Phtheochroa Stevens 1829

Phtheochroa Stevens, 1829

Type species: Tortrix rugosana Hübner, [1796–1799]

Species currently included in Phtheochroa have been treated variously as Hysterosia Stephens, 1852, Trachysmia Guenée, 1845, or Phtheochroa, but there has been considerable inconsistency in the application of these names. The type species of the three genera have very similar male genitalia and a forewing costal fold in the male. Although male secondary structures such as a costal fold typically are unreliable indicators of relationship, within Cochylini a male costal fold occurs only in the species of this genus (but not all included species have a costal fold).

Based on facies, species of Phtheochroa (sensu stricto) (type species rugosana Hübner [1796–1799]) can be separated from those of Hysterosia (sensu stricto) by a banded forewing pattern, usually with conspicuously upraised scales, and a reduction or loss of the forewing costal fold. However, on the basis of the male genitalia of the type species, Hysterosia (i.e., inopiana [Haworth 1811]) and Trachysmia (i.e., duponchelana Duponchel, 1843) are almost certainly congeneric. The type species of Phtheochroa (i.e., rugosana) has similar genitalia, but with a much shorter uncus. While a short uncus and banded forewing pattern are somewhat concordant, these characters are not shared by all species in the group. Until a phylogenetic analysis of the included species is performed, it is uncertain whether the three genera are each monophyletic (representing genera, subgenera within Phtheochora, or species groups) or one or more are paraphyletic with respect to the others. In the absence of compelling evidence to the contrary, we opt for a conservative approach and retain all in Phtheochroa.

As currently defined, Phtheochroa includes 110 species distributed primarily in the Palearctic, Nearctic, and Neotropical regions (Brown 2005). Three recently described species are known from the Afrotropical region: P. natalica Razowski, 2005, P. lonnvei Aarvik, 2010, and P. kenyana Aarvik, 2010. Most species have a well-developed, long, rodlike uncus; large, pendant socii; a large, broad phallus with 1–2 (rarely 3) long cornuti; a transtilla with a short, usually rectangular mesal lobe; and long, parallel-sided valvae with a distinct sacculus and a sclerotized costa.

Whereas most Cochylini utilize Asteraceae as larval food plants, many species of Phtheochroa apparently prefer other plant families, including Acanthaceae, Berberidaceae, Chenopodiaceae, Cucurbitaceae, Dipsacaceae, Liliaceae, Plumbaginaceae, Poaceae, Rhamnaceae, Rosaceae, Salicaceae and Ulmaceae (Brown et al. 2010).