Syrastrena Moore

Type species: minor Moore.

This genus has been reviewed by Holloway (1982: 198). The species are small, in shades of medium to pale reddish brown, with two oblique fasciae on the forewing; both fasciae consist of a pale line edged more darkly distad.

Humeral veins are present in the hindwing (Fig. 3).

Figure 3. Hindwing venation of Lasiocampidae: left, most frequent South-east Asian configuration (paralebeda); top right, gastropachine configuration (Gastropacha leopoldi), with numerous humeral veins anterior to Sc, and a major additional cell between Sc and Rs; bottom right, Syrastrena, with rather basal humeral veins, otherwise similar to Paralebeda.

The male genitalia are diagnostic, with the tegumen unsclerotised but having lateral setose processes (similar but smaller processes are present in Arguda). The valves are bifid, the dorsal and ventral processes slender and much longer than the central one. The cubile is broad, bearing two submarginal or marginal areas of spines separated by a central flange or scobinate boss. The aedeagus is very broad with no ventral spur; the vesica is very variable with several short lobes, some of which bear scobinate patches or terminal spines.

Like the previous two genera, Syrastrena is restricted to the Oriental tropics. It occurs in Mindanao but has not been recorded elsewhere in the Philippines or from Sulawesi

Taxonomic Note

A. Zwick (pers. comm.) has identified two further species of the sumatrana group from Borneo, in addition to borneensis (Note 64). Species A has been recorded from G. Kinabalu and G. Trus Madi in Sabah over an altitude range of 1100m to 1500m. One of the specimens from the Mulu survey attributed to borneensis in Part 3 has been determined as Species A by A. Zwick (pers. comm.); it was taken in lower montane forest at 900m on the limestone G. Api (slide 941). Species B has also been taken on G. Trus Madi, but occurs also in S. Kalimantan at the site 15km NE of Loksado; it has been recorded at altitudes from 800m to 1250m. All three Bornean species have the three patches of cornuti in the aedeagus vesica that typify the sumatrana complex, situated to the right, dorsally and to the left (A. Zwick, pers. comm.): the left patch is particularly long and narrow in borneensis; the same patch has a distinct gap or excavation in its lateral edge in species A; the dorsal patch in species B is much reduced, with very few spines.