LECTOTYPE ♂ «India (S): North Kanara, Karwar [18.viii.1923] (T.R. Bell)» [NHMUK]; implicitly designated by Jordan, 1938, Novit. zool. 41: legend to plates III & IV.
SYN. & STAT. REV.
Proposed as a subspecies of Polyptychus trilineatus. Raised to species status by Melichar et al., 2018, A field guide to hawkmoths of the state of Karnataka, India: 39.
[Melichar et al. (2018: 39) (STI 21973) raised Polyptychus trilineatus sonantis to species status “mainly because two subspecies of the same species cannot live together, and also for the great difference in the shape of the harp in the male genitalia” (this difference then not being described further). Insofar as it goes, this brief reasoning is correct. However, a more comprehensive study of the Polyptychus trilineatus group in SW India shows that Melichar et al. (2018) appear to have made significant errors and omissions, and the situation still remains to be fully elucidated. Analysis of DNA barcode sequences in BOLD reveals that the included samples from SW India fall into three BINs. Some individuals cluster with numerous samples of Polyptychus trilineatus trilineatus from the Himalayan region, China (Yunnan), Thailand and Vietnam in BIN AAB4760 (this BIN also includes samples of Polyptychus trilineatus kelanus from Sumatra, Polyptychus trilineatus mincopicus from the Andaman Islands and maybe Polyptychus trilineatus costalis from Hainan, suggesting that these three taxa should be treated as synonyms of Polyptychus trilineatus trilineatus, but that issue is not relevant to the present problem). In particular, two are very close to samples from Nepal and the Khasi Hills, Meghalaya, with a maximum divergence between any of these four being 0.48%. This divergence is remarkably low for samples of non-feeding Smerinthinae separated geographically by 1750-2000km and large areas of apparently unsuitable habitat. The second BIN, ACE4677, comprising further SW Indian samples likely represents the “true” Polyptychus trilineatus sonantis, as it is closest to the large Polyptychus trilineatus trilineatus cluster (BIN AAB4760). These two together are then sister to Polyptychus trilineatus javanicus from Java (BIN AAF0168). The third BIN, AAL5672, is well separated from the other two and clusters rather with Polyptychus claudiae from Sulawesi, although not especially closely, being some 5.5% divergent. It comprises five samples also from SW India.
Regarding the male genitalia, those illustrated by Melichar et al. (2018: 39) as Polyptychus trilineatus trilineatus agree in all respects with those illustrated by Jordan (1938: 127) (STI 18661), in particular in having a juxta in which the ventral process has an apical “fish-tail” shape and the dorso-lateral processes are well-developed and asymmetrical, with the left being shorter and bluntly rounded apically and the right being longer and sharply pointed apically. They are said to be those of a male from “India”, but it is unclear whether they are from one of the Karnataka males or from elsewhere in that country. The male genitalia of the lectotype of Polyptychus trilineatus sonantis agree with the descriptions given by Jordan (1930, STI 18656; 1938, STI 18661). Here, the apex of the ventral process of the juxta is shaped like a bill hook (with the point directed to the right) and the dorso-lateral processes are very small or even absent. In marked contrast, although it is difficult to discern the detail due to the small size and poor quality resolution of their photograph, the genitalia illustrated by Melichar et al. (2018: 40) as being those of “Polyptychus sonantis” appear to have a pair of ventral processes on the juxta, not a single structure as is found in all the current subspecies of Polyptychus trilineatus, indeed a “major difference”. If this structure truly is double (rather than a dissection artefact), then such specimens cannot be Polyptychus (trilineatus) sonantis.
Further work is clearly required to resolve this situation. For the moment, the following position is adopted here.
1. BIN AAB4760 represents Polyptychus trilineatus trilineatus and the two SW Indian samples in BOLD that cluster in this BIN are treated as potentially mislabelled or otherwise erroneous pending further detailed evidence to the contrary.
2. The samples from SW India with the apparently double ventral juxta process most probably represent an undescribed species but this, and whether they equate to BIN AAL5672, remains to be confirmed.
3. Given that, then the argument for separate species status for Polyptychus sonantis based on sympatry with Polyptychus trilineatus trilineatus no longer holds. Polyptychus trilineatus sonantis is therefore once again treated here as a subspecies of Polyptychus trilineatus and provisionally equated with BIN ACE4677. Specimens of Polyptychus trilineatus luteatus from Sri Lanka should be DNA barcoded as it is expected that they will be very close to, if not in the same BIN as, Polyptychus trilineatus sonantis. If they are then considered consubspecific, the valid name for the taxon will be Polyptychus trilineatus luteatus.]
The above confusion (in square brackets) was resolved, and the misinterpretation of the genitalia photograph clarified, by Melichar, Haxaire & Manjunatha, 2021, European Ent. 13 (1): 12. Polyptychus sonantis is a valid species.