Onycholyda Takeuchi 1938

Genus Onycholyda Takeuchi, 1938

Pamphilius (Onycholyda) Takeuchi, 1938: 218.

Onycholyda: Beneš, 1972b: 385.

Onycholyda is a compact genus, well defined by the characters given in the key (see Shinohara 2002b for more details). Morphologically, this is regarded as a monophyletic group having the following autapomorphies: anterior part of malar space with setiferous area (female) or pit (male) (Fig. 2: 3a); supraocular area in male with narrow, dull, densely pubescent patch; facial crests in male developed, sharply carinate (e.g., Figs 34e, 39e, 43e); ventral inner surface of fore tibia with disconnected row of scale-like setae; tarsal claws with acute basal lobe (Fig. 2: 3c). The monophyly of this genus is also supported by our molecular analyses, as discussed above.

Shinohara (2002b) divided the world species of this genus into two species groups, the O. amplecta group and the O. luteicornis group, based on morphology. In our molecular work, 14 species of the O. amplecta group and five species of the O. luteicornis group were used for the COI analysis, and 10 species of the O. amplecta group and four species of the O. luteicornis group were used for the NaK analysis. In general, interspecific relationships were poorly resolved in our Onycholyda trees. In the COI analysis (Figs 138, 139), three Nearctic species of the O. luteicornis group (O. luteicornis, O. nigritibialis and O. sitkensis) formed a clade, though with only 61% UFBoot support, but two Palaearctic species of this species group (O. armata and O. kumamotonis) were rather distantly separated from them and located among the members of the O. amplecta group. In the NaK analysis (Fig. 153), the two Palaearctic species of the O. luteicornis group (O. armata and O. kumamotonis) were retrieved as monophyletic with 100% UFBoot support and the two Nearctic species of this species group (O. luteicornis and O. nigritibialis) were also retrieved as monophyletic with 95% UFBoot support, but these Palaearctic and Nearctic clades did not form a clade and were recovered among the members of the O. amplecta group. Thus, the result of our COI and NaK analyses did not support the dichotomous division of the genus into species groups advocated by Shinohara (2002b). On the other hand, it is interesting that in the COI tree all the 17 Nearctic specimens of six species were retrieved as a monophyletic group with 99% UFBoot support and each of the O. amplecta group (O. amplecta, O. rufofasciata and O. multisignata) and the O. luteicornis group (O. luteicornis, O. nigritibialis and O. sitkensis) formed a clade with low UFBoot support of 61%. The intrageneric relationships in Onycholyda still need a revision.

This genus is most diverse in warm temperate regions of eastern Asia. There are 42 valid species worldwide (Taeger et al. 2010; Shinohara & Wei 2012, 2016; Shinohara et al. 2018c), of which 32 occur in eastern Asia. In the Russian Far East and Korea, only eight Onycholyda species have been found, whereas ten species are known to occur in Japan and 19 species in China.

The larvae of Onycholyda species feed on the host leaves singly or gregariously in simple leaf-rolls or, when they become larger, often in webs. All known larvae feed on shrubby or herbaceous Rosaceae, except for one doubtful record of Cornus (Cornaceae) in North America (Middlekauff 1964; Shinohara et al. 2019). Most species are associated with the genus Rubus and a few with the genera Filipendula and Agrimonia (Middlekauff 1964; Shinohara 2002b; Shinohara & Wei 2010, 2016; Shinohara & Lee 2011; Shinohara et al. 2018b, c).