Arctesthes Meyrick, 1885

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

Genus Arctesthes Meyrick, 1885

Arctesthes Meyrick, 1885. New Zealand Journal of Science 2: 589. Replacement name for Stratonice Meyrick, 1884 (Transactions and proceedings of the New Zealand Institute 16: 64; unavailable, preoccupied by Stratonice Malmgren, 1867 ( Annelida: Polychaeta)). Type species: Fidonia catapyrrha Butler, 1877, by original monotypy.

Arcteuthes Meyrick, 1888. Transactions and proceedings of the New Zealand Institute 20: 47. Incorrect subsequent spelling.

Diagnosis.

Based on the redescription by Craw (1986) and on comparison of specimens and genitalia slides in NZAC, Arctesthes is closely related to Notoreas . It can be distinguished from Notoreas by features of the male genitalia, as follows: in Arctesthes the juxta is a single tongue-like plate; in Notoreas , the base plate is emarginate and separated from a posterior sclerite (the ventral manica pad of Craw (1986)) by membrane; in Arctesthes , the labides are short to moderately long and robust (very short in A. siris ); in Notoreas , they are usually long to very long and narrow; the costal sclerite of the valva in Arctesthes is small and smooth; in Notoreas it is very large and strongly scobinate. The larvae of Notoreas are restricted to Thymelaeaceae as host-plants; known larvae of Arctesthes are more or less polyphagous on herbaceous plants.

Redescription

(updated from Craw (1986)). Small diurnal larentiines with cryptic forewings and black and orange hindwings. Head: male antennae bipectinate, with pectinations 3 –5× width of flagellum; female antennae simple. Male abdominal segments 7-8 reduced; S7 with short, eversible pouch-like coremata. Male genitalia: uncus moderately short to rather long, narrow, digitate, curved; valva more or less oblong, with costa sclerotised for ca ½ valva length and more or less projecting beyond outline; sacculus ending in small weakly scobinate cushion-like ( catapyrrha , siris ) or large, curved, spinulose projection ( titanica , avatar ); juxta tongue-like; dorsal manica pad strongly scobinate / coarsely spinulose; phallobase tapering; vesica with 2-3 small spine-like cornuti only ( catapyrrha ), with 3 spine-like cornuti and a comb-like group ( siris ) or with 2 comb-like groups of cornuti ( titanica , avatar ). Female genitalia: ovipositor lobes (papillae anales) forming compact ‘pad’, strongly setose throughout; apophyses posteriores long and narrow; apophyses anteriores much shorter and more robust; S8 sclerite narrow, strap-like; ostium very narrow ( catapyrrha , siris ) to very broad ( titanica , avatar ); ductus bursae variable in sclerotisation and rugosity; ductus seminalis arising dorsally at ductus / corpus bursae junction; corpus bursae weakly membranous, more or less round, without signa.

Distribution.

Endemic to the South Island of New Zealand.

Biology.

Adults diurnal. Known larvae ( catapyrrha , siris ) more or less polyphagous on low herbaceous plants in native and / or modified swards.

Remarks.

Craw (1986: 132) included the following characters in his redescription of Arctesthes : 'sacculus reduced, no free arm; apex a rounded, low mound...vesica with three cornuti...ostium a narrow circular opening...ductus bursae much longer than wide’. These have been revised in the description above following the discovery of A. titanica and A. avatar . Males of both new species have a large free arm of the sacculus, and a pair of comb-like groups of cornuti in the vesica; females of both have a very broad ostium and a ductus bursae that is wider than long. Craw (1986) also overlooked the presence in A. siris of a set of close-set comb-like cornuti in the vesica; only A. catapyrrha has the cornuti reduced to 2 or 3 in number as per his description. In spite of their differences from the previously described species, A. titanica and A. avatar are referred to Arctesthes based on the other morphological characters mentioned in the Diagnosis above; as stated elsewhere, further studies on the phylogeny and genus classification of New Zealand Xanthorhoini are needed.