The Isalo serotine (Laephotis malagasyensis) is a vesper bat of Madagascar in the genus Laephotis. It is known only from the vicinity of the Isalo National Park in the southwestern part of the island, where it has been caught in riverine habitats. After the first specimen was caught in 1967, it was described as a subspecies of Eptesicus somalicus (now Neoromicia somalica) in 1995. After four more specimens were collected in 2002 and 2003, it was recognized as a separate species. Because of its small distribution and the threat of habitat destruction, it is considered "vulnerable" in the IUCN Red List.
Laephotis malagasyensis is a relatively small species, with a forearm length of 30 to 32 mm (1.2 to 1.3 in) and a body mass of 3.9 to 9 g (0.1 to 0.3 oz). The fur is dark brown above and mixed buff and gray below. The ears are translucent and the tibia is short. The baculum (penis bone) resembles that of N. melckorum, but is smaller. The duration of the echolocation call, which consists of a component with rapidly falling frequency and one showing more stable frequency, averages 4.9 ms and the interval between calls averages 69.1 ms.
Taxonomy
In their 1995 review of Malagasy bats, Randolph Peterson and colleagues established Eptesicus somalicus malagasyensis, a new subspecies of Eptesicus somalicus (currently Neoromicia somalica). They had only a single specimen and noted that further material was needed to assess the new form's relationship with E. somalicus. Studies in 2001 and 2002 provided evidence that E. somalicus and related species are not closely related to Eptesicus (nor to Pipistrellus, where they have also been placed), so that these species were allocated to the separate genus Neoromicia. In 2004, Steven Goodman and Julie Ranivo reviewed the Malagasy subspecies after collecting two more specimens and concluded that it was distinct enough to be classified as a separate species, Neoromicia malagasyensis. Two years later, Paul Bates and colleagues reported on two more specimens and showed that the bacula (penis bones) of N. malagasyensis and N. somalica are different, providing further evidence that they are distinct species. However, they recommended that further research assess the degree of difference between N. malagasyensis and N. matroka (formerly in Eptesicus, but placed in Neoromicia by Bates and colleagues, and later placed in Laephotis), which occurs further east in Madagascar. The IUCN Red List currently again classifies the species in Eptesicus, as Eptesicus malagasyensis. In 2020, a phylogenetic analysis found it to belong to Laephotis as opposed to Neoromicia, and classified it as such.
Laephotis malagasyensis is one of at least six species of small vespertilionid bats ("pipistrelles") on Madagascar, in addition to L. matroka, L. robertsi, Pipistrellus hesperidus, P. raceyi, and Nycticeinops anchietae. The classification of these bats has historically been controversial, leading to many changing identifications and generic assignments. The genus Laephotis is exclusively African and included 4 species in the 2005 third edition of Mammal Species of the World; more species, like L. malagasyensis and L. matroka, have been added since. Common names proposed for this species include "Isalo Serotine" and "Peterson's 'pipistrelle.
Description
Laephotis malagasyensis is a relatively small "pipistrelle", but larger than Neoromicia somalica. The fur on the back is long and dark brown and the underparts contain both gray and dark buff hairs; there, the fur becomes lighter towards the tail. The fur is darker than in N. somalica, but paler than in L. matroka. The brown ears are translucent. The tragus (a projection on the inner side of the outer ear) is similar to that of N. somalica, but may be a little narrower. Relative to the two other Malagasy Laephotis species, the tibia is short. A single baculum (penis bone), 2.2 mm long, has been studied. It resembles the baculum of L. robertsi, but is smaller. As in L. matroka, the distal (far) end is flat and displaced downwards, but the L. malagasyensis baculum has a smaller area and less well-developed flanges at the sides and a smaller vertical extension of the bone.
The skull is somewhat smaller than that of L. matroka and the braincase and palate are narrower. Compared to N. somalica, the skull is broader. The ridge on the lacrimal bone is better developed, the palate is broader, the frontal bones contain a depression and are swollen at the sides, the mastoid bones are smaller, and the coronoid and angular processes of the mandible (lower jaw) are more prominent.