Laothoe amurensis subsp. sinica (Rothschild & Jordan, 1903)

SYN. & STAT. REV. Proposed as a subspecies of Amorpha amurensis. Implicitly raised to species level by Chu & Wang, 1980, Economic Insect Fauna of China 22: 43. However, they misidentified Cypoides chinensis as "Laothoe sinica". Raised to species level by Pittaway, 1993, The hawkmoths of the Western Palaearctic: 106. Implicitly reinstated as a subspecies of Laothoe amurensis by Bridges, 1993, Cat. Fam. Gen. Spec. Sphingidae of the World: VIII.12. Reinstated to species level by Zolotuhin, 2018, Eversmannia 54: 10. Zolotuhin (2018) (STI 21919) distinguished Laothoe sinica from Laothoe amurensis based on several minor characters of the habitus and male genitalia, together with a DNA barcode divergence between them of 2.5-2.8%. In terms of the habitus, L. sinica was said to differ in the broader outer part to the forewing, a vaguer and smoother pattern of transverse lines and bands, and a forewing antemedial band is always broken (although the depth of this break varies). Examination of 30 specimens from Sichuan and Shaanxi in NHMUK showed that while generally true, there is nevertheless considerable overlap in these characters with specimens from the Russian Far East, and both populations are highly variable. Differences in the male genitalia are limited to the shape of the juxta (somewhat shorter in sinica than in amurensis) and the form of the cornuti on the phallus vesica. However, the differences in the latter are relatively minor and also inconsistent between the illustrated specimens from Sichuan and Shaanxi; indeed, Kitching & Cadiou (2000) (STI 18788) commented that there is considerable intraspecific variation in cornuti shape in Laothoe populi, and that in this species, they are at best indicative of subspecies differentiation. The same is considered here to apply to populations of Laothoe amurensis. Regarding the DNA barcode divergence, Řezáč (2018) (STI 21910) commented in his study on Rhodoprasina that in that genus “intraspecific divergences are of the order of 4% [and] differences below 2%, unless supported by conspicuous traits in habitus and the structure of the genitalia, cannot be considered significant, even at subspecies level”. This seems to be generally true of many Smerinthini that do not feed as adults and thus, in the absence of such morphological differences, the divergence of 2.5-2.8% between sinica and amurensis would indicate subspecies differentiation at best. Taken together, there is thus no justification for treating Laothoe sinica as a species separate from Laothoe amurensis but rather as a subspecies, Laothoe amurensis sinica.