Euptychia celmis var. bonaërensis, Burmeister, 1878

Cong, Qian, Barbosa, Eduardo P., Marín, Mario A., Freitas, André V. L., Lamas, Gerardo & Grishin, Nick V., 2021, Two new species of Hermeuptychia from North America and three neotype designations (Nymphalidae: Satyrinae), The Taxonomic Report of the International Lepidoptera Survey 9 (7), pp. 1-21 : 10-12

Euptychia celmis var. bonaërensis [sic] Burmeister, 1878 is a junior objective synonym of Yphthimoides acmenis ( Hübner, 1823)

A number of Satyrini Boisduval, [1833] species have a dry season form, in which patterns of eyespots and stripes are much reduced to nearly absent, and the ventral side is paler, of mottled appearance ( Freitas et al. 2010; Freitas et al. 2021). Similar to that, the original illustration of Megisto acmenis Hübner, 1823 (type locality "Baltimore") reveals "not the slightest trace of any eyespots" on the ventral side of its wings ( Hübner 1823) ( Fig. 37a ). Type specimens of this species have not been located and its type locality is likely erroneous ( Scudder 1875; Weymer 1910 -1912) leading to confusion about this taxon. For instance, there is a Hermeuptychia specimen of unknown provenance in BMNH labeled "acmenis " and illustrated in D’Abrera (1988). This Hermeuptychia specimen, representing a rather extreme example of the dry season form or aberration, cannot be confidently identified to species without dissection or DNA sequencing, because many Hermeuptychia species are similar to this form. The status of M. acmenis and the Hermeuptychia "acmenis " specimen were discussed in detail by Viloria (2021), who concluded that M. acmenis belongs to Hermeuptychia based on this specimen and wing shape similarity of the illustrated M. acmenis type (s) and Hermeuptychia . However, the progression of ventral wing pattern deterioration in Hermeuptychia is inconsistent with that of M. acmenis . Hermeuptychia possesses submarginal wavy lines that are similar in intensity to the two median lines. These lines tend to deteriorate similarly. I.e., if the median lines are expressed clearly (as in the M. acmenis illustration), then the submarginal lines are clear as well. If the submarginal lines are obsolete, then the median lines are obsolete too (as in the Hermeuptychia "acmenis " specimen).

A more detailed analysis of the Hermeuptychia "acmenis " specimen reveals that its wing patterns on the ventral side and size do not agree with the original description and illustration of M. acmenis . In particular, in this specimen: (1) both hindwings have clearly defined traces of eyespots: small brown spots in cells CuA 1 -CuA 2 (larger) and RS-M 1 (smaller), but the description states: "von Augenpuncten nicht die geringste Spur", i.e., not the slightest trace of any eyespots ( Hübner 1823: 11); (2) the hindwings are rather uniform in color and median lines are not visible: only a slightly paler diffuse postmedian band stands out from the brown background, vs. two prominent median lines outlining a darker area between them in the illustration of M. acmenis ; (3) the forewing has a long dash along the distal end of discal cell, but the illustration shows a very short mark in that area; (4) the ventral side of the wings is of less mottled apperance than shown in the illustration; (5) the forewing length is <17 mm, but the illustration depicts a larger specimen, as extrapolated from the comparison with Adelpha plesaure Hübner, 1823 illustrated on the same plate (likely to scale): the forewing length is expected to be 18 mm or more. Moreover, the original description of M. acmenis states: "Mit M. Euridice hat sie viel ähnliches" (With M. Euridice has much in common), and Lethe eurydice (Linnaeus, 1763) is larger than most Hermeuptychia . Therefore, at the very least, this Hermeuptychia "acmenis " is not the specimen illustrated in the orginal description, not a syntype, and probably not M. acmenis at all.

To prepare for a more detailed genomic study of Hermeuptychia , we investigated M. acmenis further. If Baltimore was the correct locality, the only somewhat similar species that may reach this latitude is Cyllopsis gemma (Hübner, 1818) . The similarity is in the placement and shape of lines and, in particular, in the degree of mottling and color gamut. However, if M. acmenis were C. gemma , it would have been an unusual aberration that totally lost the ventral hindwing submarginal patch of "spider-eye" spots. We have not seen such an aberration, although some of the more southern Cyllopsis R. Felder, 1869 species do experience deterioration of eyespots, e.g., Cyllopsis pyracmon (Butler, 1867) .

