Theloderma woltersi, Ninh & & & & & Ziegler & Thomas, 2024

Theloderma woltersi , new species

( Figs. 2, 3)

Holotype. IEBR.A.5246 (Field number CB.010828), adult male, collected by T. T. Nguyen et al., in June 2019, in the forest near Phia Oac–Phia Den National Park, at an elevation of 1,900 m), Cao Bang Province, northern Vietnam.

Paratypes. Two adult males IEBR.A.5247, IEBR.A.5245 ( CB.010824, CB.010827) and one adult female IEBR.A.5244 ( CB.010826) specimen were collected in June 2019 by the same team and with the same data as the holotype .

Diagnosis. Morphologically, the new species from Cao Bang Province can be assigned to the genus Theloderma by a combination of the following characteristics: Small in size (SVL 25.1–26.2 mm in males, 30.3 mm in female), distinct

Theloderma woltersi , 0.00–0.26

new species

T. auratum 12.17– 0.00

12.28

T. bicolor 9.79– 10.28– 0.00

10.37 10.58

T. corticale 11.40– 11.32– 8.37–8.58 0.00–0.63

11.73 11.77

T. hekouense 4.19–5.25 8.76– 6.90–9.83 8.96– 0.16–0.66

10.94 11.14

T. khoii 11.11– 11.35– 3.66–3.68 9.17–9.24 7.05–9.84 0.00

11.20 11.44

T. lacustrinum 13.37– 14.67 11.50– 13.54– 10.58– 12.44– 0.00

13.58 11.87 13.56 13.73 12.53

T. lateriticum 13.46– 14.00– 12.30– 12.73– 10.29– 13.40– 8.74–9.82 0.52–3.92

14.21 15.06 13.39 13.92 14.10 13.58

T. leporosum 12.48– 11.97– 10.63– 11.13– 9.11– 10.88– 11.88– 11.93– 0.00

12.57 12.27 10.96 11.18 11.67 10.92 11.98 13.02

T. palliatum 11.63– 10.39– 10.91– 11.27– 8.21– 11.80– 13.22– 13.31– 11.83– 0.39

11.87 10.64 11.23 15.53 10.49 11.93 13.46 14.27 11.93

T. rhododiscus 3.90–4.44 11.71– 10.74– 10.53– 3.96–4.95 10.98– 12.92– 13.15– 11.77– 11.42– 0.91–2.08

12.76 11.50 11.39 11.38 13.45 13.68 12.50 12.16

T. truongsonense 13.74– 13.84 12.80 14.63– 10.47– 12.78– 14.78 14.93– 14.61– 14.38– 13.91–

13.81 14.84 13.16 12.88 17.32 14.69 14.65 14.70

R. calcaneus 13.64– 14.67 13.89– 13.92– 10.73– 14.36– 16.27 16.34– 15.44– 14.68– 12.94– 15.55

13.91 14.21 14.21 13.37 14.47 17.32 15.51 14.92 13.70

R. kio 14.95– 15.34 15.73– 16.58– 11.90– 15.54– 15.89 16.86– 15.34– 15.07– 14.14– 14.41 12.11 15.24 16.39 16.95 14.55 15.67 17.59 15.54 15.45 15.04

tympanum, round canthus rostralis, bony ridges from canthus rostralis to occiput lacking, and skin of head not co-ossified to the skull, tip of finger dilated into disc (see Liem, 1970; McLeod & Ahmad, 2007; Rowley et al., 2011; Hou et al., 2017). However, because morphological synapomorphies are lacking for the genus Theloderma , and thus its monophyly is not certain ( Bain et al., 2009; Li et al., 2009; Rowley et al., 2011) we additionally used molecular evidence to provide independent support for the species’ distinctiveness and its phylogenetic placement within Theloderma .

The new species is distinguished from its congeners and other larger rhacophorid species from Vietnam, south China, Northeast India, and mainland Southeast Asia by a combination of the following characters: 1) Size small (SVL 25.1–26.2 mm in males, 30.3 mm in female); 2) head longer than wide (HL/HW 1.15–1.18 in males and 1.09 in female); 3) vomerine teeth absent; 4) snout pointed and truncated (SL/SVL 0.15–0.18 in male; 0.14 in female); 5) eye large, without spines on upper eyelid; tympanum distinct, with distinct tympanic annulus; 6) tibiotarsal articulation reaches beyond tip of snout; 7) dorsal skin slightly rough with large irregular gland ridges and warts, ventral surface granular; 8) webbing between fingers weak (I1½–1½II¾–1¾III1¾–1¾IV), webbing between toes moderate (I½–1½II1¼–1¾III½–1¾IV¾–¾V); tips of all digits dilated but all considerably smaller than tympanum; 9) dorsal surface brown with dark spots; and 10) lateral and ventral body cream with blotches; and 11) large nuptial pads and an inner vocal sac in males.

