Limnonectes finchi ( Inger, 1966 )

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 : 39-41

publication ID	https://doi.org/10.11646/zootaxa.5650.1.1
publication LSID	lsid:zoobank.org:pub:F8B8158B-26F9-4E1A-A1CF-A20A72F2D875
persistent identifier	https://treatment.plazi.org/id/62199F50-FFC1-FFE5-FF34-FB40FD03F834
treatment provided by	Plazi
scientific name	Limnonectes finchi ( Inger, 1966 )
status

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Limnonectes finchi ( Inger, 1966) View in CoL

Rana microdisca (nec Boettger, 1892) — Boulenger 1920: 57 (partim).

Rana microdisca finchi — Inger 1966: 222; Inger et al. 1986: 523.

Rana finchi — Inger & Voris 1988: 1060; Inger & Stuebing 1992: 46 (partim).

Limnonectes finchi View in CoL — Inger et al. 2000: 16 (partim); Inger et al. 2017: 79 (partim).

Holotype. FMNH 77499 About FMNH , adult male, from Kalabakan , Tawau District, Sabah [ Malaysia], collected 28 June 1956 by R. F. Inger.

Paratypes. FMNH 63297 About FMNH , 63350 About FMNH , 76570 About FMNH , 76575–76576 About FMNH , 76579–76581 About FMNH , 76583–76588 About FMNH , 76592–76593 About FMNH , 76597– 76599 About FMNH , 76601 About FMNH , 76603–76504 About FMNH , 76626 About FMNH , 77497 About FMNH , eight unsexed juveniles, two subadult males, eight adult males, and six adult females , FMNH 77564 About FMNH , 18 About FMNH tadpoles, all collected by R. F. Inger at Deramakot in the Kinabatangan basin, at Kalabakan , and at the Sepilok Forest Reserve, North Borneo [Sabah, Malaysia] between 9 June 1950 and 28 June 1956. The paratype FMNH 76597 About FMNH (adult male, RFI field # 1277 from “ Deramakot, Kinabatangan District, N [orth]- Borneo ”) has been exchanged with the Naturhistorisches Museum Wien, Austria, in 1962 and is deposited under NMW 16961 View Materials ( Fig. 3I View FIGURE 3 ; Gemel et al. 2019) .

Referred specimens. NMBE 1072557 View Materials , adult male , NMBE 1072558 View Materials , adult female, from Tembaling Waterfall (4.941332°, 117.807974°; 265 m), Danum Valley Conservation Area , Sabah, Malaysia, collected in March 2015 by S. T. Hertwig et al .. NMBE 1072461 View Materials , adult male, from Sulphur Hot Spring (4.4155°, 117.9012; 360 m), Tawau Hills NP, Sabah, Malaysia, collected 14 March 2015 by S. T. Hertwig et al .. NMBE 1072364 View Materials , adult female, from Rhino Pool, Danum Valley Conservation Area , Sabah, Malaysia, collected 2 March 2015 by S. T. Hertwig et al .. NMBE 1072468–1072469 View Materials , two adult females, from Galas Waterfall (4.41569°, 117.889795°; 397 m), Tawau Hills NP, Sabah, Malaysia, collected 12 March 2015 by S. T. Hertwig et al .. NMBE 1072719 View Materials and 1072724, of undetermined sex, both from Tembaling Waterfall (4.941332°, 117.807974°; 265 m), Danum Valley Conservation Area , Sabah, Malaysia, collected on 28 February and 1 March 2015 , respectively, by J. Flury, A. Haas and S . T. Hertwig . NMBE 1064091 View Materials , of undetermined sex, from Sungai Tawau (4.461083°, 117.920764°; 828 m), Tawau Hills National Park , Sabah, Malaysia, collected on 11 August 2007 . NMBE 1072599 View Materials , of undetermined sex, from Headquarters of Danum Valley Conservation Area (159 m), Sabah, Malaysia, collected on 7 March 2015 by J. Flury, A. Haas and S . T. Hertwig .

