The Coastal Lobe-lipped Bat: a new range-restricted species from the coastal lowlands of southern Papua New Guinea

The Coastal Lobe-lipped Bat (Chalinolobus orarius) is a newly named species recognised from museum specimens collected in Papua New Guinea (PNG) previously thought to represent the Hoary Bat (C. nigrogriseus) of northern Australia. This new addition to the bat fauna of New Guinea raises doubt about all past Hoary Bat records from New Guinea and northern Australia, where the new species might also occur and highlights the importance of museum collection in underpinning the natural sciences.

Lobe-lipped or Wattled Bats

The lobe-lipped or wattle bats of the genus Chalinolobus are named for the small, variably shaped skin lobes on their lips. Chalinolobus comprises six Australian bat species, plus one endemic species each in New Caledonia and New Zealand.

One species, the Hoary Bat, is a small insectivorous bat with a wingspan of about 26 cm and body weight of 5 to 10 g. They are common across northern Australia, extending down the east coast to northern New South Wales (NSW). These delightful little bats have beautiful, soft, dark-coloured body fur. Prior to our research, the Hoary Bat was the only Chalinolobus species recorded from the island of New Guinea, where it was first recorded in the 1890s and is known from only five localities across southern coastal Papua New Guinea.

However, on close examination we discovered that the specimens from New Guinea could be easily distinguished from the Hoary Bat from external features — once you know how! The New Guinean bats have a conspicuously enlarged “flap” or lobe formed by the outer ear margin, where it joins the angle of the mouth, which is very small in the Hoary Bat. Further, whereas the New Guinean specimens have an additional cusp on the first upper incisor, there is usually no additional cusp on Hoary Bat upper incisors. They also differ consistently genetically, leading us to recognise the New Guinea specimens as a distinct species new to science. Chalinolobus orarius also known as the Coastal Lobe-lipped Bat, was named orarius from the Latin meaning “of the coast”.

Lobe-lipped bat limbo: past records need to be re-examined

The discovery of this new species demands a re-assessment of the number of species of lobe-lipped bat in New Guinea and their conservation status. It also requires a review of past records of the similar Hoary Bats from Australia and Gould’s Wattled Bat (C. gouldii) from northern Australia.

Although the Coastal Lobe-lipped Bat has a combination of unique morphological features not found in any other species of Chalinolobus, this discovery now generates uncertainty about past identification of specimens from both New Guinea and northern Australia. First, we were unable to examine all museum specimens in world collections in our study, and so all Hoary Bat records from New Guinea now need to be re-examined. Second, the discovery of this new species opens the possibility that the Australian Gould’s Wattled Bat might also occur in New Guinea. The latter species is the only other lobe-lipped bat with an enlarged ear flap and small individuals of the species might be confused with the Coastal Lobe-lipped Bat in New Guinea. Third, the Coastal Lobe-lipped Bat might also occur in northern Australia and if so, is likely to have been misidentified as Hoary Bats, or even as small, dark Gould’s Wattled Bat.

These potential sources of confusion highlight a neglected aspect of bat field identification: people often give priority to different field identification features to determine species identity. For example, if body size is prioritised over incisor and ear shape, then the Coastal Lobe-lipped Bat would be mistaken for Hoary Bats, or as a small example of Gould’s Wattled bat if the presence of an ear flap was prioritised, or as a Hoary Bat if a priority is given to the presence of a secondary incisor cusp. Only a combination of features will reveal the true species identity in this genus.

Coastal Lobe-lipped Bat biology

Lobe-tipped bats have been recorded infrequently in PNG over the past 140 years and are known from only ten sites in five districts: two in the Trans-Fly, Western Province; Port Moresby (six sites), Kupiano on the south-eastern coast, and a 19th century specimen from Fergusson Island.

The distribution, biology and conservation status of the Coastal Lobe-lipped Bat will remain poorly understood until more bat research is undertaken in New Guinea. Past knowledge of New Guinea Chalinolobus was mainly an extrapolation of knowledge about the Hoary Bat of northern Australia with the exception that it was thought to be uncommon in New Guinea.

It seems that the Coastal Lobe-lipped Bat is one of a small number of bat species from the Australo-Papuan region that are largely restricted to coastal lowlands. We reviewed the known localities of Chalinolobus species from PNG and were surprised to find all were below 100 m elevation. Habitats surrounding these sites were dominated by savannah woodland, wetlands, and swamp woodland. The Coastal Lobe-lipped Bat is confirmed from two of these sites (Port Moresby and Serki, Western Province) but a clearer understanding of the habitat and biology of this species awaits confirmation of the identity of the Chalinolobus records not examined in our study.

The importance of museum collections

Our discovery illustrates the importance of routinely taking tissue samples and museum specimens during bat surveys in northern Australia and New Guinea, even for widely distributed, common species that were thought to be taxonomically stable. Prior to our study, it was thought that the species taxonomy of northern Australian and Papuan Chalinolobus had been solved by the last major taxonimic study published in 1971. It also demonstrates how taxonomic changes can render atlas and database records next to useless unless they backed up by tissue samples or museum voucher specimens. So, the discovery of a new species might not just be a simple additive process of increasing our scientific knowledge, but can also change past understanding of the distribution and ecology of those species with which it has been confused in the past. A revision of past concepts of the biology of these species can only be done from museum specimens and further field work.

Dr Harry Parnaby: Research Associate, Terrestrial Vertebrates, Australian Museum Research Institute.

Andrew King: Technical Officer, Australian Centre for Wildlife Genomics, Australian Museum Research Institute.

Steve Hamilton: School of Biological, Earth and Environmental Sciences, University of NSW, Sydney, NSW 2052, Australia.

Dr Mark Eldridge: Senior Principal Research Scientist, Terrestrial Vertebrates, Australian Museum Research Institute.