Bioacoustics of Kalophrynus calciphilus

Diagnosis. The species is allocated to Kalophrynus for showing the following characters considered diagnostic for the genus ( Parker 1934 , Inger 1966 ): One or more transverse folds across the palate in front of the oesophagus; finger and toe tips not dilated; no spine-like projections at heel or elbow; snout short, less than twice the eye diameter; inner metatarsal tubercle low, not shovel-like; tympanum visible; skin thick and glandular. The new species is distinguishable from its congeners by the combination of the following characters: (1) SVL of adult males 29.7– 30.1 mm , adult females 35.5–38.8 mm ; (2) snout obtusely pointed in dorsal outline; (3) tympanum diameter slightly larger than half the eye diameter; (4) upper jaw with weak dentition; (5) fore limbs slender; (6) Finger IV shorter than Fingers I and II; (7) subarticular tubercles prominent, numbering one on Fingers I, II, and IV, and two on Finger III; (8) one smaller, supernumerary metacarpal tubercle present between each finger and palmar tubercle; (9) nuptial pads or asperities absent; (10) heel reaching to posterior margin of eye when legs are adpressed to body; (11) foot shorter than tibiofibula; (12) Toe III longer than Toe V; (13) toes webbed, formula being I 1 –2.5 II 2 - – 3+ III 2– 4 IV 4– 1 V ; (14) subarticular tubercles on Toes I–IV prominent; (15) inner and outer metatarsal tubercle prominent; (16) dorsum and flanks black in life; (17) white dorsolateral line running on both sides of body; (18) chin and chest black, abdomen and proximal third of thigh grey in life; (19) iris red to reddish-orange in life; (20) advertisement call a single note, consisting of 7 pulses and lasting 161 ms on average, with dominant frequency at 2250–2650 Hz.

