Metaterpna Yazaki, 1992

Jiang, Nan, Stüning, Dieter, Xue, Dayong & Han, Hongxiang, 2016, Revision of the genus Metaterpna Yazaki, 1992 (Lepidoptera, Geometridae, Geometrinae), with description of a new species from China, Zootaxa 4200 (4), pp. 501-514 : 502-503

Metaterpna Yazaki, 1992

Metaterpna Yazaki, 1992 , Tinea 13 (Suppl. 2): 8. Type species: Terpna differens Warren, 1909 .

Pitkin et al. (2007) provided already a number of characters defining the genus Metaterpna . They are summarized and completed here as follows:

External characters and w ing pattern. Antenna in male bipectinate, with rather short, flattened, distally roundly enlarged, dorsally unscaled rami, arising proximally on ventral side of flagellomers, their length gradually tapering towards tip of antenna, apical section of varying length without rami; female antenna simple filiform or slightly serrate, flagellomers finely setose laterally and ventrally. Shaft of antenna dorsally scaled in both sexes. Frons flat, with smooth surface, scaling smooth or rough. Labial palpus long, protruding widely beyond frons, with third segment small to moderately long, even longer in females. Haustellum well developed. Hind tibia in male not or only slightly dilated, without hair-pencil, with two pairs of spurs in both sexes (index of spurs 0-2-4). Chaetosema small, round, near margin of compound eye.

Forewing without fovea, with black postmedial line strongly dentate at middle and angled anteriorly, shallowly concave near costa, deeply incurved near hind margin; pinkish white or indistinct red brown subapical patches outside postmedial line present, other large whitish or red brown patches often also present at anal angle, the latter almost absent in the type-species; antemedial line strongly oblique. Hind wing with a very large white, creamcoloured or greyish basal area, reaching the narrow, dentate postmedial line; there is a second, broader, smooth line running from apex to tornus of hindwing, touching the postmedial line only at middle. Submarginal area of hindwings with a diffuse, darker band, pinkish or olive and striated dark brown. Margin undulating, with a thin, black line.

Venation ( Fig. 1). Forewing with R1 diverging shortly before upper angle of cell, R2 to R5 stalked, R2 diverging more basally than R5; both R2-5 and M1 not stalked, but arising together from upper angle of the cell; M3 and CuA1 separate at base. Hind wing with Sc+R1 running close to cell for a rather long distance (slightly longer in M. thyatiraria ); Rs and M1 arising from upper angle of cell; M3 and CuA1 separate at base; A3 present, but short and weak.

Pitkin et al. (2007) provided additional morphological characters defining the genus. See also redescriptions below.

Genitalia. Male. Uncus strongly developed and fairly stout, with apex slightly bifid or with a pair of diverging processes, the latter smooth or with a small, V-shaped, spinose cleft posteriorly. Socii very large and strongly diverging, tapering from a clubbed base to an acute or truncate tip, the latter reaching the level of apex of uncus or even projecting beyond it. Gnathos with median region roundly expanded, tongue-like and finely spined dorsally; lateral arms expanded and strongly developed, forming a lobe-like process near the base of the uncus, sometimes a second one more ventrally. Valve with broadly sclerotized costa and a digitate, apically spined process near base (short and without spines in the type-species). Sacculus strongly modified.

Female. Ovipositor lobes modified, very thick, irregularly papillate, strongly sclerotized and with a few ridges on the inner margin. Sterigma transversely sclerotized, with a round, postvaginal plate at centre. Ductus and corpus bursae small, membranous, the latter without signum.

Biology. Adults of Metaterpna are active from May to early October, and the altitude range is from 1100–4500 m, based on the label-data. Nothing is known about the pre-imaginal stages or the food-plants.

Distribution. China (Southwest, South-Central), India (North), Nepal.

As far as known, species of Metaterpna are distributed exclusively in the latitude range between 24˚to about 33˚N, and from 77˚ (Simla, Western Himalaya ) to 108˚E (Shaanxi, C. China) longitude range. M. differens is restricted to certain areas of the Himalayas, including the southern edge of Tibet , Nepal, and North India . M. thyatiraria and M. batangensis are distributed in South-Western to South-Central China, from Hengduan Mountains to Qinling Mountains .