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| Top: Tylototriton pasmansi sp. nov. (holotype); Center: Tylototriton pasmansi obsti ssp. nov. (holotype); Bottom: Tylototriton sparreboomi sp. nov.
Bernardes, Le, Nguyen, Pham, Pham, Nguyen, Rödder, Bonkowski & Ziegler, 2020
Photographs: C. T. Pham (upper row) and A. V. Pham (central and lower rows).
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Abstract
The Tylototriton asperrimus complex from northern Vietnam is reviewed based on morphological comparisons and analysis of the mitochondrial marker NADH dehydrogenase subunit 2 (ND2). Based on molecular divergences, which were revealed to be higher than in other congeners, in concert with morphological differences, two new species and one subspecies are described herein: Tylototriton pasmansi sp. nov. differs from T. asperrimus sensu stricto by 3.2 to 3.6 % genetic divergence and a combination of distinct morphological characters, such as head slightly longer than wide, distinct mid-dorsal ridge, relatively wide distance between the eyes, tips of fingers reaching the eye when foreleg is laid forward, labial and gular folds present, central belly skin with tubercles shaped like transverse wrinkles and distinct, pointy to round rib nodules. The population of T. pasmansi sp. nov. consists of two subclades, the nominotypic one occurring on the eastern side of the Da River (or Black River, including Hoa Binh and Phu Tho provinces), and another occurring on the western side (including Son La and Thanh Hoa provinces). These two subclades differ by 2.5 to 3.1 % genetic divergence and distinct morphological characters. The western subclade is herein described as Tylototriton pasmansi obsti ssp. nov., which differs from the nominotypic form by a wider head, longer and narrower snout, shorter femur length, and an overall less granulose skin, without an increased concentration of warts on the body sides.
A second new species, Tylototriton sparreboomi sp. nov. is described from Lai Chau Province. It differs from T. asperrimus sensu stricto by 4.1 to 4.2 % and from Tylototriton pasmansi sp. nov. by 3.6 to 4.5 % genetic divergences as well as by a combination of distinct morphological characters, such as head longer than wide, tips of fingers reaching nostril when foreleg adpressed along head, rib nodules distinct, round and relatively enlarged, and wide distance between the eyes.
Keywords: conservation, crocodile newts, cryptic diversity, new records, South East Asia
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| Figure 1. Current distribution map of the genus Tylototriton, from South and Central China, to northern Vietnam, Laos, Thailand, Myanmar, India, Bhutan and Nepal (Hernandez 2016; Qian et al. 2017; Grismer et al. 2018; Wang et al. 2018; Grismer et al. 2019; Hernandez et al. 2019; Zaw et al. 2019). In red the distribution areas belonging to the subgenus Tylototriton, and in blue the distribution areas belonging to the subgenus Yaotriton (Dubois and Raffaëlli 2009). The numerical identification corresponds to the different species and undescribed taxa as follow: 1 T. himalayanus 2 T. cf. himalayanus (Bhutan) 3 T. cf. verrucosus (Manipur) 4 T. kachinorum 5 T. verrucosus 6 T. ngarsuensis 7 T. shanorum 8 T. shanjing 9 T. pseudoverrucosus 10 T. taliangensis 11 T. kweichowensis 12 T. yangi 13 T. pulcherrimus 14 T. anguliceps 15 T. uyenoi 16 T. podichthys 17 T. panhai 18 T. notialis 19 Tylototriton taxon 2, this study 20 Tylototriton taxon 3, this study 21 T. ziegleri 22 T. vietnamensis 23 T. hainanensis 24 T. cf. hainanensis (Baise) 25 T. cf. wenxianensis (Libo) 26 T. cf. wenxianensis (Guizhou) 27 T. asperrimus 28 T. cf. asperrimus (Guangdong) 29 T. lizhengchangi 30 T. liuyangensis 31 T. broadoridgus 32 T. cf. wenxianensis (Chongquing and Hubei) 33 T. wenxianensis 34 T. dabienicus 35 T. anhuiensis and 36 T. panwaensis. |
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| Figure 2. Distribution map of the new populations of Tylototriton from North Vietnam, based on the following symbols: square (taxon 3, this study) the population from Sin Ho District, Lai Chau Province; diamond (taxon 1, this study) the upper one identifies the population from Van Ho District, Son La Province, and the lower one identifies the population from Thuong Xuan District, Thanh Hoa Province; triangle (taxon 2, this study) the upper one identifies the population from Tan Son District, Phu Tho Province, the middle one identifies the population from Da Bac District, Hoa Binh Province, and the lower one identifies the population from Lac Son District, Hoa Binh Province. The two populations identified by the circles represent T. asperrimus sensu stricto from China. |
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| Figure 9. Dorsal and ventral views of the new taxa in life. Top: Tylototriton pasmansi sp. nov. (holotype); Center: Tylototriton pasmansi obsti ssp. nov. (holotype); Bottom: Tylototriton sparreboomi sp. nov.