Diagnosis. Limnonectes finchi belongs to the L. finchi species group, showing the typical characters of the group, including moderate size (SVL of males to 39.0 mm, of females to 45.6 mm); odontoid processes in lower jaw low and inconspicuous in both males and females; dorsum granular with interrupted, longitudinal dorsal rows of elongate tubercles; interorbital distance shorter than upper eyelid width; pineal spot distinctly visible; toes not fully webbed; and horseshoe-shaped dermal ridge in middle of dorsum posterior to arm insertion. The species shows a unique combination of morphological characters that distinguish it from the other species in the group, including dorsum with moderately amount of more or less densely scattered enlarged tubercles, cloaca without tubercles; skin on ventral side of head and chest hardly thickened; chest fold indistinct; loreal region oblique; pineal spot oval, at level with anterior eye edge; vomer processes bearing 7–9 teeth, almost in contact to each other medially, separated from each other by less than one-sixth length of individual process and from choana by about one-fourth length of individual process; hindlimbs long, tibiotarsal joint reaching well beyond snout; first finger relatively short, about as long as second and fourth fingers); low dermal fold present on postaxial side of Toe V. The species differs from the other species of the group by at least 4.4% in the sequence of the 16S barcoding gene. The advertisement call is a long rising trill, consisting of 31–34 notes, lasting 2.0– 2.2 s, at a dominant frequency of 0.8–1.1 kHz with a weak frequency modulation and an amplitude maximum at the end of the call.

Description of adult male (NMBE 1072461). SVL 31.6 mm; body sturdy, widest at level of arm insertion, markedly tapering to groin ( Fig. 3I View FIGURE 3 ); head large (HL/SVL 0.37, HW/SVL 0.37), as wide as long (HW/HL 1.00); snout moderately long (SL/HL 0.45), rounded in both dorsal view and profile, slightly projecting beyond lower jaw, as wide as long (SL/EE 1.01); canthus rostralis distinct between eye and nostril, straight-lined; loreal region oblique, moderately concave; nostrils rounded, directed dorsolaterally, situated closer to tip of snout than to eye (EN/NS 1.18), separated from each other by distance larger than distance between eye and nostril (NN/EN 1.27); eye directed anterolaterally, considerably protruding, large (ED/HL 0.35), its diameter shorter than snout (ED/SL 0.76); interorbital distance slightly smaller than upper eyelid width (IO/EW 0.96) and smaller than internarial distance (IO/NN 0.75); pineal spot distinctly visible, oval, at level of anterior eye edge; tympanum and its annulus distinctly visible; tympanum separated from eye by little more than one-third of its diameter (ET/TD 0.38); tympanum diameter smaller than eye diameter (TD/ED 0.68); upper jaw with dentition; odontoid processes in lower jaw low, inconspicuous; choanae small, subtrapezoid, located far anterolaterally at margins of roof of mouth, not covered by palatal shelf of maxilla in ventral view; vomer processes well developed, bearing teeth, large, almost in contact to each other medially, separated from each other by less than one-sixth length of individual process and from choana by about one-fourth length of individual process ( Fig. 4I View FIGURE 4 ); tongue comparatively short, bilobed for about one-fifth of its length, free distally for about two-thirds its length; median lingual process absent; vocal sac apertures very small and inconspicuous, short, at corner of mouth.

Dorsal surfaces of head, trunk and limbs rough, with scattered enlarged tubercles; tubercles in anterior half of dorsum more or less longitudinally enlarged, forming indistinct, interrupted ridges; tubercles in posterior part of dorsum rounded; inverted-v-shaped dermal ridge in middle of back just behind level of arms; dorsal surfaces of forearm, hand, tarsus and foot shagreened; lateral surfaces of trunk areolate with very few scattered small tubercles; thick dorsal skin of trunk ending abruptly at level of posterior end of upper eyelid, forming indistinct transverse dermal edge between eyes; dorsal and lateral faces of head finely granular; supratympanic fold thick and conspicuous, extending from posterior end of orbit to insertion of arm, curved; few enlarged tubercles on posterior part of upper eyelid; very conspicuous and large tubercle just posterior to mouth opening; skin on ventral side of head smooth with weak dermal folds parallel to posterior part of mandible; skin smooth on chest and abdomen; skin on ventral side of head and chest hardly thickened compared to skin on abdomen; transverse chest fold between arm insertions indistinct; ventral side of limbs smooth; cloaca without dermal flap and without tubercles.

Forelimbs moderately sturdy; hand relatively small (HND/SVL 0.26); tips of fingers rounded, swollen and enlarged into disks; disk on Finger IV slightly smaller than disk on other fingers; relative length of fingers: IV = II = 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 much larger and more prominent than distal ones; subarticular tubercle of Fingers I and II larger than proximal subarticular tubercles on Fingers III and IV; finger webbing absent; thenar tubercle distinct, oval, flat, about one-third length of metacarpal of Finger I; inner palmar tubercle small, rounded, flat, on proximal end of metacarpus of Fingers II and III; outer palmar tubercle about as long as inner palmar tubercle but more distinct, on proximal third of metacarpal of Finger IV, fused with inner palmar at proximal base, about half size of thenar tubercle; nuptial pads absent.

