Amiga arnaca sericeella (Bates, 1865), comb. n. et

Nakahara, Shinichi, Lamas, Gerardo, Tyler, Stephanie, Marin, Mario Alejandro, Huertas, Blanca, Willmott, Keith R., Mielke, Olaf H. H. & Espeland, Marianne, 2019, A revision of the new genus Amiga Nakahara, Willmott & Espeland, gen. n., described for Papilioarnaca Fabricius, 1776 (Lepidoptera, Nymphalidae, Satyrinae), ZooKeys 821, pp. 85-152 : 101-102

Amiga arnaca sericeella (Bates, 1865), comb. n. et stat. n. Figs 2m, n, 6

Euptychia sericeella Bates (1865: 202). Type locality: Vera Paz, Guatemala. Lectotype (here designated) ♀: Godman-Salvin Coll. 1904.-1. B.C.A. Lep. Rhop. Euptychia sericeella , Bates. // B.M. TYPE No. Rh 3181 Euptychia sericeella , ♀ Bates. // Forests of N. Vera Paz. F.D.G. & O.S. // Type. Sp. Figured. // ♀ // (NHMUK) [examined].

Euptychia sericeella : Butler 1867: 489; Kirby 1871: 53; Butler 1877: 122; Godman and Salvin 1880-1881: 89-90, pl. 8, figs 20, 21; Weymer 1911: 219; Riley and Gabriel 1924: 53; Gaede 1931: 464; D’Abrera 1988: 770-771.

Chloreuptychia sericella [sic]: Forster 1964: 120-121, fig. 132.

Chloreuptychia sericeella : R. de la Maza and J. de la Maza 1993: 182; Salinas-Gutiérrez et al. 2004: 136; Lamas 2004: 218.

Identification and taxonomy.

Bates (1865) described Euptychia sericeella based on an unspecified number of “male” specimen(s) from Vera Paz, Guatemala. Nevertheless, the only syntype specimen that we have located , in the NHMUK, is a female, a fact also noted by Godman and Salvin (1880: 89-90), who had this specimen in their possession and referred to it as "our specimen, marked as the type". This specimen (B.M. TYPE No. Rh 3181) was also referred to as a type by Riley and Gabriel (1924: 53) and D’Abrera (1988: 770-771). Because of the complexity of euptychiine taxonomy, to provide an unambiguous reference for this name we here designate this specimen as the lectotype of Euptychia sericeella (lectotype designation). Bates explicitly stated that the taxon was closely allied to Eu[ptychia]. ebusa (= Amiga arnaca arnaca comb. n.), indicating that he clearly regarded Euptychia sericeella and Amiga arnaca arnaca as two different species. Despite the ambiguous diagnosis provided in the original description ("the fore-wing having a narrow costal border, the apex, and a broader outer border of a brown hue"), the lectotype, figured in Warren et al. (2018), exhibits several rather distinctive phenotypic differences compared to specimens from South America and Nicaragua to western Ecuador. Presumably due to these wing pattern differences, described further below, subsequent authors treated E. sericeella as a species-level taxon (e.g., Butler 1867, 1877; Weymer 1911; Gaede 1931; Forster 1964; Lamas 2004). Specimens from Zelaya department, Nicaragua (e.g., FLMNH-MGCL-263066, 263067, 263072) are phenotypically similar to specimens known from Costa Rica to western Ecuador, and A. a. sericeella thus seems to replace A. a. adela n. ssp. with little or no obvious gap or dispersal barrier separating these taxa, and conversely with no known area of sympatry. Furthermore, the presence of an iridescent bluish-lilac reflection between the postdiscal band and umbra in some specimens of the subspecies from Nicaragua, Costa Rica, and Panama might be a result of introgression with A. a. sericeella . Finally, divergence in the DNA barcode between a specimen from Honduras (LEP-16997) phenotypically similar to the lectotype of sericeella and other Central American A. arnaca from further south is no greater than between east and west Andean A. arnaca (Table 2). Based on these considerations, we downgrade E. sericeella to subspecific rank, proposing, for the first time, what we believe to be the most parsimonious hypothesis of a single species. This null hypothesis remains to be more strongly tested when new evidence, such as distributional, behavioral, or genetic data, becomes available.

Both sexes of A. arnaca sericeella comb. n. et stat. n. differ from the nominotypical subspecies in the following respects: DHW feeble pearly reflection restricted to posterior one-third of hindwing and not extending into discal cell; ventral ground color somewhat paler; discal band, postdiscal band, submarginal band on the ventral forewing and ventral hindwing narrower; ventral hindwing postdiscal band not bent inwards in cell Cu2 and gently curving towards inner margin (but see also below); ventral ocelli smaller (but see also below); bluish-lilac reflection on ventral surface appearing purplish.

Variation.

The ventral ocelli are variable in terms of size; while many specimens seem to possess ventral ocelli smaller than the nominotypical subspecies and A. arnaca indianacristoi ssp. n., some appear to have ocelli that are similar to the aforementioned two taxa in terms of size. The VHW postdiscal band is bent inwards in cell Cu2 in some specimens, whereas it gradually curves towards the inner margin in other specimens.

Distribution

(Fig. 6). This subspecies ranges from southern Mexico to Honduras, where it appears to be uncommon.

Examined specimens

(46 ♂, 23 ♀). See Appendix for the data of these specimens.