Tylototriton soimalai, Pomchote & Peerachidacho & Khonsue & Sapewisut & Hernandez & Phalaraksh & Siriput & Nishikawa, 2024

Pomchote, Porrawee, Peerachidacho, Parada, Khonsue, Wichase, Sapewisut, Pitak, Hernandez, Axel, Phalaraksh, Chitchol, Siriput, Parunchai & Nishikawa, Kanto, 2024, The seventh species of the newt genus Tylototriton in Thailand: a new species (Urodela, Salamandridae) from Tak Province, northwestern Thailand, ZooKeys 1215, pp. 185-208 : 185-208

Tylototriton soimalai sp. nov.

Figs 2 , 5 , 6 , 7 , 8 (Thai name: Ka Tang Nam Doi Soi Malai) (English name: Doi Soi Malai Crocodile Newt )

Tylototriton uyenoi : Hernandez (2017): 110.

Type material.

Holotype • CUMZ -A-8253 , adult male, collected from Doi Soi Malai , Mae Tuen Wildlife Sanctuary, Tak Province, northwestern Thailand, at ca 1,500 m a. s. l., collected on the 31 August 2022 by Porrawee Pomchote and Pitak Sapewisut. Data regarding the specific location (geographical coordinates) of the new species cannot be publicly disclosed due to the need to prevent illegal hunting, which has been increasing dramatically in Thailand. However, the data are available to the editors or reviewers if necessary . Paratypes • CUMZ -A-8254 and CUMZ -A-8256 ; two adult males, same data as the holotype .

Etymology.

The specific epithet soimalai refers to Doi Soi Malai, Mae Tuen Wildlife Sanctuary, the type locality of the new species; it is a noun in apposition, thus invariable.

Diagnosis.

Tylototriton soimalai sp. nov. is assigned to the genus Tylototriton by having a combination of dorsal granules present, dorsolateral bony ridges on head present, knob-like warts or rib nodules on dorsolateral body present, and quadrate spine absent. Tylototriton soimalai sp. nov. is distinguished from its congeners by a combination of the following morphological characters: (1) medium-sized, adult SVL 66.3–66.5 mm in males; (2) skin rough with fine granules; (3) head longer than wide; (4) snout blunt or truncate in dorsal view, and extending beyond the lower jaw in lateral view; (5) sagittal ridge on head narrow, short, and distinct; (6) dorsolateral bony ridges on head pronounced, with rough surface, posterior ends weakly or hardly curved medially in dorsal view, and oriented rather parallel to the body axis in lateral view; (7) parotoids distinct, oriented rather parallel to the body axis and posterior ends slightly or hardly curved upwards in lateral view; (8) vertebral ridge prominent, wide, and not segmented; (9) rib nodules distinct, rounded, and isolated but posterior nodules connected, 14–16 along each side of body; (10) limbs long, tips of forelimbs and hind limbs overlapping when adpressed along body; (11) tail laterally compressed, lacking lateral grooves, and tip pointed; (12) background coloration black; (13) dorsal, ventral, and lateral of head, parotoids, vertebral ridge, rib nodules, limbs, vent region, and whole tail with orange markings.

Description of holotype.

Body slim and long (RTRL 80.0 %); skin rough; fine granules dense on dorsum, dense on both sides of body and tail, and sparse on ventral trunk; head longer than wide (HW / HL 0.8), hexagonal in shape, depressed, and slightly oblique in profile; snout truncate in dorsal view, projecting beyond lower jaw in lateral view; eyes protrude from dorsolateral portion of head in dorsal view, and upper eyelids prominent in lateral view; nostrils close to snout tip, visible from dorsal view; sagittal ridge on head narrow, short, and distinct; dorsolateral bony ridges on head pronounced, rough, and posterior ends weakly curved proximally in dorsal view; labial fold absent; tongue oval, attached to anterior floor of mouth, free laterally and posteriorly; vomerine tooth series in an inverted V-shape, converging anteriorly, and reaching choanae; parotoids distinct, projecting posteriorly, posterior ends hardly curved medially in dorsal view, oriented rather parallel to body axis and hardly curved upwards in lateral view; gular fold present; costal folds absent; vertebral ridge prominent, wide, and not segmented, separated from sagittal ridge on head; rib nodules distinct, rounded, forming knob-like warts, 14 on left side and 16 on right side of body from axilla to base of tail; rib nodules isolated but posterior nodules connected; rib nodules slightly increasing in size from most anterior to third nodule, then decreasing posteriorly; forelimbs (41.8 % SVL) longer than hind limbs (39.5 % SVL); tips of forelimb and hind limb overlapping when adpressed along body; fingers and toes well developed, free of webbing; fingers four, comparative finger lengths 3> 2> 1> 4; toes five, comparative toe lengths 3> 4> 2> 5> 1; tail laterally compressed, lacking lateral grooves, dorsal fin and ventral edge smooth, tip pointed; tail as long as body length (101.5 % SVL); cloaca slightly swollen; vent slit longitudinal.

