Arctesthes catapyrrha (Butler, 1877)

Patrick, Brian H., Patrick, Hamish J. H. & Hoare, Robert J. B., 2019, Review of the endemic New Zealand genus Arctesthes Meyrick (Lepidoptera, Geometridae, Larentiinae), with descriptions of two new range-restricted species, Alpine Entomology 3, pp. 121-136 : 121

Arctesthes catapyrrha (Butler, 1877) Figs 1-6, 14, 18, 20, 21-23, 30, 34 (map)

Fidonia ? catapyrrha Butler, 1877. Proceedings of the Zoological Society of London for 1877: 392, pl. 43 fig. 2.

Arctesthes catapyrrha kaikourensis Prout, 1939. In Seitz, A., The Macrolepidoptera of the World (Stuttgart) 12: 247. Described as subspecies; synonymised (by implication) by Dugdale (1988: 171, as ' ab. kaikourensis '); synonymy upheld here.

Type material.

Fidonia catapyrrha : Lectotype: male (here designated), 'Type [red-ringed circular label] / N. Zeal. 77.34 / Fidonia catapyrrha Butler Type’ (BMNH) (not examined, but photograph seen).

Note.

Fidonia catapyrrha was described from an unspecified number of specimens, but since Butler (1877) stated that it was in both collections that he had received (from Enys and Hector), he clearly had more than one specimen. There is no mention of type material in the original description, so the type series must be regarded as syntypic (ICZN Article 73.1) and neither the labelling of a specimen by Butler as ‘Type’ ( Dugdale 1988: 171) nor the mention of a holotype by Dugdale constitutes a valid lectotype designation (Article 74.5). The specimen hitherto regarded as holotype is here designated lectotype to prevent further confusion. Hector’s collection was probably largely from Otago and Enys’ from mid-Canterbury: Dugdale (1988: 171) suspected the lectotype to be from Canterbury based on the strong red flush on the hindwing underside, but this character is not restricted to Canterbury specimens and cannot be relied on as an indication of the type locality.

Arcesthes catapyrrha kaikourensis: Lectotype: male (designated by Dugdale (1988: 171)), 'Mt Tapuae-nuku (slopes of) 1.3.16 / 219 z’ (MONZ) (not examined but photograph seen).

Note.

Prout (1939) clearly described kaikourensis as a subspecies rather than an aberration of catapyrrha , so the name is available under the Code; Dugdale (1988: 171) incorrectly listed the name as an aberration. The description of A. c. kaikourensis runs as follows: 'According to Hudson (1928): "a local variety occurs in the Kaikoura Mountains, having the upperside of the hindwing bright orange. ”’ Based on this, and the lack of specimens under this name in the BMNH (J.S. Dugdale, notebooks), it is very likely that Prout took the remarkable action of describing the subspecies without seeing any material. This does not affect the availability of the name (ICZN Article 13.1). Specimens with bright orange hindwings occur perhaps throughout the range of A. catapyrrha , and there appears to us no evidence to support the separation of any populations as subspecies. Therefore the synonymy implied by Dugdale (1988) in indenting this name under catapyrrha is upheld here.

Diagnosis.

Differences from A. siris and A. titanica are detailed under those species, below.

Redescription.