Weymer (1910 -1912) likened M. acmenis to Cissia phronius (Godart, [1824]) , which in size is more similar to L. eurydice , and larger than Hermeuptychia , in agreement with our M. acmenis size estimates from the original illustrations ( Hübner 1823). As Weymer noted, darker dots in the median lines of C. phronius are absent in M. acmenis , therefore the two are distinct species and should be kept as such. Moreover, wingshape of C. phronius is different: the forewing is elongated and the hindwing has crenulate margins. Dry season forms of Emeryus difficilis ( Forster, 1964) are known to possess similar hindwing pattern to that of M. acmenis and essentially lack the eyespots ( Zacca et al. 2020). However, E. difficilis is larger (forewing ~ 21 mm), has well-expressed submarginal lines on the dorsal surface of the wings, and its hindwing outer margin is crenulate. These characters are not consistent with the original illustration of M. acmenis .

Out of all Satyrini worldwide, the only species known to us that may have the following combination of characters: mottled appearance of wings' ventral side, with two median lines, darker between them and paler just outside this darker median band framed by the two lines, with a small dash at the end of the forewing discal cell, and lacking essentially any spots in the postmedian areas of both wings, is Yphthimoides celmis (Godart, [1824]) . Such dry season specimens look rather similar to the original illustration of M. acmenis . For instance, a butterfly photographed in Brazil: Paraná, Tapejara and shown on the iNaturalist website ( Barbosa 2019) ( Fig. 37b ) comes particularly close to M. acmenis . Moreover, an individual from Argentina: Buenos Aires Province, Parque Pereyra ( Braun 2019) ( Fig. 37c, d ) is entirely missing "a trace of any eyespots".

The only notable discrepancy is that the hindwing darker discal band is more strongly curved towards the anal margin in the M. acmenis illustrated by Hübner (1823) than in Y. celmis . However, the same discrepancy is also present in the Hermeuptychia "acmenis " specimen in BMNH: traces of median lines are not convex thus differing from the original illustration. This illustrated curvature, also mentioned by Weymer (1910 -1912), is reminiscent of some species of Erebia Dalman, 1816 and Oeneis Hübner, [1819] , but none of these species fits other features of the M. acmenis pattern. The closest might be Erebia fasciata A. Butler, 1868 , but it has at least some red-toned areas on the forewing, and the submarginal dark area on both wings below is more clearly defined than the M. acmenis illustration shows. Thus, we hypothesize that the strongly curved band may have been an atypical feature of the illustrated specimen or an artistic interpretation, and agree with Lamas (2004) who placed M. acmenis in Yphthimoides Forster, 1964 . One of the most commonly encountered species, Yphthimoides celmis , is found in southeastern South America. A number of species described in the same publication with M. acmenis come from South Brazil, and at least one from Argentina, so it is possible that M. acmenis was also collected in that region and mislabeled "Baltimore" at some point ( Hübner 1823).

Although as documented in the literature, most of Hübner types were likely lost ( Hemming 1937; Calhoun 2018), N.V.G. searched for possible M. acmenis syntypes in the collections of the Muséum National d'Histoire Naturelle, Paris, France (MNHP), the Natural History Museum, London, UK (BMNH) and the Museum für Naturkunde, Berlin, Germany (ZMHB). These searches were unsuccessful, leading us to believe that the syntypes are no longer extant, and we proceeded with the neotype designation. There is an exceptional need to designate the neotype of M. acmenis , because the identity of this species and its type locality have been unclear, and it was confused with Hermeuptychia in collections and publications ( D’Abrera 1988; Viloria 2021). To proceed with a meaningful integrative revision of Hermeuptychia , it is essential to have M. acmenis defined objectively and in agreement with the original description and original illustrations. Our investigations show that populations currently assigned to Y. celmis from around Buenos Aires ( Argentina) agree with what is known about M. acmenis ( Fig. 37 ). Therefore, we decided to select a specimen from these populations as the neotype of M. acmenis . The specimens with reduced or lacking eyespots from the region have been named Euptychia celmis var. bonaërensis [sic] Burmeister, 1878, which is characterized in the original description as "a remarkable variation ... almost without eyes" ( Burmeister 1878). To simplify the synonymy, we hereby designate the specimen curated as the lectotype of Euptychia celmis var. bonaërensis Burmeister, 1878 , illustrated in Warren et al. (2016), as the neotype of Megisto acmenis Hübner, 1823 . Its forewing length is about 18 mm, which is in agreement with the size estimated from the original illustration of M. acmenis .

