Ciampa arietaria, Guenee, 1858

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

Ciampa arietaria and Chlenias ‘zonaea’

The relationship between these two robust­bodied Australian nacophorines species was very well supported (Fig. 10) and the sequence divergence between the two was only 1.8% (28S D2) (Appendix 6). C. arietaria is the most widespread in this genus of four species, is one of very few native geometrids that are pests on herbaceous plants and has been recorded feeding on lucerne, Erodium l’Hérit , lupins and Arctotheca (capeweed). All species occur in southern Australia and the adults are moderate in size. The forewings are fuscous or brown streaked and are often suffused with lighter and darker fuscous shades resulting in longitudinal stripes that afford camouflage in low­growing vegetation; the hindwings are plain greyish­white. At rest the wings are folded flat over the abdomen. It is a common and widely distributed species ranging from southern Queensland to most of southern and south­eastern Australia ( Common 1993). Chlenias is an assemblage of superficially similar, polyphagous species, which are usually difficult to separate even on genitalic characters (data not shown) and, consequently, considerable confusion in identity has arisen. This large genus has many undescribed species and is widespread in the southern half of Australia. Several species often coexist in a particular habitat. C. ‘zonaea’ is a moderately large moth with cryptically coloured, longitudinally striated, narrowly elongate forewings in varying shades of brown and grey. The hindwings are a uniform greyish brown. This species flies in autumn and is common in eucalypt forests.

The adults of C. arietaria and C. ‘zonaea’ are superficially similar and the species also share many morpological similarities in all life­cycle stages. The eggs of C. arietaria (Fig. 101) and Chlenias spp. (Fig. 97) are very similar and distinctive. These eggs are subellipsoid, inconspicuously marked apart from slightly elevated aeropyles that are only present in a band around the anterior pole. The chorion was also granulated in all species of Chlenias examined.

Common adult features

­bipectinate with long rami; one apical sensilla chaetica and one subapical sensilla chaetica present on ramus; frontal basal shelf present; projection dorsad to antenna absent; rough projecting vestiture on frons; short, labial palps; areole present in forewing; narrow forewings; thoracic crest; hind­tibia not dilated; A3 pecten absent; simple, wide valvae; simple fold in anellifer; simple, straight, acute uncus; small socii; cristate hairs absent; strongly developed, broad, U­shaped gnathos; absence or reduction of articulated processes of anellus; moderately large juxta (Figs 94, 98); curved aedeagus (Figs 95, 99); wide ovipositor; lamella postvaginalis rectangular, sclerotised; small, sclerotised colliculum; membranous, moderately wide, short ductus bursae; bursa copulatrix poorly differentiated; signum absent (Figs 96, 100).

Differences in adult features

­ C. arietaria has a distinctive two­pronged protuberant frons (Fig. 102), C. ‘ zonaea’ has a rounded and flattened frons; hair­pencil and groove only present in C. ‘ zonaea’; distinct cornuti (weak) present in C. ‘zonaea’ only (Fig. 95); C. arietaria only has a narrowed, anterior caecum in aedeagus (Fig. 99); corpus bursae relatively longer in C. arietaria (Figs 96, 100).

The larvae of both species are also superficially similar and are both aposematically coloured. This adaptation is often associated with polyphagy and also occurs in Nisista notodontaria and Capusa Walker , which have also been recorded as feeding on a number of unrelated plant species. Larve share the following features:

—first instar larval setae of medium length; typical ennomine chaetotaxy; SV1, SV3 and V1 vertically aligned on A1; L3, SV1 and V1 vertically aligned on A3–5; crochets are arranged as a biordinal interrupted mesoseries, but in C. ‘zonaea’ incompletely interrupted by a short series of vestigial, hookless crochets; five lateral setae on A6 proleg; absence of extra prolegs.

Differences in larval features

—spinneret short in C. arietaria , long in C. ‘zonaea’; hypoproct truncated and rounded in C. arietaria only; setae of first instar larvae are clubbed in C. arietaria .

C. arietaria and C. ‘zonaea’ are strongly united by both molecular and morphological data. Unusual features in C. arietaria such as a truncated hypoproct and clubbed setae in the first­instar larvae are possibly related to feeding on low­growing or herbaceous plants as these attributes are also present in non­arboreal feeders. For example truncated hypoprocts are present in the archiearine Acalyphes philorites , the sterrhine Scopula perlata and the noctuid Proteuxoa cryphaea and clubbed first instar setae in the nacophorine Amelora sparsularia , the sterrhine S. perlata and the noctuid Agrotis porphyricollis . The distinctive two­pronged extension of the frons of C. arietaria (Fig. 102) is most likely an adaptation for burrowing through hard, dry soil on eclosion. This feature is likely to be an adaptation to the habitat of the species and therefore homoplasious. On this basis it is likely that these two genera are closely related enough to be combined into one taxon, although formalising of this synonomy will have to await more thorough examination of the other species in both genera.

Probable synapomorporphies

—short, anteriorly directed, acute crest on pronotum of adult; simple fold in anellifer; absence or reduction of the following structures that are commonly present in other Australian nacophorine genitalia: cristate hairs, articulated processes of the anellus and signa; absence of extra vestigial prolegs in larvae.

Egg characters, though distinctive, are shared by Smyriodes . The absence of extra larval prolegs, although unusual in robust­bodied Australian nacophorines, is also a feature of several other nacophorine genera e.g. Amelora , Furcatrox , Cassythaphaga and Corula .