Adult male (Figs 1-3, 14, 18): Wingspan 14-19 mm. Antennal pectinations long, up to ca 4 –5× flagellum width. Labial palpi with numerous long erect black hairlike scales laterally and ventrally, mixed with long white hairlike scales ventrally. Head and thorax grey to blackish, with variable admixture of white scales, sometimes with suffusion or overlay of bright orange-brown scaling of varying extent; strip of pure white scales along antero-ventral margin of eye. Forewing ground colour (areas between transverse markings) grey to blackish depending on variable admixture of whitish scales; proximal line white to greyish, with gentle convex curve (away from wing base); antemedian line white to greyish, with gentle convex curve; discal dot black, more or less equidistant between antemedian and postmedian lines or closer to antemedian; central fascia usually pallid in central band around discal dot, dark lines or bands either side of this band parallel with antemedian and postmedian lines; postmedian line greyish to white, strongly sinuous, with large V- to U-shaped evagination centrally, section between evagination and costa straight to weakly convex; veins often more or less distinctly lined blackish beyond discal cell; distal line whitish, often indistinct; fringe basally more or less distinctly chequered, distally whitish to grey. Forewing sometimes with suffusion of bright orange-brown scaling, especially along veins and in terminal area. Hindwing ground colour bright orange; basal blotch more or less suffused blackish; antemedian line distinct, weakly W-shaped, blackish; postmedian line very variably developed, sometimes almost obsolete, sometimes more or less continuous with terminal line, leaving only narrow orange area between, blackish, weakly V-shaped; terminal line a blackish suffusion, often obsolete; series of black dashes along termen distinct in specimens with terminal line obsolete; fringe basally blackish, distally greyish to white, sometimes with weakly chequered appearance. Forewing underside (Fig. 14) pale to bright orange; antemedian line indistinct or absent; discal dot distinct, black; postmedian line usually distinct, black, sometimes double centrally, with strong median evagination; white spot on costa between postmedian line and subterminal fascia; subterminal fascia more or less developed as blackish suffusion bordering subterminal line towards costa, sometimes continued as narrower line to tornus; subterminal line white, usually only distinct towards costa; terminal fascia blackish, often suffused bright reddish brown or rose-brown towards apex, sometimes obsolete (i.e. termen orange as ground-colour). Hindwing underside pale orange (this colour usually confined to a wedge-shaped streak in wing centre); a more or less well-defined strip along costa and around termen bright rose-brown, this colour sometimes extending as suffusion through centre of wing to base; broad white streaks subcostally and along anal margin to 2/3 length of wing; subbasal, antemedian and postmedian lines usually very distinct and rather broad, blackish, sometimes postmedian indistinct or obsolete; antemedian line sometimes preceded by distinct spot above middle; postmedian line with variably defined narrow white distal margin. Abdomen blackish, sprinkled white and with distal margin of each segment white; anal tuft mixed blackish and white.

Male abdomen and genitalia (Figs 21-23): S3-6 moderately elongate (rectangular), either uniformly well sclerotised or rather weakly sclerotised except along caudal margin; T2-6 either evenly sclerotised, or sclerotisation strongest in 2 lateral patches caudally on each segment. Uncus digitate, moderately robust, very blunt apically; labides robust, straight to gently curved, with weakly to strongly hooked apices; dorsal scobinate portion of manica with blunt teeth of various sizes; juxta tongue-shaped to arrowhead-shaped; valva very short, with smoothly rounded apex; basal costal sclerite with straight or concave costal edge, ending in blunt process more or less strongly projecting beyond valval costa; sacculus process a short rounded lobe, not reaching valval costa, finely and evenly scobinate; saccus short to long, blunt, Y-shaped, variably recurved under genital capsule. Phallus (Fig. 23) with tongue-like apical process; vesica with 2 or 3 small, rather weakly to moderately melanised spine-like cornuti.

Adult female (Figs 4-6): Wingspan 14-20 mm. Similar to male, but antennae without pectinations; labial palpi without lateral hairlike scales and with ventral scaling much shorter than in male, usually white without or with few black scales; forewing and hindwing both tending to be slightly narrower than in male; forewing markings tending to be better defined with cross-lines more distinct and central fascia often broader; hindwing upperside with postmedian line usually less distinct than in male.

Female genitalia (Fig. 30): Total length ca 2.4-2.8 mm. Ovipositor lobes subtriangular, apically blunt. S8 with strongly sclerotised, strongly concave, round to lobe-shaped lamella postvaginalis. Ostium round, narrow; antrum a variably distinct flask- or cup-shaped sclerotised chamber; ductus bursae with strongly rugose posterior portion and smoothly sclerotised anterior portion. Corpus bursae membranous, round to oblong.

Distribution.

