Crocidosema nitsugai sp. nov. (Lepidoptera, Tortricidae, Olethreutinae, Eucosmini) is described and illustrated from the Andes of northern Chile based on adults obtained from larvae collected on leaves, flowers and unripe fruits and seeds of Lupinus oreophilus Phil. (Fabaceae). This represents the first record of insect herbivory on this Chilean endemic perennial herb. The genitalia morphology of C. nitsugai suggests a close evolutionary relationship with two congenerics from high elevation environments of the Ecuadorian and Peruvian Andes.

Crocidosema Zeller, 1847 (Lepidoptera, Tortricidae, Olethreutinae, Eucosmini) is a mainly Neotropical genus with 69 described species, 45 of which have their type locality in South America (Gilligan et al. 2018). Many of the South American representatives were described in the last fifteen years based on the study of specimens collected relatively recently using light traps in different localities of Brazil, Colombia, Ecuador, Peru and Venezuela (Razowski and Wojtusiak 2006a, b, 2008a, b, 2009, 2010, 2011, 2013; Razowski and Becker 2014, 2017). Crocidosema insulana Aurivillius, 1922, is the only species of the genus native to Chile, originally described from Masatierra, Juan Fernandez Islands, and subsequently recorded from most of the mainland part of the country (Razowski and Pelz 2010). Crocidosema aporema Walsingham, 1914, an important pest of several legume crops described from Costa Rica and currently widespread in Central and South America (Gilligan and Epstein 2014), is also recorded from Chile in the agricultural literature (Artigas 1994).

The northernmost part of Chile has a considerable diversity of arid environments along a wide elevational gradient from the lowlands of the Atacama Desert to the highlands of the Andes (Luebert and Pliscoff 2006). Within this elevational gradient, records of native species of Tortricidae are mainly restricted to habitats below 1000 m elevation (Clarke 1987; Brito and Vargas 2018), with the exception of one species that reaches about 2000 m in the transverse valleys of the Atacama Desert (Vargas-Ortiz and Vargas 2018). However, the high elevation habitats of this region harbor a distinctive native flora (Gatica-Castro et al. 2015), some of whose species support populations of host-specific Lepidoptera (Vargas 2014; Ramírez-Fischer et al. 2016), suggesting that the current absence of records of Tortricidae in this area is likely a sampling artifact. In support of this suggestion, adults of this family were recently obtained from larvae collected on Lupinus oreophilus Phil. (Fabaceae), a perennial herb endemic to the elevational belt between 2700 and 4400 m in the Andes of northern Chile (Orrego et al. 2013). The Near Threatened status of populations of the shrub was recently proposed (Gatica-Castro et al. 2015). Subsequent examination of the morphology of the micromoths revealed that they represent a previously unknown species of Crocidosema, whose description is provided below.

The sampling was undertaken near Putre (18°12’58”S; 69°33’38”W), Parinacota Province, at 3670 m elevation on the western slopes of the Andes of northern Chile. The site has a tropical xeric bioclimate with seasonal rains mainly concentrated between December and March (Luebert and Pliscoff 2006). This rainfall regime allows the development of a seasonal vegetation growth that reaches higher coverage shortly after the rains (Muñoz and Bonacic 2006). Larvae were collected on leaves, flowers and fruits of L. oreophilus in March 2019 following the summer rainfall. The collected larvae and the respective plant organs were placed in plastic vials with paper towel at the bottom and brought to the laboratory, where the vials were periodically cleaned and fresh leaves, flowers and fruits were provided until the larvae finished feeding and pupated. After pupation the vials were regularly observed until the emergence of adults, which were mounted. The abdomen of the adults was removed, cleared in hot 10% KOH for a few minutes, stained with Eosin Y and Chlorazol black and slide-mounted with Euparal. Images were captured with Sony CyberShot DSC-HX200V and Micropublisher 3.3 RTV-QImaging digital cameras attached to a Leica M125 stereomicroscope and an Olympus BX51 optical microscope, respectively.

MNNC Museo Nacional de Historia Natural de Santiago, Santiago, Chile

IDEA Colección Entomológica de la Universidad de Tarapacá, Arica, Chile

Although many species of Crocidosema have been described recently from the Neotropics, the discovery of C. nitsugai during a short field trip following the summer rainfall in the type locality highlights the need for additional sampling in different Neotropical environments to more accurately characterize the taxonomic diversity of this genus. Surveys of native plants appear to be especially valuable, because these provide the first insights on the host range of each newly found species (e.g. Brito and Vargas 2018). Host plants have been recorded for only nine species of Crocidosema, six of which feed on plants of only one family, whereas three feed on plants of more than one family. At one extreme is the widespread C. plebejana Zeller, 1847, whose larvae have been collected on representatives of nine families (Brown et al. 2008). Fabaceae has been recorded as host for four species of Crocidosema (Brown et al. 2008), among which only the Neotropical pest C. aporema feeds on Lupinus (Callohuari et al. 2018).

Crocidosema nitsugai represents the first record of insect herbivory on L. oreophilus. Previous studies indicated consumption of L. oreophilus by two herbivorous rodents in high elevation environments of the Andes of northern Chile (Cortés et al. 2002). The host plant range of C. nitsugai appears to be narrow, as it was absent in surveys undertaken on about ten plants of each of the additional native species of Fabaceae found in the study site: Adesmia verrucosa Meyen, A. spinosissima Vogel, Dalea pennellii (J.F. Macbr.) J.F. Macbr. var. chilensis Barneby and Senna birostris (Dombey ex Vogel) H.S. Irwin & Barneby var. arequipensis (Meyen ex Vogel) H.S. Irwin & Barneby. However, surveys for C. nitsugai should be expanded to additional Fabaceae of northern Chile outside the study site, where three other species of Lupinus have been recorded (Gatica-Castro et al. 2015). In addition, as Near Threatened status was recently proposed for L. oreophilus (Gatica-Castro et al. 2015), further studies are needed to understand better the effect of herbivory by larvae of C. nitsugai on populations of this plant.

The Andes uplift has been recognized as an important event in the diversification of several Neotropical animal groups, including Lepidoptera (Massardo et al. 2015; De-Silva et al. 2016). Unfortunately, despite a few recent additions (Vargas and Mundaca 2016; Vargas 2018), the taxonomy and natural history of the micromoths of the Andes of northern Chile have been little studied, impeding further evolutionary studies with these organisms. Indeed, C. nitsugai is the first species of Tortricidae described from these arid high elevation environments. Its genitalia are remarkably different of those of C. insulana, the only other representative of the genus native to Chile (Razowski and Pelz 2010), suggesting that they are only distantly related. The close morphological resemblance of the genitalia of C. nitsugai with those of other two highland species, C. marcapatae (Cusco, Peru, 3600 m) and C. pusula (Carchi, Ecuador, 2200 m), suggest that a group of closely related Crocidosema diversified along the still underexplored high elevation environments of the Andes, an evolutionary scenario that should be assessed in further studies.

I thank John W. Brown and David C. Lees for valuable suggestions on a previous version of the manuscript, Sebastián Espinoza-Donoso for editing the figures, Lafayette Eaton for checking the English and my brother Alberto for introducing me to the wonderful music of Nitsuga Mangoré.