Isognathus caricae subsp. rainermarxi Eitschberger, 1999

Proposed as a subspecies of Isognathus caricae. Raised to species status by Eitschberger, 2008, Neue ent. Nachr. 62: 108. Resynonymized with Isognathus caricae as a subspecies exilis by Kitching and Rougerie et al., 2018, Biodivers. Data J. 6: e22236. Eitschberger (1999) (STI 17710) differentiated Isognathus caricae rainermarxi from the nominotypical subspecies in habitus on the basis of the slightly larger size and more rounded forewing shape, the paler ground colour of the forewing upperside (thereby rendering the transverse banding pattern more contrasting) and the stronger black coloration on the veins of the hindwing upperside (often merging together). Small differences were observed in the female genitalia, but Eitschberger concluded that “on the basis of only two preparations [one of each subspecies], no conclusions can be drawn from this”. Rather larger differences were observed in the shapes of the harpe, apical spinose ridge of the phallus and the size and shape of the field of cornuti on the vesica, but again, probably because only a single preparation of each subspecies was studied, Eitschberger did “not dare to decide whether these were species [level] characters”. However, without apparently studying additional genitalia preparations, Eitschberger (2008) (STI 17760) later decided that, “On the basis of the different genital structure and also the completely different appearance and different wing shape (Eitschberger, 1999: 22-227 [sic]), this taxon [Isognathus caricae rainermarxi] is here raised to species status, even if the egg morphology, particularly the number of fields of the micropyle rosette, 16 in an egg of I. caricae (L.) (Fig. 4) and 12 (Fig. 8) and 15 (not illustrated, the quality is poor) in two eggs of I. rainermarxi Eitschberger, 1999 stat. nov., only insignificantly differentiates them”. The reason for this change of opinion is unclear, especially as no additional evidence for species status was provided. The morphological differences are small compared to those between other species of Isognathus. Furthermore, the DNA barcodes of the holotype and paratypes of Isognathus caricae rainermarxi are only 0.0 – 0.50% divergent from those of samples of Isognathus caricae caricae and all samples form a single tight cluster, within which those of the Isognathus caricae rainermarxi do not form a geographically distinct coherent subcluster. Nevertheless, the morphology does suggest some degree of differentiation, albeit insufficient to warrant species status. Hence Isognathus caricae rainermarxi is here treated again as a subspecies of Isognathus caricae. Further study, however, may yet show that even that is not warranted.