Limnonectes suboliferus, 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 : 37-39

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.15820507
persistent identifier	https://treatment.plazi.org/id/62199F50-FFC3-FFEB-FF34-FDE4FCF3FC60
treatment provided by	Plazi
scientific name	Limnonectes suboliferus
status	sp. nov.

Treatment

Limnonectes suboliferus sp. nov.

Rana palavanensis (nec Rana palavanensis Boulenger, 1894 )— Boulenger 1920: 59 (partim); van Kampen 1923: 182 (partim). Rana microdisca palavanensis (nec Rana palavanensis Boulenger, 1894 ): Inger 1966: 222 (partim).

Limnonectes palavanensis View in CoL (nec Rana palavanensis Boulenger, 1894 )— Das et al. 2008: 152; Inger et al. 2017: 87 (partim).

Holotype. NMBE 1059945 View Materials , adult female, from the “Frog Pond” (1.606397°, 110.188612°; 295 m), Kubah National Park , Matang Range, Sarawak, East Malaysia (Borneo), collected on 24 September 2009 by J. M. Dehling and D. M. Dehling ( Fig. 3H View FIGURE 3 ).

Paratypes. NMBE 1056615 View Materials , adult male from the type locality, collected on 9 April 2009 by J. M. Dehling . NMBE 1059943 View Materials , 1059944 View Materials , 1059946 View Materials , 1059947 View Materials , four adult males; same collection details as holotype . NMBE 1065317–1065318 View Materials , two adults of undetermined sex, from Kampung Sebako (1.736725°, 109.737347; 20 m), at the foot of Gunung Pueh, Sarawak, Malaysia, collected on 16 August 2011 by A. Haas, Y. M. Pui and R. Sujang . NMBE 1057078 View Materials , from stream behind frog pond (326 m), Kubah National Park , Sarawak, Malaysia, collected on 17 August 2010 by A. Haas and S . T. Hertwig . NMBE 1063852 View Materials , from Matang , Sarawak, Malaysia, collected on 9 March 2005 by I. Das, N. Yaakob and J. Sukumaran . NMBE 1063936 View Materials from Matang Wildlife Centre (1.6094°, 110.1601°; 15 m), Kubah National Park, Sarawak, Malaysia, collected on 4 August 2006 by I. Das, G . V. A. Gee and A. Haas . NMBE 1064798 View Materials , tadpole, from Kubah National Park , Sarawak, Malaysia, collected on 4 August 2006 by I. Das, G . V. A. Gee and A. Haas . NMBE 1064829 View Materials , tadpole, from Kubah National Park (310 m), Sarawak, Malaysia, collected on 27 August 2006 by I. Das and A. Haas . NMBE 1064849 View Materials , tadpole, from Kubah National Park (310 m), collected on 3 March 2007 by I. Das, A. Haas and T. Riehl . NMBE 1068207 View Materials , NMBE 1068211 View Materials , two adults of undetermined sex, from stream behind frog pond (326 m), Kubah National Park , collected on 10 August 2012 by A. Haas and J. Hofmann . NMBE 1068312 View Materials , adult of undetermined sex from Kubah National Park (295 m), collected on 4 September 2009 by H. Dobbeck and F. Meyer . NMBE 1069798 View Materials , tadpole, from Kubah National Park (310 m), collected on 7 September 2009 by I. Das, A. Haas and A. Jankowski . NMBE 1069822 View Materials , tadpole, from Kubah National Park , collected on 17 August 2010 by A. Haas and S . T. Hertwig . NMBE 1101222 View Materials , adult male, from Viewpoint Trail (1.695378°, 109.844108°; 144 m), collected on 17 March 2019 ; NMBE 1101223–1101225 View Materials , three adult males, from Summit Trail (1.713522°, 109.836314°; 419 m), collected on 19 February 2019; all from Gunung Gading National Park, Sarawak, Malaysia, collected by L. Etter, S . T. Hertwig and F. Heussler .