Hindlimbs sturdy, very long (LEG /SVL 1.86); heel reaching about one SL beyond tip of snout when legs adpressed forwardly to body; tibiofibula long (TFL/SVL 0.60), 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 0.91); 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+/2+ II 1+/2.25 III 1.25/3 IV 3+/1.25 V ( Fig. 6 View FIGURE 6 ); weak dermal fold on postaxial side of Toe V from proximal end of metacarpus to disk; inner metatarsal tubercle prominent, elongated, half as long as metatarsus of Toe I; outer metatarsal tubercle absent.

Colouration. In life ( Fig. 12 View FIGURE 12 ), dorsum medium olive-greenish brown; larger tubercles on dorsum light to reddish brown; interorbital bar dark brown with narrow light brown anterior edge, continued onto posterior part of upper eyelids; dorsal face of head anterior to interorbital bar light olive-greenish brown with dark brown speckling; pineal spot whitish; sides of head to tympanic area with alternate bands of dark olive-greenish brown and greenish white bands; tympanum covered with dark brown spot; supratympanic fold reddish brown; flanks light greenish grey; arms brown-greenish grey with small light reddish brown tubercles; fingers light grey with dark grey blotches; legs greenish light brown with mid-brown crossbars and small, light reddish brown tubercles; crossbars narrower and more frequent on thigh than on crus; toes reddish crème-coloured; webbing dark olive green; ventral side of head, arms, and legs off-white; dark brown spots along mandibular edge; throat mottled dark brown. In preserved state, dorsum dark greyish brown; dorsal pattern elements dark brown ( Fig. 3I View FIGURE 3 ); limbs including fingers and toes somewhat lighter brown; reddish life colouration faded to light brown; ventral side light grey.

Variation. The examined specimens match the paratype as well as the original description of the type series of L. finchi by Inger (1966). SVL of adult males is 31.6–39.7 mm, of adult females 36.3–45.8 mm ( Table 2; see also Inger & Voris 1988). Pedal webbing variation is I 1 [29],1+ [71] /1.75 [14],2 [57],2+ [29] II 1+/2 [14],2+ [86] III 1+ [29],1.25 [57],1.5 [14] /3- [57],3 [43] IV 3- [43],3 [43],3+ [14] /1+ [29],1.25 [28],1.5 [43] V ( Fig. 6 View FIGURE 6 ).

Bioacoustics. Two advertisement calls from a single uncollected male were recorded in Danum Valley, Sabah. The advertisement call is a long series of 31–34 notes with a total duration of 2.0– 2.2 s ( Fig. 11A View FIGURE 11 ; Table 3). It is emitted after irregular intervals of several seconds. Note duration regularly increases from 31 ms in the first note of the call to 34 ms in the last note. Internote interval increases from 29 ms between the first two notes to 47 ms between the last two notes of a call. As a consequence, note repetition rate decreases from 16.6 notes/s between the first two notes to 12.4 notes/s between the last two notes of the call. Amplitude is strongly modulated and exhibits a regular increase from the beginning to the end of the call ( Fig. 11A View FIGURE 11 ). Three prominent frequency bands are visible with prevalent bandwidth between 500 and 1500 Hz. There is a more or less regular frequency increase between individual notes from the beginning to the end of the call and another one within each note. In the third note of the call, the fundamental increases from 559 Hz to 602 Hz, the dominant frequency from 818 Hz to 861 Hz, and the third harmonic from 1,162 Hz to 1,248 Hz; in the last note of the call the fundamental increases from 559 Hz to 732 Hz, the dominant frequency from 861 Hz to 1,076 Hz, and the third harmonic from 1162 Hz to 1,421 Hz ( Fig. 11A View FIGURE 11 ).

Distribution. Northeastern Borneo between sea level and around 1,100 m ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 ).

Ecology. The holotype was observed carrying tadpoles at the edge of a rain pool on a road through a logged area ( Inger 1966). 18 tadpoles were collected and the total number of tadpoles was estimated to be twice that number ( Inger 1966). Eggs are deposited in moist leaf litter on the underside of dead leaves and are guarded by the male ( Inger et al. 1986, Inger & Voris 1988). After hatching, the tadpoles crawl onto the male’s back and are then transported ( Fig. 10G View FIGURE 10 ) to a pond or other small water body in which they develop until metamorphosis ( Inger & Voris 1988). Tadpoles are found in pools of rain water on the forest floor ( Inger 1985). Tadpoles of the species were briefly described by Inger (1966) and in detail by Inger (1985).

Etymology. The species epithet is a patronym honouring O. C. Finch “for much assistance and pleasant companionship” to R. F. Inger in the field ( Inger 1966).

Suggested English name. Rough Guardian Frog.