Argyrotaenia socoromaensis sp. nov. (Lepidoptera, Tortricidae, Tortricinae, Archipini) from the arid Andes of northern Chile is described and illustrated. Adults are sexually dimorphic, with differences in wing size, shape and pattern. The larvae feed on Stevia philippiana Hieron. (Asteraceae) and Lupinus oreophilus Phil. (Fabaceae). Genetic distance between DNA barcodes of male and female adults reared from larvae collected on the two hosts was 0–0.2% (K2P). The discovery of A. socoromaensis sp. nov. represents the first record of the genus Argyrotaenia Stephens, 1852 and the tribe Archipini for the Chilean fauna of Tortricidae.

Andes, arid environments, DNA barcoding, larval polyphagy, new record, new species, sexual dimorphism, taxonomy

The updated, online world catalogue of the family Tortricidae (Gilligan et al. 2018) includes 116 species in the genus Argyrotaenia Stephens, 1852 (Tortricinae, Archipini). The widespread Palearctic A. ljungiana (Thunberg, 1797), senior synonym of the type species Tortrix politana Haworth, 1811, is the only Old World representative of the genus, while all the others occur from Canada to Argentina in the New World (Razowski 1997; Brown and Cramer 1999; Gilligan et al. 2018). As part of recent taxonomic studies of the Caribbean fauna of the tribe Archipini, some species included in Argyrotaenia by Gilligan et al. (2018) were either transferred to other genera or synonymized, and new ones were described (Austin et al. 2019; Austin and Dombroskie 2020a, b), bringing the current total to 114. Several members of the genus, such as A. ljungiana and A. sphaleropa (Meyrick, 1909), are pests of cultivated plants (Trematerra and Brown 2004; Gilligan and Epstein 2012; Gonsebatt et al. 2018; Ruiz-Galván et al. 2023).

Forty-three species of Argyrotaenia have their type locality in South America (Gilligan et al. 2018). Although some of them were described from Argentina, Bolivia and Peru (e.g., Razowski 1988; Razowski and Becker 2000, 2010; Trematerra and Brown 2004; Razowski and Wojtusiak 2010), the genus remained unknown in neighboring Chile (Razowski and Pelz 2010). However, recent surveys on the arid western slope of the central Andes yielded the first individuals of Argyrotaenia in this country. Subsequent morphological examination revealed that they belong to an undescribed species resembling the little-known A. oriphanes (Meyrick, 1930), described from Agualani, Puno, Peru. However, the two species can be separated based on differences in wing pattern and genitalia morphology of the male. As the Chilean specimens were reared from larvae collected on plants belonging to two distantly related families and showed differences in size, shape and pattern of male and female forewings, their conspecificity was assessed with mitochondrial DNA sequences of the barcode region (Hebert et al. 2003).

The aim of this contribution is to describe a sexually dimorphic, polyphagous new species of Argyrotaenia from the arid western slope of the central Andes, a discovery that represents the first record of this genus and the tribe Archipini from Chile.

The adult specimens examined in this study were reared from larvae collected on inflorescences of Stevia philippiana Hieron. (Asteraceae) and Lupinus oreophilus Phil. (Fabaceae) in April, 2021 and May, 2023 in the surroundings of Socoroma Village (18°17'22"S, 69°35'12"W) at about 3400 m elevation on the western slope of the Andes in the Parinacota Province of northern Chile. The abdomen of each adult was removed and placed in hot KOH 10% for a few minutes for dissection of the genitalia, which were stained with Eosin Y and Chlorazol Black and mounted on slides with Euparal. The holotype, paratypes and their genitalia slides are deposited in the “Colección Entomológica de la Universidad de Tarapacá” (IDEA), Arica, Chile.