Diagnosis. Limnonectes suboliferus 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 toes very extensively webbed; supratympanic fold curved; pineal spot usually well discernible, rarely indistinct, slightly in front of anterior upper-eyelid edge; vomer ridges long, widely separated from each other; postpalpebral ridge weakly developed, inconspicuous; lumbar and median ridges low and inconspicuous; ventral side of snout with evenly scattered, tiny, glandular pits in males; size relatively small with SVL of adult males 25.8–31.2 mm, of adult female holotype 35.5 mm. The species differs from all other species of the group by at least 6.2% in the sequence of the 16S barcoding gene. The advertisement call is a brief chirp, 132–231 ms in duration at a dominant frequency of 1.6–2.0 kHz with marked frequency modulation, given in bouts of up to 11 calls. The species occurs in lowland rainforest below 400 m.

Description of holotype. Adult female; SVL 35.5 mm; body moderately sturdy, widest at temporal region, slightly tapering to groin ( Fig. 3H View FIGURE 3 ); head large (HL/SVL 0.39, HW/SVL 0.36), slightly longer than wide (HW/HL 0.93); snout moderately long (SL/HL 0.42), subacuminate in dorsal view, slightly protruding in lateral profile, slightly wider than long (SL/EE 0.94); canthus rostralis distinct between eye and nostril, almost straight-lined in dorsal view; loreal region oblique; nostrils oval, directed laterally; situated closer to tip of snout than to eye (EN/ NS 1.27), separated from each other by distance larger than distance between eye and nostril (NN/EN 1.24); eye directed anterolaterally, moderately protruding, moderately large (ED/HL 0.31), its diameter shorter than snout (ED/ SL 0.75); interorbital distance greater than upper eyelid width (IO/EW 1.23) and smaller than internarial distance (IO/NN 0.76); pineal spot weakly discernible, slightly in front of level of anterior upper-eyelid edge; tympanum and its annulus distinctly and fully visible, not covered by supratympanic fold, its posterior edge concealed by thickened skin; tympanum separated from eye by one-third its diameter (ET/TD 0.33); tympanum diameter smaller than eye diameter (TD/ED 0.58); upper jaw with dentition; odontoid processes in lower jaw low, inconspicuous; choanae small, rounded, located anterolaterally at margins of roof of mouth, not covered by palatal shelf of maxilla in ventral view; vomer processes bearing teeth, long, separated from each other and from choana by distance about two-thirds of length of individual process ( Fig. 4H 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.

Dorsal surfaces of head, trunk and limbs and lateral surfaces of trunk finely shagreened; small tubercles sparsely scattered medially of supratympanic fold and around upper eyelid; low horseshoe-shaped dermal ridge in middle of back just behind level of arms; dorsolateral ridge prominent, from posterior end of upper eyelid to groin; postpalpebral ridge weakly developed, inconspicuous, narrow and low from upper eyelid to just behind level of horseshoe-shaped ridge; lumbar ridge low, narrow and inconspicuous from horseshoe-shaped ridge almost to vent, interrupted above pelvis; median ridge inconspicuous, narrow and low from level of posterior upper-eyelid edge to vent; supratympanic fold thick and conspicuous, extending from posterior end of orbit to insertion of arm, curved ( Fig. 5H View FIGURE 5 ); ventral side of head smooth; indistinct transverse chest fold between arm insertions; ventral side of trunk weakly areolate; 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: I = II = IV <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, prominent, about one-third length of metacarpal of Finger I; inner and outer palmar tubercles fused proximally, forming large, roughly U-shaped, prominent tubercle on proximal half of Fingers II–IV.

Hindlimbs sturdy, very long (LEG /SVL 1.96); heel reaching about one SL beyond tip of snout when legs adpressed forwardly to body; tibiofibula long (TFL/SVL 0.64), longer than thigh (TFL/THL 1.17); heels overlapping each other considerably when knees flexed and thighs held perpendicularly to median plane; foot shorter than tibiofibula (FOT/TFL 0.87); relative length of toes: I <II <V <III <IV; toe tips rounded, 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-/1.75 II 1/2 III 1/2+ IV 2+/1 V ( Fig. 6 View FIGURE 6 ); narrow dermal ridge on preaxial side of Toe I and on postaxial side of Toe V from proximal end of metacarpus to disk; inner metatarsal tubercle prominent, elongated, about two-fifths length of metatarsus of Toe I; outer metatarsal tubercle absent.

