Art. IX.—Description of a New Species of Moth (Pasiphila lichenodes).
[Read before the Wellington Philosophical Society, 8th September, 1886.]
The genus Pasiphila is a very distinct genus of the New Zealand Geometrina, containing some of the smallest moths in that division. In his monograph of the New Zealand Geometrina,* Mr. Meyrick maintains that there is but one species of this genus in New Zealand, and to this opinion I have already made objection in a paper in the “New Zealand Journal of Science”. for July, 1884, in which it was urged that at least two species had been included under the name Pasiphila bilineolata. Since then I have bred out a third form from the caterpillar state; so that, besides the species to be described to-night, there are at least three other species of Pasiphila in New Zealand. I have also, besides these, several doubtful forms; but Mr. Meyrick has admitted to me that he had wrongly included four, if not five, distinct species under the one name. As, however, he intends shortly to write upon this subject, it will be well to leave to him the disentanglement of the synonomy, as it is a matter upon which, perhaps, he alone is qualified to speak with authority. Here I take the opportunity of acknowledging Mr. Meyrick's kindness and readiness in furnishing information regarding insects sent to him.
Those that are acquainted with English moths may easily recognize the New Zealand species of Pasiphila by their likeness in size and appearance to the various species of Eupithecia, to which the New Zealand genus is closely allied. The members of this genus are small moths, usually less than an inch across
[Footnote] * “Trans. N.Z. Inst.,” vol. xvi., p. 49; xvii., p. 62; xviii., p. 184.
the wings, and they rest on tree-trunks or rock-faces with their wings flatly spread out, the inner half of the hindwings not being covered by the forewings, and sharing the colouring and markings of the forewings. The neuration of the forewings also serves readily to distinguish this genus, for usually in the forewings of our Geometrina, twelve veins can be counted along the margin; but in this genus, and in the next to it,—namely, Elvia—the eleventh vein coalesces with the twelfth and appears only as a short bar from the upper side of the small cell to the twelfth vein, so that only eleven veins appear on the margin.
Expanse, 16–19 mm. General description: Ground colour glaucous-green, with finely crenulated black lines, and two conspicuous, irregular, transverse bands of light brownish-red or chocolate colour, one near the base, the other near the hindmargin.
Detailed description: Forewings with slightly arched costa, hindmargin with a slight swelling or convexity about the middle, not crenulate; ground colour glaucous-green, becoming paler with exposure. Basal area very pale pinkish or reddish-brown, bordered by a black line sharply angulated at the middle, and followed by a broad pinkish or reddish-brown band, also bordered on the outer side by a black line. This band is contracted about the lower side of the cell, so as to be nearly divided, into two unequal blotches. The centre of the wing is occupied with a broad belt of the glaucous-green ground colour, boldly angulated about the middle of the outer side. This central belt is occupied with three finely crenulated black lines, which are so closely placed that they seem almost to divide the central belt into imbricating green scales edged with black. The central belt is also bordered along the outer edge by a black line. Between the central belt and the sub-marginal line is another broad belt, of a chocolate or reddish-brown colour, sometimes divided into two unequal blotches by the angulation of the outer side of the central belt. This reddish-brown band is crenulated on the outer side and edged with a pale sub-marginal line which follows the crenulations. Between this and the margin the ground colour appears without any distinct markings. The black lines of the forewing are sometimes edged with paler lines. The hindmargin is edged with an interrupted black line. Fringe fuscous and pale alternately. Hindwings with a distinct convexity, rather below the middle of the hindmargin. Inner half with colour and markings similar to those of the forewings. Outer half paler, greyish or whitish, markings not so distinct. Below, the forewings are fuscous, with a few of the black lines showing along
the costal edge, while the hindwings are greyish white, with a black discal dot and a few faint lines.
This species has received its specific name because its colourings and markings seem to me to have a protective likeness to those of the thallus and thecœ of some lichens. It occurs not uncommonly in the forest about the river-bed in the upper part of the Leith Valley, Dunedin. I have collected specimens in the latter part of January; and it is not known to Mr. Fereday or to Mr. Meyrick, except from my specimens; hence its range must be somewhat limited.
I stated that I had bred out three species of Pasiphila from the larval state, and the descriptions of the larvæ are here subjoined. Specimens of the perfect insects have been sent to Mr. Meyrick for identification. There seem to be differences between these caterpillars quite unusual in the case of closely-allied species. The first and second descriptions are reprinted from the “N.Z. Journal of Science” for July, 1884:—
No. 1. Pasiphila, sp.?
“Larva smooth, green, about 10 mm. long; an indistinct dorsal and sub-dorsal stripe of darker green; underside green, with a light ventral stripe; head yellowish. Formed small rough earthen cocoons on the surface of the earth. The food-plant is Myoporum lœtum. Larvœ in March. (See ‘N.Z. Journ. Sc.,’ March, 1882, p. 95.)”
No. 2. Pasiphila, sp.?
“Larva about 12 mm. long. Colour brownish; surface very rugged; body tapering somewhat towards the head. Two pair of small dorsal tubercles about the middle, the posterior pair being larger. Oblique lateral dark markings faintly seen on the dark ground colour; below lighter. I have beaten this larva from Aristotelia, from Leptospermum ericoides, and from a mixed growth of bramble (Rubus) and Muhlenbeckia. Larva in December and January.”
No. 3. Pasiphila, sp.?
Larva loopers from 13 to 17 mm. long, with a black median dorsal line, and on each side of it a black sub-dorsal line. The whole dorsal area between the sub-dorsal lines is brown, or brownish-black, while the rest of the back is greenish-white; below greenish-white; lateral line and median ventral line, white; there are sometimes dark blotches above the lateral line, while below it the ground colour is suffused with purplish-black. The median dorsal line is often bordered with greenish-white.
The larvæ were found about full-grown, feeding on Veronica salicifolia, in the Leith Valley, Dunedin, in the beginning of April. Two of the moths were reared, one of which had the
ground-colour greenish, while the other was brownish. At the same time, and on the same plants, a considerable number of larvæ, resembling the above in shape and size, were collected. Some of these had the ground-colour green, with very faint dorsal and sub-dorsal lines, the dorsal area being green, or only faintly clouded with black. Others had the ground-colour green, while the dorsal and sub-dorsal lines were distinct and black, and the dorsal area between the sub-dorsal lines was filled with alternate light and reddish - brown blotches. The two last forms had their other characters as in the first-described form, and they may be immature stages, or the larva may be a variable one.