Idiodes apicata

Young, Catherine J., 2006, Molecular relationships of the Australian Ennominae (Lepidoptera: Geometridae) and implications for the phylogeny of the Geometridae from molecular and morphological data, Zootaxa 1264 (1), pp. 1-147 : 1-147

Idiodes apicata , Corula geometroides and Conosara castanaea

This clade was poorly supported by bootstrap analysis. The sequence divergence percentage between the lithinine I. apicata and the other two species was 7.6% (28S D2). The Lithinini is one of the most widespread ennomine tribes and occurs on every continent ( Weintraub et al. 1995). Idiodes is one of the most species rich lithinine genera and consists of a total of nine Australian species and possibly a number of undescribed species ( Holloway 1987). It is a widespread genus that extends from southern Australia through Melanesia to the Philippines but appears to be most diverse in southeastern Australia. I. apicata is also widely distributed in Australia from tropical Queensland to most of southern Australia ( Common 1993). Adults are moderately large moths. Both forewings and hindwings are similarly coloured and patterned and are usually an ochreous brown with a darker oblique line although variations are common. Wings are spread widely and are appressed to the substrate at rest. Lithinine caterpillars are fern­feeders and, typically, Idiodes Guenée larvae feed on Pteridium esculentum Forst. (Bracken Fern) (Pteridophyta) .

I. apicata shares the following features with the two nacophorines:

—rounded, non­protuberant frons ( C. geometroides only); short labial palps ( C. geometroides only); frons basal shelf absent; small projection dorsad to antenna; nonfoveate forewing; A3 pecten without swollen hind­tibia ( C. castanaea only); simple, acute uncus; socii; large V­shaped gnathos; articulated processes of the anellus (Fig. 109); several discrete cornuti attached to the vesica (Fig. 110); antrum; large corpus bursae; signum ( C. geometroides only) (Fig. 111).

Differences in adult morphology between I. apicata and the two nacophorines are as follows:

—ciliate antennae; areolate forewing; relatively long epiphysis; relatively long hindtibia; hair­pencil and groove in hind­tibia; uncus relatively long; modified cucullus (Fig. 109); sclerotised ductus bursae (Fig. 111).

The long hind­tibia in I. apicata was distinctive among all species surveyed in this study and may be an apomorphy for the genus. It is not known whether this limb elongation is characteristic of other Lithinini .

The eggs of I. apicata are very similar to those of Amelora leucaniata , nebulosa and zophopasta (Young, in press). Shared characteristics are:

—loose or loosely attached; domed aeropyles, large openings present on all surfaces; double­ridged cell walls (Fig. 112).

Idiodes Guenée eggs also exemplify the more typical lithinine characteristics as described by Salkeld (1983). The eggs of this species closely resemble those of two Nearctic lithinine species described by Salkeld, Petrophora subaequaria Walker and Homochlodes fritillaria Guenée. Common features are: narrow, rather elongated eggs with a markedly truncated anterior pole; marked all over by quadrate, elongated, concave cells with moderately broad, double­ridged and elevated walls; prominent longitudinal ribs; elevated aeropyles with large to very large openings; rough chorion (Fig. 112).

Larval and pupal material for C. castanaea were unavailable; however larval features in common between I. apicata and C. geometroides are as follows:

—short spinneret; SV1, SV3 and V1 on A 1 in vertical alignment; no extra prolegs.

However there were also some important differences in larval morphology between the two species. The crochet arrangement in the mature larvae of C. geometroides is a uniordinal uninterrupted mesoseries whereas in I. apicata the more common biordinal, incompletely interrupted mesoseries is present. Uniordinal crochets are unusual in mature geometrid larvae however they were also noted in the geometrine H. percomptaria , the larentiine Euphyia nr. severata, the oenochromines s. l. Dichromodes and N. curtaria and the sterrhine Scopula perlata . L3, SV1 and V1 on A3–5 are in vertical alignment in I. apicata but not in C. geometroides . Six lateral setae are present on the A6 proleg of I. apicata whereas only four are present in C. geometroides . Interestingly, this number of A6 lateral setae unites the Amelora group i.e. A. sparsularia , Androchela milvaria , Cassythaphaga macarta and D. amblopa (McQuillan 1996) and also the robust­bodied genus, Capusa .The crochet arrangement in the first instar larva of I. apicata is also an unusual uniordinal penellipse broken laterally instead of the more common interrrupted mesoseries found in this study. This configuration was also present in the Australian nacophorines Melanodes anthracitaria and Capusa cuculloides . Thus I. apicata also shares two unusual larval features with Capusa : six A6 lateral setae and the crochet arrangement in the first instar larva.

Shared pupal features were as follows:

—smooth cuticle; exposed labium; concealed meta­tibia; pro­thoracic spiracle present, only well­developed in C. geometroides ; punctures small, deep, dense, randomly distributed, on meta dorsum and A 1–7 in I. apicata , but on A 1–8 in C. geometroides ; dorsal groove, deep, well­developed.

Fore­femora are exposed and the lateral groove developed only in I. apicata . Instead of the bifurcate cremaster present in Corula Walker , I. apicata has four pairs of cremastral setae. In this latter aspect I. apicata is distinct from the Amelora group (McQuillan 1996) despite sharing egg characteristics, absence of extra larval prolegs and six lateral setae on the larval A6 proleg