Colouration. In life ( Fig. 7H View FIGURE 7 ), dorsum mid-brown, darkening to dark brown between interorbital bar and horseshoe-shaped tubercle; horseshoe-shaped tubercle blackish brown with light brown fringe posteriorly; dorsolateral fold marked by narrow red line, bordered medially with narrow light brown band and laterally with wide black band; interorbital bar wide, black with narrow white anterior edge, and light brown posterior edge, continued onto posterior part of upper eyelids; dorsal face of head anterior to interorbital bar light brown with orange tinge and central black spot around orange pineal spot; sides of head dark brown with large black supralabial flecks; tympanic area yellow with small red dots anteriorly; supratympanic fold dark brown; flanks light brown with large black sports surrounded by light brown narrow fringe; light bluish dots speckled on ventral part of flanks; arms orange brown with small red dots and few large, black spots, widened to crossbars on lower arm and fingers; legs greyish mid-brown with blackish brown crossbars; crossbars more frequent on thigh and tarsus than on crus; toes proximally reddish brown, distally red; ventral side of head, arms, and legs dark yellow; dark brown spots along mandibular edge; chest and abdomen bright yellow; greyish brown speckling along postaxial side of lower arm and tarsus, and on preaxial and postaxial sides of thigh and crus; palmar side of hand and plantar side of foot dark brown.

In preserved state, dorsum of holotype light brown overall; dorsolateral ridge greyish light brown; horseshoe-shaped tubercle, interorbital bar and crossbands on arms and fingers dark brown; crossbars on legs mid-brown, almost faded on tarsus; upper eyelids with bluish tinge ( Fig. 3H View FIGURE 3 ); ventral side of head, arms and legs pale yellow; spots on mandibular edge light brown; chest and abdomen off-white with bluish tinge; palmar side of hand and plantar side of feet light brown.

Variation. The paratypes match the holotype in general appearance and proportions. Males lack nuptial pads and have weak dermal folds parallel to posterior part of mandible and several evenly scattered, tiny, glandular pits on ventral side of head. The vocal sac aperture is slit-like, directed posterolaterally, situated at corner of mouth. The pineal spot is well discernible in most paratypes. SVL of adult males is 25.8–31.2 mm ( Table 2). Pedal webbing variation of paratypes is I 1- [73],1 [27] /2- [82],2 [18] II 1 [91],1+ [9] /2 III 1 [82],1+ [18] IV 2 [9],2+ [82],2.25 [9] /2 [9],2+ [55],2.25 [27], 2,5 [9] /1 [55],1+ [45] V ( Fig. 6 View FIGURE 6 ) .

Bioacoustics. Advertisement calls of males (n=3: NMBE 1059943, 1059946, and an uncollected male) are brief chirps, 132–231 ms in duration, emitted in bouts of up to 12 calls, in which individual calls are separated from each other by intervals of 311–903 ms ( Fig. 11F View FIGURE 11 ; Table 3). The dominant frequency is at 1.6–2.0 kHz with a marked frequency modulation ( Fig. 11F View FIGURE 11 ).

Distribution. The species is distributed in lowland rainforest in western Sarawak (Kubah National Park, Gunung Gading National Park, Gunung Pueh; Fig. 8 View FIGURE 8 ) between 15 and 330 m ( Fig. 9 View FIGURE 9 ).

Ecology. We observed calling males and gravid females in distances of between 10 and 20 m from a permanent pond in secondary ridge-top kerangas forest in Kubah National Park. Adult males were also recorded calling, and observed guarding an egg clutch and carrying tadpoles ( Fig. 10C&D View FIGURE 10 ) in flat riverine forest in the same area.

Etymology. The species epithet is composed of the Latin noun suboles, meaning “offspring”, and the Latin suffix -ferus (from ferre = “to carry”), meaning “the one who carries”; and means “the one that carries the offspring”, in allusion to the males of the species carrying their tadpoles.

Suggested English name. Western Guardian Frog.