Harpiola isodon

Saikia, Uttam, Ruedi, Manuel, Chakravarty, Rohit, Kamalakannan, Manokaran, Lyngdoh, Jennifer, Gautam, Amlanjyoti, Goswami, Rajib & Csorba, Gábor, 2025, A golden jewel: first report of golden-haired tube-nosed bat Harpiola isodon (Chiroptera: Vespertilionidae) from India, Zootaxa 5696 (2), pp. 269-278 : 271-275

Morphology

The small tube-nose bat V/M/ERS/785 had a forearm length of 36.4 mm. This adult female had a long, soft fur with dark brown roots and yellow-brown tips. A greyish, white-tipped fur prevailed on the chest. Hairs with shiny golden tips were scattered across the dorsal aspect, giving it a bright, shiny appearance under artificial light ( Fig. 1 ). The nostrils and most of the muzzle were dark, getting lighter towards the eyes. The nostrils projected sideways, but not to the extent as seen in Murina species. The ears were roughly triangular, especially the upper half, with a concave anterior border and convex posterior border ending in a somewhat pointed tip. However, when viewed from a lateral angle ( Fig. 1A ), the ears appeared narrow with straight borders and roundish tips. The tragus was broad at the base and gradually narrowed towards the tip with a not-so-pointed tip. The tragus reached about half the length of the pinna. The wing membrane was attached to the base of the toe, while the interfemoral membrane was attached to the base of the tibia. The wing membrane was mostly hairless on both sides, whereas the tail membrane was fully covered with hairs on the dorsal side and the proximal edge of the ventral side. The tail tip remained out of the interfemoral membrane for about 5.5 mm. The calcar extended to about one-third of the tail membrane and was without any lobe. The thumbs were relatively long with curved claws (in total 14.0 mm).

The skull was lightly built with a short and broad rostrum and a moderately ascending braincase. The rostrum had a deep and wide depression. In occlusal view, the braincase appeared bulbous. There was no trace of a sagittal crest, while the lamboid crest was appreciably developed. The zygomatic arches were slightly flared at the posterior end and had almost parallel sides converging with the maxilla. The narial emargination was deep and U-shaped. The dentition was characteristic with the incisors subequal in height and about three-fourths of the height of the canines. The canine was reduced in bulk, and the height of the cheek teeth decreased from the canine. The molars were without mesostyles, the first molar being the widest and the third highly reduced. The mandible had a high coronoid process, in contrast to the holotype of H. isodon and the examined specimens from Taiwan and mainland China ( Table 1 ), where the coronoid process was lower ( Kuo et al. 2006). Lower canine was bilobed and equal in height and basal area to the first and second premolars ( Fig. 2 ).

The male specimen of “ H. grisea ” at ZSIK matched perfectly well in all respects to our new specimen. Unfortunately, no DNA studies could be performed on this older specimen due to the method of preservation. The ZSIK specimen lost its original coloration due to a prolonged period of preservation under unfavorable conditions. However, it was clearly described as having clove brown hair roots with shiny golden hair tips on the back and silvery hairs with dark roots on the underpart ( Bhattacharyya 2002). The re-measured values of the cranium were also very close to those of the new specimen, except for the lower coronoid process in the latter, but comparable to other specimens from SE Asia and China ( Table 1 ). Most importantly, the structure of the cheekteeth of the ZSIK specimen conformed well to the type specimen of H. isodon , as against that of H. grisea ( Kuo et al. 2006) . Therefore, we re-identify this ZSKI specimen as belonging to H. isodon .

Molecular phylogenetics

We obtained 317 bp of the COI and 214 bp of the CytB genes of the female H. isodon from Mizoram. Compared to other sequences available in the GenBank, the COI sequence was the least divergent from H. isodon from mainland China and Vietnam (K2P distance 2.6 – 2.9%). In comparison, it differed by 5.3% from a specimen from the island of Taiwan. The pattern of divergence regarding the CytB gene was similar, with sequences from mainland China diverging by 1.9–2.9% from the Mizoram specimen, but more so from those from Taiwan (5.5%). These percentages of divergence are generally considered in the high end of intra-specific variation for mammals ( Bradley and Baker 2001), but still relatively modest according to the large geographic distance separating these samples.

Phylogenetic reconstructions based on K2P distances confirm the monophyly of H. isodon ( Fig. 3 ). Still, because the DNA fragments compared here are very small (about 300 bp each) and the taxon sampling is modest, these reconstructions must be considered as preliminary. In particular, relationships within the outgroups lack resolution (<70% bootstrap support) to be meaningful.

