Diversity and biogeography of a species‐rich ant fauna of the Australian seasonal tropics

Abstract

Although ants are an ecologically dominant and extensively studied faunal group throughout the tropics, there is a poor understanding of tropical ant diversity and distribution at large spatial scales. Here we use a collection developed from 3 decades of ant surveys to present the first analysis of ant diversity and biogeography of a large tropical region. Our objective was to document the species richness, composition, and biogeographic distributions of the ant fauna of the 400 000 km "Top End" of Australia's Northern Territory. The known Top End ant fauna comprises 901 native species from 59 genera. The richest genera are Pheidole (90 species), Melophorus (83), Monomorium (83), Camponotus (71), Meranoplus (63), Polyrhachis (57), Rhytidoponera (50), Tetramorium (43), Cerapachys (32), and Iridomyrmex (31). The fauna is the center of diverse radiations within species-groups of genera such as Meranoplus, Rhytidoponera, and Leptogenys. It also includes IndoMalayan species that have likely bypassed the normal dispersal route into Australia through Cape York Peninsula in North Queensland. Faunistic similarity with other regions of far northern Australia is associated more with rainfall than with geographic proximity. Most (60%) of Top End ant species have not been recorded elsewhere, and, despite uncertainties relating to species delimitation and sampling intensity, this appears to be a credible estimate of the level of endemism. Such exceptionally high endemism can be attributed to the Top End's geographic isolation from other regions of northern Australia with comparably high rainfall.

Ants in Australia’s Monsoonal Tropics: CO1 Barcoding Reveals Extensive Unrecognised Diversity

“…By way of comparison, a recent CO1 analysis of the ant fauna of Brazil's southern Atlantic Forest indicated that species richness was only 10% higher than previously appreciated [85], rather than the several-fold increase that is apparent for the AMT. Our findings call for a re-evaluation of the recent assessment based on the TERC collection that 900 species are known from the Top End of the Northern Territory [40]. Since this assessment, an extensive survey of remote areas of Kakadu and Nitmiluk National Parks have revealed >100 additional species (Oberprieler and Andersen unpubl.…”

“…Based on specimens in the Commonwealth Scientific Industrial Research Organisation (CSIRO) Tropical Ecosystems Research Centre's (TERC) ant collection in Darwin, there appears to be at least 26 valid species, one of which (Papyrius sp. 1) seemingly occurs throughout the AMT [40,41] and is one of our target species (Figure 2A). Syntypes of P. nitidus queenslandica are from Mackay on the central Queensland (Qld) coast, and Papyrius sp.…”

“…The AMT ant fauna also shows remarkably high levels of endemism. For example, 60% of the >900 morpho-species recorded from the Top End of the Northern Territory have not been found elsewhere [40], and 40% of the ant species known from the Mitchell Falls area of the North Kimberley appear to be endemic [41]. Despite such high levels of regional endemism, a substantial proportion of the AMT ant species appear to be distributed throughout the region [40].…”

The importance of sampling intensity when assessing ecosystem restoration: ants as bioindicators in northern Australia

“…However, most ant species in northern Australia are undescribed and these were identified to species‐group following Andersen () and assigned code numbers that have been used in previous studies of ants in the region (e.g. Andersen et al ; Oberprieler et al ).…”

Establishment of Alluaud's Little Yellow Ant,Plagiolepis alluaudiEmery (Hymenoptera: Formicidae: Formicinae): First Continental New World Record

“…Wetterer (2014) lists several islands in the Lesser Antilles (Barbados, St. Lucia, Grenada, Anguilla, St. Martin, St. Kitts, Nevis, Guadeloupe, and Martinique) and in Bermuda (Wetterer 2017) as occupied by P. alluaudi. A few additional invasive establishments of P. alluaudi include Capricorna Cays, Australia (Hoffmann & Kay 2009); 'Top End', Northwest Territory, Australia (Andersen et al 2016); and Nansei Islands, Japan (Harada et al 2015).…”