Metallolophia Warren, 1895

Han, Galsworthy, A. & Xue, 2005, A revision of the genus Metallolophia Warren (Lepidoptera, Geometridae, Geometrinae), Journal of Natural History 39 (2), pp. 165-195 : 166-170

Metallolophia Warren

Metallolophia Warren, 1895: 88 . Type species: Hypochroma vitticosta Walker 1860 (Borneo: Sarawak), by original designation.

Tribal and subtribal affiliation

Metallolophia belongs to the group of stout-bodied genera within the Geometrini tentatively defined as the subtribe Pseudoterpniti by Holloway (1996). Holloway provided a number of characters defining the genus, in particular the presence of dark streaks or spots basal to the fore wing discal spot, and the diagnostic ornamentation of the valve, consisting of ‘a rather boarmiine-like expansion and setation to the apex of the costa; a central basal lobe; a sclerotised, digitate or blade-like saccular process’. He mentioned in addition the apical saw-like serration on the aedeagus, and the single moderate, rather blunt cornutus distally on the small vesica. Additional distinctions from closely related genera are given in the section below on ‘diagnosis’. Contrary to Holloway (1996), a lack of setal patches on the third sternite does not define the genus, since we found such patches in a number of species of the genus ( Figure 79 ). Dr Dieter Stüning (in private correspondence) found that the setae on the cucullus of the valvae are very specialized, being scale-like, apically flattened and dentate ( Figure 80 ). This character could be diagnostic for the genus, though not all species have been examined for this character.

Description

Frons not prominent; palpus short, strong, the third segment minute in male, variable in female; antenna in male lamellate in type species, variable in remaining species ( Figure 1a–d ), in female simple; body stout, coax and ventral side of thorax hairy; abdomen with dorsal crests on segments 2–4, in some species metallic and glossy. Wings with outer margin crenulate or rounded, hind wing in male with inner margin elongate; discal spots on both upperside and underside of wings prominently large, pale centred and bounded by a dark line. In most species, a tinge of purple or violet on wings, especially on underside.

Venation ( Figure 1e ). Fore wing: subcosta and R 1 free, R 2–5 stalked, discocellulars curved, M 2 arising from the middle of the discocellulars, generally not close to M 1. Hind wing: Rs arising from cell, not stalked with M 1; 3A present.

Male genitalia. Uncus vestigial, socii like pencil tips, lying close to each other. Saccus small. Valva generally broad, costa expanded to the apex, with a thick patch of scale-like setae; a well-developed basal lobe extending to the centre of the valva; saccular process sclerotized, terminal part expanded, covered with minute spines; aedeagus with a sclerotized saw-like band, vesica small, with a single ‘Y’-shaped cornutus. In most species, male abdomen with a pair of setal patches on 3rd sternite, sometimes the two setal patches expanded and joined together.

Female genitalia. Apophyses anteriores wanting; apophyses posteriores moderately long; ductus bursae short and broad, corpus bursae pyriform, semi-sclerotized, without signum.

Differentiation from related genera

This genus differs from Aeolochroma Prout in that the discocellulars of the fore wing are not angled at M 2, and the inner margin of the hind wing is elongate, and always distinctly longer than the costa; from Pachyodes Guenée in that the frons is not prominent (in Pachyodes the frons is very strongly protuberant), vein M 2 of the fore wing arises from the middle of the discocellulars, and generally not close to the base of M 1. In general, characters of the genitalia as described by Holloway (1996) are the best distinction, but the most constant external characters of Metallolophia are: the discal spots on both upperside and underside are prominently large, especially on the fore wing, pale centred and bounded by a dark line; on the underside of the fore wing there is always a round black or dark purple spot proximally to the discal spot and a purplish streak below the round spot; in most species there is a tinge of purple or violet on the wings, especially on the underside.

1.

