Tylonycteris tonkinensis Tu, Csorba, Ruedi & Hassanin

Tu, Vuong Tan, Csorba, Gábor, Ruedi, Manuel, Furey, Neil M., Son, Nguyen Truong, Thong, Vu Dinh, Bonillo, Céline & Hassanin, Alexandre, 2017, Comparative phylogeography of bamboo bats of the genus Tylonycteris (Chiroptera, Vespertilionidae) in Southeast Asia, European Journal of Taxonomy 274 (274), pp. 1-38 : 13-16

Tylonycteris tonkinensis Tu, Csorba, Ruedi & Hassanin sp. nov.

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Fig. 5 B

Tylonycteris robustula Thomas, 1915 (partim): 227.

Tylonycteris robustula – Osgood 1932: 236. — Tate 1942: 268. — Hendrichsen et al. 2001: 90. — Kruskop 2013: 221. — Thomas et al. 2013: 229.

Etymology

The specific epithet refers to the current restricted occurrence of the new species in north-eastern Laos and northern Vietnam ( Fig. 1 ). The Vietnamese portion of this region was previously called “Tonkin” during the Nguyễn dynasty and French colonial era (from the 19th to the mid-20th centuries) to separate it from the country’s centre (Annam) and southern regions (Cochinchina). The proposed English name is “Tonkin’s greater bamboo bat” and the proposed Vietnamese name is ‘Dơi ống tre Bắc Bộ’.

Type material

Holotype

VIETNAM: ♂, Copia Nature Reserve , Co Ma commune, Thuan Chau District, Son La Province, 21°21.727′ N, 103°30.562′ E, 1286 m a.s.l., 9 May 2011, Vuong Tan Tu leg. ( IEBR-VN11-0055 ; field number Tu.090511.3; tissue code VN11-0055). Body in alcohol, skull removed. Mass: 4 g. Measurements (in mm): FA: 27.0; HB: 41.0; Tail: 33.0; Ear: 11.0; GLS: 12.60; CCL: 11.59; UCI: 1.98; CC: 4.06; M3M3: 5.46; IC: 3.97; MB: 7.42; BW: 7.07; CM3: 3.96; ML: 8.64; CM3: 4.22. Accession numbers of mitochondrial and nuclear sequences: KX496422–KX496429 .

Paratypes

LAOS: 3 adult ♂♂ ( MHNG 1926.059 , MNHN 2006-90 , MNHN 2006-93 ), 1 adult ♀ ( MHNG 1926.057 ), Hat Hin, Nam Sing River , Phongsaly Province, 21°40.14′ N, 102°13.26′ E, 2004, Manuel Ruedi leg., body in alcohol, skull removed.

VIETNAM: 1 ♂ ( IEBR-VN11-1804 ), Hang Kia, Pa Co Nature Reserve , Hoa Binh Province, 20°44.910′ N, 104°54.900′ E, 1080 m a.s.l., 2012, Vuong Tan Tu leg., body in alcohol, skull removed.

Accession numbers of DNA sequences for paratypes are given in Appendix 1.

Referred material

Specimens identified as T. robustula collected from Na Don, Phuong Vien, Cho Don (Bac Kan Province) and Na Hang Nature Reserve (Tuyen Quang Province) ( Appendix 1) are also referred to T. tonkinensis sp. nov.

Description

A member of the T. robustula species complex comprising representatives of the Tr3 haplogroup found in northern Indochina. Externally, individuals are small, with a forearm length of 25.1–27.8 mm ( Table 2 ). The head is dorsoventrally very flattened. Pelage coloration is relatively variable, more or less golden red at the base of the dorsal fur, to dark brown near the tips of the dorsal hairs, and lighter golden brown on the underparts ( Fig. 5 B). The ears have a triangular shape, with broadly rounded tips. The tragus is short and blunt. The wing membranes are dark brown. The base of thumbs and soles of hind feet have fleshy pads ( Fig. 5 B).

