When reinstating Poliana weiglei to species status, Eitschberger & Melichar (2017) (STI 21737) chose to diagnose it in relation to Poliana wintgensi from East Africa, rather than Poliana laucheana (=Poliana buchholzi auct.), in which it had previously been included as a junior synonym. They seem to have done this on the basis of a similarity in size and forewing upperside colour pattern, despite noting that “Das Genital von P. laucheana kommt in der Form dem von P. weiglei näher” [“the genitalia of P. laucheana come closer in form to those of P. weiglei”]. Indeed, the genital morphology, as well as DNA barcodes (see below), strongly supports a close relationship between Poliana weiglei and Poliana laucheana. In particular, the shape of the harpe is very similar in Poliana weiglei and Poliana laucheana, compared to Poliana wintgensi. In both the former two species, the dorsal edge of the harpe bears three to eight strong spines, the length, curvature and arrangement of which is highly variable both individually and between the left and right valves, whereas that of Poliana wintgensi is a simple hook, that may also bear a single strong curved spine. Poliana weiglei differs from Poliana laucheana in that the basalmost edge of these spines is generally curved over so that all the spines are directed distally or even slightly ventrally, rather than being straight and oblique. Eitschberger & Melichar (2017) claimed that only in Poliana laucheana (and their “Poliana raymurphyi”, here treated as a junior synonym of Poliana laucheana) were the undersides of the labial palps and thorax tinged to a variable degree with pink, in contrast to pure white in Poliana weiglei and Poliana wintgensi. However, examination of the series of Poliana weiglei from Ivory Coast in NHMUK revealed several did have a slight pink tinge to the labial palps, which adds additional support to a close relationship between Poliana weiglei and Poliana laucheana. Finally, the pale pattern element on the posterior margin of the forewing upperside between the antemedial and postmedial bands is often suffused with grey-brown scales in Poliana weiglei, whereas it is a more pure white in Poliana laucheana, although there is some degree of overlap. With regard to DNA barcodes, there is currently only a small number of samples in BOLD but the divergence of the single sample of Poliana weiglei (MA-05-02-02-12) is only 0.31-0.82% different from the seven full-length samples of Poliana laucheana (including one from East Africa; see also “Poliana raymurphyi”, STI: http://sphingidae.myspecies.info/taxonomy/term/5844). In view of these genetic data, whether the small morphological differences described above are sufficient to warrant full species status for both Poliana weiglei and Poliana weiglei must remain open to question. If they are treated as conspecific, then Poliana weiglei would be the valid name for the species.
Eitschberger & Melichar (2017: 12) recorded a specimen of Poliana weiglei from Babanki, Cameroon. This is most unlikely as it appears that Poliana weiglei is found only in West Africa west of the Dahomey Gap. The specimen in question is probably a small specimen of Poliana laucheana but this requires confrmation. It is not mapped here.