Limnonectes nephophilus, Dehling & Neokleous & Das & Grafe & Min & Hertwig, 2025

Dehling, Maximilian, Neokleous, Dario N., Das, Indraneil, Grafe, Ulmar, Min, Pui Yong & Hertwig, Stefan T., 2025, Cryptic radiation within the tadpole-carrying Guardian Frogs from Borneo, Limnonectes palavanensis and L. finchi (Anura: Dicroglossidae), with the description of eight new species, Zootaxa 5650 (1), pp. 1-80 : 24-26

publication ID	https://doi.org/10.11646/zootaxa.5650.1.1
publication LSID	lsid:zoobank.org:pub:F8B8158B-26F9-4E1A-A1CF-A20A72F2D875
DOI	https://doi.org/10.5281/zenodo.15820489
persistent identifier	https://treatment.plazi.org/id/62199F50-FFF0-FFD4-FF34-FC09FCCAF87A
treatment provided by	Plazi
scientific name	Limnonectes nephophilus
status	sp. nov.

Treatment

Limnonectes nephophilus sp. nov.

Rana palavanensis (nec Rana palavanensis Boulenger, 1894 ): Inger 1985: 52 (partim).

Holotype. NMBE 1056394 View Materials , adult male, from Camp 3 (4.038079°, 114.888078°; 1,350 m), Gunung Mulu National Park, Sarawak, Malaysia, collected in March 2009 by J. M. Dehling, N. W. Tinggang, Y. M. Pui, S. T. Hertwig and A. Jankowski ( Fig. 3D View FIGURE 3 ).

Paratypes. BMNH 1978.214 – 215 , two adult males, collected on 7–8 September 1977 at the type locality by J. Dring ; BMNH 1978.1666 – 1667 , two adult females , BMNH 1978.1668 – 1669 , two juveniles, all from the type locality, collected in 1978 by J. Dring . NMBE 1065176–1065177 View Materials , two tadpoles, from Camp 4 (4.044178°, 114.913847°; 1,800 m), Gunung Mulu National Park , Sarawak, Malaysia , collected on 29 March 2007 by S. T. Hertwig and K. Lilje . NMBE 1061685 View Materials , adult female , NMBE 1061686 View Materials , adult male, collected on 24 February 2013 by S . T. Hertwig, A. Jankowski, Y. M. Pui ; NMBE 1073768 View Materials , adult male , NMBE 1073755 View Materials , adult female, collected on 6 March 2016 by J. Flury , A. Haas, S . T. Hertwig, Y. M. Pui and N. Reichen; all from Lepo Bunga (3.941808°, 115.544667°; 1,760 m), Gunung Murud , Pulong Tau National Park, Sarawak, Malaysia . NMBE 1061641–1061642 View Materials , two juveniles, collected on 29 February 2012 by S . T. Hertwig, A. Jankowski and Y. M. Pui ; NMBE 1073581 View Materials , adult male , NMBE 1073590 View Materials , adult female , NMBE 1073706 View Materials , 1073709 View Materials , two juveniles, collected on 9–12 March 2016 by J. Flury , A. Haas, S . T. Hertwig, Y. M. Pui and N. Reichen; all from Church Camp (3.926317°, 115.513889°; 2,100 m), Gunung Murud , Pulong Tau National Park, Sarawak, Malaysia . NMBE 1073578 View Materials , adult male, from Summit Trail (2,100 m), Church Camp, Gunung Murud , Pulong Tau National Park, Sarawak, Malaysia , collected on 10 March 2016 by J. Flury, A. Haas, S. T. Hertwig, Y. M. Pui and N. Reichen . NMBE 1073715 View Materials , unsexed adult, from Lepo Bunga (3.941808°, 115.544667°; 1,760 m), Gunung Murud , Pulong Tau National Park, Sarawak, Malaysia , collected on 7 March 2016 by J. Flury, A. Haas, S. T. Hertwig, Y. M. Pui and N. Reichen .