Echolocation calls

We recorded steep frequency-modulated, broadband calls of very short duration ( Fig. 4 ) that are typical of the subfamily Murininae . The call measurements based on 16 pulses were as follows (mean ± SD): SF = 131.71 ± 12.71 kHz; EF = 53.68 ± 4.16 kHz; PF = 87.06 ± 4.75 kHz; D = 3.43 ± 1.08 ms.

Natural history notes

The Mizoram specimen was caught at Hmuifang village situated at an elevation of 1690 m a.s.l. The area sits across a mountain ridge surrounded by tropical wet evergreen and semi-evergreen forest. The female specimen was captured in a two-bank harp-trap (Austbat, Australia) set across an enclosed forest opening of c. 3 m wide, which leads to contiguous forest across a hill slope. Although an acoustic lure was set near the trap, we could not determine if the lure attracted it as it was used intermittently. The earlier Mizoram specimen housed in ZSIK was collected in a mist net erected across a small pool with thick undergrowth at Sairep, a hilltop village surrounded by tropical evergreen forest. All previous records of this species and H. grisea as well are from mountainous forests between 1000 - 2463 m a.s.l. indicating that it is a highland forest species (Hutton 1872, Kuo et al. 2006, Kruskop et al. 2024, Li et al. 2024). In Vietnam, this bat was reportedly observed foraging over small forest streams with fast and manoeuvrable flight, and a lactating female was recorded in May ( Kruskop & Shchinov 2010). In our trapping location, we also noted a few fast-moving small bats effectively avoiding the harp trap. The two other species recorded during the same trapping session in this area were Rhinolophus lepidus /pusillus and Murina jaintiana .

Figures

FIGURE 1. Habitus (A and B), dorsal (C), and ventral (D) aspects of the adult female H. isodon (V/M/ERS/785) from Mizoram, India. Not to scale.

FIGURE 2. Lateral view of skull and mandible (A, E), dorsal view of skull (B, F), occlusal view of mandible (C, G), and ventral view of skull (D, H) of H. isodon (V/M/ERS/785; A-D) and ZSIK 25081 (E-H) from Mizoram, India.

FIGURE 3. Neighbour-joining trees based on pairwise K2P genetic distance measured for 214 bp of the CytB gene (left) or 317 bp of the COI gene (right). Numbers above nodes represent the percentage of bootstrap support above 70%. GenBank numbers associated with each reference sequence are also indicated. The new Mizoram specimen is part of the H. isodon clade. Murina spp. and Myotis spp. were considered as outgroups.

FIGURE 4. Spectrogram of H. isodon echolocation calls from Mizoram, India.

Tables

TABLE1. Comparative measurements of H. isodon from Mizoram, India and Southeast Asia. The acronyms of

Character	H. isodon (V/M/ ERS/785, ♀)	H. isodon (ZSIK 25081, ♂)	H. isodon from Taiwan and mainland China (n=13 except mentioned otherwise)
WT	8g
HB	39.1	42.7	-
TL	31.6	27.5	-
E	11.7	12.1	-
TR	5.8	6.0	-
FA	36.4	32.4	32.2 (31.6-35.6) (n=12)
TB	14.7	14.8	-
HF c.u.	9.4	8.2	-
3MT	34.7	31.5	-
4MT	33.7	30.0	-
5MT	34.6	29.7	-
1 PH 3MT	16.5	14.3	-
2 PH 3MT	12.6	10.4	-
GTL	15.20	15.60	15.64 (14.76-16.48)
CCL	14.84	13.90	13.95, 14.05 (n=2)
ZW	9.80	9.40	8.98 (8.43-9.35)
BW	8.00	7.90	7.82 (7.40-8.32)
PoC	5.08	4.72	4.71 (4.51-4.90)
MAW	8.22	7.93	7.66 (7.36-8.29)
SKH	6.90	6.56	6.29 (6.14-6.60)
CM 3	5.50	5.26	5.22 (4.97-5.63)
M 3 -M 3	5.34	5.44	5.18 (4.90-5.53)
C 1 -C 1	3.50	3.56	3.83 (3.65-4.13)
ML	11.29	10.03	10.72 (10.15-11.32)
CM 3 COH	6.00 4.52	5.56 3.89	5.54 (5.28-5.90) 3.62 (3.37-3.98)