Aemilia, Kirby, 1892

Schmidt, Christian, 2009, Revision of the " Aemilia " ambigua (Strecker) species-group (Noctuidae, Arctiinae), ZooKeys 9 (9), pp. 63-78 : 66-67

Generic placement of the “ Aemilia ” ambigua- group

The unnatural placement of Aemilia ambigua within Aemilia was recognized by Watson and Goodger (1986), who placed this taxon within Aemilia “ sensu lato.” An additional Aemilia species, A. carmen Schaus , was inadvertently omitted by these same authors. While investigating the generic placement of A. ambigua , it became apparent that the male genitalic structure of A. ambigua is virtually identical in gross morphology to that of A. carmen (illustrated in Watson 1971), despite marked differences in wing pattern. “ Aemilia ” carmen and the ambigua- group are very similar structurally to Pseudohemihyalea daraba (Druce) and P. anapheoides (Rothschild) and to a lesser extent also to P. testacea (Rothschild) and P. ochracea (Rothschild) . Furthermore, the phenotype of P. anapheoides shows characters transitional between those of the typical banded Pseudohemihyalea pattern and that of the ambigua -group in that the forewing banding is highly reduced, the ground colour is whitish yellow, and the veins are outlined in rusty brown. The pink colouration of the dorsal abdomen is shared among P. ambigua , P. schausi , P. testacea , P. daraba and P. anapheoides . The following structural characters are shared between A. carmen , the ambigua -group, P. daraba and P. anapheoides : base of uncus broad and lobe-like (deeply excavated in P. s chausi and the P. edwardsii group), apex of uncus tapering to a point (bifid in edwardsii group), process of transtilla relatively small and scobinate (with large cornuti in some Pseudohemihylea species; transtilla elongate, large and finger-like in Amastus ); valve flattened and lobate overall, divided into two lobes beyond apical third or less (deeply divided and/or with a third, costal process in some Pseudohemihylaea and most Amastus species). Wing venation, palp structure and structure of the spines on the legs are fairly constant across Amastus and Pseudohemihylaea, and are consistent with those of the ambigua- group and A. carmen .

The close relationship between ambigua and carmen as indicated by male genitalic morphology (female carmen were unavailable for study) is also supported by molecular data (mtDNA cox1 gene), with the two clustering together (4 % divergence) in a neighbour-joining tree containing representatives of most Central and North American arctiine genera (C. Schmidt, M. Laguerre, B. Vincent, unpubl. data). Both ambigua and carmen group within the current concept of Pseudohemihyalea , including the type species, P. schausi Rothschild. Based on this morphological and molecular evidence, Pseudohemihylea ambigua comb. n. and P. carmen comb. n. are accordingly transferred to Pseudohemihyalea . Pseudohemihyalea carmen and P. daraba are possibly the sister group to the ambigua -group, as suggested by morphology and mtDNA sequence data (COI barcode fragment). The striate forewing pattern of the ambiguagroup appears to be a derived trait, likely linked with a larval host shift to conifers from the broad-leaved trees utilized by other Pseudohemihylaea species (e.g., P. edwardsii on Quercus species; McFarland 1975). Larvae of P. ambigua feed on Ponderosa pine ( Pinus ponderosa Dougl. ex Lawson ) (R. Nagle, pers. comm.), and it is probable that other species of the ambigua- group also feed on pines. The striate white-and-tan wing pattern (mimicking dead pine needles) is an interesting example of convergent evolution in cryptic colouration in pine-feeding Lepidoptera , as a similar pattern occurs also in such unrelated groups as the Geometridae , such as the Caripeta piniata (Pack.) group and particularly Sabulodes niveostriata (Cockerell, 1894) , which often occurs in strict sympatry with P. ambigua . A parallel (but evolutionarily independent) host switch has occurred (possibly multiple times) in Lophocampa Harris , where two lineages (L. roseata- group and L. argentata- group) feed on conifers, compared to deciduous trees for most congeners.

Pseudohemihyalea has a long and confusing taxonomic history, primarily a result of confusion with the genus Amastus . In describing Hemihyalea, Hampson (1901) distinguished this genus from Amastus by differences in the branching of the forewing radial veins. As noted by Dyar (1914), the branching pattern of the radial vein is highly variable in Hemihyalea and Amastus (as it is in a number of other arctiine genera such as Grammia , Apantesis and Phragmatobia ), so this character is not diagnostic. In reviewing Hemihyalea, Rego-Barros (1956) recognized two additional genera, Machadoia Rego-Barros and Pseudohemihyalea , although only six species were examined. Pseudohemihyalea was later placed into synonymy under Hemihyalea by Watson and Goodger (1986). Toulgoët (1988) considered the type species of Hemihyalea ( Phaegoptera cornea Herrich-Schäffer, 1853 ) to be congeneric with Amastus and accordingly synonymized the two, subsequently raising Pseudohemihylaea from synonymy ( Toulgoët 1992) and providing a review of the genus ( Toulgoët 1994), consisting primarily of those species treated as Hemihyalea by Watson and Goodger (1986). To complicate matters further, when describing Pseudohemihyalea , Rego- Barros believed the type-species to be Phaegoptera rhoda Druce, 1894 but the species he diagnoses and illustrates is Hemihyalea schausi Rothschild, 1909 ( Toulgoët 1994) . Following Toulgoët’s (1994) review, several additional taxa were described or revised (see Toulgoët 1996, 2001).

In summary, Pseudohemihyalea as currently defined is a relatively small group of about 30 species restricted to Central America and southern North America. Toulgoët (1994) arranged 20 species of Pseudohemihyalea into three groups, but provided no diagnostic characters or synapomorphies for the genus or for the three species-groups. Genitalic structure is very diverse in the mansueta -group ( Toulgoët 1994) which may prove to be a polyphyletic assemblage. In addition, at least one species likely does not belong to Pseudohemihyalea ( Toulgoët 1994) , so much work is still needed to establish relationships among Pseudohemihyalea and related genera, and to objectively define the generic limits of the genus.