Eupithecia copaquillaensis sp. nov. (Lepidoptera, Geometridae, Larentiinae, Eupitheciini) is described and illustrated. Adults of this new species were discovered using a light trap in the Copaquilla ravine, at about 2800 m elevation on the western slope of the Andes of northern Chile. The morphology of the genitalia of E. copaquillaensis resembles that of E. atacama (Vojnits, 1985), which is also Chilean. However, the shape of the smaller cornutus and the signa in the male and female genitalia respectively enable accurate differentiation of the two species. DNA barcodes are used to associate male and female E. copaquillaensis.

The widespread moth genus Eupithecia Curtis, 1825 (Larentiinae, Eupitheciini) is the most speciose of the family Geometridae (Lepidoptera), with more than 1300 species listed in the latest world catalogue (Parsons et al. 1999). Despite this impressive number, new species continue to be discovered in different parts of the world (e.g. Ferris 2007; Mironov and Ratzel 2012; Mironov and Galsworthy 2014; Skou et al. 2017; Seven et al. 2019).

Based on the study of the Palaearctic, Nearctic and Oriental fauna, Mironov and Galsworthy (2012) redefined Eupithecia and indicated a combination of some key features in the male genitalia for distinguishing the genus from the morphologically closely related genera of Eupitheciini: uncus broadest basally and hook-like distally with one or two tips, juxta “hourglass shaped” with a bilobed calcar, anterior arm of labides curved with a setose finger-like papilla at apex, and sternum VIII modified with patches of sclerotization. Furthermore, recent molecular phylogenetic studies that included Old World representatives of Eupithecia suggest that the genus represents a monophyletic group (Õunap et al. 2016; Brehm et al. 2019).

About a fourth of all the known species of Eupithecia are recorded in the Neotropical Region (Herbulot 2001). It has been suggested that the moist environments of the Andes are the most species-rich for this genus in the world (Brehm et al. 2019), based on the high species richness revealed in recent studies performed in the moist forests of the Ecuadorian Andes (Brehm et al. 2016). In contrast, the species richness of Eupithecia appears to be lower in the arid environments of South America (Rindge 1987).

Parsons et al. (1999) listed 61 species of Eupithecia with type locality in Chile; four others were added later (Parra and Ibarra-Vidal 2002; Vargas 2011). Most of the Chilean Eupithecia occur in the central and southern zones of the country (Vojnits 1985, 1992, 1994; Rindge 1987, 1991). In contrast, only five species have been recorded in the extremely arid environments of the northernmost part, at about 18–19°S, only one of which is known to occur in the highlands of the Andes (Rindge 1987; Vargas 2011). Adults of a second high-elevation species were recently collected in northern Chile. The examination of their genitalia revealed that the moths represent an undescribed species, whose description is provided here. DNA barcodes of one female and one male were used to confirm conspecificity.

The studied specimens were collected using a light trap in December, 2020 in the Copaquilla ravine (18°23'55"S, 69°37'49"W) at about 2800 m elevation on the western slopes of the Andes. Their abdomens were removed, cleared in hot KOH 10% for a few minutes, stained with Eosin Y and Chlorazol black and slide-mounted with Euparal. Images were captured with a Sony CyberShot DSC-HX200V digital camera attached to a Leica M125 stereo microscope and a Micropublisher 3.3 RTVQImaging digital camera, attached to an Olympus BX51 microscope. The distribution map was generated using SimpleMappr (Shorthouse 2010). Specimens will be deposited in the “Colección Entomológica de la Universidad de Tarapacá”, Arica, Chile (IDEA).

Genomic DNA was extracted from legs of one female and one male using the QIAamp Fast DNA Tissue Kit, following the manufacturer’s instructions, and sent to Macrogen Inc. (Seoul, South Korea) for purification, PCR amplification and sequencing of the barcode region (Hebert et al. 2003) using the primers (LEP-F1 and LEP-R1) and following the procedures described in Hebert et al. (2004). The sequences were aligned with ClustalW in MEGA X (Kumar et al. 2018) to search for variable sites and were analyzed using the BOLD Identification System (Ratnasingham and Hebert 2007).

Eupithecia copaquillaensis sp. nov. is the second species of the genus known to occur in the arid highlands of the western slopes of the Andes of the northernmost part of Chile. The only conspecific previously recorded in the same area is E. tarapaca Rindge, 1987, whose larvae feed on flower buds of Balbisia microphylla (Phil.) Reiche (Vivianiaceae) (Vargas 2016). However, the two species are easily separated based on morphology, because in the latter the male sternum VIII is a narrow piece with two short apical arms, the larger cornutus is a broad piece slightly shorter than the phallus and the smaller cornutus is a C-shaped piece, all of which remarkably contrast with the morphological pattern of E. copaquillaensis sp. nov.

Figures 8–11. 

Genitalia of Eupithecia atacama (Vojnits, 1985). 8. Male genitalia in ventral view, phallus removed; 9. Phallus in lateral view; 10. Smaller cornutus; 11. Female genitalia in ventral view. Scale bar: 0.4 mm.

Rindge (1987) arranged the species of Eupithecia of Chile in two Sections, namely 1 and 2, with the latter subdivided into four Groups named A to D, based on the morphology of the male segment VIII and male and female genitalia. The tergum fully sclerotized and the sternum as two separate longitudinal rods in the male segment VIII, the elongated valva, uncus with single apex and vesica with two cornuti in the male genitalia, and the corpus bursae with longitudinal striations in the female genitalia suggest that E. copaquillaensis sp. nov. is related to the species of Section 1, in which Rindge (1987, 1991) included the morphologically close E. atacama and four others: E. atacamaensis Rindge, E. guayacanae Rindge, 1991, E. osornoensis Rindge, 1987 and E. seatacama Rindge, 1987. However, the monophyly of this species group, as well as the phylogenetic relationships of all the Neotropical fauna of Eupithecia, must be reassessed using modern procedures.

Perhaps discouraged by the extremely arid conditions, surveys for geometrid moths have been scarce on the western slopes of central Andes. For instance, in the case of Eupithecia, the holotype of E. tarapaca was until a few years ago the only specimen reported in the scientific literature from above 3000 m in the northernmost part of Chile (Vojnits 1985, 1992, 1994; Rindge 1987, 1991). In accordance with recent additions to other genera of Geometridae (Palacios et al. 2020; Vargas et al. 2020; Vargas 2021), the discovery of E. copaquillaensis sp. nov. confirms the need for further studies to characterize better the overlooked fauna of geometrid moths harbored by the high elevation environments of central Andes.

I would like to thank Anthony Galsworthy for kind and valuable comments and suggestions on a previous version of the manuscript; Marcelo Vargas-Ortiz for the kind company in fieldwork and for performing DNA extraction; Wilson Huanca-Mamani for allowing the use of the molecular biology equipment and Lafayette Eaton for checking the English.