Date of this Version
Skelley PE, Tang W. 2020. Two new species of Pharaxonotha Reitter among the early-diverging lineages, with a key to the species of the genus (Coleoptera: Erotylidae: Pharaxonothinae). Insecta Mundi 0837: 1–11.
Michael C. Thomas Festschrift Contribution
Two species of the early-diverging lineages of Pharaxonotha Reitter (Coleoptera: Erotylidae: Pharaxonothinae) are described: Pharaxonotha taylori Skelley and Tang, new species, and Pharaxonotha thomasi Skelley and Tang, new species. A new key to described species of Pharaxonotha, based on previously unused characters, is presented.
In recent phylogenetic analyses of beetle diversity based on a large nuclear data set (McKenna et al. 2019) and on nuclear and mitochondrial legacy loci (Powell, pers. comm. 2020), the New World genus Pharaxonotha Reitter (Erotylidae: Pharaxonothinae) was shown to be sister to all remaining Erotylidae in a clade comprised of the Erotylidae+Phytophaga, which includes Cucujoidea, Chrysomeloidea and Curculionoidea. Since these three superfamilies of Coleoptera contain the majority of beetle pest taxa on human plant crops, a closer examination of this genus may provide some insight into the origin and evolution of these insect groups of agricultural concern. Except for the type species of Pharaxonotha, P. kirschii Reitter, which is a minor stored products pest, all other species of the genus that have been studied are inhabitants of cycad cones (Pakaluk 1988; Chaves and Genaro 2005; Franz and Skelley 2008; Skelley and Segalla 2019). Exclusion experiments on two of these species indicate that they are pollinators of cycads (Tang 1987; Valencia-Montoya et al. 2017), and it is probable that these ancient plant and beetle lineages have coevolved for many millions of years. Leschen and Buckley (2007) hypothesize that fungivory may be the ancestral state in the Erotylidae, however, adult and early instar larvae of Pharaxonotha floridana (Casey) inhabiting cycad cones appear to be pollen feeders, while late instar larvae feed on cone sporophyll and axis tissue (Norstog et al. 1992). Tang et al. (2018b, 2020) presented preliminary relationships of species within Pharaxonotha, based on analysis of the 16S rRNA gene, recognizing three distinct radiations: early-diverging lineages, a Caribbean radiation and a recent radiation. Pharaxonotha may inhabit cycad cones in the New World with other beetle genera, including Ceratophila Tang, Skelley and Perez-Farrera (Erotylidae: Pharaxonothinae) in the cycad host Ceratozamia Brongn., and primitive weevils of the subtribe Allocorynina (Belidae) in the host cycads Dioon Lindl. and Zamia L. (O’Brien and Tang 2015; Tang et al. 2018a, 2018b, 2020).
The purpose of this paper is to describe two species in the early-diverging lineages of Pharaxonotha identified in those analyses as D0063 from Panama and D0066 from Honduras, inhabiting the cycad genus Zamia. A revised key to all species of Pharaxonotha is presented. Only previously described species of the Caribbean and recent radiations are represented in this review. Others in these and the early-diverging lineages will be described in future papers.