Thyroptera tricolor, Spix, 1823

Don E. Wilson & Russell A. Mittermeier, 2019, Thyropteridae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 418-423 : 423

4 .

Spix’s Disk-winged Bat

Thyroptera tricolor

French: Thyroptere tricolore / German: Spix-Haftscheibenfledermaus / Spanish: Tiréptero tricolor

Taxonomy. Thyroptera tricolor Spix, 1823 ,

“ad littora fluminis Amazonum.” Restricted by A. M. Husson in 1962 to “lower Amazon River below Santo Antonio Dolca at the mouth of the Rio Ica,” Brazil.

Phylogenetic analysis of mitochondrial genes indicates that T. tricolor and T. lavali are sister taxa. Monotypic.

Distribution. Disjunct distribution in Central America from S Mexico (Veracruz and Chiapas) through Guatemala, Belize, and Honduras to NE Nicaragua and from extreme S Nicaragua through Costa Rica to Panama, and widely distributed in N South America from Colombia E to E & SE Brazil and S to E Peru and N Bolivia; also on Trinidad 1.

Descriptive notes. Head-body ¢. 42—49 mm, tail 25-30 mm, ear 11-13 mm, hindfoot 4-7 mm, forearm 33-5-40 mm; weight 3-4-5-1 g. Greatest length of skull 13-6— 15-7 mm, condylo-incisive length 12:9-14-4 mm,rostral length 5-3-5-5 mm, zygomatic breadth 6-9-7-7 mm, and maxillary tooth row length 5-5-6-3 mm. Long dorsal fur of Spix’s Disk-winged Bat is dark brown and white to yellow at the base. Unicolored ventral fur is white to whitish. Ears are dark brown to almost black. Females have larger forearms than males. Caudal membrane is naked, and wings have wart-like structures. Calcar has two lappets. Thumb disk is nearly round.

Habitat. Lowland forests. Spix’s Disk-winged Bats are usually found inside curled leaves of Heliconia (Heliconiaceae) , but they have been found in leaves of Musa (Musaceae) , Calathea (Marantaceae) , and Phenakospermum (Strelitziaceae) . In Costa Rica, they are found in mixed primary forests and secondary forests with different aged trees. One individual was found in a mixed upland forest of arborescent palm Iriartea deltoidea ( Arecaceae ) and Miconia sp. ( Melastomataceae ), with rolling hills, in Camisea, Peru.

Food and Feeding. Spix’s Disk-winged Bat can consume up to 0-8 g of insects/night. Feces of Spix’s Disk-winged Bat collected in Heliconia and Calathea leaves often contained dipterous larvae of Sarcofahrtiopsis. These flies were collected at roostsites in tropical lowland rainforests at Cano Palma Biological Research Station, Costa Rica, and Barro Colorado Island, Panama. These fly larvae were found in fresh feces in sites that bats occupied shortly before sunrise.

Breeding. Ovulation of Spix’s Disk-winged Bats occurs in July-August in Costa Rica. Females gave birth to one young a year after one synchronized breeding season. In Costa Rica, females and their offspring belonged to the same social group, but males were from different social groups that were separated by more than 500 m.

Activity patterns. Roost sites of Spix’s Disk-winged Bats are usually upright tubular or conical leaves, with openings 3.5-27. 6 cm in diameter. These sites are located c¢. 4 m aboveground. Besides using furled leaves for shelter, Spix’s Disk-winged Bats can use leaves to amplify incoming sounds and outgoing social calls. Shelters are temporary, and new roosts are selected every night. Spix’s Disk-winged Bat is the only species of Thyropteraknown to use this type of shelter. Ventralfuris light, perhaps to help it blend in inside furled translucent leaves. These furled leaves grow in shaded and unshaded areas.

Movements, Home range and Social organization. Home ranges of most social groups or colonies of Spix’s Disk-winged Bats in Costa Rica did not overlap; colonies that overlapped might have been related. Mean distances travel between roosting sites for most colonies were 14-55 m. Size of a roosting area was ¢. 855 m?®There were 3-3 colonies or 19-8 ind/ha. Spix’s Disk-winged Bats are agile and maneuverable when flying 3-5 m aboveground in forests. They seemed to communicate locations of roosts to other group members. There is speculation that knowledge of a roosting territory is the adaptation that keeps other bats from roosting in limited numbers of furled leaves.

Status and Conservation. Classified as Least Concern on The IUCN Red Lust.

Bibliography. Buchalski et al. (2014), Chaverri & Gillam (2013), Husson (1962), Medina-Fitoria et al. (2015), Pape et al. (2002), Velazco et al. (2014), Vonhof & Fenton (2004), Wilson & Findley (1977).

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Plate 33 Species Accounts

Distribution. Disjunct distribution in Central America from S Mexico (Veracruz and Chiapas) through Guatemala , Belize , and Honduras to NE Nicaragua and from extreme S Nicaragua through Costa Rica to Panama , and widely distributed in N South America from Colombia E to E & SE Brazil and S to E Peru and N Bolivia ; also on Trinidad 1.