(Fig. 34). Widespread in the central and southern South Island, becoming very local north of mid-Canterbury and not definitely known from the Nelson district. Hudson (1928) gives 'near Nelson’, but no specimens from this area have been seen in collections and the record requires confirmation.

WD, MB, KA, MC, SC, MK, OL, CO, DN, FD, SL

Biology.

This small geometrid is widespread in open low vegetation in the eastern and central South Island, but also near the West Coast in riverbed vegetation. It is found in coastal turfs (i.e., saltmarsh, dune slacks, and river-mouth habitats) as well as riverbeds, river terraces, saltpans, kettleholes, lake-edge turfs and short tussock grasslands of the interior valleys; it also occurs up to 1920 m on the drier eastern and central South Island mountains in cushionfield, snow banks, wetland and open, often depleted grasslands. It can be locally abundant over cushionfield, bare ground or low herbs and grasses, flying by day low to the ground. It often settles and is easily observed as it sunbathes on bare ground or low vegetation, or feeds on flowers (e.g. Aciphylla aurea ( Apiaceae ), Gentiana spp. ( Gentianaceae )). The species is a survivor and can sometimes be found in quite modified short and open grasslands, some of which are kept short by local management needs, such as at the Saint Clair Golf Course in Dunedin or Waimate Airstrip.

The brightly coloured larvae (Fig. 20) ( Patrick and Chisholm 1989) are polyphagous, having been found and reared from various native and exotic plant species including Trifolium (exotic clover, Fabaceae ), the creeping Nertera balfouriana , Nertera setulosa , and Coprosma atropurpurea (all Rubiaceae ), Scleranthus, Stellaria and Colobanthus (all Caryophyllaceae ), Polygonum plebeium ( Polygonaceae ), Oreomyrrhis rigida ( Apiaceae ) and the cushionplant Raoulia tenuicaulis ( Asteraceae ). In captivity the larvae will readily feed on Plantago and Epilobium and as these plants are present at many of its known sites, they are possible natural hostplants. Interestingly larvae have been observed in captivity to be cannibalistic on fellow larvae that had died. The larvae are active by day, and grow to 16mm. No detailed description of the larva is available, but a drawing of the habitus was provided by Craw (1986: fig. 21) and a brief description is made here from photographs (see Fig. 20): the head is reddish brown with paler marbling; prothorax red-brown dorsally; the body pale grey to rosy pink, with an interrupted broad green dorsal line on the abdominal segments, bordered by oblique subdorsal stripes that are green anteriorly and black posteriorly; there is some white between the dorsal line and the subdorsal stripes; the stripes merge on the thorax into a broad blackish subdorsal line tinged green centrally; anal prolegs brown. Larvae move forward with a quick, repetitive, jerking action.

The adults first appear by mid-September at low altitude sites, and the last records are from early May. Most alpine and high alpine records are between December and March. There appear to be up to three generations per year at lowland and inland montane sites, but perhaps just one at the highest altitudes.

Remarks.

This is a common and widespread species: BHP has made 214 records since 1971 (BHP notebooks, Christchurch). There is considerable variation in the form of the saccus in the male genitalia of A. catapyrrha . While most specimens have a long saccus that is more or less aligned with the genital capsule (Fig. 22), a few have a much shorter saccus that is recurved beneath the capsule. Since this character does not seem to align consistently with any other morphological character or any area of distribution, and since one specimen from Mt Maungatua DN (genitalia slide NZAC Geo. 45) has a saccus of intermediate form, no taxonomic significance is accorded to the variation here.

Prout (1939) described ab. fasciata as a form of Arctesthes catapyrrha . Dugdale (1988: 171) mentions a female ‘holotype’ collected by Philpott at Ben Lomond OL designated by Prout in the BMNH. Since the original description makes it clear that the name fasciata refers to an aberration, it is infrasubspecific and therefore unavailable (ICZN Article 45.6.2). The provisions of the Code do not apply (Article 1.3.4), and no type material was mentioned in the original description, so the ‘holotype’ mentioned by Dugdale has no nomenclatural status.