Arctesthes avatar Patrick, Patrick & Hoare

Patrick, Brian H., Patrick, Hamish J. H. & Hoare, Robert J. B., 2019, Review of the endemic New Zealand genus Arctesthes Meyrick (Lepidoptera, Geometridae, Larentiinae), with descriptions of two new range-restricted species, Alpine Entomology 3, pp. 121-136 : 121

Arctesthes avatar Patrick, Patrick & Hoare sp. nov. Figs 12, 13, 17, 19, 28, 29, 33, 35 (map)

Type material.

Holotype: male (pinned), 'NEW ZEALAND NN Denniston - Rochfort wetland area 855m 16-18 Feb 2015 Brian Patrick / NZAC slide Geo. 46 genitalia ♂' [41°46.3'S, 171°45.3'E] (NZAC). Paratypes (1 male, 1 female): 1 male, NN: Denniston Plateau 640-720 m, 16-18 Feb 2015, B.H. Patrick (Fig. 12); 1 female, NN: Mt Rochfort 1000m, 16 Feb 2015, B.H. Patrick (genitalia on slide NZAC Geo. 47) [41°46.7'S, 171°44.6'E] (both NZAC).

Other material examined.

1 male, same data as holotype; 2 males, 1 female (Fig. 13), NN: Denniston Plateau 640-720 m, 16-18 Feb 2015, B.H. Patrick; 1 male, Denniston Plateau wetland 650 m, 3 Mar 2012, B. & H. Patrick (Fig. 17). (BPNZ, NZAC).

Diagnosis.

Arctesthes avatar is superficially similar to A. titanica . However, the species are almost certainly strongly allopatric and should be identifiable based on locality alone. The most conspicuous diagnostic characters are on the hindwing upperside and underside as follows: A. avatar has a very distinct wedge-shaped area of dark shading on the hindwing upperside from the base, enclosed by the strongly developed dorsal half of the antemedian line: in A. titanica , the antemedian line is reduced to a smudge on the anal margin only. Arctesthes avatar also has a strong dark terminal shade on the hindwing but lacks black dashes along the termen itself; in A. titanica the black dashes are present and distinct, but there is no terminal shading. The hindwing underside in A. avatar is predominantly very pale orange with only the antemedian line and terminal shading showing up conspicuously darker; in A. titanica , the hindwing underside is predominantly mid-brown with the area beyond the antemedian line and the subterminal line showing up conspicuously paler. In the male genitalia, the longer, narrower labides and much shorter sacculus process easily distinguish A. avatar from A. titanica .

Description.

Adult male (Figs 12, 17): Wingspan 20-22 mm. Very similar to A. titanica , with the following differences. Forewing with antemedian and postmedian lines slightly better defined than in titanica ; postmedian line with indentation above median evagination and level with discal spot tending to be more pronounced than in titanica . Hindwing with dark antemedian line reaching much further across wing than in titanica (about half way to costa), and then diverting basad to join small variably distinct discal dot; terminal line present as dark brown fascia, with weakly scalloped inner margin; black dashes along termen absent. Forewing underside (Fig. 17) with postmedian line more distinct than in titanica and almost complete, reaching to near dorsum. Hindwing underside with blackish suffusion from base; area basad of antemedian line largely pale orange (not brown) and without dark edging to basal blotch; white fascia beyond antemedian line rather indistinct; from here to terminal fascia pale brownish orange, with brownish smudge at anal angle representing postmedian line; subterminal line very faintly paler, not distinct as in titanica (where it stands out against brown background).

Male genitalia (Figs 28, 29): S3-4 elongate (subrectangular); S6 elongate (trapezoidal, tapered distally), S5 more squarish, all sternites evenly sclerotised; T2-6 evenly sclerotised. Uncus digitate, narrow and minutely hooked apically; labides large, robust (but distinctly narrower than in A. titanica ), strongly C-shaped, blunt apically; dorsal scobinate portion of manica with rather few sharp teeth; juxta moderately narrow, flat, tongue-shaped, with rounded bifid apex; valva moderately short, rather narrow, with rounded apex; basal costal sclerite with sinuous central process, distinctly projecting beyond valval costa, (apex of sclerite bluntly rounded); sacculus process robust, short, truncate, with concave distal margin, barely projecting beyond valval costa and apex not reaching valval apex, apically with dense fine spinules; saccus moderately short, V-shaped (narrower than in A. titanica ), hardly recurved under genital capsule. Phallus without distinct tongue-like apical process; vesica scobinate, with two symmetrical cornutal patches, each containing numerous rather long, curved spine-like cornuti.

Adult female (Figs 13, 19): Wingspan 20 mm. Similar to male, but antennae without pectinations; forewing ground colour distinctly paler than in male, with central fascia more strongly contrasting; forewing fringe chequered dark and pale.

Female genitalia (Fig. 33): Total length ca 2.0 mm. As described above for A. titanica , but smaller; ovipositor lobes slightly blunter.

Distribution.

(Fig. 35). Only known from the Denniston Plateau / Mt Rochfort area in the north-western South Island (Nelson district).

NN.

Biology.

The species has been found at 640-1000 m a.s.l. in ephemeral wetlands of short sedges and herbs, including Liparophyllum , Donatia , Ficinia , Oreobolus and Euphrasia species. Specimens have been disturbed or taken flying by day from 6 February to 22 March. Females were observed to lay eggs in rows on the underside of leaves of Liparophyllum gunnii ( Menyanthaceae ) growing in the wettest areas. A larva reared from the egg in captivity was briefly described as brown dorsally, paler ventrally, and fed on dying leaves, stems and roots of Liparophyllum , but rearing was unsuccessful and it was not photographed. In a 2015 survey, BHP and Ian Millar found that Liparophyllum was the only dicot herb present at all sites where the moth was found, so, unlike other Arctesthes species, A. avatar may be monophagous on this plant.

Etymology.

Forest & Bird, who organised the Denniston Plateau BioBlitz at which this species was found, ran a public competition to choose a name for this species. The ' avatar moth’ was picked as the winning entry. The name refers to the James Cameron movie Avatar; like the indigenous people and fauna of that film, the moth is vulnerable to habitat change or destruction in its very limited area of occurrence. The original avatars of Hindu mythology were incarnations of deities, especially of Vishnu: one of these, Varaha the boar, is depicted in a Pahari miniature painting of ca 1740 with the black, white and orange coloration of A. avatar killing a demon and rescuing the Earth on his tusks (image available from Wikipedia: https://en.wikipedia.org/wiki/Chamba,_Himachal_Pradesh). The name is to be treated as a noun in apposition.

Remarks.

The discovery of this species in 2012 was briefly discussed by Patrick and Patrick (2015). At first known only from a single specimen from one small site on the Denniston Plateau, it has since been discovered to be more widespread in wetlands from the Denniston Plateau to nearby Mt Rochfort, though still extremely localised and confined to potentially vulnerable wetland sites on the margins of a coal-mining area. The largest known population currently exists on the northern side of the old Denniston soccer field, where a wetland sward has developed. As with A. titanica , a high conservation status is appropriate for this moth.