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!

now appears to be a mainly Sundanian genus of some complexity, with its centre of diversity in Borneo.

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