Clemensia umbrata Packard

Schmidt, B. Christian & Sullivan, J. Bolling, 2018, Three species in one: a revision of Clemensiaalbata Packard (Erebidae, Arctiinae, Lithosiini), ZooKeys 788, pp. 39-55 : 40

Clemensia umbrata Packard stat. rev. Figs 1-4, 13, 16

Clemensia umbrata Packard, 1872: 85. Type locality. Congress Springs, Santa Clara Co, California [lost] male holotype. Note. The type locality was given as “California” in the original description, and Edwards (1874) later writes that the only type was destroyed in the mail when Packard returned it, and clarifies the source of the type material as "Congress Springs, Santa Clara County."

Clemensia irrorata H. Edwards, 1874, p.185. Type locality. "Victoria, V.I. [Vancouver Island, British Columbia]"

Diagnosis.

Clemensia umbrata is most similar to C. albata ; flight time and locality aid in separating the two. Both species occur together only from southern Quebéc and eastern Ontario southward; C. umbrata is the only Clemensia species across the boreal forest region and the Pacific Northwest (Figure 19). Where the range overlaps that of C. albata , the phenology differs in that C. umbrata is univoltine with adults in July and early August (as early as June in the southern Appalachians) (Figure 22), whereas C. albata is bivoltine in the Northeast and possibly multivoltine farther south. In northeastern North America the flight peaks of C. albata are in mid-June and late August largely outside that of C. umbrata (Figure 22), but the flight periods of the two overlap in late July and possibly early August. In the eastern US C. umbrata becomes increasingly restricted to higher elevations southward, whereas C. albata is more widespread. For example, in North Carolina C. umbrata is usually found above 3100' whereas C. albata occurs below 4600'. Similar habitat/ecozone segregation likely occurs elsewhere, but further study is needed.

Externally, C. umbrata differs from C. albata in its larger size in regions of sympatry (northern boreal C. umbrata are smaller and not noticeably significantly larger than C. albata ), with male forewing length of 12.3 mm (n = 9) versus 10.8 mm (n = 6) in C. albata . Wing pattern differences are difficult to discern, especially flight-worn individuals, but C. umbrata has a more contrasting forewing pattern that is more suffused with grey and black, and often with a diffuse dark grey postmedial patch near the anal margin; this patch is absent or much more restricted in C. albata .

Internally, the male genitalic structure of C. umbrata and C. albata differs in the shape of the basal ventral diverticulum of the vesica, which is bilobed in C. umbrata versus heart shaped in C. albata (Figs 13, 14). The female corpus bursae of C. umbrata (Figure 16) is less elongate with longer internal spinules and a more broadly joined appendix bursae compared to C. albata and C. ochreata .

Biology.

Dyar (1904) describes the egg and first two instars based on samples from southeastern British Columbia, stating that larvae overwinter (as second instar?). The egg is unusually large with a diameter of 0.8 mm. The eggs are covered with setae from the female abdominal tip. McCabe (1981) described the larval biology, but it is unclear if his account is referable to C. albata or C. umbrata . Larvae probably graze algae growing on tree bark and possibly other substrates according to McCabe (1981), but both Dyar (1904) and Miller and Hammond (2000) state that larvae feed on lichens; a larva likely referable to C. umbrata was found on white birch cut for firewood in Renfrew Co, Ontario in late June (J. Dombroskie, pers. comm.). Miller and Hammond (2000) report this species as feeding in lichens on trees and large shrubs in the Pacific Northwest, especially on gary oak. Clemensia umbrata was collected 74 times during the Canadian Forest Insect Survey, always from conifers, and mostly from white spruce (49/74 collections; McGugan 1958). This may however indicate larvae feeding on algae-encrusted conifer twigs, whereas algal growth is usually limited to thicker branches and trunks of birch, where larvae are less likely to be collected by conventional sampling methods. Clemensia umbrata is univoltine throughout its range, with peak adult abundance in late July in northeastern North America (Figure 22), but appearing as early as June in the southern Appalachians. In the boreal region the larva is present from mid-May to mid-July (presumably having overwintered as a second or third instar), and with most collections from mid-June ( McGugan 1958).

Distribution.

Clemensia umbrata occurs from Nova Scotia across the boreal region to the Pacific coast, southward into central California and northern Idaho (Figure 19; Pacific Northwest Moths website). The northernmost records are for north-coastal British Columbia (Figure 19), southernmost Northwest Territories (southwest of Hay River; McGugan 1958), and Havre-St.-Pierre, Québec ( Handfield 2011). Clemensia umbrata is absent from the entire central and southern Rocky Mountain region of the USA. The extent of distribution in the eastern US is still poorly defined; minimally, C. umbrata occurs in the northern Great Lakes region, Vermont, and the southern Appalachians (Tennessee and North Carolina), but it is likely more widespread in the Appalachians.

Remarks.

As defined here, C. umbrata represents the taxon that occurs across most of Canada and western USA that was previously called C. albata . In most of its range (except eastern North America), it is the only Clemensia species. Although no California specimens of C. umbrata were available for DNA analysis, examined California material was not distinguishable morphologically from that of the Pacific Northwest, with the latter genetically very similar to the transboreal/Appalachian taxon. The distribution of C. umbrata is continuous along the Pacific coast from southern British Columbia to central California (Figure 19; see also Pacific Northwest Moths website), and we accordingly treat all as a single species under the name umbrata .