Tylototriton guilinensis sp. nov.

Figs 5 ‒ 7

Holotype.

GXNU YU 001042, adult male collected on 16 July 2025 by Wei Xiao and Xinbin Chen from Tianhu Lake, Quanzhou County, Guilin City, Guangxi Zhuang Autonomous Region, China (26°06'34.22"N, 110°53'56.69"E, 1789 m elevation).

Paratypes.

Three adult males (GXNU YU 000981, GXNU YU 000982, and GXNU YU 000983) and one adult female (GXNU YU 000984) collected by Wei Xiao, Xiangjian Wu, Yuanqiang Pan, and Xinbin Chen on 10 May 2025 from the type locality; and one adult male (GXNU YU 001043) collected on 16 July 2025 by Wei Xiao and Xinbin Chen from the type locality.

Etymology.

The new species is named after its type locality, Guilin City in the Guangxi Zhuang Autonomous Region. We propose the Chinese name as “ 桂林疣螈 ” (Guì Lín Yóu Yuán) and the English common name as “ Guilin Crocodile Newt. ”

Diagnosis.

Tylototriton guilinensis sp. nov. can be distinguished from all other congeners by the following combination of morphological characteristics: (1) medium body size (117.9 ± 9.5 mm); (2) rib nodules flatten, indistinct, not separated, and almost in continuous longitudinal rows forming a dorsolateral fold; (3) orange coloration of the rib nodules absent; (4) orange markings on the parotoid absent; (5) head wider (HDW) than long (HDL) (HDL / HDW = 0.92‒0.99); (6) finger tips extending beyond the snout when forelimbs stretched forward; (7) tips of forelimbs and hindlimbs reaching and overlapping when folded towards the body; (8) snout truncate, nearly square shaped in dorsal view; (9) gular fold present; (10) adult males possessing cloacal papillae within the fissure; (11) peripheral area of cloaca orange; and (12) the orange coloration at the ventral edge of tail contacted with the orange coloration around the cloaca.

Description of holotype.

Adult male with medium size. Total length (TOL) 131.0 mm, snout-vent length (SVL) 67.8 mm, tail length (TAL) 72.2 mm; head wider than long (HDL / HDW = 0.96); snout truncate, nearly square-shaped in dorsal view, snout length exceeding eye diameter; projecting beyond lower jaw in lateral profile (Fig. 5); eyes relatively large (3.0 mm), laterally positioned but visible dorsally; eyelids nearly circular; gape straight, extending posteriorly beyond posterior eyelid margin; maxillary and premaxillary teeth present; vomerine teeth arranged in a continuous inverted V-shaped ridge between nostrils, extending to level of posterior orbital margin; tongue elliptical, attached anteriorly with free lateral margins; cranial ridges prominent, forming a nearly Π-shaped longitudinal ridge from snout tip to occiput with smooth margins; gular fold distinct; skin texture rough, densely covered with small granules on head dorsum, dorsal trunk, lateral flanks, and tail; dorsolateral warts flattened, inconspicuous, non-discrete, forming an almost continuous ridge; labial margins, digit tips, ventral surfaces of limbs, and ventral tail margin smooth. Limbs relatively slender; limb tips overlapping when adpressed to body; fingertips extending beyond snout when forelimbs adpressed anteriorly. Forelimbs with four fingers, relative length III> II> IV> I; hindlimbs with five toes, relative length III> IV> II> V> I; all digits slightly depressed, tips bluntly rounded, lacking webbing; tail height exceeding tail base width; dorsal tail fin thick and short; ventral tail fin slender, originating at tail base and not connecting to posterior margin of cloacal slit; cloacal region smooth; vent a longitudinal slit; distinctive orange pigmentation present on digit tips, pericloacal area, and ventral tail margin, forming a continuous stripe connecting cloacal and tail regions.

Coloration of holotype in life.

Dorsal skin pale orange; ventral skin black; the parotoid gland region is pale orange; the ventrolateral edge of the tail, the extremities of the limbs, and the area surrounding the cloaca are orange-red (Fig. 5).

Coloration of holotype in preservative (75 % ethanol).

Dorsal skin black; ventral skin is tan; the parotoid gland region is black; the ventrolateral edge of the tail, the extremities of the limbs, and the area surrounding the cloaca are pale yellow (Fig. 6).

Secondary sexual characteristics.

Adult males have papillae within the cloacal slit, whereas adult females exhibit a relatively smooth cloacal slit.

Morphological variation.

Three paratypes (GXNU YU 000983, GXNU YU 000984, and GXNU YU 001043) exhibit a vermilion spot on the palmar region at the base of the fourth finger (Fig. 7 D ‒ I). Paratype GXNU YU 000983 exhibits a vermilion pigmentation on the dorsal tail tip (Fig. 7 J). Four paratypes (GXNU YU 000982, GXNU YU 000983, GXNU YU 000984, GXNU YU 001043) possess horn-like projections on the parotoid glands (Fig. 7 A ‒ C).

Ecology, habitat, and distribution.

Tylototriton guilinensis sp. nov. was discovered in a roadside pond and adjacent marsh wetlands at Tianhu Lake, Quanzhou County, Guangxi Zhuang Autonomous Region, China (Fig. 8). This species is currently known only from the type locality. During the survey in May 2025, coinciding with the breeding season, aggregations of individuals were observed in marshes and ponds after 19: 30, though no eggs or larvae were detected. Sympatric species observed during the surveys include Hynobius maoershanensis, Quasipaa boulengeri, Hoplobatrachus chinensis, Protobothrops jerdonii, and Azemiops feae. The newt primarily inhabits evergreen broadleaf forests and marsh wetlands at elevations of 1,600 –1,800 m. Breeding habitats are aquatic, comprising two types: ponds and marsh wetlands. Dominant vegetation in breeding areas consists of evergreen broadleaf canopy and wetland herbaceous plants. The microenvironment is characterized by dense canopy cover, high humidity, and a thick humus layer (Fig. 8).