Referred material. BMNH 1978.216 , tadpole, from the type locality, collected on 8 September 1977 by Julian Dring .

Diagnosis. Limnonectes nephophilus sp. nov. belongs to the L. palavanensis species group, showing the typical characters of the group, including small size (SVL <40 mm); odontoid processes in lower jaw low and inconspicuous in both males and females; dorsum finely shagreened, with prominent longitudinal dorsolateral glandular ridges; interorbital distance equal to or larger than upper eyelid width; toes not fully webbed; and horseshoe-shaped dermal ridge in middle of dorsum posterior to arm insertion. The species differs from all other species of the group by a unique combination of morphological characters, including toe webbing very reduced; supratympanic fold subangular with anterior part shorter than posterior part; pineal spot distinctly discernible, slightly anterior to level of anterior upper-eyelid edge; vomer ridges short, widely separated from each other; median ridge low, indistinct, running from level of nostrils to level of pelvis; postpalpebral and lumbar ridges absent; size relatively large with SVL of adult males 26.1–31.9 mm, of adult females 33.1–37.6 mm. The species differs from all other species of the group by at least 5.7% in the sequence of the 16S barcoding gene. The advertisement call is a sharp chirp, 75–90 ms in duration at a dominant frequency of 2.5–3.0 kHz with a marked frequency modulation, given in call bouts of up to 21 calls with an intercall interval of 135–383 ms. The species occurs in montane rainforest between 1,200 and 2,100 m.

Description of holotype. Adult male; SVL 28.4 mm; body moderately sturdy, widest at temporal region, slightly tapering to groin ( Fig. 3D View FIGURE 3 ); head large (HL/SVL 0.37, HW/SVL 0.38), about as wide as long (HW/HL 1.03); snout moderately long (SL/HL 0.40), rounded in both dorsal view and profile, slightly projecting beyond lower jaw, wider than long (SL/EE 0.82); canthus rostralis distinct between eye and nostril, slightly concave; loreal region oblique, moderately concave; nostrils rounded, directed laterally, situated slightly closer to tip of snout than to eye (EN/NS 1.09), separated from each other by distance much larger than distance between eye and nostril (NN/EN 1.70); eye directed anterolaterally, moderately protruding, large (ED/HL 0.32), its diameter shorter than snout (ED/SL 0.80); interorbital distance greater than upper eyelid width (IO/EW 1.19) and smaller than internarial distance (IO/NN 0.69); pineal spot distinctly discernible, slightly anterior to level of anterior upper-eyelid edge; tympanum and its annulus distinctly visible, except posterior one-fourth which is covered by thick skin; tympanum separated from eye by little more than one-third of its diameter (ET/TD 0.37); tympanum diameter smaller than eye diameter (TD/ ED 0.61); upper jaw with dentition; odontoid processes in lower jaw low, inconspicuous; choanae small, rounded, located far anterolaterally at margins of roof of mouth, covered by palatal shelf of maxilla in ventral view; vomer processes bearing teeth, short, separated from each other and from choana by length of individual process ( Fig. 4D View FIGURE 4 ); tongue moderately long and narrow, bilobed for about one-sixth of its length, free distally for about half its length; median lingual process absent; vocal sac apertures slit-like, directed posterolaterally, situated closer to corner of mouth than to base of tongue.

Dorsal surfaces of head, trunk and limbs finely shagreened; lateral surfaces of trunk finely areolate with scattered small tubercles; dorsolateral ridge prominent, from posterior end of upper eyelid to groin; median ridge low, indistinct, running from level of nostrils to level of pelvis; postpalpebral and lumbar ridges absent; horseshoe-shaped dermal ridge low, in middle of back just behind level of arms; supratympanic fold thick and conspicuous, extending from posterior end of orbit to insertion of arm, subangular with anterior part shorter than posteroventrally directed posterior part ( Fig. 5D View FIGURE 5 ); row of small tubercles on lateral edge of upper eyelid, postaxial side of forearm, and lateral part of head; ventral side of head smooth with weak dermal folds parallel to posterior part of mandible; weak transverse chest fold between arm insertions; ventral side of trunk weakly areolate with sparsely scattered small tubercles; ventral side of limbs smooth; cloaca without dermal flap.

