Hypsugo dolichodon n. sp.

Figs. 1–5

Hypsugo CMF sp.A: Francis et al. 2010: 7

Holotype. ROM 110459 (collector number # 970505.05), immature female, in alcohol, skull removed. Collected by Charles M. Francis and Antonio Guillén on 5 May, 1997.

Type locality. 14°57’N, 107°08’E, Xe Kaman proposed dam site, 10 km east from Ban Paam, Attapu Province, Lao PDR, 150 m a.s.l.

Paratypes. ROM 110462 (# 970506.12), immature male, collected at the type locality on 6 May, 1997; ROM 110464 (# 970508.21), immature female, collected at 14°58’N 107°13’E, Attapu Province, Lao PDR, 150 m a.s.l. on 8 May, 1997. All bodies in alcohol, skulls removed.

Referred material. VIETNAM: ROM 110807, adult female, dry skin and skull, 11°25’N, 107°26’E Dong Nai, Cat Tien National Park, 100 m a.s.l.

Etymology. From the Greek words “dolichos” (= long, enlarged) and “oodontos” (= tooth) referring to the long upper canine of the new species which separates it from SE Asian congeners. The proposed English name is Long-toothed Pipistrelle.

Diagnosis. A medium-sized representative of Hypsugo (FA 35.2-38.4 mm, CCL 12.45-13.31 mm) with a relatively robust skull, almost flat cranial profile and well-developed upper canines which are almost twice as high as P4 (Fig. 1).

Description. Medium-sized Hypsugo (Table 1). The colour of the wings and other skin parts is nearly black. The ears are relatively short and wide, somewhat rounded with a short, squarish tragus (Fig. 2). The dorsal fur (based on colour photographs and the dry study skin of the ROM 110807 specimen) is blackish brown, with paler tips. On the ventrum the hairs have two bands of colour: the basal half is blackish brown and the distal half dirty white (Fig. 3). The Epiblema is very low and elongated, the calcar extends to half of the free edge of the uropatagium and is poorly developed.

The skull is rather large with a relatively robust, long and narrow rostrum (Fig. 1). The cranial profile is evenly ascending with no depression between the rostrum and the flattened braincase. The highest point of the skull is the posterior part of the braincase. The supraorbital tubercles are distinct. The zygoma has no dorsal eminences. The skull lacks a sagittal crest; the lambdoid crest is pronounced and reaches the posterior-most part of the lambdoid. The anterior palatal emargination posteriorly extends to the tip of P2; the posterior palatal emargination has a wide and strong palatal spike. The anteorbital foramen is large. The basioccipital pits are shallow, but visible. The auditory bullae are relatively large (Fig. 4).

The second upper incisor (I2) is clearly bifid. The cavity of I3 is directed labially. The I3 is shorter than I2, but its basal dimensions are larger. The I3 and C are not in contact. The upper canine is relatively slender; its height much exceeds that of P4. P2 is about 2/3 of the crown area of the I3, displaced lingually, and is visible between C and P4 when viewed from the labial side. P4 has a well-developed antero-lingual cingular cusp. In the lower dentition i1 and i2 present three lobes, whereas i3 possesses an additional fourth lobe on the lingual side. The lower molars are clearly myotodont (Fig. 5).

Comparisons. H. dolichodon n. sp. is distinguishable by the combination of the black or nearly black ear, muzzle and wings, relatively large P2 visible in lateral view, and shallow basioccipital pits from all other known Southeast Asian species of Hypsugo except H. pulveratus.

Although with overlapping values, H. dolichodon n.sp. is significantly (p<0.05) larger than H. pulveratus in the following measurements: FA, MAW, BCW, CM3L, ML and cm 3L. The epiblema of H. dolichodon n.sp. is narrow and elongated (vs. more definite in H. pulveratus). The rostral profile of the skull is almost flat (vs. with a distinctly elevated frontal region). Both upper and lower canines become narrow beyond the cingular ring and their height exceeds that of the corresponding second premolars (vs. relatively and absolutely shorter in H. pulveratus) (Figs. 1, 4).

Principal Component Analysis. In addition to the morphological comparisons and univariate statistical analyses, Principal Component Analysis (PCA) was used to compare H. pulveratus and H. dolichodon n. sp. The PCA results on 14 craniodental measurements showed good separation between the two species (Fig. 6, Table 2). PC1 is a size axis and PC2 indicates the wideness of the skull, with high loadings on IOW, BCW and MAW, indicating H. dolichodon n. sp. has a relatively wider braincase with greater interorbital width.

Genetic relationships. DNA barcodes for 4 specimens of H. dolichodon n. sp. from Lao PDR and Vietnam deposited in ROM, as well as 3 specimens from Vietnam which are deposited in ZMMU (these additional specimens were not examined as part of this study) were published by Francis et al. (2010) as “ Hypsugo CMF sp. A”. No intraspecific variation in the barcode was detected within the series, even from distinct localities, suggesting that all of these specimens represent the same species. The sequences differed by 12.4–14.0% (mean 13.7%) from the next nearest neighbour for which DNA barcodes were available, which was H. pulveratus. They diverged by 15.6 to 18.0% (mean 16.4%) from a series of H. cadornae. These levels of divergence clearly support the recognition of H. dolichodon n. sp. as a distinct species.

Distribution and ecological notes. The known distribution of this species is limited to Lao PDR and southern Vietnam. All of the Lao specimens were captured in mist nets near the Xe Kaman, a moderately large, fast-flowing river 50–100 m across, flowing through lowland evergreen rainforest in the Dong Amphan National Biodiversity Area. Two of them were caught in nets set perpendicular to the river, along its bank, and one was set across the mouth of a small tributary. All of the ROM and ZMMU Vietnamese specimens came from Cat Tien National Park. The ROM specimen was collected near the headquarters of the Park, close to the Dong Nai River. This area is generally described as lowland rain forest with dipterocarp trees (Scott 1989).