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

Abstract

The species of the ant genusStrumigenysSmith, 1860 found in Hong Kong are reviewed based on new sampling efforts performed over the past five years (2014–2018). Prior to this, 12Strumigenysspecies 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., andS.nathistorisocsp. n., and describe for the first time the worker caste ofS.formosaTerayama, 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.hexameraBrown, 1958,S.membraniferaEmery, 1869,S.nepalensisBaroni Urbani and De Andrade, 1994, andS.rogeriEmery, 1890) which are considered to be introduced to Hong Kong. A global review of the introducedStrumigenysspecies is presented. The taxonomic validity ofS.feaeandS.formosensisis 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.

A new subterranean species and an updated checklist of Strumigenys (Hymenoptera, Formicidae) from Macao SAR, China, with a key to species of the Greater Bay Area

“…Originally described from Taiwan, this species is more widespread within continental Asia since it has also been recorded in Hong Kong, Macao, Guangdong, Guangxi (China) as well as in Thailand. In both Macao and Hong Kong ( Tang et al 2019 ), this species is relatively common and is known from two and ten sites within these regions, respectively.…”

“…In 2017, opportunistic leaf litter extractions and hand collection expanded the list of Strumigenys species for Macao with four additional species records ( Leong et al 2017 ). Thus prior to this study, two native (i.e., Strumigenys exilirhina Bolton, 2000 and Strumigenys minutula Terayama & Kubota, 1989) and three introduced Strumigenys species (i.e., S. emmae , S. membranifera , and S. nepalensis ) had been recorded in Macao, far less than the 24 species recorded in the neighboring territory of Hong Kong ( Tang et al 2019 ).…”

“…Yet, the Strumigenys diversity currently reported within tropical regions is likely underestimated. For example, in Southeast Asia, several authors have shown that unrecorded and undescribed Strumigenys species should be expected within several countries (e.g., Guénard et al 2010 ; Eguchi et al 2011 ; Liu et al 2015 ; Jaitrong et al 2016 ; Tang et al 2019 ). Accordingly, recent work sampling leaf-litter ant communities in Yunnan and Hong Kong resulted in a substantial increase in their known Strumigenys diversity, both because of unrecorded and undescribed species ( Liu et al 2015 ; Tang et al 2019 ).…”

“…Phylogenetically, species of Strumigenys were recently moved from the Dacetini to the Attini tribe based on molecular analyses, strengthening their position as the sister taxon to the phalacromyrmecine ants ( Ward et al 2015 ). Ecologically, Strumigenys species tend to be associated with primary and secondary forest habitats, with a few species, including several tramp species (e.g., Strumigenys emmae Emery, 1890, Strumigenys membranifera Emery, 1869), relatively common in open and disturbed habitats such as urban parks ( Kitahiro et al 2014 ; Tang et al 2019 ). At the microhabitat level, Strumigenys are typically encountered within the leaf-litter covering forests floors, though a few species nest under bark or epiphytes ( Longino 2006 ), are associated with the accumulated leaf litter in trees ( Nadkarni and Longino 1990 ) or forage on the understory vegetation ( Lattke et al 2018 ).…”

“…Seventy-eight years later, a second record, Strumigenys sylvestrii Emery, 1906, was published by Hua (2006) . This record is, however, most certainly erroneous ( Tang et al 2019 ). In 2017, opportunistic leaf litter extractions and hand collection expanded the list of Strumigenys species for Macao with four additional species records ( Leong et al 2017 ).…”