Kerivoula whiteheadi Thomas, 1894

Type locality: Molino, Isabela Province, Luzon.

Specimens examined. Philippine specimens examined are listed in Appendix A.

Distribution. Endemic to the Philippines (Bohol, Camguin Norte, Cebu, Lubang, Luzon, Mindanao, Mindoro, Palawan, Sicogon, Siquijor and Tumaguin; Fig. 2). The type locality “Molino” probably refers to a currently nonexistent village on the east bank of the Ilagan River downstream from the city of San Mariano (M. van Weerd, pers. com., 6 May 2019).

Description. Total length 67–86 mm, tail 29–41mm, ear 12–18 mm, forearm 29–33 mm, mass 2.5–5.5 g (Table 1). A clear north-south gradient in size exists from Camiguin Norte Island (north of Luzon, largest) to southern Mindanao (smallest; Tables 1 and 4). A small, delicate bat (Fig. 12A) with funnel-shaped ears, a long, slender tragus, and simple nostrils (Fig. 12C). The dorsal fur varies from dark brown (on Luzon) to reddish brown (on Mindanao), with the ventral fur somewhat paler (Fig. 12A, B). Each hair in the dorsal pelage has three bands (dark gray-brown base, light buff mid-band, and rufus-brown to bright rufus tips (Fig. 12D). The ventral hairs are also banded with a dark gray-brown base and light brown tips (Fig. 12E). The wing and tail membranes are dark. A scattering of a few short hairs is present along the posterior margin of the interfemoral membrane, but there is no definite fringe. Thick hair is present along the dorsal tail membrane, along the legs and on the feet (Fig. 12B).

Skull as shown in Figure 13. GTL12.16–14.60, CCL 11.08–13.66 mm, GBB 6.42–7.14 mm, BH 5.15–6.09 mm, PC 2.92–3.26, C–M 3 4.89–5.94 mm, M 2 –M 2ext 4.31–5.11 mm, C 1 –C 1 1.36–1.93 mm, C–M 3 5.23–6.32 mm, MDL 9.22–11.24 mm (Table 1). The skull of K. whiteheadi (Fig. 13) is small and the braincase is highly inflated, producing a pronounced forehead. The rostrum narrows anteriorly, and the upper toothrows converge moderately. The center of the dorsal surface of the rostrum often has a ventral depression along the midline, above the level of the molars. The cochlea are large, and the basioccipital region is narrow. The height of the second upper incisor is half or slightly more than half of the first incisor. The first and second upper premolars, and all three lower premolars, are of nearly equal crown area, and are strongly laterally compressed (Fig. 7C). The lingual shelves of M 1 and M 2 are relatively small, leaving a broad embrasure at their posterior margins. The first lower incisor usually has three cusps, the second has three cusps, and the third usually has three cusps but occasionally two; they overlap substantially (Fig. 7D).

Comparisons. Kerivoula whiteheadi differs from K. pellucida as noted above. Kerivoula whiteheadi and K. “ hardwickii A” are similar in size (average forearm length 31.1 and 33.0 mm, CCL 11.9 and 11.6 mm, respectively), but where they overlap geographically, K. hardwickii are slightly larger. K. whiteheadi is smaller overall than K. “ hardwickii B” (forearm length 35.0 mm, CCL 13.2 mm). The dorsal pelage of K. whiteheadi has a reddish tone (Fig. 12B, D), rather than medium or dark brown in the Philippine K. hardwickii . Both species have hairs that are dark at the base on the dorsum and venter with color bands—three dorsally and two ventrally (Fig. 12D, E). K. whiteheadi overall appears more bicolored than Philippine K. hardwickii with a rufus-brown dorsum and grayish-brown venter, whereas Philippine K. hardwickii appears brown overall (although there is some variation). A fringe of short, inconspicuous hairs along the posterior edge of the interfemoral membrane is present on Philippine K. hardwickii, but absent on K. whiteheadi (Fig. 12A). The wing attaches at a similar point below the outside toe of both species (Fig. 12A). The penis of male K. whiteheadi does not widen distally and lacks a characteristic nub that is present on the penis of males in Philippine K. hardwickii (J. Sedlock, pers. obs.). The skulls of K. whiteheadi usually have a more abrupt forehead than Philippine K. hardwickii . The latter often has a slight sagittal crest posterior to the interorbital region, a structure that is absent in K. whiteheadi (Figs. 8, 13). The depression along the midline of the rostrum in K. whiteheadi is absent in Philippine K. hardwickii . The teeth of Philippine K. hardwickii are proportionately substantially larger and more robust than those of K. whiteheadi (Fig. 10A, B). In Philippine K. hardwickii, the second upper incisor is about one-third the height of the second incisor; in K. whiteheadi, the second incisor is half or more the height of the first incisor (Figs. 7C, D, 10A, B). Finally, Philippine K. hardwickii lack the conspicuous lateral compression of the premolars present in K. whiteheadi .

Kerivoula whiteheadi differs from K. papillosa in being much smaller overall in size (mean total length 79.9 mm and forearm length 31.1 mm, rather than 101.6 mm and 42.5 mm, respectively, mean CCL 11.99 mm rather than 15.78 mm; Table 1, 3; Heaney et al. 2010; unpublished data). The dorsal pelage of K. whiteheadi has a reddish tone with a distinct banding patterns on hairs (Fig. 12), rather than medium or dark brown with no clear banding pattern (but darker at base). K. whiteheadi ’s skull is small and delicate lacking a sagittal crest (Fig. 13), rather than larger and more robust with a sagittal crest (Fig. 9). Premolars are elongate (Fig. 7C, D), rather than round (Fig. 10C, D).

Echolocation. The echolocation calls of K. whiteheadi in the Philippines are similar to those of K. pellucida in that they are broadband, high frequency, and short duration (Fig. 11; Table 5). Peak frequency of K. whiteheadi calls is 138 kHz. However, as stated above, K. whiteheadi calls are significantly shorter in duration and have a narrower bandwidth than those of K. pellucida (Table 5). There were no significant differences in call attributes among populations from Bohol, Cebu and Siquijor islands; however, we had sufficient recordings from only those three central Philippine islands and not from Luzon and Mindanao, which represent the largest and smallest individuals within the species, respectively.

Ecology. Kerivoula whiteheadi exhibits a broad tolerance of vegetation types and elevations in the Philippines, from highly disturbed and fragmented lowland forest near sea level, to pristine montane forest at 1465 m above sea level (Sedlock 2002; Sedlock et al. 2008, 2011, 2014; Heaney et al. 2016). It has also been reported in karst areas within disturbed forest on limestone in the central Philippines and on Palawan Island (Esselstyn et al. 2004; Sedlock et al. 2014). Pregnant females have been captured in April, June and August, suggesting an asynchronous reproductive period as in Kerivoula species in Peninsular Malaysia (Nurul-Ain et al. 2017). No reports of roosting behavior exist from the Philippines. The authors have observed its slow and maneuverable flight, and its keen ability to quickly find and retreat into hollows or holes when released within a flight tent or room. For example, one individual flew up the leg of a pair of pants hanging over a line within minutes of release. When perching on the net wall of the flight tent, K. whiteheadi curls up with its head upright rather than hanging down (Sedlock 2002).