Description of holotype. Adult male, small-sized (SVL 25.1 mm), body distinctly flattened, dorsoventrally compressed; head longer than wide (HL/HW 1.2); snout pointed and truncated, its length about 0.16 body length; canthus rostralis oval, very oblique, slightly concave loreal region; interorbital distance wider than internarial distance and upper eyelid (IOD/IN 1.2; IOD/UEW 1.1); distance between anterior corner of eyes about 0.6 distance between posterior corner of eyes; nostril oval, laterally directed, inside the rather enlarged tubercle on the tip of snout, nostrils closer to tip of the snout than to eyes (NS/EN 0.6); pupil circular; tympanum nearly two times the width of third finger disk (TYD/fd3 2.5), separated from eye by 0.3 of tympanum length (TYE/TYD 0.3); pineal ocellus absent; spinules on upper eyelid absent; supratympanic fold distinct but intermittent, extending from behind the eye to beyond level of the axilla, composed of large irregular gland ridges closely arranged; vomerine teeth absent; tongue large, almost covering half of mouth, heartshaped, dorsal surface smooth, bifid and free posteriorly; vocal sacs indistinct.

Forelimbs moderately strong and long, (FLL 4.9 mm, HAL 12.7 mm); relative length of fingers: I <II <IV <III; tips of fingers dilated into large, rounded and flattened disks, with grooves separating dorsum of disks from venter; disc of finger III approximately half of tympanum diameter (fd3/TYD 0.4); subarticular tubercles large and distinct, with indistinct supernumerary tubercles; subarticular tubercle formula: 1, 1, 2, 2; nuptial pad on lateral side of thumb well developed; outer side of fourth finger fringed and distinctly serrated; webbing between fingers weakly developed, about 50% between base and proximal subarticular tubercles, webbing formula I1½–1½II¾–1¾III1¾–1¾IV ( Fig. 4)

Hindlimbs strong and long, tibia length about five times greater than tibia width (TbL 14.0 mm, TbW 2.8 mm); tibia length about five times greater than tibia width (TbL/ TbW 5.0), longer than thigh length and shorter than foot length (TbL/FeL 1.1; TbL/FoL 0.8), tibiotarsal articulation reaching the posterior edge of snout when hindlimbs adpressed forward; relative length of toes I <II <V <III <IV; toes with rounded disks, tips of toes dilated into flattened disks with grooves that separate dorsum of disks from venter, smaller than the ones on fingers; webbing formula I½–1½II1¼–1¾III½–1¾IV¾–¾V ( Fig. 4); large

Distribution and conservation status. Theloderma woltersi , new species, is currently known only from the type locality in Phia Oac–Phia Den National Park, Cao Bang Province, northern Vietnam ( Fig. 6).

subarticular tubercles roundish: 1, 1, 2, 3, 2; large inner metatarsal tubercle oval and raised, without outer metatarsal tubercle; with small warts on the inner aspect of metatarsal area; the outer side of the fifth toe fringed, distinctly serrated.

Skin texture in life. Dorsal surface of head, dorsum, arms and legs generally smooth, but with some very small tubercles; outer side of limbs and flank with granules, throat and chest smooth, belly and ventral side of thighs slightly granular, supratympanic and dorsolateral folds absent.

Colouration in life. Background of dorsal surface reddishbrown with two to four small black blotches; flank displays well-defined cream and dark grey pattern; dorsal surface of the forelimbs with a black bar in the middle of the arm, fingertips brown, and the hindlimbs have a black bar at the middle of the thigh and a dark bar in the middle of the tibia; dorsal surface of hindlimbs light brown with black or dark grey blotches; belly and ventral surface of limbs cream with larger dark blotches forming a network; chin and throat dark brown with small white spots; tips of toes and fingers red-orange; loreal area dark grey without spots; supratympanic line reddish; iris red-orange; pupils black.

Colouration in preservative. The red-brown, red-orange, and reddish colour pattern in life fades into grey or greyish in preserved state.

Sexual dimorphism and variation. Males are smaller than females and can be further distinguished from females by the presence of nuptial pads.

Etymology. We dedicate the species name to the late Jürgen Wolters, founding member of Stiftung Artenschutz, which supports current conservation-based mossy frog research in Vietnam. Furthermore, Stiftung Artenschutz has been dedicated to supporting amphibian research through its specialised amphibian program for over 15 years.

Ecological notes. Theloderma woltersi , new species, was found in a water tank near a ranger station at an elevation of 1,900 m a.s.l. ( Fig.5).

Comparisons. We compare the new species with all species in the genus Theloderma in Vietnam and bordering countries.

