Chris A. Johns

Molecular Phylogeny, Revised Higher Classification, and Implications for Conservation of Endangered Hawaiian Leaf-Mining Moths (Lepidoptera: Gracillariidae: Philodoria)

Abstract: The leaf-mining moth genus Philodoria Walsingham (Lepidoptera: Gracillariidae) is composed of 30 described species, all of which are endemic to the Hawaiian Islands. Philodoria is known to feed on 10 families of endemic Hawaiian host plants, with several species recorded only from threatened or endangered hosts. Beyond their dependence on these plants, little is known of their evolutionary history and conservation status. We constructed a molecular phylogeny of Philodoria to assess validity of its current subgeneric classification and to help guide future work on this threatened Hawaiian lineage. Mitochondrial and nuclear DNA sequences from three genes (CO1, CAD, EF-1α) combining for a total of 2,041 base pairs, were collected from 11 Philodoria species, incorporating taxa from both currently recognized subgenera. These data were analyzed using both parsimony and model-based phylogenetic approaches. Contrary to the most recent systematic treatment of Philodoria, our results indicate strongly that the two currently recognized Philodoria subgenera are not monophyletic and that morphological characters used to classify them are homoplasious. Based on our robust results, we revised the higher classification of Philodoria: the subgenus Eophilodoria Zimmerman, 1978 is established as subjective junior synonym of Philodoria Walsingham, 1907. We also present new host plant and distribution data and discuss host range of Philodoria as it pertains to endangered Hawaiian plants.

Hawaiian Philodoria (Lepidoptera, Gracillariidae, Ornixolinae) leaf mining moths on Myrsine (Primulaceae): two new species and biological data

Abstract This paper provides new taxonomic and biological data on a complex of gracillariid moths in the endemic genus Philodoria Walsingham, 1907 that are associated with Myrsine (Primulaceae) in the Hawaiian Islands, United States. Two new species, Philodoria kauaulaensis Kobayashi, Johns & Kawahara, sp. n. (host: Myrsine lanaiensis, M. lessertiana, and M. sandwicensis) and P. kolea Kobayashi, Johns & Kawahara, sp. n. (host: M. lessertiana) are described. Biological data are provided for two previously described species that also feed on Myrsine: P. auromagnifica Walsingham, 1907 and P. succedanea Walsingham, 1907. For the first time we detail and illustrate genital structures, immature stages, biology, and host plants of P. auromagnifica and P. succedanea. Philodoria kolea, P. auromagnifica, and P. succedanea occur in sympatry on the island of Hawaii (Big Island), but each species differs in behavioral characters: P. kolea utilizes leaves of seedlings and forms a serpentine mine, whereas the latter two utilize leaves of larger plants, and form linear or serpentine to blotch mines. More broadly, leaf mine forms and diagnostic characteristics of the Myrsine-feeding species complex of Philodoria (as currently known) are reviewed and illustrated.

Origin and macroevolution of micro-moths on sunken Hawaiian Islands

The origins and evolution of Hawaiian biodiversity are a matter of controversy, and the mechanisms of lineage diversification for many organisms on this remote archipelago remain unclear. Here we focus on the poorly known endemic leaf-mining moth genus Philodoria (Lepidoptera, Gracillariidae), whose species feed on a diversity of Hawaiian plant lineages, many of which are critically endangered. We use anchored hybrid enrichment to assemble the first phylogenomic dataset (507 loci) for any Hawaiian animal taxon. To uncover the timing and pattern of diversification of these moths, we apply two frequently used dating calibration strategies, biogeographic calibrations and secondary calibrations. Island calibrations on their own resulted in much younger and unrealistic dates compared to strategies that relied on secondary calibrations. Philodoria probably originated on the now partially sunken islands of Laysan or Lisianski, approximately 21 Ma, and were associated with host plants in the families Ebenaceae, Malvaceae or Primulaceae. Major feeding groups associated with specific host-plant families originated soon after the plants colonized the islands. Allopatric isolation and host shifts, in concert and independently, probably play major roles in the diversification of Philodoria. Our dating results indicate that Philodoria is among the oldest known Hawaiian arthropod lineages, and that island calibrations alone can lead to unrealistically young dates.