Color of holotype.

In life, dorsal ground coloration is black, while the ventral color is dark grayish, paler than dorsum. Dorsal, ventral, and lateral of head, parotoids, vertebral ridge, rib nodules, limbs, vent region, and whole tail are orange. Tip of tail is slightly paler than dorsal and lateral sides of tail. Ventral side of head, part of pectoral and pubic region, limbs, and tail are paler than dorsum. The palest is the ventral edge of the tail. The paler region between the ventral edge of the tail and the area of the vent is connected. After preservation in ethanol for approximately one year, the background color is blackish brown, and the color markings are faded to pale orange.

Measurement of holotype

(in mm). SVL 66.5; HL 18.0; HW 14.3; MXHW 16.6; SL 6.3; LJL 16.2; ENL 4.0; IND 3.7; IOD 8.9; UEW 4.2; UEL 2.1; OL 2.5; AGD 38.1; TRL 53.3; TAL 67.5; VL 6.5; BTAW 9.4; MTAW 2.5; BTAH 7.9; MXTAH 10.3; MTAH 10.6; FLL 27.8; HLL 26.3; 2 FL 4.2; 3 FL 5.1; 3 TL 6.3; and 5 TL 2.9.

Variation.

All specimens generally exhibit a similar morphology and coloration; however, some differences were observed among the three specimens. The snout of the holotype is truncate, while those of two paratypes ( CUMZ -A-8254 and CUMZ -A-8256 ) are blunt. The sagittal ridge is most distinct in the holotype, followed by CUMZ -A-8256 and CUMZ -A-8254 , respectively. Dorsolateral bony ridges of the holotype and one paratype ( CUMZ -A-8254 ) weakly curve medially in dorsal view, in contrast to the other paratype where they hardly curve medially in dorsal view. The posterior ends of parotoids in two paratypes slightly curve upwards in lateral view compared to the holotype that hardly curve upwards in lateral view. Rib nodules of the holotype are 14 on the left side and 16 on the right side of the body from axilla to base of tail, while the two paratypes have 14 on left side and 15 on right side ( CUMZ -A-8254 ) or 15 on both left and right sides ( CUMZ -A-8256 ). One paratype ( CUMZ -A-8256 ) has five fingers on the left forelimb; moreover, all finger lengths on the left forelimb are short. The dorsal tail fin is smooth in the holotype, whereas in the other paratypes it is uneven with CUMZ -A-8256 exhibiting the most pronounced unevenness. The color marking on the dorsal side of the holotype is the palest compared to the two paratypes. The palest color marking on the ventral side of the head is clearly observed in one paratype ( CUMZ -A-8254 ) followed by CUMZ -A-8256 and the holotype, respectively. The part of the ventral trunk of two paratypes exhibits a pale color marking, whereas there is no pale color marking on the ventral trunk of the holotype.

Larva.

Two larvae one nearly double the size of the other (Fig. 2 ). Head large. Eyes well visible. Three pairs of external gills present. Body and tail laterally compressed. Skin smooth. Costal grooves of larger-sized larva rather distinct, but smaller-sized larva indistinct. Dorsal and ventral fins present. Background color of larger larva pale brown with scattered black pigments. Parts of lateral body, ventral fin, and around eyeballs silver-purple, while the smaller larva had a pale brown background with dense black pigments. Parts of lateral body, and around eyeballs silver-purple. External gills of both larvae red-brown.

Comparisons.

Tylototriton soimalai sp. nov. is a member of the subgenus Tylototriton based on the molecular phylogenetic analyses. The new species can be distinguished from the other members of the subgenus Tylototriton as follows: from T. anguliceps , T. phukhaensis , T. kachinorum , and T. shanorum by having a narrow, short, and distinct sagittal ridge (vs prominent in T. anguliceps , narrow, long, and distinct in T. phukhaensis , very weak and almost indistinct in T. kachinorum , and absent in T. shanorum ); from T. verrucosus and T. podichthys by having rough dorsolateral bony ridges (vs smooth in T. verrucosus and very rough in T. podichthys ); from T. zaimeng by having an inverted V-shape of the vomerine tooth series (vs a bell-shape in T. zaimeng ); from T. panwaensis by having a non-segmented vertebral ridge (vs weakly segmented in T. panwaensis ); from T. himalayanus by lacking grooves on either side at the base of tail (vs present in T. himalayanus ); from T. shanjing by having no sharp contrast between the orange crown of the head and black nape (vs sharp contrast in T. shanjing ); from T. yangi by having uniformly orange parotoids (vs black coloration except for posterior end of parotoids with orange coloration in T. yangi ); from T. kweichowensis by having isolated pale markings on rib nodules (vs connected markings forming continuous pale dorsolateral lines in T. kweichowensis ); from T. ngarsuensis by having orange markings on parotoids, vertebral ridge, rib nodules, and limbs (vs dark-brown, nearly black coloration in T. ngarsuensis ); from T. houi by having orange markings on the head, trunk, limbs, and tail (vs extensive orange-red markings in T. houi ); and from T. pulcherrimus by lacking pale spots located ventrolaterally and on flanks (vs present in T. pulcherrimus ).

