Achlyodes erisichthon Plötz, 1884

Zhang, Jing, Cong, Qian, Shen, Jinhui, Song, Leina & Grishin, Nick V., 2023, Genomics-based taxonomic rearrangement of Achlyodini and Carcharodini (Lepidoptera: Hesperiidae: Pyrginae), Insecta Mundi 2023 (16), pp. 1-33 : 13

Achlyodes erisichthon Plötz, 1884 is a junior subjective synonym of Quadrus (Zera) servius ( Plötz, 1884) , not a subspecies of Quadrus (Zera) tetrastigma (Sepp, [1847])

Genomic comparison of the lectotype of Achlyodes servius Plötz, 1884 (type locality in Brazil, sequenced as NVG-21115E08) from “Rio” in MFNB (white ventral hindwing by inner margin) with specimens identified by us as Quadrus (Zera) tetrastigma erisichthon ( Plötz, 1884) (type locality not stated, syntypes not located, specimens from SE Brazil with ventral hindwing largely pale-orange, yellower by inner margin but not white) reveals the lack of genetic differentiation between them ( Fig. 1 , 2a ), i.e., their COI barcodes are identical. Therefore, these taxa are different color morphs of the same species, and we propose that Achlyodes erisichthon Plötz, 1884 is a junior subjective new synonym of Quadrus (Zera) servius ( Plötz, 1884) , not a subspecies of Quadrus (Zera) tetrastigma (Sepp, [1847]) . We note that A. servius and A. erisichthon were proposed in the same work (on the same page) issued on the same date, and we give precedence to the name A. servius acting as First Revisers (ICZN Code Art. 24.2.2.).

Furthermore, in the absence of extant type specimens, the identity of A. erisichthon remains somewhat uncertain, and we use this name for the taxon identified as such by Evans (1953). Judging from the original description ( Plötz 1884) and copies (in BMNH and USNM) of the unpublished and lost illustration t[afel]. 982 by Plötz ( Godman 1907), we believe that Evans identified this species correctly. Moreover, due to the extensive tawny coloration of the ventral forewing, prominent forewing subapical spots, and other wing pattern details as illustrated in the drawings, A. erisichthon is not conspecific with Q. tetrastigma , a conclusion that would hold even if Evans misidentified A. erisichthon . However, two characters of the A. erisichthon drawing reveal an unusual specimen, i.e., four—instead of the usual three—forewing subapical spots (also mentioned in the original description) and the absence of a dark cross-bar in the forewing discal cell, which is mostly violaceous—instead of dark-brown in the middle—cast certain doubt on the identification of this taxon and even its attribution to Quadrus (Zera) .

Nevertheless, out of all Hesperiidae species known to us worldwide (the type locality of A. erisichthon was not stated), Quadrus (Zera) is the best match to the drawing due to this violaceous coloration, s-shaped placement of the forewing subapical spots, and other details of wing pattern, in particular, on the ventral side. While we have seen Quadrus (Zera) specimens with a vestigial 4 th subapical forewing spot, none was suitable for the neotype of A. erisichthon because these specimens did not agree with the drawing and the original description in other characters. In its largely tawny hindwing, A. erisichthon is also similar to Quadrus (Zera) gellius ( Mabille, 1903) (type locality in “ Ecuador ”, likely in SE South America). However, the hindwing is more uniformly tawny in the latter species, but the original description of A. erisichthon specifically mentions greenish-gray overscaling by the inner margin ( Plötz 1884). This overscaling is typical of Q. servius form lacking extensive white area on the ventral hindwing and is the manifestation of this white overscaling, but much reduced.

Finally, Plötz studied Q. servius specimens from SE Brazil (at least four, see above), proposing this name for the white-overscaled form. It is likely that he also encountered the tawny hindwing form from the same area and, additionally noticing four (not three) subapical spots on an unusual specimen, considered it to be a closely related but distinct species he called A. erisichthon , which he placed in the key next to Q. servius and, therefore, these two species were likely quite close to each other in appearance. We suggest the synonymy proposed above for all these reasons, and will be looking for a specimen suitable for A. erisichthon neotype designation, keeping in mind that it could be not yet re-discovered species different from all others currently known.

Figures

Figure 1. The nuclear genome-based phylogeny of Achlyodini (continued in Fig. 3). Only the segment of the tree corresponding to the subtribe Pythonidina is shown. The bottom segment of the tree (subtribe Achlyodinia) is replaced with four dots and is shown in Fig. 3. The tree is constructed from protein-coding regions in autosomes. The tree is rooted with Carcharodus alceae (NVG-18087F02, GenBank barcode OR665734), not displayed. Statistical support values are shown by nodes. For each specimen, its name adopted in this work is given first, and a previously used name is listed in square brackets (if different), supplemented with the DNA sample number, type status (HT holotype, LT lectotype, ST syntype, T type, PT paratype, and PLT paralectotype), general locality and collection year (“old” means collection year known, but likely before 1950, mostly around the turn of 20th century). See Table S1 in the Supplemental file (Zhang et al. 2023d) for additional data about these specimens. Synonyms are given in parentheses preceded by “=”. The type status refers to this synonym if the synonym name is provided. Names of genera (larger font, more prominent tree branches, on the left) and subgenera (smaller font, less prominent tree branches, on the right) are shown by the clades corresponding to these taxa. New genus-group names are highlighted in yellow. Branches leading to the type species (or their closest sequenced relatives) of valid genus-group names are marked with large black dots and refer to the subgenus (in parenthesis) given in the corresponding name, or the genus if the subgenus is not specified. The same notations are used in Fig. 3–6. Names of taxa that before this work were placed in genera Pythonides (red), Gindanes (cyan), Quadrus (green), Ouleus (blue), and Zera (purple) are shown in color to illustrate rampant violations of monophyly in these taxa, corrected here.

Figure 2. Quadrus (Zera) nuclear genome-based phylogeny and type specimens. a) The nuclear genome-based phylogeny of selected species: Q. vivax sp. n. (red), Q. hyacinthinus (purple), Q. hosta (cyan), Q. servius stat. rest. (blue and magenta, with its synonym Achlyodes erisichthon labeled in blue) rooted with the remaining Zera species (not shown; see Fig. 1). Specimens shown below are highlighted in yellow; see Fig. 1 for other notations. b) Lectotype of Quadrus (Zera) servius designated herein, with its labels shown above on the right. c) Holotype of Quadrus (Zera) vivax sp. n. Specimens are in dorsal (left) and ventral (right) views, data in text. The scale bar at the bottom refers to specimens; the scale bar at the top refers to labels reduced by 1/3 compared to specimens.