400.

Chilean Myotis

Myotis chiloensis

French: Murin du Chili / German: Chile-Mausohr / Spanish: Ratonero de Chile

Taxonomy. Vespertilio chiloensis Waterhouse, 1838,

“amongst the islets on Eastern side of Chiloe,” Los Lagos, Chile.

Subgenus Pizonyx; albescens species group. Holotype was caught in January 1836 by a Lieutenant Sullivan and given to Darwin during the H. M. S. Beagle voyage, butit was apparently lost. Neotype was designed in 1973 from “Cucao, Chiloe Island, Chile.” Recent taxonomic review indicates that northern Chilean populations from Coquimbo and Limache (Valparaiso) might be a distinct taxon. Monotypic.

Distribution. Chile (from Valdivia S to the N shore of Navarino I) and W & S Argentina (from Neuquén to Tierra del Fuego). Records from N Chile, probably represents another taxon.

Descriptive notes. Head-body 43-45 mm, tail 28-39 mm, ear 9-12 mm, hindfoot 7-9 mm, forearm 34-5—41- 2 mm; weight 6-9 g. It has woolly fur of medium length (dorsal fur 5-8 mm; ventral fur 4-7 mm), but fur texture is difficult to describe in some individuals. Solar radiation and precipitation affect fur color latitudinally, and southern populations have darker fur. Dorsal fur is generally reddish to coffeebrown, with two-thirds of bases slightly darker than tips. Bases of ventral hairs are dark brown, and tips vary from medium to light brown. Ears are comparatively short, extending forward halfway from eye to nostril. Antitragal notch is barely evident. Tragus is pointed, curving slightly outward above and convex below, with 3-8-5-mm triangular lobule at outer base. Membranes are mummy brown, and plagiopatagium is broadly attached to foot at base of toes. Trailing edge of uropatagium does not have fringe of hairs, but a few hairs are present. Skull is moderate in size (greatest length of skull 13-:8-15- 3 mm); length of rostrum is almost as long as braincase; occipital is rounded; sagittal crest is generally absent, and when present,it is very low; lambdoidal crests are present and low; and P° is in tooth row, aligned with other premolars. Baculum is extremely simple, without knobs. Bacular measurements of one specimen from Chile were: length 0-6 mm, depth 0-2 mm, and width 0-4 mm. Chromosomal complement has 2n = 44 and FN = 50, with three large pairs and one small pair of metacentric and 17 pairs of acrocentric autosomes. X-chromosome is submetacentric.

Habitat. Evergreen-deciduous forests and temperate forests (south-central Chile), Patagonian subtropical montane forests and scrublands (Argentina), and agricultural landscapes with plantations of Pinus (Pinaceae) and Eucalyptus (Myrtaceae) . The Chilean Myotis has the southernmost distribution known for any bat in the world and is associated with subtropical climates.

Food and Feeding. The Chilean Myotis forages in forested areas and over water. It feeds on insects, mainly nematocerans ( Diptera) that are captured in flight. There are also records of it eating Tipulidae flies in southern Chile.

Breeding. The Chilean Myotis is monoestrous, and age of first pregnancy is ten months. Females give birth to one young per year at the beginning of summer. A pregnant female was captured in Argentina with single embryo that had crown—-rump length of 15 mm.

Activity patterns. Foraging activity of the Chilean Myotis begins at sunset and lasts for ¢.3 hours—a unimodal pattern clearly distinct from bimodal patterns of most insectivorous bats. Due to reduced mean basal metabolic rate and occurrence in subtropical zones, it has a single and short euthermic period of 2-3 hours, followed by long period of daily torpor or natural hypothermia. Chilean Myotis use a wide variety of buildings and natural roosts, including ground holes, fissures in tree bark, caves, abandoned mines, crevices in walls, attic spaces, and under tiles or other roofing. Other smaller underground structures, such as rock crevices or ledges, are also used as roost. Wing morphology is consistent with highly maneuverable flight needed to forage in cluttered habitats, including edge habitats and forest with clearings. Its low aspect ratio (mean 5-8) and low wing loading (6-8 N/m?) indicate high energetic cost and low flight speed, respectively. Echolocation calls contain single harmonics and are characterized by downward FM at beginning of signal, followed by narrowband QCF component. Search calls consist of short (less than 4 milliseconds) broadband signals sweeping down between 89 kHz and 39 kHz, with most energy at 47 kHz. Pulses are emitted at mean intervals of 95-1 milliseconds.

Movements, Home range and Social organization. The Chilean Myotisis usually found cohabiting roosts with other bat species, especially Brazilian Free-tailed Bats (Tadar:- da brasiliensis), Common Big-eared Brown Bats (Hustiotus macrotus), Small Big-eared Brown Bats ( H. montanus), and Southern Big-eared Brown Bats ( H. magellanicus).

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Chilean Bat is widespread and presumably has a large population.

Bibliography. Barquez & Diaz (2016d), Barquez et al. (1999), Galaz & Yanez (2006), Galaz et al. (2009), LaVal (1973b), Mann (1978), Meynard et al. (2014), Novaes, Wilson et al. (2018), Ossa & Rodriguez-San Pedro (2015), Ossa et al. (2010), Rodriguez-San Pedro & Simonetti (2013b), Simmons (2005), Trouessart (1904), Waterhouse (1838), Wilson (2008b).