Distribution.

Tylototriton soimalai sp. nov. is currently known from only Doi Soi Malai, Mae Tuen Wildlife Sanctuary, Tak Province, northwestern Thailand. However, Doi Soi Malai-Mai Klay Pen Hin National Park, which is contiguous to Mae Tuen Wildlife Sanctuary, is also expected to be a habitat for this species.

Natural history.

The new species were found during the midday, at ~ 12: 00 h when the adult males came up to the water surface, and the two larvae lived in a single isolated mud puddle situated along the road to the top of Doi Soi Malai during the rainy season, which is the breeding season of Tylototriton species. The puddle had turbid water and the bottom was deposited with muddy sediment. The surrounding area of the puddle consisted of evergreen hill forests. The puddle size was approximately 1,000 cm long, 500 cm wide, and 35 cm in maximum depth. No fish were observed.

Conservation recommendation.

The type locality of Tylototriton soimalai sp. nov. is a well-known destination for mountain biking and 4 × 4 road trips, particularly in the period following the late rainy season, starting from October onwards, when these activities extend to the summit of Doi Soi Malai. Although, the Department of National Parks, Wildlife and Plant Conservation (DNP) has imposed a ban on motor races in Thai NPs and WSs ( The Nation 2019), some mountain biking and 4 × 4 road trips continue to violate these regulations by entering the Mae Tuen Wildlife Sanctuary (Park rangers, personal communications), likely due to the paved road that runs through the sanctuary, providing easy access ( Pattanavibool and Dearden 2002). This could have adverse effects on the population of this new species, particularly during the larval stage, because the breeding site we found in this study is situated along the road leading to the summit of Doi Soi Malai. In nature, the breeding season of Thai Tylototriton species is around the end of April to August during the monsoon season ( Pomchote et al. 2008; Hernandez and Pomchote 2020 a, 2021). Aquatic larvae of Tylototriton inhabit the breeding water for several months and undergo complete metamorphosis before the efts start to move to land ( Hernandez 2016). Based on data from Thai Tylototriton species in their natural habitat, larvae were found in the water bodies from August to November in T. panhai ( Hernandez and Pomchote 2020 a) , from August to December in T. uyenoi ( Nishikawa et al. 2013 a; Pomchote, unpublished data), in December in T. verrucosus (Pomchote, unpublished data), and from December to March in T. anguliceps (Pomchote, unpublished data). Therefore, the breeding site should not be disturbed by any anthropogenic activities, especially road disturbances. We strongly recommend that the road to the summit of Doi Soi Malai be opened only after the breeding site has dried up, or alternatively, the road should be accessible during the winter and dry seasons, with walking to the peak as the preferred option.

Based on our multiple surveys conducted across various locations at Mae Tuen Wildlife Sanctuary in all seasons, we encountered only a few newts during the most recent survey at a single location on the 31 August 2022, suggesting that the population of the new species is small. Moreover, in addition to the road disturbances mentioned earlier, both the areas surrounding and within Mae Tuen Wildlife Sanctuary have been heavily impacted by habitat alteration and deforestation, leading to forest fragmentation, primarily due to agricultural activities, especially cabbage cultivation ( Pattanavibool and Dearden 2002). Due to the reasons mentioned above, we recommend that Tylototriton soimalai sp. nov. be listed as Endangered (EN) [IUCN Red List criteria B 1 ab (iii) + 2 ab (iii)] and, a conservation plan is urgently needed for this new species.

Figures

Figure 2. The two larvae of Tylototriton soimalai sp. nov. in life.

Figure 5. Three-dimensional model of the skull of Tylototriton soimalai sp. nov. (left), T. umphangensis (center), and T. uyenoi (right) based on micro-CT reconstruction. Top dorsal view Second from the top anterior view Second from the bottom posterior view Bottom anteriodorsal view. White arrows representing directions of posterior ends of dorsolateral bony ridges.

Figure 6. The male holotype of Tylototriton soimalai sp. nov. (CUMZ - A- 8253) before preservation A dorsal view B ventral view C dorsal head D ventral head E lateral head F dorsal right hand G ventral right hand H dorsal right foot I ventral right foot J cloacal area.

Figure 7. Holotype (CUMZ - A- 8253) and paratypes (CUMZ - A- 8254 and CUMZ - A- 8256) of Tylototriton soimalai sp. nov. before preservation A dorsal view B ventral view.

Figure 8. The male holotype of Tylototriton soimalai sp. nov. (CUMZ - A- 8253) observed at the type locality.