Castnia amethystina
Creators: name: Worthy, Robert
name: González, Jorge M.
name: Zilli, Alberto
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Lepidoptera
Castniidae
Castnia
Castnia amethystina

description: amethystina (Houlbert, 1917)
(Figs. 8A, B)
“ Castnia Amethystina ♀, sp. nov. ” Houlbert, 1917, Études de Lépidoptérologie comparée 13: 54–55.
Type material: Described from a single male, not a female as stated in the original description (cf. Houlbert, 1917, 1918), which is the holotype by monotypy (Fig. 8A). At the time of description, it was in the collection of Charles Oberthür (1845–1924), it is now in NHMUK.
Type locality: Panama. No more information is available from either Houlbert’s writings or the specimen labels.
Taxonomic status: A weakly defined subspecies of Amauta papilionaris (Walker, [1865]) closest to the south Peruvian-Bolivian populations known as ssp. lionela, the two possibly forming a so-called polytopic subspecies (cf. Mayr 1963, 1969; Zilli 1996). Originally described as a species but sunk to a subspecies of A. papilionaris by Miller (1995).
Male genitalia: Uncus simple with wide and almost rounded apex. Gnathos sclerotised, bifid anteriad; tip level with or slightly exceeding uncus. Cucullus and valvula slightly rounded apically. Valvae are distinct, short, and wide. Ventral margin of valvae sharply cut. Sacculus projected and continues with the arms of the saccus. Anterior projection of saccus quite long. Vinculum semi-circular, small, crescent-shaped. Phallus curved, with distal section about three times the length of coecum, narrowed beyond junction with coecum, then slightly curved, with subterminal portion enlarged, rounded, and slightly contorted. Apex of phallus with a terminal, sclerotised section. The vesica opens to the left near end of the phallus.
Distribution: Specimens are only known from Panama and Costa Rica (Limón province). Specimens from Colombia and Venezuela appear to be Amauta p. papilionaris (see papilionaris below) (Fig. 14).
Discussion: Houlbert (1917) picks out the darker ground colour and the much smaller forewing white discal spot as the main differentiating features for this subspecies. His conclusion is hardly surprising as he was comparing the type with Westwood’s (1877) stylised figure of papilionaris (Fig. 8C). The actual holotype of A. papilionaris (Fig. 8D) (and all other specimens examined) have a much darker ground colour than Westwood’s figure, the same as in amethystina, and the discal spot is variable in size, many being the same size as in amethystina. Westwood’s figure exaggerates the width of the forewing pale yellow postmedian band and the size of the discal spot. The holotype of amethystina has a much broader forewing band than papilionaris and is in fact analogous to the southernmost subspecies of papilionaris – lionela. The hindwing blue postmedian band is of variable width in all populations but there is a suggestion that it is slightly narrower in amethystina. We have recently found a second specimen of amethystina from Costa Rica in CAS (Fig. 8B), which is in good agreement with the general appearance of the holotype. The differences in these two specimens compared with nominotypical papilionaris are considered to be enough to provisionally accept the subspecific separation of amethystina. More specimens are needed to confirm this.
Rothschild (1919) stated that amethystina differs from papilionaris papilionaris by its small size and narrow blue postmedian band on the hindwings. However, as previously mentioned these are variable features and can also be found in many specimens of p. papilionaris. Rothschild also stated that he had one male of amethystina from Merida, Venezuela collected by Salomón Briceño (1826–1912); this specimen is now in NHMUK and appears not to be any different from A. p. papilionaris.
Apolinar María (1945) figures a specimen (in colour) that he calls Amauta amethystina Hlb. possibly the first time that specific epithet is used in the Colombian lepidopterological literature. This same specimen is mentioned from years prior “…we received a beautiful specimen of Castnia papilionaris Wkr. from…, El Baldío. [… a town of recent foundation in the Eastern Cordillera of Bogotá] … the moth appears darker than the one [of papilionaris in Strand] …. Another very notable difference is the complete absence, in the insect that is in our collection, of the yellow discal spot that appears in the forewing of typical specimens.” (Apolinar María 1915). The illustrated specimen seems to be A. p. papilionaris.
Material examined: In addition to the holotype, 1♂ Limón, Provincia de Limón, Costa Rica, Nicholas Zakharoff (CAS), was examined for this study. For comparison, several specimens from Colombia and Venezuela were also examined.
description: Published as part of Worthy, Robert, González, Jorge M. & Zilli, Alberto, 2022, A review of the genera Amauta Houlbert, 1918 and Divana J. Y. Miller, 1982 (Lepidoptera: Castniidae) with description of a new genus, pp. 301-342 in Zootaxa 5194 (3) on pages 321-322, DOI: 10.11646/zootaxa.5194.3.1, http://zenodo.org/record/7154442