Chlenias ochrocrana, Turner, 1947

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

Chlenias ochrocrana and Gastrina cristaria

The percentage sequence divergence (28S D2) between these two Australian nacophorines species is 1.9%. Turner placed C. ochrocrana into the moderately large genus Chlenias Guenée , based largely on external characteristics in his New Australian Species of the Boarmiadae ( Lepidoptera ) of 1947. Chlenias is an assemblage of superficially similar species, which are sometimes difficult to separate even on genitalic characters and, consequently, considerable confusion in identity has arisen. C. ochrocrana is a moderately large geometrid with elongated triangular forewings that are coloured in varying shades of brown in the male and greyish and reddish brown in the female. The female is distinguishable from the male by the presence of a white, irregular, postmedial band on the forewing. Hindwings are a uniform pale brown in both sexes.

G. cristaria is a somewhat smaller moth with elongate triangular forewings, similar in colouration to the males of C. ocrochrana but with fasciae more strongly marked on the forewings. The hindwings of this species are also pale brown but with darker marginal bands. Wings are held roof­wise at rest. C. ochrocrana is found in moist, relatively highaltitude eucalypt and mixed forests, whereas G. cristaria ranges from the Bunya Mts in Queensland to Victoria and Tasmania ( Common 1993) and is commonly found in dry sclerophyll forests where the larvae feed on Acacia sp ..

Both species are robust­bodied moths with long­branched bipectinate antennae. C. ochrocrana has apical and sub­apical stout sensilla chaeticae on the antennal rami, whereas G. cristaria lacks distinct apical sensilla. Unusally the rami of G. cristaria have a mesal rather than basal origin on the antennal segment. A well­developed projection dorsad to the antennal base is present in both species but is larger in G.cristaria . The frons of both species is squared and protuberant with a roughly projecting vestiture and basal shelf. Labial palps are short and horizontally oriented. Forewings lack foveae and an areole is present. An A3 setal comb together with swollen hind­tibia and hair­pencil is only present in G. cristaria .

Similarities in male genitalia are as follows (Figs 88–91):

—simple, straight, long, robust uncus; small socii; large gnathos; cristate hair (sparse in G. cristaria ); moderately small juxta; simple valvae; apically acute, short and wide aedeagus.

Female genitalia:

—large membranous corpus bursae; large, well­developed, stellate signum (Figs 92, 93).

However there are differences betweeen the genitalia of the two species. C. ochrocrana has a pair of long, slender, articulated processes of the anellus (Fig. 88), structures that are absent in G. cristaria (Fig. 90), although widespread in the Australian Nacophorini . G. cristaria has two pair of lobes attached to the transtilla and also two pairs of elongate lobes attached to the anellifer (Fig. 90). These modifications of the male genitalia are unusual in the Australian Nacophorini . Discrete cornuti are also well developed in C. ochrocrana (Fig. 89) whereas they are absent in G. cristaria (Fig. 91)

C. ochrocrana also bears some resemblance to Chlenias spp. , e.g. C. ‘zonea’. Both are robust­bodied species with long­branched bipectinate antennae. In this case C. ’zonaea’ shares the apical and sub­apical sensillae chaeticae on the rami also present in C. ochrocrana and also a frons with a rough projecting vestiture, basal shelf and short labial palps. C. ’zonaea’ also lacks an A3 pecten. This species also shares some male genitalic characters with C. ochrocrana (Figs 88, 94). Unlike G. cristaria , processes of the anellus are present in both species, but are very small and inconspicuous in C. ’zonaea’ as in other Chlenias species. The aedeagus is short and stout and the narrow valvae are unmodified in both species, except that C. ’zonaea’ has a small fold in the anellifer. There is also a small juxta and a well­developed gnathos in both species (Fig. 88, 94).

However there are some important differences between C. ochrocrana and other Chlenias species :

—squared and protuberant frons, compared to rounded and non­protuberant in Chlenias ; projection dorsad to antennal socket, absent in C. ’zonaea’; no dorsal thoracic crest (characteristic of the genus); relatively broad fore­wings, Chlenias species usually have narrow fore­wings, especially in the females; spatulate, long uncus, compared to short and acute in Chlenias ; well­developed cristate hair, absent in Chlenias (Figs 88, 94); many and strongly­developed cornuti, few and weak in Chlenias (Figs 89, 95); bursa copulatrix well­differentiated, poorly differentiated in Chlenias ; ductus and corpus bursae large, ductus well­sclerotised, with well­developed signum, in Chlenias both the ductus and corpus bursae are small, and the ductus only weakly sclerotised, a signum is absent (Figs 92, 96). No immature stages are available for C. ochrocrana thus no comparsion could be made with the immature stages of G. cristaria or indeed with other Chlenias species.

It is likely that C. ochrocrana has been misplaced in Chlenias as this species does not have typical Chlenia s exterior or genitalic characters and a congeneric relationship is not supported by molecular data. However, although support for a sister relationship between G. cristaria and C. ochrocrana is moderately strong from sequence data, morphological characters most likely do not indicate a congeneric association. Correlation from immature characters would be useful in further clarifying this relationship.