Oruza Walker

Type species: costata Walker, India.

Synonym: Curvatula Staudinger (type species pallicostata Strand, Russia (Siberia) = mira Butler).

This genus is treated in a very broad sense by Poole (1989), but much more narrowly by Edwards in Nielsen et al. (1996). The latter course is followed here, with most other species-groups included by Poole being assigned to other genera. However, a few distinctive species that are not referable to any of these are retained in “ Oruza” until a more comprehensive review of the wider Oruza and Lophoruza Hampson complex can be undertaken.

Species of Oruza have a much more uniform ground colour to the wings, in that markings are relatively obscure, finely paler lines, and the costal zone is only narrowly paler, if at all. The fasciation is usually ochreous rather than white and consists of transverse antemedial and postmedial fasciae on the forewing, more or less straight or shallowly concave distad, and a central postmedial on the hindwing, curved roughly parallel to the distal margin. There are even finer submarginals, irregularly zigzag, except for that on the forewing where the anterior third to half is also shallowly concave distad.

The male abdomen has the eighth segment virtually unmodified, the sclerites short, with the tergite equal, or broader than the sternite, and with very shallow, obtuse apodemes. The genitalia have the valves virtually divided into three, with a slender costal arm extending beyond the flimsy, narrow, setose, tongue-like cucullus. There is also a robust digitate process from the apex of the sacculus that is about half the length of the costal process. The uncus is relatively short and robust compared to that in other genera of the complex.
The female genitalia have the apodemes of the eighth segment moderate to short, sometimes with small pockets between them and the ostium. The ductus bursae is uniformly sclerotised, and the corpus bursae arises from it with only the vestige of a basal coil if at all, the ductus seminalis arising laterally from it subbasally with only a slight protrusion. The main part of the corpus bursae is an elongate pyriform with fine general scobination distal to this protrusion.

The genus has a small number of species extending from Siberia through the Oriental and Australian tropics and subtropics. Only one true Oruza has been recorded from Borneo. Other named species from the region (in addition to those described below) that show the diagnostic features are: cervinipennis Warren (New Guinea, Australia, ?Sulawesi); kuehni Warren (Kei Is., ?Sulawesi); xanthobela Hampson comb. n. (Philippines). There is one montane species, O. odontota Fletcher (1961; Ruwenzori) comb. n., in Africa; it was originally described in Corgatha Walker.

In addition, there is a trio of species that includes the Bornean lacteicosta Hampson that is placed here in Oruza because of the characteristics of O. crocodetoides sp. n., where the facies is typical of the genus, but the male genitalia show the unusual features of the uncus and valves seen in this trio. The forewing facies is distinctive, with a relatively narrow pale costal band of even width that extends across the anterior half of the thorax only. The ground colour is otherwise dark brown. All the wings have a major pale patch on the tornus, that of the forewing being larger, extending anteriorly to the costal band in the type species, which also has an oblique, pale discal mark. As well as lacteicosta, the trio includes O. glaucotorna Hampson (Japan, Korea) and O. microstigma Warren  (N.E. Himalaya, Luzon).

The male abdomen in the trio has only short apodemes to the basal sternite, and the eighth sternite has a transversely oval frame with slight lateral rods. The male genitalia have valves that are relatively broad as in Eugnathia, but with distinct, short, robust, costal and saccular processes. The uncus bears a diagnostic dorsal spur or spine subbasally.

The female genitalia in this trio (microstigma Warren) have a doubled pouch between the apodemes and the ostium. The ductus bursae is very short, and the corpus bursae has a slightly larger and expanding section between it and the origin of the ductus seminalis. There is a similar short neck-like section distal to this before the corpus bursae expands into a broader, sausage-like distal section. At the distal end of the short zone of expansion is a girdle of spines like that seen in some Obana species and the Arasada group of genera (p. 118 et seq.).
Sugi (1987) illustrated the larva of O. mira. It lacks prolegs on A3 and A4 and is covered with dense secondary setae or pubescence (also seen in Zurobata vacillans Walker and Ataboruza divisa Walker, described on p. 103 and p. 109). The body is cylindrical, stout, without processes, cryptically mottled brown. The larva feeds on dead foliage. Sugi drew attention to parallels in proleg loss, secondary setae and feeding habits with the Palaearctic Trisateles Tams.