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Orthocabera Butler
Gen. rev.
Type species: sericea Butler, Himalaya to Taiwan and Japan.
Synonym: Microniodes Hampson (type species obliqua Hampson,
Sri Lanka) praeocc.
This genus is revived to include most species previously assigned to Myrteta
Walker that were not placed in Micronidia Moore by Yazaki (1992).
Typical Myrteta (type species planaria Walker, Himalaya) has male
genitalia and modified eighth sternite as in the Macariini, but lacking uncal
‘horns’ and with normal chaetosemata (See
Macariini). The species
similar in facies and probably therefore true Myrteta are the Chinese M.
sinensaria Leech, M. tripunctaria Leech and M. interferenda Wehrli
and the Japanese M. angelica Butler. The larva of M. angelica was
described by Sato (1977) and feeds on Styrax (Styracaceae). The Japanese
species unio Oberthür has genitalia and, to some extent, facies as in Myrteta
and should be retained there or in the genus of which it is type species, Taeniophila
Staudinger.
A further Japanese species, punctata Warren, has male genitalia
with the ventral portion of the valve expanded as in Micronidia and Orthocabera
but otherwise with a macariine appearance, lacking the derived features of
these other two genera. Sato (1977) described the larva. It feeds on Acer (Aceraceae).
Sato & Nakajima (1975) included Malus (Rosaceae) as a host-plant, but
this is based on a misidentification in earlier literature (K. Yazaki, in
litt.). The genus- group name Lamprocabera Inoue has been associated
with this species through misidentification (Fletcher, 1979).
Micronidia and Orthocabera share a number of features. In the genera
discussed above, the dorsal arm of the valve is densely setose over the apical
half. In Micronidia the setation is reduced to a few short, stout ones at
the apex of the arm, with a fringe of finer, larger ones round the outside of
the curve of the process, mostly the distal half, and largest towards the base
of that half. Orthocabera shares the short apical setae and the more
slender, curved nature of the arm, but the setae on the shaft are much sparser,
interspersed with a few very long ones. In both genera the neck of the tegumen
adjacent to the uncus is elongated, perhaps the most unambiguous synapomorphy.
The gnathus is stronger in Orthocabera, and the exterior face of
the lower portion of the valve is shallowly corematous. The saccus is very
shallow. The uncus has the apex produced beyond the basal, setose, triangular
part. The aedeagus vesica usually has a single stout cornutus lying centrally,
reflexed, adjacent to a dense mass of spines. In Micronidia there is only
the large cornutus, though this state also occurs secondarily in a few Orthocabera
species.
All genera discussed here have a comb of setae on male sternite 3. The
female genitalia have a long, slender, curved, fluted lower sclerotised zone to
the bursa in Micronidia, whereas this is broader in Orthocabera (Bornean
species examined), shorter than the distal part of the bursa. In both genera the
signum is of the stellate mushroom type.
The genera differ in a number of external features. The male antennae
are simple in Micronidia, bipectinate in Orthocabera. The
fasciation on the pure white ground in Micronidia is transverse, broad,
pale grey, whereas in Orthocabera it is oblique, fine, linear or broken
linear, brown or reddish, usually with a dark discal spot on the forewing. Micronidia
has black, marginal patches on either side of CuA1 of the hindwing; in Orthocabera
it is often angled at M3.
In the larvae, Orthocabera species in Japan have an extra pair of
setae in the posterior group on the anal shield (three pairs instead of two)
compared with Myrteta and punctata (Sato, 1977). There are no data
on the condition in Micronidia. The host-plants of Japanese Orthocabera
are Camellia and Stewartia (Theaceae).
In addition to the species discussed below in relation to Bornean Orthocabera,
the genus includes: O. subvitrea Hampson comb. n. (N.E. Himalaya);
O.
obliqua Hampson comb. n. (Sri Lanka); O. moupinaria Oberthur comb. n.
(W. China, N. Burma); O. luteifrons Swinhoe comb. n. (N.E. Himalaya);
O.
tinagmaria Guenée comb. n. (China, Japan); and probably (not dissected)
O.
fuscolineata Swinhoe comb. n. (N.E. Himalaya) and O. minor West
comb.
n. (Luzon).
The relationship of Micronidia and Orthocabera is not
clear. The features appear somewhat intermediate between those of the Macariini
and Cassymini. The dorsal arm of the valve is more as in the Cassymini, but the
venation features of that tribe are absent. Other groups in the old Myrteta conglomerate
appear to be more readily referable to the Macariini, but are not necessarily
related to Orthocabera.
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