ACHERONTIINI

Kitching, Ian J., 2002, The phylogenetic relationships of Morgan’s Sphinx, Xanthopan morganii (Walker), the tribe Acherontiini, and allied long-tongued hawkmoths (Lepidoptera: Sphingidae, Sphinginae), Zoological Journal of the Linnean Society 135 (4), pp. 471-527 : 512-519

MONOPHYLY OF ACHERONTIINI

Boisduval ([1875]) first proposed the tribe Acherontiini for the highly distinctive genus Acherontia . Rothschild & Jordan (1903) expanded the concept to include Agrius (as Herse ), Coelonia and Megacorma , and later ( Rothschild & Jordan, 1916) Callosphingia . Rothschild & Jordan (1903: xcii) clearly appreciated the distinction between symplesiomorphy (“resemblance preserved”; “preserved characters of the common ancestor”) and synapomorphy (“resemblance acquired”; “similarities which are the outcome of evolution”). However, they did not make the conceptual leap that in a phylogenetic framework taxa can only be grouped using the latter type of resemblance. As a result, their higher taxa were based on a mixture of plesiomorphic and apomorphic characters, which can only be teased apart through careful study of their group diagnoses and ‘pedigrees’ (phylogenetic trees).

A comparison of their diagnoses of Acherontiini (as Acherontiicae) and Sphingini (as Sphingicae) shows that Rothschild & Jordan (1903) characterized the

› Figure 26. One of five most parsimonious cladograms obtained from analysis of the complete data set, but with characters 6 and 51 deactivated, under IW. Unambiguously optimized characters only are shown. Unique characters are indicated by closed circles, homoplasies by open circles.

· former tribe essentially on the basis of two apomorphic characters: “second segment [of labial palp] impressed, this cavity covered by a roof of long scales ” [italics in original] and “harpe short, divided into two or three processes”. These correspond to characters 3: 1 and 68: 1 of the present analysis. In contrast to Rothschild & Jordan (1903: 31), who described the labial palp of Xanthopan as having the “internal surface of second segment concave nearly as in Acherontiicae, but densely scaled” [italics in original], I interpreted the condition in this genus to be the same as in Acherontiini . Instead, Xanthopan differed in having parallel roof scales, whereas in Acherontiini , these scales are directed towards the midline, where they are apically depressed, and in which depression the outer surface of the apex of the pilifer rests (4: 1).

In addition to these apomorphic features recognized by Rothschild & Jordan (1903), I can add lateral compressed stridulatory curtain scales (33: 1) and extended corners on the juxta (49: 1), which occur in all genera of Acherontiini . In addition, all Acheronti- · ini except Acherontia have apically convergent and twisted pilifer bristles (7: 1) and all but Acherontia atropos and A. styx have short, stout setae on the valve (59: 1). These latter two species are also the only Acherontiini lacking folded membranous flanges around the ostium bursae (78: 3), structures that also occur in Pantophaea jordani . Finally, all Acherontiini have plectral scales that are strongly curved basally (53: 1), but such scales are also seen in both species of Panogena . Likewise, the characteristic projecting saccus (46: 1) of Acherontiini (except Callosphingia ) also occurs in Panogena , although only in P. lingens .

The monophyletic status of Acherontiini is also unaffected by the application of different weighting regimes, or by the inclusion/exclusion of characters derived from the immature stages. Overall therefore the monophyly of this tribe is highly corroborated.