved nearly 90° laterally to project dorsolaterally with tip slightly dorsal to costa. Digitus weak, broadly triangular. Apex of valve as described above without an expanded cucullus or corona. Aedeagus long and tubular, 8 × as long as wide, gradually widening from mid-shaft to apex, bearing patches of fine spinules on left side of mid-portion and on right side of apex. Vesica a simple membranous tube, 0.8 × as long as aedeagus and 0.3 × as wide as long; basilar vesica recurved 180° dorsad and rightward so that mid-vesica projects toward base of aedeagus and distal portion curved additional 45° leftward to overlap aedeagus. Female genitalia - Not examined.

Distribution and biology.

This moth is restricted to the immediate Pacific Coast of Oregon and Washington, usually within several hundred meters of the shore. It has been collected from the vicinity of Newport on the central Oregon coast north to Neah Bay on the northwest tip of the Olympic Peninsula in Washington. Subspecies Xestia perquiritata orca flies during late July and August. The food plant is unknown, but other subspecies of Xestia perquiritata have been reared from conifers in the family Pinaceae , particularly firs ( Abies spp.) and spruces ( Picea spp.) ( Lafontaine 1998). Based on the composition of the forests where Xestia perquiritata orca occurs the most likely food plant is Sitka spruce ( Picea sitchensis (Bong.) Carr.), although grand fir ( Abies grandis (Dougl.) Forbes) is possible.

Remarks.

The genus Xestia was revised for North America by Lafontaine (1998). He considered a specimen in the CNC from Newport, Oregon to be a melanic Xestia perquiritata partita (McDunnough), the western North American subspecies of this boreal and montane moth. At the time, the coast population was only known from a few specimens from this locality and only one of these was at the CNC. It is now apparent that distinct coastal populations of Xestia perquiritata have a range that extends at least as far north as the Olympic Peninsula and are nearly uniform in appearance. This subspecies might have a wider distribution on the coasts of northwestern California, British Columbia, and Alaska.