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Xerodes
Guenée
Type species: ypsaria Guenée
Synonyms: Zethenia Motschoulsky (type species rufescentaria Motschoulsky,
Japan) syn. n.; Gyadroma Swinhoe (type species testacearia Moore);
Zygoctenia Warren (type species cinerosa Warren, Adonara).
The concept of Xerodes is broadened here to include the eastern
Palaearctic genus Zethenia and Bornean taxa associated with Paradarisa
Warren in the BMNH collection. All have generally similar brown or grey-brown facies mostly with punctate postmedials and angles to the wing
margins in the median vein zone. The male antennae are fasciculate, strongly so
in typical Xerodes. There is a well-developed, shallow, triangular fovea.
Features of the male and female abdomen serve to define the genus and
suggest a relationship to Paradarisa. In the male, sternite 2 is distally
bilobed, bearing tufts of hair scales, a feature most strongly developed in
typical Xerodes but also seen in Paradarisa. Typical Xerodes has
eversible pockets laterally between segments 4 and 5. The setal comb on
sternite 3 is broad with the sclerotisation of the sternite obtusely constricted
on either side of it. In the genitalia the distal margin of the tegumen is
bilobed and tufted with hair-scales. The gnathus is apically broad, rugose. The
transtillae are ring-like to triangular in appearance (weak in X. lignicolor and
allies). The valve lacks a strong cucullus but may have a process or spur distal
to the sacculus on the ventral margin. In Paradarisa there is a central
spined process as well as saccular projections. The juxta bears a few enlarged
setae on each side, a pair of extremely enlarged ones in typical Xerodes. The
aedeagus vesica has a single large distal cornutus (a cluster of spines in Paradarisa).
In the female genitalia the ovipositor lobes and apodemes are elongate,
the apodemes of segment 8 much shorter. The ductus is short, sclerotised,
laterally scrolled. The neck of the bursa is long, sclerotised and fluted,
expanding horn-like into the distal bulb where the signum is a coarsely spined
disc, lacking a mushroom stalk base.
Sugi (1987) illustrates the larvae of Japanese Zethenia. They are
elongate, with fine but irregular linear markings of a cryptic nature. The back
of the abdominal zone terminates in two small, dark tubercles made more
conspicuous by pale patches just anterior to them. Of the two Japanese species
discussed, one is polyphagous, the other restricted to conifers.
The Bornean species are all montane.
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