Rhinolophus arcuatus, Peters, 1871

Burgin, Connor, 2019, Rhinolophidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 280-332 : 319

82 .

Arcuate Horseshoe Bat

Rhinolophus arcuatus

French: Rhinolophe arqué / German: Bogen-Hufeisennase / Spanish: Herradura arqueado

Taxonomy. Rhinolophus arcuatus Peters, 1871 ,

“ Luzon ,” Philippines .

Rhinolophus arcuatus is included in the euryotis species group and appears to be paraphyletic with. inops and. subrufus . Rhinolophus arcuatus currently represents a species complex within the Philippines, where at least two morphs (large and small) are present that are commonly associated with distinct habitat types within a single island, although there are many divergent genetic lineages and a lot of morphological variation. Rhinolophus mcintyrei , R. belligerator , and. proconsulis were previously considered subspecies of A arcuatus , but genetic and morphometric data support their recognition as distinct species, with the restriction of true. arcuatus mainly to the Philippines; however, several populations were not covered in the study by L. E. Patrick and colleagues in 2013 that split these species; records from Sumatra, Wetar, Buru, and Ambon Islands are tentatively included in. arcuatus but probably either belong to. mcintyrei , R. belligerator , or. proconsulis , or represent a distinct species. There is another undescribed species morphologically similar to. arcuatus from the central highlands of Sulawesi, which is here included in the distribution of. arcuatus . Even within the Philippines, this species probably represents a species complex. Five subspecies tentatively recognized.

Subspecies and Distribution.

R .. arcuatus Peters, 1871 — N Philippines, including Palawan I.

R .. angustifolius Sanborn, 1939 — Wetar I.

R .. beccarii K. Andersen, 1907 — W Sumatra.

. a. exiguus K. Andersen, 1905 - S Philippines S to Tawi-Tawi Is.

R. a. toxopeusi Hinton, 1925 - Buru and Ambon Is.

An undescribed taxon (probably representing a separate species) occurs in the C highlands of Sulawesi.

Descriptive notes. Head—body c. 49-62 mm, tail 15—21 mm, ear 17- 2—22 mm, hindfoot 10—12 mm, forearm 40—50 mm; weight 6—9 g. There are at least two morphs throughout the Philippines: small morph, with mean forearm length of 45- 3 mm and a narrower noseleaf; and large morph, with mean forearm length of 46- 6 mm and a wider noseleaf. Dorsal pelage is slightly reddish brown or dark brown (hairs lighter at the base), whereas ventral pelage is buff to gray brown. Ears are moderately long. Noseleaf has straight-sided lancet with pointed tip; connecting process is arcuate, forming semicircle; sella is broadly ovate and wide basally, being slightly narrower than intemarial cup for much of its length before tapering slightly toward the rounded tip; horseshoe is relatively wide (7- 7—10 mm), nearly covers muzzle, and has slight median emargination. Lower lip has three mental grooves. Skull is relatively slender (zygomatic width either slightly larger than or subequal to mastoid width); braincase is elongate and slightly inflated; interorbital region is abruptly narrowed; anterior median swellings are well developed and circular in outline; posterior swellings are less pronounced but still defined; rostral profile is distinctly concave in lateral view; sagittal crest is moderately developed; frontal depression is variably shallow to deep; supraorbital crests vary from slightly to well developed; canines are relatively slender and slightly curved. P2 is small to medium-sized with well-developed cusp and completely within tooth row; P3 is either missing, or small when present, but is completely extruded from tooth row; P2 and P4 are variably touching or barely separated. Dental formula is the usual of 32 teeth for the genus, or only 30 teeth when a lower premolar is missing. Chromosomal complement has 2n = 58 and FN = 60 (large morph from Camarines Sur Province, Philippines).

Habitat. Found in a variety of habitats, including primary and secondary forests, such as montane and mossy forests on Luzon, being common in most lowland areas. Recorded from sea level up to 2500 m in the Philippines.

Food and Feeding. The Arcuate Horseshoe Bat feeds mainly on a variety of moths but also beetles, flies, other small insects, and spiders on occasion. It probably forages by both aerial-hawking and some gleaning, similarly to other horseshoe bats.

Breeding. Females give birth to a single young.

Activity patterns. Arcuate Horseshoe Bats roost in caves, crevices, rocky overhangs, and hollow trees during the day. Call shapes are FM/CF/FM, and peak F were reported at 69-8 kHz for the small morph but 66 kHz for the large morph; female calls were at slightly higher frequencies than males, within both morphs in the Philippines.

Movements, Home range and Social organization. The Arcuate Horseshoe Bat appears to roost in small colonies.

Status and Conservation. Classified as Least Concern on The IUCNed List. Although the Arcuate Horseshoe Bat is currently considered widespread, the taxonomy of most populations of this species is uncertain, and settling on a conservation status is not possible at this time. The species is widespread through the Philippines but may be threatened by cave disturbance for guano mining, and hunting and general habitat loss.

Bibliography. Csorba eta /. (2003), Esselstyn, Widmann & Heaney (2004), Flannery (1995a), Heaney, Balete, Dolar eta/. (1998), Heaney, Balete, Gee eta/. (2005), Heaney, Balete & Rickart (2016), Heaney, Gonzales eta/. (11991), Ingle & Heaney (1992), Lepiten (1995), Patrick eta /. (2013), Philip (2008), Rickart, Heaney eta /. (1993), Rickart, Mercier (1999), Rosell-Ambal, Tabaranza & Wright (2008), Sedlock eta/. (2008).

Figures

On following pages: 78. New Guinea Broad-eared Horseshoe Bat (Rhinolophus euryotis); 79. Sulawesi Broad-eared Horseshoe Bat (Rhinolophus tatah; 80. Poso Horseshoe Bat (Rhinolophus belligerator); 81. Bornean Woolly Horseshoe Bat (Rhinolophus proconsulis); 82. Arcuate Horseshoe Bat (Rhinolophus arcuatus); 83. Philippine Forest Horseshoe Bat (Rhinolophus inops); 84. Small Rufous Horseshoe Bat (Rhinolophus subrufus); 85. Large Rufous Horseshoe Bat (Rhinolophus rufus); 86. Intermediate Horseshoe Bat (Rhinolophus affinis); 87. Homfray's Horseshoe Bat (Rhinolophus andamanensis); 88. Croslet Horseshoe Bat (Rhinolophus coelophyllus); 89. Shamel's Horseshoe Bat (Rhinolophus shameli); 90. Vietnamese Brown Horseshoe Bat (Rhinolophus microglobosus); 91. Lesser Brown Horseshoe Bat (Rhinolophus stheno).

Subspecies and Distribution. R .. arcuatus Peters, 1871 — N Philippines , including Palawan I. R .. angustifolius Sanborn, 1939 — Wetar I. R .. beccarii K. Andersen, 1907 — W Sumatra. . a. exiguus K. Andersen, 1905 - S Philippines S to Tawi-Tawi Is. R. a. toxopeusi Hinton, 1925 - Buru and Ambon Is. An undescribed taxon (probably representing a separate species) occurs in the C highlands of Sulawesi.