Notes on Isonomeutis aumaropa Meyr. (Lepidoptera).
[Read before the Nelson Philosophical Society, 26th October, 1927; received by Editor, 28th October, 1927; issued separately, 14th February, 1928.]
The genus Isonomeutis was erected by Meyrick in 1887 for the reception of a peculiar little Pyralid-like species taken at Whangarei. Since then the moth has been found at Wellington and Nelson, the probability being that it occurs in suitable localities throughout the North Island and the northern portion of the South. The larva is said by Hudson to live under the bark-flakes of the matai (Podocarpus spicata), feeding on the softer growing portion and subsequently forming a tough pupal cocoon of silk covered with fragments of bark.
In the original description Meyrick placed the species in the Conchylidae (now known as the Phaloniidae), but in his “Revision of the classification of the New Zealand Tortricina” (Trans. N.Z. Inst., 43, 78) he states that after further study he has concluded that “Isonomeutis is not correctly referable to this group” (the Tortricoidea) and that he has removed it to the Plutellidae. In 1923, however, the genus is referred back to the Tortricoidea and placed, with a second species, I. restincta, in the family Copromorphidae, which includes one other New Zealand species, Phycomorpha metachrysa Meyr.
Hudson has given coloured figures of the female moth and the larva in his Manual of New Zealand Entomology, pl. 13, figs. 2 and 2A, but, as far as I am aware, no structural figures have yet been published. It may be useful, therefore, to present a series of these and to comment on their characteristics with a view to more definitely fixing the systematic position of this interesting and puzzling genus.
It will be noted that in the anal area of the forewing there is only one vein, and that it is not forked basally. This vein may be called 2A or 2A + 1A. The anal furrow is hardly marked at all, there being only the merest indication of it near the base. Culb is rather remote from the angle, but Cula, the branches of M, and R2, R4, and R5 are almost equidistant at their bases. R2 rises from the cell slightly basad of Culb, and R1 at about middle of cell. Se is in a normal position, pursuing a course about halfway between the costal margin and the radius. No part of M is present within the cell. In the hindwing 3A is present and 2A and 1A are coincident except for a short distance at the base. The anal fold is well marked but does not contain any vein. Culb is fairly remote from the angle of cell; Cula and M3 are connate; M1 rises from about the middle of the oblique discocellulars with M2 a little nearer to it than to M3;
R is remote from M1 and proceeds straight from the upper angle of cell, reaching margin at apex. Sc is basally connate with R, gradually diverging from the lower vein. The course of the basal portion of M is weakly marked within the cell.
In studying the venation there are three points to which attention must be directed, namely, the reduction of the veins in the anal
Fig. 1.—Isonomeutis aumaropa Meyr. A, forewing. B, hindwing. C, head, lateral view. D, antenna, basal portion. E, maxilla. F, labrum with pilifers. G, labial palp, denuded. H, male genitalia, lateral view. I, harpe, inner view. J, aedeagus and juxta. K, uncus, dorsal view.
area, the basal position of those veins which rise from the end of the cell, and the fact that there are no stalked veins. In the Tortricoidea the main anal vein is normally strongly forked basally, and there is at least an apical remnant of the vein occupying the anal furrow. In the hindwing the almost complete coincidence of the first and second anal veins should be noted, also the basal connection of Cula and M3.
The Head, Mouth-Parts, etc.
The antennae of the male are filiform and pubescent, with 38 segments in the flagellum. Palpi long, porrected, pointed, rough-
Fig. 2.—Phycomorpha metachrysa Meyr. A, forewing. B, hindwing. C, head, lateral view. D, antenna, basal portion. E, maxilla. F, labrum with pilifers. G, labial palp, denuded. H, male genitalia, lateral view, with left hair-sac removed and right hair-sac displaced. I, harpe, inner view. J, aedeagus. K, tegumen, ventral view. L. juxta.
scaled above and beneath, with terminal segment hidden. Haustellum developed; maxillary palpi reduced, 4-segmented. Thorax without crests; posterior tibiae smooth.
Tegumen broad; uncus long, curved, laterally compressed. Gnathos absent. Vinculum moderate, arms rather broad, without saccus. Aedeagus moderate, apex irregular. Juxta a shield, with pair of small lobes and weak lateral processes attached to small transtilla. Harpes broad, entire, with inner transverse lobe near base and small transtilla.
We are now in a position to compare the characters of Isonomeutis with Phycomorpha, an undoubted genus of the Copromorphidae and in fact, differing only from the type genus in the stalking of veins R3 and R4. These differences may be tabulated as under.
|Forewing, 1A||Not forked basally.||Strongly forked basally.|
|Culb, M3 and M2||Not approximated at base.||Approximated at base.|
|Culb to R3||Equidistant at point of origin.||Unequally spaced at origin.|
|Hindwing, Cula and M3||Connate.||Short-stalked.|
|M2||Not approximated to M3||Approximated to M3.|
|Pectinations||Not present.||Dense pectinations on bases of M, Cu2, and 1A.|
|Labial palp||Terminal segment concealed; second segment very long, about eight times as long as third.||Terminal segment not concealed; second segment about three times as long as third.|
|Head||Frons with projecting scales.||Frons without projecting scales.|
|Thorax||Without crest.||Slight posterior crest.|
|Posterior tibiae||Smooth.||Slightly roughened above.|
|Uncus||Not recurved.||Strongly recurved.|
|Hair sacs||Absent.||Present, large.|
|Harpes||Simple, broad, entire, with transverse basal lobe.||Very highly specialized, narrow, intricate, with basal lobe absent.|
It will be seen at once that there are many and important differences between the two genera, and reference to the figures will render this still more apparent. Without so widening the definition of the Copromorphidae as to destroy the group's systematic value it does not seem possible to include Isonomeutis therein; nor is the writer prepared to refer it to any other family. Probably the best course in the present state of our knowledge is to regard this interesting genus as representing a distinct family, with considerable affinity to the Oecophoridae. In passing, attention may be called to the very close resemblance of the male genitalia of Phycomorpha to the Plutellid type. If considered on these characters alone, Phycomorpha might reasonably be referred to the Plutellidae, and there is quite probably some real relationship.