Copaquilla moth (Plutella copaquillaensis) from larvae collected on Neuontobotrys lanata in arid Andean highlands, Chile

NEWS - Copaquilla moth (Plutella copaquillaensis Vargas sp. nov.) newly recognized in the genus based on adult specimens raised from larvae collected on Neuontobotrys lanata (Walp.) Al-Shehbaz (Brassicaceae) in the arid Andean highlands of northern Chile. The new species resembles Plutella xylostella Linnaeus 1758 in wing pattern, but differs in genital morphology.

Plutella Schrank 1802 (Lepidoptera, Plutellidae) is a widespread genus of moths containing 26 species. The larvae feed on plants in the Brassicaceae, except for a lineage endemic to the Hawaiian Islands, whose host plants are in the Capparaceae, a member of the Brassicales closely related to the Brassicaceae and Cleomaceae.

The circumscription of Plutella is controversial because of the variation in genital morphology. Unlike the large number of studies on P. xylostella, many members of this genus are poorly known. Apart from the diamondback moth, only two species have previously been recorded in Chile, Plutella deltodoma Meyrick 1931 and Plutella diluta Meyrick 1931, which are restricted to the southern temperate rainforests.

Rearing larvae collected on cruciferous plants native to the arid Andes of northern Chile allowed Héctor Vargas of the Universidad de Tarapacá to obtain specimens with wing patterns similar to P. xylostella. Further examination of the genital morphology revealed the moths to be distinct.

P. copaquillaensis is recognized by genital morphology. Males lack the gnathos and the basal hook-like process of the phallus ("lateral hook"), have triangular juxta and a cluster of spiniform setae on the saccule near the convex part of the ventral margin of the valve and females have a posterior projection on the VIIth sternum that appears between two small excavations.

The forewing pattern is variable and closely resembles that of P. xylostella. Although the forewings of some specimens of P. copaquillaensis are more yellowish than those of P. xylostella, most of the variation overlaps between the two species. However, differences in genital morphology allow accurate identification.

P. xylostella has a gnathos and a pair of hook-like basal processes at the base of the phallus, lacks juxta and has a cluster of spiniform setae on the saccule near the base of the valve and is displaced from the edge in males and a posterior projection on sternum VII appearing between two prominent folds in females.

The forewing pattern of P. copaquillaensis is also very similar to that of Plutella australiana Landry & Hebert 2013. However, the two species can be separated using the same characteristics of the male and female genitalia that allow separation of P. xylostella.

The new species is only known from the type locality, the Copaquilla Ravine, at 3100 m elevation on the western slopes of the Andes in northern Chile. N. lanata is the only documented host plant. The distribution range of N. lanata extends from southern Peru to central Chile. The larvae feed on the flowers of this plant.

DESCRIPTION

Male. Forewing length 7.1–7.5 mm.

Head. Vertex mostly pale yellow, creamy white behind antenna; frons creamy white; occiput creamy white behind vertex, yellowish-brown behind eye; ocellus present. Labial palpus porrect; first segment creamy white; second segment triangular in lateral view due to forward projected scales, outer surface yellowish-brown, inner surface creamy white; third segment upturned, mostly creamy white with scattered yellowish-brown scales. Antenna with scape and pedicel creamy white, flagellum creamy white dorsally and single transverse stripe of creamy white scales ventrally on each flagellomere.

Thorax. Mostly creamy white dorsally, with scattered pale yellow scales; tegula yellowish-brown. Foreleg mostly brownish-grey with scattered creamy white scales; mid-leg mostly creamy white with scattered brownish-grey scales; hind leg creamy white. Forewing upper surface mostly yellowish-brown with scattered creamy white, pale yellow and blackish-brown scales on basal three quarters; dorsal band extended from base to about three quarters of forewing length, pale yellow, anterior margin with three scallops, the outer expanded by a patch of creamy white scales; a yellowish-brown band with poorly-defined anterior margin lines the dorsal band from base to just before the third scallop; apical area mostly pale yellow with scattered yellowish-brown and blackish-brown scales; lower surface brownish-grey; fringe with narrow creamy white scales with blackish-brown or yellowish-brown tip. Some specimens with a blackish-brown, instead of yellowish-brown, band lining the dorsal band. Hind wing upper and lower surfaces and fringe brownish-grey.

Abdomen. Mostly brownish-grey with scattered creamy white scales. Segment VIII with well-developed pleural lobes and pair of coremata.

Male genitalia. Uncus absent. Tegumen a narrow, sclerotised transverse band; with pair of ventral pedunculi, each broadly fused to the respective arm of the vinculum; with pair of teguminal processes slightly longer than pedunculi, widely separated dorsally, ventrally fused near the middle. Anal cone mostly membranous, with slightly sclerotised ventral longitudinal patch slightly shorter than teguminal processes. Gnathos absent. Saccus continuous with vinculum, about three times the length of the ventral pedunculi of the tegumen; posterior two-thirds a triangular, concave plate, anterior third finger-like. Juxta triangular, about 0.25x length of saccus. Valva semicircular, about 1.2x length of saccus, maximum height about half length; ventral margin nearly straight, slightly convex near middle; apex and dorsal margin rounded; inner wall with sacculus reaching the convex part of the ventral margin of the valva, with a cluster of spiniform setae in distal area; outer wall with broad membranous area with outline similar to that of valva. Phallus slightly longer than valva, mostly needle-like, with bulbous base and pointed tip, vesica without cornuti; bulbus ejaculatorius semicircular, similar in size to base of phallus.

Female. Forewing length 7.1–7.6 mm. Similar to male, but head and thorax more yellowish-brown and lighter and more variable forewing pattern, with dorsal band of forewing poorly differentiated.

Female genitalia. Papillae anales slightly sclerotised, with scattered setae. Posterior apophyses straight, about 1.7x length of papillae anales. Tergum VIII a transverse stripe with small triangular expansion in the middle of anterior margin and setae on posterior margin. Anterior apophyses slightly longer than posterior apophyses, mostly straight, slightly curved near base, with ventral branch extended to the anterior tip of the respective part of the lamella postvaginalis. Lamella postvaginalis a pair of triangular sclerites with setae on posterior margin. Sternum VII with slightly upcurved posterior projection arising from the middle of the posterior margin between two small excavations; length about 1.7x basal width. Ostium bursae at the tip of the posterior projection of sternum VII. Ductus bursae with well-sclerotised, upcurved posterior half, about twice the length of posterior projection of sternum VII; anterior half membranous, straight. Corpus bursae elongated, pear-shaped, membranous, without signa.

Original research

Vargas HA (2024). A new species of Plutella Schrank (Lepidoptera, Plutellidae) from the Andes of northern Chile. Biodiversity Data Journal 12: e139664, DOI:10.3897/BDJ.12.e139664

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