Forelimbs moderately sturdy; hand relatively small (HND/SVL 0.24); tips of fingers rounded, slightly enlarged into disks; relative length of fingers: II = IV <I <III; subarticular tubercles rounded, well developed, numbering one on Fingers I and II, two on Fingers III and IV, proximal tubercles on Fingers III and IV larger and more prominent than distal ones; finger webbing absent; thenar tubercle distinct, oval, flat, little more than one-third length of metacarpal of Finger I; inner palmar tubercle indistinct, small, rounded, flat, on proximal end of metacarpus of Fingers II and III; outer palmar tubercle indistinct, flat, elongated, on proximal half of metacarpal of Finger IV; nuptial pads absent.

Hindlimbs sturdy, very long (LEG /SVL 1.84); heel reaching to tip of snout when legs adpressed forwardly to body; tibiofibula long (TFL/SVL 0.57), slightly longer than thigh (TFL/THL 1.11); heels overlapping each other considerably when knees flexed and thighs held perpendicularly to median plane; foot slightly shorter than tibiofibula (FOT/TFL 0.93); relative length of toes: I <II <V <III <IV; toe tips rounded, slightly enlarged into disks; subarticular tubercles numbering one on Toes I and II, two on Toes III and V, and three on Toe IV; pedal webbing formula I 1.5/2.25 II 1.5/3- III 2.25/3.25 IV 3.25/2+ V ( Fig. 6 View FIGURE 6 ); dermal flap on postaxial side of Toe V, widest from proximal end of metacarpus to proximal subarticular tubercle, continued to disk; inner metatarsal tubercle very prominent, elongated, half as long as metatarsus of Toe I; outer metatarsal tubercle absent; low ridges of callous tissue from proximal plantar part of metatarsus to proximal subarticular tubercle on Toes I, II, and V.

Colouration. In life ( Fig. 7D View FIGURE 7 ), dorsum of holotype including lateral parts light brown with orange tinge; interorbital bar blackish brown; head anterior to interorbital bar as well as tympanic area bright orange; horseshoe-shaped tubercle slightly darker brown than dorsum and dark brown in the centre; two large black dots in longitudinal row at level of pelvis; area around cloaca dark brown; supratympanic fold dark grey; dorsolateral fold red in anterior part, lightening to orange posteriorly, bordered laterally by thin black line; tympanum light brown; side of snout light brown with larger dark brown spots and dark bar along canthus rostralis; arms orange, darkening to light brown towards hands; lower arm with dark brown crossbands; hands yellowish brown; legs reddish light brown with greyish light brown crossbands; tarsus and toes red; ventral side of head, chest, arms, lower legs and tarsus yellowish bright orange; large dark brown spots in infralabial region; throat speckled with minute brown dots; abdomen bright yellow, darkening laterally, with white speckling; thighs dark orange, darkening to reddish preaxially and postaxially; preaxial side of thighs with bluish white speckling; plantar side of feet blackish.

In preserved state ( Fig. 3D View FIGURE 3 ), dorsum creamish light brown; arms, fingers and toes as well as dorsal part of snout yellowish light brown; upper eyelids light blue; legs reddish light brown; upper arms without crossbands; lower arms, fingers, legs including feet with regular dark brown crossbands; interorbital bar blackish brown; supratympanic fold greyish brown; dorsolateral fold bordered laterally by thin black line; tympanum light brown; three large dark brown spots below eye and nostril on each side; horseshoe-shaped tubercle slightly darker brown than dorsum and dark brown in the centre; two large black dots in longitudinal row at level of pelvis; area around cloaca dark brown; ventral side of head, chest, arms and lower legs yellowish cream-white; large dark brown spots in infralabial region; throat speckled with minute brown dots; abdomen hardly pigmented, blueish white; thighs reddish cream-coloured.

