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Spilosoma Curtis

Type species: menthastri Denis & Schiffermuller (= lubricipeda Linnaeus), Europe.

This genus as currently indexed at the British Museum (Natural History) has numerous synonyms. However, it contains a number of distinctive groups and is probably paraphyletic. It is currently being studied by A. Watson (African taxa) and W. Thomas (Oriental taxa) who are likely to resurrect some of these genus-group names when their revisions are complete.

It shares a number of general features of the male genitalia with the next four genera: an eighth sternite divided into three sclerites, the lateral ones often long and perhaps serving as additional clasping organs, and with double (Spilosoma) or fourfold (Creatonotos) coremata basally within the central one; simple bilobed valves; a simple more or less triangular uncus, surrounded by a zone of sclerotisation on the intersegmental membrane; an aedeagus that usually terminates in a darkly sclerotised zone with one or more spines; an aedeagus vesica that is large, globular or more elongate, often with minor lateral lobes, zones of scobination and sometimes clusters of cornuti.

The female genitalia of these genera have paired glands dorsally between the ovipositor lobes as in many other Arctiinae. The development of these is highly variable, from small and simple, to large with branching in two or three dichotomies. Spilosoma lubricipeda has a single bursa with two round, scobinate signa. Variations in the wider group include three or no signa, or scattered spines (Creatonotos), and the presence in some taxa of a well developed appendix bursae. All Bornean ‘Spilosoma’ have the latter and all have a bursa without signa.

Bornean taxa in the Spilosoma complex fall into three groups as follows:

(1) The ericsoni group (ericsoni Semper, groganae Holloway rubriventris Talbot). This group is restricted to Sundaland and eastwards (Holloway, 1982: 216). The body is bright red except for the thorax which is cream, usually with a dorsal black streak. The male antennae are black, narrowly bipectinate, with a subapical creamy white zone on the dorsal side of the flagellum. The forewings are cream or pink, rather elongate, the hindwings red. In the male genitalia the lateral processes and coremata (a pair) of sternite 8 are well developed, particularly in groganae; the aedeagus usually lacks major fields of cornuti in the vesica, and the apical process is serrate. In the female (groganae examined) the dorsal glands are well developed with three dichotomies, the anal tube between the ovipositor lobes is broad, scobinate, and the duct to the appendix bursae is strongly sclerotised.

(2) The hosei group (hosei Rothschild, thomasi sp. n.). This group is also Sundanian. Both wings and the body are pale yellow above and below. The thorax does not have a dorsal black streak. The male antennae are similar in coloration to those of the first group but somewhat more broadly bipectinate. The coremata of the eighth sternite in the male are weak. The aedeagus apical sclerotisation supports several spines of unequal size, the largest centrally, and the vesica has a patch of stronger scobination or of definite spines near the base. In the female genitalia (hosei examined) the bursa and appendix bursae are small, the latter relatively short, both set on a short, sclerotised ductus; the dorsal glands of the ovipositor lobes are only weakly developed. W. Thomas (pers. comm.) refers this group to the oldest specific name, punctata Moore (Java).

(3) The strigatula group (strigatula Walker, griseabrunnea Holloway, hypogopa Hampson). The wings and body are dull red or creamy yellow; the underside of the wings is usually paler than the upperside, though sometimes with a reddish suffusion on the forewings basally or more extensively (hypogopa). The antennae are pale cream colour throughout, strongly bipectinate in the male. The coremata in the male eighth sternite are moderate. The aedeagus has a single apical spine, often set on an umbonate base; the vesica has three or more fields of robust cornuti. The valves of the male genitalia tend to be narrow. In the female genitalia (hypogopa) the dorsal glands are small, bifid, but the bursa and appendix bursae are strongly developed, the ductus sclerotised, flexed, as in the first group.

The two remaining species, borneensis Rothschild and vandepolli Rothschild, may fall into the second and third groups respectively. The former has weak coremata on the male eighth sternite and aedeagus ornamentation as in other members of the group; in the female the dorsal glands are only weakly developed but the bursa and extent of sclerotisation of the ductus are greater than in hosei. The abdomen is reddish above, not concolorous with the thorax. W. Thomas (pers. comm.) relates borneensis and allies to the Indian S. casigneta Kollar. S. vandepolli has fawn antennae and narrow valves in the male as in the strigatula group, and also a dorsal streak to the thorax, but the aedeagus lacks an apical spine and has only one major field of scobination in the vesica; the female genitalia have small dorsal glands.

The larvae are typical 'woolly bear' arctiines with dense tufts of plumose secondary setae on verrucae (see illustrations in Sugi (1987)). The colour is reddish to dark brown, possibly with a pale dorsal stripe. Pupation is in a dense cocoon in which the larval setae are embedded.

A wide range of host-plants has been recorded for the genus.

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