Genomic DNA was extracted from legs of the micromoths using the the QIAamp Fast DNA Tissue Kit (Qiagen). PCR amplification of the barcode region (Hebert et al. 2003) was performed with the primers LCO1490 and HCO2198 (Folmer et al. 1994) using a protocol of 5 min at 94 °C, 35 cycles of 30 s at 94 °C, 30 s at 47 °C, 1 min at 72 °C and a final elongation step of 10 min at 72 °C. DNA purification and sequencing were performed at Macrogen Inc. (Santiago, Chile). The sequences obtained were deposited in the BOLD database of the Barcode of Life Data System (Ratnasingham and Hebert 2007). The software MEGA11 (Tamura et al. 2021) was used to perform sequence alignment with the ClustalW method and to assess the genetic divergence between sequences with the Kimura 2-Parameter (K2P) method.

The uniqueness of the fauna of Tortricidae of Chile has been widely recognized (Obraztsov 1964; Razowski 1988; Brown 1999; Razowski and Pelz 2010). More than 80% of the species recorded in this country are endemic (Urra 2020). South-central Chile also harbors some endemic genera, among them Accuminulia Brown, 1999, Parvulia Urra, 2016 and Natria Urra, 2020 (Brown 1999; Urra 2016, 2020), while some other genera inhabiting this area have relatively narrow geographic ranges in South America with additional records restricted to neighboring countries, as in the case of Chileulia Powell, 1986, Proeulia Obraztsov, 1964 and Ptychocroca Brown & Razowski, 2003 (Brown and Razowski 2003; Razowski and Pelz 2010; Cepeda and González 2015). In contrast, species recorded in northern Chile belong to more widespread genera, such as Cryptophlebia Walsingham, 1900 and Strepsicrates Meyrick, 1888 (Clarke 1987; Vargas-Ortiz and Vargas 2018). The discovery of A. socoromaensis sp. nov. reinforces this pattern by adding the record of another widespread genus to the arid environments of northern Chile.

Host plant records of the Palearctic A. ljungiana and many Nearctic Argyrotaenia suggest that polyphagy is very common in this genus, while a few species have narrower host ranges, feeding on plants belonging to a single family (Brown et al. 2008). Such variation in host ranges can occur even among members of the same species group (Landry et al. 1999). Host plants have been recorded for only a few Neotropical species (Brown et al. 2008). Among the South American fauna, published host records mainly involve A. loxonephes (Meyrick, 1937) and A. sphaleropa (Meyrick, 1909), two remarkably polyphagous pest species whose larvae feed on plants belonging to 16 and 21 families, respectively (Trematerra and Brown 2004). The polyphagy of A. socoromaensis sp. nov. fits the more common host range currently recognized for the genus.

Sexual dimorphism, mostly related to wing pattern, has been documented for several members of Argyrotaenia (Obraztsov 1961; Powell 1965; Austin and Dombroskie 2020a). Correct association of males and females can be particularly difficult in species with marked sexual dimorphism, as in the case of A. montezumae (Walsingham, 1914), whose female was originally described under another specific name currently recognized as a synonym (Obraztsov 1961; Gilligan et al. 2018). The remarkable sexual dimorphism of A. socoromaensis sp. nov. involves differences in wing size, shape, and pattern.

DNA barcodes have been used successfully to explore host plant ranges and to associate females and males of sexually dimorphic species of Tortricidae (Hulcr et al. 2007; Corley and Ferreira 2017; Austin and Dombroskie 2020a). Although the description provided here for A. socoromaensis sp. nov. is based on only three specimens, the analysis of their DNA barcodes accurately supports the recognition of the male holotype and the two female paratypes as members of a single species with sexually dimorphic adults and polyphagous larvae. The discovery of A. socoromaensis sp. nov. raises to 105 the species and 38 the genera recorded for the Chilean fauna of Tortricidae (Razowski and Pelz 2010; Cepeda and Curkovic 2020; Urra 2020), and highlights the need to explore further the overlooked diversity of micromoths of the natural environments of the arid western slopes of the central Andes.

I thank John W. Brown for important comments and suggestions on a previous version, Wilson Huanca-Mamani for the use of facilities for DNA extraction and Lafayette Eaton for checking the English.