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POSTSCRIPT
- the genus Cerasana Walker |
Since going to press I became suspicious about the series of Cerasana anceps
Walker from Borneo: the variability was such as to suggest a species
complex. Kiriakoff (1968) included several names in synonymy with anceps
and it became evident from the original descriptions and specimens in
the BMNH that rubripuncta de Joannis (= lemeemagdalenae Lemee
& Tams) from Vietnam and basipuncta Semper (Philippines) were
good species.
Dissection of Bornean material revealed the presence of three species, two
endemic C. anceps is also known from Sumatra (material in
collection of Dr. R. Bender) and one also recorded from Peninsular
Malaysia, Sumatra and Mindanao. The two endemics share asymmetry of the
valves of the male genitalia and are probably sister-species. One, anceps
itself, is illustrated on Plate 2 and the genitalia of the other are
depicted in Fig. 22.
The widespread species is smaller (21-23mm) than the others, less
heavily marked, more yellowish in colour; the discal marks above and below
on both wings are usually faint rather than picked out with dark brown. In
the male genitalia the valves are symmetrical, bifid, with a small,
slender ventral process and a smaller, similar but less sclerotised dorsal
process; the aedeagus is straight with a lateral spine at two thirds and a
subapical thorn-like spine directed basad (illustrated by Kiriakoff
(1968: fig. 22)). The eighth tergite has short, broad lateral lobes and a
central, somewhat separated process articulated between the lateral lobes
and the tegumen of the genitalia. This central process is long, with
straight sides tapering to a square apex. The eighth sternite bears long
anteriorly directed apophyses as in the other two species, but also a pair
of more anterior, heavily sclerotised triangular processes. Bornean
material is restricted to a single male from Sandakan. The name lutea Pagenstecher
(1890, Dt. ent. Ztschr. Iris, 3: 14) may be referable: it has not
been possible to examine the type (Palawan) but the span of 45mm given for
the female is more in accord with this species than with the other two.
The commonest Bornean species is anceps itself, illustrated in
Plate 2. It is much larger (30-32mm) with narrower forewings and more
definite fasciation and discal spotting. The male genitalia have the fused
part of the tegumen twice as elongate as in the other species; the left
valve is very much longer than the right as in Fig. 22 but twice as broad,
irregular, round-ended and finely setose. The aedeagus is flexed slightly
at one third and again at right angles at two thirds in the reverse
direction; at the distal flexure there is a plate-like process with a
rounded, serrate distal margin. The central portion of the eighth tergite
is apically trilobed, the lateral margins flexed dorsad, the central lobe
bearing a pair of ventral flanges; the interior, dorsal margins of the
lateral lobes are straight, adjacent over the basal half and deeply,
roundly excavate over the distal half; each of the lateral lobes bears a
square flange ventrally, subapically. The distal margin of the eighth
sternite is broadly, squarely excavate.
The male genitalia of the third species are shown in Fig. 22. It is
slightly smaller than anceps in size (27-30mm), with deeper
forewings. The fasciation of both wings is slightly more intense, greyer;
there are usually distinctive dark grey dots, one at the base of the
forewing and three (two anteriorly, one posteriorly) on the thorax; two
grey dots on the costa associated with the antemedial are closer together
and more basal than in anceps. The male genitalia are as
illustrated and include the simple, apically rounded central portion of
the eighth sternite still attached to the tegumen. The aedeagus is
straight, expanded over the apical third, with a lateral lobe just basal
to the expansion; part of the apical margin is coarsely scobinate. The
lateral lobes of the eighth tergite are produced into slender triangular
processes. The posterior margin of the eighth sternite is irregularly
rounded and the slender apophyses are relatively much longer than in the
other species. The species appears to be new and is here described as Cerasana
alleni sp. n. Holotype  ,BRUNEI:
75m, Rempayoh, primary forest, Feb. 1982 (Lt. Col. M.G. Allen) BM
notodontid slide 975. Paratype, S.E. BORNEO: Samarinda, ix 1913 (M.E.
Walsh) BM notodontid slide 1187. Two specimens from coastal forest at
Seria in Brunei are probably alleni but have not been dissected. A
female labelled as from Singapore (H.N. Ridley) may also be alleni
but the provenance may be Borneo: I suspect much Ridley material in
the BMNH has been mislabelled ‘Singapore’ as there are several
examples of otherwise Bornean species that are exclusive to montane forest
types not known in Singapore!
Cerasana now appears to be a mainly Sundanian genus of some complexity, with its
centre of diversity in Borneo.
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