Comparisons.

The new species belongs to the T. asperrimus species group (Fig. 3). It can be distinguished from members of the T. taliangensis group (T. taliangensis and T. pseudoverrucosus) by body relatively robust, TAL / SVL <120 % in adult males (vs. body slender, TAL distinctly larger than SVL, TAL / SVL> 125 % in adult males), and from members of the T. verrucosus group (T. kweichowensis, T. himalayanus Khatiwada, Wang, Ghimire, Vasudevan, Paudel & Jiang, 2015, T. kachinorum Zaw, Lay, Pawangkhanant, Gorin & Poyarkov, 2019, T. shanorum, T. ngarsuensis, T. yangi, T. anguliceps Le, Nguyen, Nishikawa, Nguyen, Pham, Matsui, Bernardes & Nguyen, 2015, T. phukhaensis Pomchote, Khonsue, Thammachoti, Hernandez, Peerachidacho, Suwannapoom, Onishi & Nishikawa, 2020, T. uyenoi, T. panwaensis, T. podichthys Phimmachak, Aowphol & Stuart, 2015, T. pulcherrimus, T. shanjing, T. verrucosus) by tail with different colorations, the ventral tail ridge with orange margin (vs. tail with uniform coloration, orange or light brown, much brighter and lighter than the ground coloration of body).

Within the T. asperrimus species group, the new species is closely related to T. gaowangjienensis and T. dabienicus. The new species can be distinguished from T. gaowangjienensis by head wider (HDW / TOL 0.128 ± 0.0080) than long (HDL / TOL 0.122 ± 0.0060) (vs. head longer [HDL / TOL 0.142 ± 0.0131] than wide [HDW / TOL 0.111 ± 0.0041]), longer SVL (SVL / TOL 0.544 ± 0.0335 vs. 0.498 ± 0.0332), wider HDW (HDW / TOL 0.128 ± 0.006 vs. 0.111 ± 0.0041), taller TH (0.068 ± 0.0062 vs. 0.057 ± 0.0026), and longer HL (0.115 ± 0.0071 vs. 0.054 ± 0.0140); from T. dabienicus by head wider (HDW / TOL 0.128 ± 0.008) than long (HDL / TOL 0.122 ± 0.0060) (vs. head longer [HDL / TOL 0.138 ± 0.0085] than wide [HDW / TOL 0.104 ± 0.0085]), finger tips extending beyond the snout when forelimbs stretched forward (vs. finger tips reaching the anterior corner of the eye), tips of forelimbs and hindlimbs overlapping when folded towards the body (vs. tips of fingers and toes do not meet or just meet when limbs are adpressed to the body), longer SVL (SVL / TOL 0.544 ± 0.0335 vs. 0.479 ± 0.0184), wider HDW (HDW / TOL 0.128 ± 0.0080 vs. 0.104 ± 0.0085), taller TH (0.068 ± 0.0062 vs. 0.054 ± 0.0042), and longer HL (0.115 ± 0.0071 vs. 0.066 ± 0.0057).

The new species differs from T. asperrimus, which was also recorded from northeastern Guangxi (Fig. 1), by rib nodules flatten, indistinct, not separated, and almost in continuous longitudinal rows forming a dorsolateral fold distinguishes (vs. rib nodules swollen, distinct, clearly separated or slightly contacted at the base) and finger tips extending beyond snout when forelimbs stretched forward (vs. reaching nostril).

The new species differs from T. daloushanensis, T. sini, T. liuyangensis, and T. joe by snout truncate, nearly square shaped in dorsal view (vs. bluntly rounded in T. daloushanensis and T. liuyangensis; nearly rounded hexagonal in dorsal view, depressed, gently sloping in profile in T. sini; and rounded in T. joe); from T. anhuiensis, T. daloushanensis, T. koliaensis, T. maolanensis, T. lizhenchangi, T. sini, T. broadoridgus, T. liuyangensis, T. tongziensis and T. wenxianensis by head wider than long (vs. longer than wide in T. anhuiensis, T. daloushanensis, T. maolanensis, T. lizhenchangi, and T. sini, head nearly as wide as long in T. broadoridgus, T. koliaensis, T. liuyangensis and T. wenxianensis); from T. hainanensis, T. lizhenchangi, T. ziegleri, and T. joe by rib nodules flatten, indistinct, not separated, and almost in continuous longitudinal rows forming a dorsolateral fold distinguishes (vs. rib nodules swollen, distinct, clearly separated or slightly contacted at the base); from T. hainanensis, T. daloushanensis, and T. liuyangensis by finger tips extending beyond snout when forelimbs stretched forward (vs. reaching eye in T. hainanensis, reaching the midpoint between eye and nostril in T. daloushanensis, reaching orbital region in T. liuyangensis, and reaching nostril in T. asperrimus); from T. sini and T. ziegleri by absence of orange coloration of the rib nodules (vs. rib nodules orange); from T. wenxianensis by peripheral area of cloaca orange (vs. peripheral area of cloaca brownish black); and from T. wufengensis by relative fingers length III> II> IV> I and relative toes length III> IV> II> V> I (vs. relative fingers length III> II> I> IV and relative toes length III> IV> II> I> V; Suppl. material 2).