Photographs: C. T. Pham (upper row) and A. V. Pham (central and lower rows).
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Tylototriton pasmansi M. Bernardes, M. D. Le, T. Q. Nguyen, C. T. Pham, A. V. Pham, T.T. Nguyen & T. Ziegler, sp. nov.
Tylototriton taxon 2 (this study).
T. vietnamensis (referring to the population from Phu Tho Province): Nguyen et al. 2009, page 327.
T. asperrimus (referring to the population from Hoa Binh Province): Yuan et al. 2011, page 583; Nishikawa et al. 2013b, page 39; Luu et al. 2014, page 55.
T. cf. asperrimus (1) (referring to the population from Hoa Binh Province): Phimmachak et al. 2015a, page 293.
T. cf. asperrimus “Lao Cai/Hoa Binh” (referring to the populations from Lac Son, Hoa Binh): Hernandez 2016, page 254.
T. cf. asperrimus “northern Vietnam” (referring to the populations from Lai Chau, Lao Cai, Hoa Binh, and Phu Tho) Hernandez 2018, page 80.
Diagnosis: The new species is diagnosed by the following combination of characters: head slightly longer than wide; snout truncate in dorsal view and slightly angular in profile; relative wide distance between the eyes; distinct mid-dorsal ridge on head; tips of fingers reaching the eye when foreleg adpressed along head; labial and gular folds present; rib nodules distinct and varying from pointy to more rounded; glandular vertebral ridge high, slightly rough and segmented; dorsal skin more granulose than ventral skin; and skin in middle of abdomen with smooth tubercles shaped like transverse wrinkles.
Etymology: The species is named after Prof. Dr. Frank Pasmans, Ghent University (Belgium), who has made considerable and path-breaking contributions in the field of infectious diseases driven amphibian declines.
Distribution: Phu Canh Nature Reserve, Da Bac District and Thuong Tien Nature Reserve, Lac Son District in Hoa Binh Province, and Xuan Son National Park, Tan Son District, Phu Tho Province, Vietnam (Fig. 2).
Natural history: Based on remote sensing information the species is known from sites with an annual mean temperature of 20.4 to 20.7 °C, ranging from 11.5 to 26.3 °C during the year. Annual precipitation is about 1624 to 1884 mm ranging throughout the year from 7.3 to 379.8 mm. Further bioclimatic information is provided in Table 6.
Tylototriton pasmansi obsti M. Bernardes, M. D. Le, T. Q. Nguyen, C.T. Pham, A. V. Pham, T.T. Nguyen & T. Ziegler, ssp. nov.
Tylototriton taxon 1 (this study).
Diagnosis: The new subspecies is diagnosed from the nominotypic subspecies Tylototriton pasmansi pasmansi by the following combination of characters: a wider head (both as head width and maximum head width), versus narrower head; a longer and narrower snout, versus shorter and wider snout; a shorter femur and associated hind-limb lengths, versus longer femur and longer hind-limbs length; less overall concentration of warts and small granules on skin, versus overall skin more granulose; and skin on lateral body with apparently same concentration of warts than dorsal side, versus higher concentration of warts on ventral side of the body than on dorsum in T. p. pasmansi.