Variation. The paratypes match the holotype in general appearance. SVL of adult males is 26.1–31.9 mm, of adult females 33.1–37.6 mm ( Table 2). Pedal webbing variation is I 1.5 [30],1.75 [40],2- [30] /2+ [20],2.25 [70],2.5 [10] II 1.5 /2.75 [10],3- [80],3 [10] III 2 [10],2+ [50],2.25 [40] /3.25 [80],3.5 [20] IV 3.25 [80],3.5 [20] /2 [20],2+ [80] V ( Fig. 6 View FIGURE 6 ) .

Bioacoustics. The description is based on calls recorded by Julian Dring at Camp 3, Gunung Mulu National Park, Sarawak, on 8 September 1977 at 1700 h. Both L. gunungensis sp. nov. and L. nephophilus sp. nov. have been collected at Camp 3 by Julian Dring. The two species differ markedly in the extent of webbing ( Fig. 6 View FIGURE 6 , Table 4). In an unpublished list provided together with recordings of the calls of some Southeast Asian frogs, J. Dring noted that the call was recorded from the “short-webbed form” of L. palavanensis , which we describe as L. nephophilus sp. nov. He did not collect a voucher specimen for the call, but stated that BMNH 1978.213 had the same call type. This specimen, a female, however, has extensive webbing and was referred by us to L. gunungensis sp. nov. We therefore tentatively assign the recorded call to the short-webbed L. nephophilus sp. nov. but point out that this assignment needs to be confirmed by future field work. The advertisement calls of males (n=3) are sharp chirps, 75–96 ms in duration, at a dominant frequency of 2.5–3.0 kHz, and with a marked frequency modulation ( Fig. 11D View FIGURE 11 ; Table 3). The calls are given in bouts of up to 21 calls, in which calls are separated from each other by an interval of 135–383 ms. A sound spectrogram and a waveform obtained from the same recording were depicted in Malkmus et al. (2002: 147; as L. palavanensis , the population herein described as L. kinabaluensis sp. nov., see above), erroneously stating that it had been recorded at an elevation of 150 m in Gunung Mulu National Park.

Distribution. The species has been recorded from montane rainforest at elevations between 1,200 and at least 2,100 m on Gunung Mulu and Gunung Murud in eastern Sarawak ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 ). The species occurs sympatrically with L. gunungensis sp. nov. in the area around Camp 3 on Gunung Mulu, Sarawak.

Ecology. We tentatively assign a tadpole (BMNH 1978.216) to this species, which according to the catalog entry had been collected “in a small silty pool, between rocks on a dry stream bed” at Camp 3 in Gunung Mulu National Park. The tadpole was included in the description of the tadpole of “ Rana palavanensis ” (sensu lato) by Inger (1985). Free-swimming tadpoles of this species in advanced stages were collected at Camp 3 (lot field number 367; A. Haas, pers. comm.) and Camp 4 (NMBE 1065176–1065177), Gunung Mulu National Park. Juveniles were observed in leaf litter away from any water body on the trail along the mountain ridge between Camps 3 and 4. The number and size of the ripe ova of the females indicate small clutch sizes. Other details of the reproduction of the species are unknown, but we expect it to reproduce in a similar way to the closely related species for which the reproduction mode is known.

Etymology. The species epithet is composed of the Ancient Greek noun νέφος [néphos], meaning cloud, and the Latinized suffix -philus (from Ancient Greek φιλεῖν [phileĩn], meaning “to love”); meaning “the one who loves clouds”, in allusion to the habitat of the new species in montane cloud forests of Gunung Mulu and Gunung Murud.

Suggested English name. Cloud-Forest Guardian Frog.