Our neotype of M. acmenis satisfies all the requirements set forth by the ICZN Article 75.3. Namely: 75.3.1. It is designated to clarify the taxonomic identity of Megisto acmenis Hübner, 1823 , which remained undefined until now, impeding future research; 75.3.2. The characters that differentiate this taxon have been given in its original description by Hübner (1823: 11): "It has much in common with M. Euridice [sic!], but not the slightest trace of any eyespots" and can be further gleaned from the original illustration: brown unspotted wings above, and below paler yellow-brown, mottled in appearance, with a slightly darker broad discal band spanning both wings and outlined by even darker lines on both sides, paler just outside the band and devoid of eyespots; 75.3.3. The neotype specimen is a male, which is also a lectotype of Euptychia celmis var. bonaërensis [sic] Burmeister, 1878 hereby designated by Gerardo Lamas, that bears the following 5 labels: [Buen. | Aires], [Typus.], [bonaërensis | Burm.], [Col. | Antigua], and [lectotype ♂ | Euptychia celmis var. | bonaerensis Burm. | 1878 | G. Lamas det. '92]. The following red rectangular label will be mailed to the curators of the collection to add to this specimen: [NEOTYPE ♂ | Megisto acmenis | Hübner, 1823 | designated by Barbosa | Freitas and Grishin]. This specimen was one of the two syntypes of E. celmis var. bonaërensis , both males with the same data in the same collection (see below), and is designated as the lectotype of that taxon to enhance the stability of nomenclature; 75.3.4. Our search for the syntypes is described above, and it was unsuccessful, leading us to believe that they are no longer extant; 75.3.5. The neotype is consistent with what is known about this taxon, in particular with the original illustration and description as detailed above; 75.3.6. The neotype is from Buenos Aires ( Argentina), and the type material was stated to be from "Baltimore", which is likely erroneous, because no similar species have been found in eastern North America ( Scudder 1875; Weymer 1910 -1912), but both localities start with the letter B, suggesting a number of speculations. The specimen(s) on which Hübner based his description and illustrations of M. acmenis was/were given to him by a certain “Herr Berg”, of whom nothing else appears to be known, except that other species forwarded by him to Hübner were supposedly obtained in Uruguay, Paraguay and Brazil, and only one other species (a crambid moth) was labeled “Baltimore” though it appears to be widespread, found from the USA south to at least Brazil; 75.3.7. The neotype is in the collection of the Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Buenos Aires, Argentina [MACN].

Lamas (2004) lists Yphthimoides acmenis ( Hübner, 1823) as a distinct species, and Euptychia celmis var. bonaërensis [sic] Burmeister, 1878 as a synonym of Yphthimoides celmis (Godart, [1824]) . We have not investigated this synonymy, but if it holds, then due to objective synonymy established here by the neotype designation of M. acmenis , Y. celmis would become a junior subjective synonym of Y. acmenis . For now, we simply transfer E. celmis var. bonaërensis [sic] from Y. celmis to Y. acmenis , keeping both Yphthimoides species as valid, to follow Lamas (2004). Furthermore, Euptychia celmis ab. “inocellata” Köhler, 1935 (an infrasubspecific name) and Epinephele euptychioides Köhler, 1939 , both from Argentina, may also belong to Y. acmenis and/or celmis , but this possibility has not been investigated further.

Figures

Fig. 37. Megisto acmenis. a. Original illustration of Megisto acmenis from Hübner (1823) and individuals of Yphthimoides celmis that are similar to it: b. from Brazil: Paraná, Tapejara photographed by Tiago Barbosa in June 2019 (CC BY-NC, Barbosa 2019); c, d. from Buenos Aires area in Argentina photographed by Holger Braun on 13 October 2019 (CC BY, Braun 2019); d. shows its enlarged hindwing submarginal area that is essentially unspotted: "von Augenpuncten nicht die geringste Spur". The images are rotated, cropped, b. flipped, and c, d. color-corrected compared to the originals.