Theloderma woltersi , new species, can be distinguished from T. bicolor , T. corticale , T. gordoni , T. ryabovi , and T. truongsonense by its small size (SVL 25.1–26.2 in males and 30.3 in female of Theloderma woltersi , new species, vs. SVL> 42–46.5 in males in T. bicolor ( Bourret, 1937) ; vs. 61.3–69.7 in males and 58–69 in females in T. corticale ( Boulenger, 1903; Luu et al., 2013; Hecht et al., 2013; Chen et al., 2018); vs. 57.5–70 in males and 71.7 in females in T. gordoni ( Taylor, 1962, Qi et al., 2018,), vs. 52.2–59.4 in males in T. khoii ( Ninh et al., 2022); vs. 43.84 in the male T. ryabovi ( Orlov et al., 2006) .

Theloderma woltersi , new species, can be distinguished from other species with similar sizes based on the following combination of morphological characteristics (see also Table 4):

Theloderma woltersi differs from T. albopunctatum by having a red-brown dorsum with some black blotches, ventral surface cream with larger dark blotches forming reticulation, iris red-orange vs. dorsum brown with some white markings, ventral surface greyish with white blotches, iris red-brown in T. albopunctatum ( Liu & Hu, 1962) ; from T. annae by having a red-brown dorsum with some black blotches, belly and ventral surface cream with larger dark blotches forming reticulation, iris red-orange vs. dorsal surface greyish green, with some mossy green, belly immaculate white, iris greyish green in T. annae ( Nguyen et al., 2016) ; from T. asperum by having a red-brown dorsum with some black blotches, belly and ventral surface cream with larger dark blotches forming reticulation, iris red-orange vs. dorsal surface of head and body bluish grey with a small brown line between eyes while the posterior part has a large chocolate area, venter blueish grey white and marbled black, brownish on the underside of arms and limbs, iris reddish brown in T. asperum ( Neang & Holden, 2008, Hecht et al., 2013, Luu et al., 2014,); from T. auratum by having a red-brown dorsum with some black blotches, belly and ventral surface cream with larger dark blotches forming reticulation, iris red-orange vs. dorsal surface golden-yellow with numerous tiny flat golden-orange tubercles, ventral surface greyish-blue with indistinct brown confluent blotches, getting smaller and denser anteriorly, forming a dense brownish pattern on throat, iris golden above and black below in T. auratum ( Poyarkov et al., 2018) ; from T. gordoni by having a red-brown dorsum with some black blotches, belly and ventral surface cream with larger dark blotches forming reticulation, iris red-orange vs. dark brown or coffee dorsum, ventral surface dark blue with numerous irregular greyish white patterns and speckles, iris pale bluish-white with irregular black patterns in T. gordoni ( Qi et al., 2018) ; from T. laeve by having head length longer than width, a red-brown dorsum with some black blotches, belly and ventral surface cream with larger dark blotches forming reticulation vs. head length as long as head width, a beige dorsum, ventral pure white in T. laeve ( Smith, 1924) ; from T. nebulosum by having a red-brown dorsum with some black blotches, belly and ventral surface cream with larger dark blotches forming reticulation, iris red-orange vs. brown dorsum with indistinct darker brown longitudinal markings running along the midline from the snout, ventral surface of body brownish black with pale bluish white marbling on chest, faint white speckling on throat, iris pale gold above and reddish brown below in T. nebulosum ( Rowley et al., 2011) ; from T. palliatum by having fingers webbed and a red-brown dorsum with some black blotches, ventral surface cream with larger dark blotches forming reticulation, iris red-orange vs. finger webbing absent, a pale brown dorsum with dark brown markings, ventral surface warm dark brown, iris pale gold in upper third, and dark reddish brown in lower two-thirds in T. palliatum ( Rowley et al., 2011; from T. petilum by having fingers webbed, a red-brown dorsum with some black blotches, belly and ventral surface cream with larger dark blotches forming reticulation vs. finger webbing absent, a light brown dorsum with dark brown reticulations and scattered black spotting, ventral creamy white in T. petilum ( Nguyen et al., 2014) ; from T. rhododiscus by having a mostly smooth red-brown dorsum with some black blotches, cream ventral with black blotches forming reticulation vs. dorsum tea-brown with numerous minute whitish granules arranged in a reticulation on the back, while the ventral surface has a dark grey or black background with white spots in T. rhododiscus ( Liu et al., 1962, Du et al., 2022) ( Fig. 7); from T. truongsonense by having fingers webbed, a red-brown dorsum with some black blotches, belly and ventral surface cream with larger dark blotches forming reticulation, iris red-orange vs. finger webbing absent, yellow-goldish dorsum separated from dark-grey ventral surface by a black stripe passing from the snout across eye and tympanum to anal region, iris golden yellow above and black below in T. truongsonense ( Orlov & Ho, 2005) ; from T. vietnamense by having a smooth reddish