Etymology: The new subspecies is named after Prof. Fritz-Jürgen Obst, the former herpetologist and director of the Museum für Tierkunde Dresden, Germany, as well as passionate Tylototriton keeper, who passed away on the 10 June 2018.
Distribution: Xuan Nha Nature Reserve, Van Ho District, Son La Province and Xuan Lien Nature Reserve, Thuong Xuan District, Thanh Hoa Province, Vietnam (Fig. 2).
Natural history: Specimens were found between 14:00 and 16:00 h inside breeding ponds. The surrounding habitat was characterized by secondary forest of large, medium and small hardwoods mixed with shrubs and vines. Air temperature at the collection time was about 25 to 30 oC and relative humidity was about 75 to 80 %. Based on remote sensing information the species occurs at sites with an annual mean temperature of 19.9 to 20.4 °C, ranging from 11.7 to 27.1 °C during the year. Annual precipitation is about 1603.5 to 1648.3 mm with yearly variations from 4.3 to 373.0 mm monthly. Further bioclimatic information is provided in Table 6.
Tylototriton sparreboomi M. Bernardes, M. D. Le, T. Q. Nguyen, C. T. Pham, A. V. Pham, T.T. Nguyen & T. Ziegler, sp. nov.
Tylototriton taxon 3 (this study).
T. sp.: Laking et al. 2017, page 2.
T. verrucosus: Orlov et al. 2002, page 101; van Dijk et al. 2009, page 1; Nguyen et al. 2009, page 329.
T. cf. asperrimus “North Vietnam”: Hernandez 2018, page 80.
Diagnosis: The new species is distinguished from other species of the genus by the following combination of characters: head longer than wide; snout truncate in dorsal view; tips of fingers reaching nostril when foreleg is laid forward; skin tubercles on ventral side shaped like transverse wrinkles; rib nodules distinct and round; vertebral ridge segmented, high and relatively wide; relatively wide distance between the eyes; and gular and labial folds present.
Etymology: The specific epithet is dedicated to late Prof. Dr. Max Sparreboom, who has made great contributions to the understanding of Urodela.
Distribution: Known only from the type locality in Lai Chau Province, northern Vietnam (Fig. 2).
Natural history: Specimens were found in water between 9:00 and 16:30 h in ponds. The surrounding habitat was secondary forest of large, medium and small hardwoods mixed with shrubs and vines. Air temperature at the sites was 23 to 27 °C and relative humidity was 80 to 85%. Based on remote sensing information, the species occurs at sites with an annual mean temperature of 19.3 °C, ranging from 11.6 to 26.1 °C during the year. Annual precipitation is about 1843.7 mm with yearly variations from 9.6 to 421.6 mm. Further bioclimatic information is provided in Table 6.
Outlook:
This study increases the currently known number of Tylototriton species from northern Vietnam, from four (T. anguliceps, T. notialis, T. vietnamensis, and T. ziegleri) to six and one subspecies, by discovering T. sparreboomi, T. p. pasmansi and T. pasmansi obsti. It also further affirms that this region supports the highest diversity within this genus (Nishikawa et al. 2013b).
The taxonomic separation of a single widespread species into multiple small-ranged taxa in turn has important implications for the conservation status of the original species (Köhler et al. 2005; Stuart et al. 2006). We therefore recommend a re-assessment of the outdated Near Threatened status of T. asperrimus sensu lato (van Dijk et al. 2008) to reflect taxonomic revisions and increasingly severe threats from international trade and habitat loss, which have taken place over the last decade.
Marta Bernardes, Minh Duc Le, Truong Quang Nguyen, Cuong The Pham, Anh Van Pham, Tao Thien Nguyen, Dennis Rödder, Michael Bonkowski and Thomas Ziegler. 2020. Integrative Taxonomy reveals Three New Taxa within the Tylototriton asperrimus Complex (Caudata, Salamandridae) from Vietnam. ZooKeys. 935: 121-164. DOI: 10.3897/zookeys.935.37138
