Syzeuxis Hampson, 1895

Li, Jing, Xue, Dayong, Han, Hongxiang & Galsworthy, Anthony C., 2012, Taxonomic review of Syzeuxis Hampson, 1895, with a discussion of biogeographical aspects (Lepidoptera, Geometridae, Larentiinae), Zootaxa 3357, pp. 1-24 : 2-3

Syzeuxis Hampson, 1895

Syzeuxis Hampson, 1895 , Fauna Br. India (Moths), 3: 330 (key), 339. Type species: Osicerda trinotaria Moore, 1868 , by original designation.

Aphantoloba Warren, 1896 , Novit. zool., 3: 117. Type species: Aphantoloba nigrinotata Warren, 1896 , by original designation.

Description Antenna of male bipectinate and ciliate apically, rami long and ciliate; filiform with cilia in female. Frons moderately protruding, smooth-scaled. Labial palpus rough-scaled, segment III very short. Hind tibia not dilated, with two pairs of spurs. Wing pattern. Forewing moderately to very broad; costa with base slightly curved, central section straight and curved near apex; apex almost a right angle, sometimes distinctly protruding; outer margin curved gently, nearly straight, or concave under apex and slightly protruding at middle then straight to anal angle; anal angle rounded, inner margin straight; antemedial and postmedial lines usually forming dark patches on costa. Hindwing narrow and long; apex and anal angle rounded; costa elongate, longer than or equal to length of inner margin; postmedial line present, but often modified to X-shaped or broadened with extension; sometimes hindwing in male with a small basal lobe. Underside: usually with distinct postmedial line on both wings. Venation ( Figure 1). forewing with one or two areoles, M1 stalked with lower margin of areole; sometimes without areole, R1 to R5 long stalked, arising before upper angle of cell, M1 not stalked; M2 arising from above middle of discocellulars. Hindwing with Sc+R1 and Rs separate and connected with a bar near center of cell. In male Rs stalked with M1 or arising from cell; discocellulars often not biangulate, M2 arising from second angle, close to M3; CuA1 shortly or long stalked with M3 with only two exceptions; CuA2 reaching anal angle, vein A missing; in female Rs and M1 shortly stalked, CuA2 reaching outer margin, 2A present. Male genitalia. Uncus flat, broad, length about 1.5 to 2 times width, usually concave at middle of posterior margin. Socii undeveloped, sometimes tiny, weak and membranous. Gnathos sclerotized, connected medially, with a large, thick, tapered median process. Valva relatively small and variously shaped, usually simple, without any process. Juxta often forming a sclerotized plate. Saccus not protruding. Aedeagus various, vesica smooth or with a bundle of spines. Abdominal sternite II of male with a central sac (not all species examined). Female genitalia. Apophyses anteriores very short, apophyses posteriores slender and long. Ductus bursae slender and long, with distinct antrum at upper part. Corpus bursae membranous, signum absent.

Diagnosis. Some species of Syzeuxis are distinctive in having a modified postmedial line on the hindwing, which is X-shaped. Moths included within Syzeuxis are externally similar to members of the genera Lobogonia Warren, 1893 , Chrioloba Prout, 1958 and Heterophleps Herrich-Schäffer, 1854 in having both antemedial and postmedial lines each forming a distinct patch on the costa of the forewing. Syzeuxis differs from Chrioloba in that the hindwing has a postmedial line, while Chrioloba lacks hindwing lines. The genus Heterophleps is characterized by having a hindwing inner margin which turns over in a flap, while this character is absent in Syzeuxis . Compared to Lobogonia , Syzeuxis has no distinct angle on vein M3 on either fore- or hindwing margin, or is only shallowly concave under the apex if a small projection is present, while a distinct angular projection is distinctly present on both wings in Lobogonia . In the male genitalia, Syzeuxis is very distinctive in having a developed, ring-shaped gnathos and median process, which is not a common feature in the tribe Trichopterygini . In addition to the distinctive gnathos, Syzeuxis also differs from Chrioloba in the shapes of uncus and valva, and from Heterophleps in having no developed basal valval lobe. In the female genitalia, Syzeuxis is also one of the few genera that lack a scobinate corpus bursae.

Distribution. China (South), India (Northeast and Bengal), Nepal, Indonesia (North Sumatra).