The skull is small (GLS: 11.91–12.60 mm), lightly built and very flat ( Fig. 5 B). The rostrum is short. The sagittal crest is absent. The lambdoid crests are well developed. The dental formula is I2/3 C1/1, P1/2, M3/3 = 32. The first upper incisor (I2) is bicuspidate, with small cusps on cingulum. I3 is unicuspidate, about half the height and crown area of I2. The upper canine has a posterior supplementary cusp. A diastema between I3 and the upper canine is clearly visible. The protocones of M1 and M2 are welldeveloped. M2 appreciably exceeds M1 in width, and its width clearly exceeds its length. M3 is relatively smaller and without a metastyle. The three lower incisors are tricuspidate. The first (PM 2) and second (PM4) premolars are approximately equal in height and crown area ( Fig. 5 B).

Remarks

In northern Indochina, T. tonkinensis sp. nov. can be distinguished from T. fulvida and T. pygmaea by its significantly larger body and skull size ( Table 2 ; Figs 4–5 ; see Feng et al. 2008 for comparisons with T. pygmaea ), by K2P distances of at least 12% for Cytb and COI sequences and by K2P distances of at least 1.5% for the concatenation of the seven nuclear genes (5604 nt) ( Appendix 5). Within the T. robustula complex, T. tonkinensis sp. nov. is morphologically overlapping with T. robustula , found in Sumatra, and T. malayana (= Tr2 haplogroup), collected from the Southeast Asian mainland, but differs from the first taxon by K2P distances of at least 5.2% in COI sequences ( Appendix 5) and from the latter by K2P distances of at least 5.5%, 8.6% and 0.4% calculated from COI sequences (657 nt), Cytb sequences (1140 nt) and the concatenation of seven nuclear DNA sequences (5604 nt), respectively ( Appendix 5).

Ecology and habitat

Like other species of Tylonycteris , T. tonkinensis sp. nov. is associated with woody bamboo groves. The new species is usually found in sympatry with the smaller species T. fulvida ( Fig. 1 ). In northwestern Vietnam, bats of the new species were captured in mist-nests set near bamboo groves in forest edges adjacent to rural-residential areas at relatively high elevations, e.g., at 1010 m a.s.l in Hang Kia, Pa Co Nature Reserve (Hoa Binh Province) or at 1286 m a.s.l in its type locality. In Laos, the known localities are found at lower elevations, between 500 and 800 m a.s.l.

Distribution

Currently, the new species is known to occur in north-eastern Laos and northern Vietnam only ( Fig. 1 ).

Figures

Fig. 1. A – B. Maps of Asia showing the distribution range (shaded) and type localities of described subspecies of T. pachypus (Temminck, 1840) and T. robustula Thomas, 1915 (Bates et al. 2008 a, 2008 b). C. Localities of Tylonycteris specimens included in this study. Triangles and circles refer to T. pachypus and T. robustula, respectively; the colours indicate the mtDNA haplogroups found in the Bayesian analyses of COI and Cytb sequences (see Fig. 2 for details).

Fig. 4. Scatter plots obtained from morphological analyses of Tylonycteris spp. A. Range of GLS measurements of specimens within each group of Tylonycteris spp. B. Range of PC * 1 scores of specimens of Tylonycteris spp. obtained from PCA of log-transformed raw data of craniodental measurements. C. Plot of PC 1 against PC 2 obtained from PCA on log-transformed standardized data. Triangles and circles refer to T. pachypus s. lat. and T. robustula s. lat., respectively. Colour patterns indicate the mtDNA haplogroups: green for Tp 3 and Tr 3 (northern Indochina); blue for Tp 2 and Tr 2 (other regions of the Southeast Asian mainland); red for Tp 1 and Tr 1 (Sundaland).

Fig. 5. Morphological characteristics of the two nominal species of the genus Tylonycteris Peters, 1872. A. T. pachypus (Temminck, 1840) (corrected taxon name is T. fulvida (Blyth, 1859 )), IEBR-VN 11 - 0 0 15. B. T. robustula Thomas, 1915 (corrected taxon name is T. tonkinensis Tu, Csorba, Ruedi & Hassanin sp. nov.), holotype, IEBR-VN 11 - 0055. Head profiles, ventral and dorsal views, fleshy pads at the base of the thumb and on the sole of the foot, and different views of the skull (dorsal, ventral and lateral). Scale = 10 mm.