–

Key to species

Postmedian line dark, completely separate from subterminal band, well expressed on underside of both wings underside sometimes with clear trace of the line on upperside; male antenna shortly bipectinate ( Figure 1c, d ) ( M. inanularia male unknown)..................... Postmedian line absent or very faint or almost completely merged with the subterminal band on the underside of the wings; male antenna lamellate or nearly simple ( Figure 1a, b ).................. 2

9 2. Postmedian line on fore wing gently curving outwards from costa to M 3, and forming a sharp tooth on Cu 1, at the nearest point to the terminal margin; undersurface of wing pale pink........... M. assamensis – Postmedian line on fore wing gently curved or wavy from costa to M 3, seldom weakly or bluntly angled, without sharp tooth, the angle nearest to the terminal margin lying on M 3, undersurface not pale pink.......... 3 3.

–

Subterminal band on underside of both wings purplish black, as strong as postmedian line, continuous throughout............ Subterminal band on underside of both wings purplish to brown, much fainter than postmedian line, interrupted at middle or disappearing below middle.. 4

5 4.

–

Anterior half of postmedian line on fore wing underside rounded and broader at its outer margin, width at M 2 about 2.5 mm......... M. devecisi Anterior half of postmedian line on fore wing underside straight and narrower at its outer margin, width at M 2 2.0 mm or less........ M. ocellata 5.

–

Most wing markings yellowish brown or golden-brown, the postmedian line on fore wing band like, yellowish brown, without blackish coloration M. flavomaculata Wing markings not yellowish brown or golden-brown, the postmedian line on fore wing thin, black or blackish................ 6 6.

–

Postmedian band on the underside of fore wing with the spot between Cu 1 and Cu 2 much expanded inwards to near the lower margin of cell, its width much larger than the width between it and cell......... M. stueningi Postmedian band on the underside of fore wing with the spot between Cu 1 and Cu 2 as wide as other spots of the postmedian line, or only a little bigger, its width much less than the width between it and cell........... 7 7.

–

Dark boundaries of fore wing discal spot very weak or completely wanting; female with the corpus bursae shorter than apophyses posteriores... M. inanularia Dark boundaries of fore wing discal spot always present and clear; female with the corpus bursae twice as long as apophyses posteriores......... 8 8.

–

Discal spot on upperside of fore wing narrower towards the costa and expanded near its base, where it is about twice as wide as at the top of the spot; underside of fore wing from near base to postmedian line suffused with purple under the cell and Cu 2, without dark streak............ M. cuneataria Width of discal spot on fore wing upperside nearly the same from top to bottom; underside of fore wing without suffusion as above or suffusion very faint, but a distinct purplish black streak near base.......... M. arenaria 9.

– Subcostal area of fore wing pale or white.. Subcostal area of fore wing not pale or white................... 10 12

10. Postmedian line of fore wing deeply bending towards base near costa... 11

– Postmedian line of fore wing nearly straight, though dentate from inner margin to costa.................... M. albescens

11. Small moths (length of fore wing 19–21 mm); underside greyish brown, fore wing with a black round dot proximally to the discal spot, hind wing underside without discal spot.................. M. vitticosta

– Large moths (length of fore wing 26–27 mm); underside purplish, fore wing with an elongate streak proximally to the discal spot, hind wing underside with dark purple discal spot................ M. opalina

12. All veins covered with dark purple on underside of the wings. M. purpurivenata

– None of the veins covered with purple colour on the underside of the wings. 13

13. Underside of both wings with broad blackish subterminal band, as dark as discal spot......................

– Underside of both wings without blackish subterminal band, or subterminal band, if present, weak and much paler than discal spot.........

14

15

14. Inner margin of the discal spots on fore wing upperside deeply concave; basal half of hind wing underside white............ M. medullosa – Inner margin of the discal spots on fore wing upperside straight as normal; basal half of hind wing underside yellow.......... M. subradiata

15. Subterminal line on hind wing upperside with two sharp black ‘teeth’ between M 1 and M 3 ................... M. variegata

– Subterminal line on hind wing upperside faint, without black ‘teeth’ between M 1 and M 3 ................... M. cineracea

Figures

Figure 1(a, b, c, d) Male antennae, (a, b): M. vitticosta (Walker), (c, d): M. arenaria (Leech). Scale bar: 1 mm; (e): venation of M. vitticosta (Walker).

Figures 79, 80. (79) Setal patch on third abdomen sternite. (80) Setae on cucullus.