Systematics and biogeography of the subantarctic Leptusa (Coleoptera: Staphylinidae: Aleocharinae: Homalotini)

Abstract

Leptusa atriceps and L. antarctica, flightess representatives of the nearly global genus Leptusa in the remote and widely distributed subantarctic islands, are taxonomically revised. Identity and the widely disjunct distribution of L. atriceps on Falkland, South Georgia, Marion, Crozet and Kerguelen Islands are confirmed. Leptusa antarctica is found to be a complex of five species restricted to the subantarctic islands of New Zealand. Two of these species, L. sparsepunctata and L. nesiotes are here reinstated from synonymy and two others, Leptusa insulae sp. nov. and Leptusa steeli sp. nov., are described as new to science. The monophyly of subantarctic Leptusa species united in the subgenus Halmaeusa was determined by a phylogenetic study of five exemplar homalotine genera and 17 representatives of Leptusa from South America and the Holarctic based on 76 adult morphological characters. Phylogenetic placement of Halmaeusa was not firmly established. Nanoglossa, a temperate South American subgenus of Leptusa was found as a possible sister group to Halmaeusa. The distribution of Halmaeusa species with two to four species that occur sympatrically on Campbell and Auckland Islands, and other species distributed across several remote islands, provides a framework for future biogeographic study of the subantarctic Leptusa.

http://www.zoobank.org/urn:lsid:zoobank.org:act:82509B9D-4BF6-47E1-B6F7-396ED193A0FA; http://www.zoobank.org/urn:lsid:zoobank.org:act:40A3D6FC-27FF-4070-88CA-1B519ABE760A

Key words:

• biogeography
• Halmaeusa
• Nanoglossa
• phylogeny
• revision
• rove beetles
• Subantarctic region

Acknowledgements

We thank all curators listed in the Materials and methods section for the loan of material that enabled this study. We also thank Adriano Zanetti, Crystal Maier, and Al Newton for searching for some of Pace’s Leptusa material. Two anonymous reviewers are greatly acknowledged for their extensive comments.

Supplemental data

Supplemental data for this article can be accessed here: https://doi.org/10.1080/14772000.2018.1547329.

Additional information

Funding

Richard Leschen was funded in part by core funding for the Crown Research Institute from the Ministry of Business, Innovation and Employment’s Science and Innovation Group. Igor Orlov's PhD scholarship and this project were funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 642241.