Review of the genus Strumigenys (Hymenoptera, Formicidae, Myrmicinae) in Hong Kong with the description of three new species and the addition of five native and four introduced species records.

Kit Lam Tang,Mac P Pierce,Benoit Guénard

doi:10.3897/zookeys.831.31515

Abstract

The species of the ant genus Strumigenys Smith, 1860 found in Hong Kong are reviewed based on new sampling efforts performed over the past five years (2014–2018). Prior to this, 12 Strumigenys species had been recorded from Hong Kong, all confirmed here. Moreover, we add to this list three newly described species: S.hirsutasp. n., S.lantauisp. n., and S.nathistorisocsp. n., and describe for the first time the worker caste of S.formosa Terayama, Lin & Wu, 1995. We report new records for nine additional species, bringing the total number of species to 24, including four newly recorded species (S.hexamera Brown, 1958, S.membranifera Emery, 1869, S.nepalensis Baroni Urbani and De Andrade, 1994, and S.rogeri Emery, 1890) which are considered to be introduced to Hong Kong. A global review of the introduced Strumigenys species is presented. The taxonomic validity of S.feae and S.formosensis is discussed in light of new specimen measurements. New ecological information on the swarming periods of 11 species is presented on the basis of year-long sampling of aerial insects. Finally, the importance of our results within Southeast Asia and the need for future sampling efforts in the region is discussed.

Highlights

With 836 described extant species (Bolton 2018), Strumigenys is a hyperdiverse ant genus both taxonomically and morphologically
Despite its hyperdiverse status, our results suggest that even 70 years after its publication, the statement by William Brown Jr (1949: 1) that “...the dacetine ants presently known from eastern Asia undoubtedly represent only a fraction of the species which exist there...” might still apply
As Hong Kong is a small territory of 1100 km2 with a history of extensive deforestation and disturbance over most of its territory (Zhuang and Corlett 1997), the discovery of three new species and nine new records (Table 2) stresses the need for further sampling and taxonomic work on this genus within southeastern China

Summary

Introduction

With 836 described extant species (Bolton 2018), Strumigenys is a hyperdiverse ant genus both taxonomically and morphologically. Strumigenys is distinguishable from other ant genera by the combination of the following characters: small size (TL: ca 2–5 mm), elongate or triangular mandibles, and for many species the presence of spongiform tissues on the propodeal declivity, petiole and postpetiole, and first abdominal segment. In the field, these species can be identified by their slow-motion, the occasional presence of thanatotic behaviour (Smith 1931; Brown 1949), and small colony sizes ranging from a few dozen to a maximum of 500 workers (Wilson 1959; Terayama et al 2014). We provide new information on the sociometry of several species collected including reproductive phenology and colony composition

Methods and materials

Results

Discussion