60.

Western False Pipistrelle

Falsistrellus mackenziei

French: Falsistrelle de McKenzie / German: \Westliche Scheinzwergfledermaus / Spanish: Falsistrela de McKenzie

Other common names: Mackenzie's False Pipistrelle, Western Falsistrelle

Taxonomy. Falsistrellus mackenziei Kitchener, Caputi & B. Jones, 1986,

“Donnelly, (34°06’S, 115°58’E),” Western Australia, Australia.

Falsistrellus mackenziei was included in FE tasmaniensis by K. F. Koopman in 1993, and at the time the two were placed in Pipistrellus, but in subgenus Falsistrellus . In 2018, the phylogenetic reconstructions of T. Gorfol and G. Csorba revealed this species to be sister to F tasmaniensis within an “Australian clade” of Vespertilioninae (including Vespadelus, and Chalinolobus), distantly related to Hypsugo petersi, which clustered with some Hypsugo species from South Asia. Monotypic.

Distribution. SW Australia, from near Perth to the W margin of the Wheatbelt.

Descriptive notes. Head-body 55-67 mm, tail 40-53 mm, ear 14-18-3 mm, hindfoot 8:2-11-6 mm, forearm 48-54 mm; weight 17-26 g. The Western False Pipistrelle is slightly larger than the Eastern False Pipistrelle ( F tasmaniensis) and has a rustier hue to the pelage. Dorsally, it is rusty brown; underparts are light cinnamon-brown. Baculum is short with a broad base, proximally widened, roof-like in cross section, and without distal expansion; unlike the Eastern False Pipistrelle, the dorsal basal transverse ridge is notched at the center; ridge projects behind ventral posterior edge of base. Skull large and robust; superorbital tubercles small to moderate; infraorbital foramen small to moderate, separated from orbit by moderate lacrimal bar; bulla length moderate. Dental formula for hoth species of Falsistrellus is 12/3, C 1/1, P 2/2, M 3/8 (x2) = 34. Dentary similar to that of Eastern False Pipistrelle, but longer relative to basicranial length. P* has buccal edge moderately notched. Condylo-canine length 17-9-18-3 mm; maxillary tooth row 7-3-7-8 mm.

Habitat. Restricted to tall forest. The Western False Pipistrelle is typically found in wet sclerophyll forest, dominated by karri ( Eucalyptus diversicolor, Myrtaceae); in high rainfall zones, it occursin jarrah (E. marginata) and tuart (E. gomphocephala) dry sclerophyll forests. Also recorded in mixed tuartjarrah tall woodlands on adjacent coastal plains. It has also been captured in Banksia (Proteaceae) woodlands on the Swan Coastal Plain.

Food and Feeding. Western False Pipistrelles forage on insects above the understory, in the tree canopy, and along forest tracks. Their high agility enables them to outmaneuver and catch airborne insect prey among massive tree trunks.

Breeding. A single young is born in spring or early summer.

Activity patterns. In 1992, over three nights 24 Western False Pipistrelles were captured while foraging 4-8 m aboveground, where their flight was fast and direct, with occasional abrupt turns. During daytime, the species roosts in hollows in old trees, branches and stumps. Echolocation calls end at low frequencies (30 kHz), with most energy at 32-34 kHz, and last c.12 milliseconds.

Movements, Home range and Social organization. The Western False Pipistrelle roosts gregariously. A colony of ¢.30 individuals was found in a karri hollow 15 m aboveground. Available data suggest that sexes segregate while roosting and foraging, at least during spring and early summer.

Status and Conservation. Classified as Near Threatened on The IUCN Red Lust. Western False Pipistrelles are only known from ¢.30 sites. Area of occurrence is less than 20,000 km? within which it occurs at relatively low densities compared to other sympatric forest-dwelling bats. It is confined to the south-western corner of Australia, and has not been seen in the northern part of its range since 1993, despite searches. Population size is reckoned to be over 10,000 mature individuals, but no census has ever been undertaken. Its habitats are subject to continued logging, burning, clearing and modification for a variety of land uses including forestry, mining, viticulture, housing development. Other threats include competition for roosting resources with feral honeybees and coconut lorikeets ( Trichoglossus haematodus) in some areas.

Bibliography. Adams et al. (1987), Armstrong, Woinarski & Burbidge (2017), Churchill (1998, 2008), Gorfol & Csorba (2018), Hill & Harrison (1987), Jackson & Groves (2015), Kitchener et al. (1986), Koopman (1993, 1994), Menkhorst & Knight (2001), Simmons (2005), Start & McKenzie (2008), Webala et al. (2011), Woinarski et al. (2014).