Description of holotype . Adult male; habitus stout; body widest at lumbar region; head short (HL/SVL 0.30), wider than long (HL/HW 0.85); snout obtusely pointed in dorsal outline, pointed in profile, projecting considerably beyond lower jaw; canthus rostralis distinct, straight in profile, slightly concave in dorsal view; loreal region vertical; nostrils directed dorsolaterally, situated in low protuberance, closer to tip of snout than to eye (EN/NS 1.70), separated from each other by distance larger than distance between eye and nostril (EN/NN 0.84); eyes directed anterolaterally, moderately large, its diameter slightly shorter than snout (SL/ED 1.08); pupils horizontal; interorbital distance larger than internarial distance (IO/NN 1.38) and upper eyelid width (IO/EW 1.58); tympanum visible but covered by skin, separated from orbit by less than one-tenth of its diameter; tympanum diameter slightly larger than half the eye diameter (TD/ED 0.54); upper jaw with weak dentition; teeth on premaxillary larger than on maxillary; dentale without dentition; vomerine teeth absent; a narrow, dark, transverse, crenulated ridge of skin on palate between choana and eye on each side of the head; tongue broad, not bifurcated, free for about half of its length; median lingual process absent; vocal sac median, subgular; slit-like openings on both sides of floor of mouth between base of tongue and angle of jaws. Fore limbs slender; hand slightly shorter than forearm (3FL/ARM 0.46); fingers slightly webbed basally; their tips rounded, not dilated; relative length of fingers: IV<I<II<III; palmar tubercle very large; subarticular tubercles prominent, rounded, large, numbering one on Fingers I, II, and IV, and two on Finger III; one smaller, supernumerary metacarpal tubercle between each finger and palmar tubercle; nuptial pads or asperities absent. Hind limbs moderately slender, short (LEG/SVL 1.38); distance between knees slightly larger than between elbows (KNE/ELB 1.05); heel reaching to posterior margin of eye when legs are adpressed to body; tibiofibula short (TFL/SVL 0.43), slightly shorter than thigh (TFL/THL 0.96); heels do not meet each other when knees are flexed and thighs are held laterally at right angle to body; foot shorter than tibiofibula (FOT/TFL 0.85); toe tips rounded, not dilated; relative length of toes: I<II<V<III<IV; toes webbed, formula being I 1 –2.5 II 2 - –3+ III 2– 4 IV 4– 1 V ; subarticular tubercles on Toes I–IV prominent, as large as or larger than finger tips, numbering one on Toe I and II, two on Toe III, and three on Toe IV; no subarticular tubercles but a layer of thickened skin on Toe V, hardly discernible; inner metatarsal tubercle prominent, large, elongate; outer one lower, smaller, and rounded. Dorsal surfaces granular; flanks, chin, chest, and ventral side of arms areolate; abdomen and ventral side of thighs coarsely areolate; lateral surfaces of thighs and ventral side of lower legs smooth; skin above vocal sac not modified; elbow and heel without dermal appendages; gland on side of head behind tympanum, delimited by sinuous groove; large, flattened, subconical tubercles on ventral side, mostly scattered on abdomen, chest, and along margin of lower jaw; supracloacal region unornamented, without ridge, flap or fold. Measurements (in mm). SVL 30.1, TFL 12.8, THL 13.3, TarL18.3, FOT 10.8, LEG 41.7, 1FL 4.1, 2FL 4.9, 3FL 7.2, 4FL 4.0, ARM 15.6, ELB 25.4, HW 10.9, HL 9.2, ED 3.5, TD 1.9, EW 2.4, IO 3.9, EN 2.4, NS 1.4, SL 3.8, EE 6.5, NN 2.8. Colouration in life. During the night, dorsum and flanks black, separated from each other by white line running on both sides of body from tip of snout along canthus rostralis and lateral margin of upper eyelid, above tympanum and gland on side of the head, dorsolaterally along the side of the trunk to groin ( Fig. 1 ); chin and chest black, colour fading to dark grey on abdomen and proximal third of thigh; ventral side of arm, distal two-thirds of thigh, tibia, and tarsus and lateral surfaces of thigh dark brown; ventral side speckled with white dots; large, flattened, subconical tubercles on abdomen, chest, and along margin of lower jaw white; volar side of hand light grey, plantar side of foot dark grey; iris red. During the day, colouration of dorsum and flanks lightened (cf. Fig. 4 ): back and dorsal side of head and limbs light brown, revealing pattern of reticulated black markings on back and arms and crossbars on hind limbs; flanks dark brown; white lateral line bordered with black on both margins; iris reddish orange. Colouration in preservative. Mainly like during the night; dorsal pattern not visible on back, faintly visible on arms and hind limbs; pupil greyish white. Variation. The male paratype has an SVL of 29.7 mm , the adult female paratypes 35.5 and 38.8 mm , and the subadult female paratype 30.3 mm . The male paratype is very similar to the holotype in body proportions. Females have narrower heads (HW/SVL 0.31–0.34 vs. 0.36) and shorter tibiofibulae (TFL/SVL 0.37–0.42 vs. 0.42–0.43) than males. Males have median subgular vocal sacs but lack nuptial pads or asperities. Advertisement call. Advertisement calls of seven individuals including the holotype were recorded from close range ( 0.5–2 m ) on Batu Bungan at elevations between ca. 140 and 200 m . The raspy advertisement call consisted of a single note and was repeated in long series. Call repetition rate within a series was 0.37 ± 0.12 (0.18–0.53) per second. The note consisted of 7 (rarely 8) pulses and lasted 161 ± 4 ms ( Fig. 5 ). Pulse repetition rate within the note was variable and ranged between 38 and 67 (mean 43) pulses per second. Pulsation was indistinct in calls recorded from longer distances (> 10 m ). Dominant frequency was at 2250–2650 Hz with an energy maximum at 2459 ± 82 Hz. Prominent harmonic frequencies were at 3200–3400 Hz and 4000–4150 Hz, and the fundamental frequency was at 1500–1700 Hz. The calls of four individuals recorded at approx. 1100 m elevation on Gunung Api had a slightly lower dominant frequency with an energy maximum at 2130 ± 22 Hz, and a lower fundamental frequency (energy maximum at 1448 ± 21 Hz). Call repetition rate within call series was 0.29 ± 0.04 per second.

Etymology. The species epitheton derives from latin calx , meaning “limestone”, and the latinized suffix - philus (from the greek ίλος), meaning “who is attracted to”; in allusion to the species' preferred habitat. Ecological notes and distribution. The new species appears to be endemic to the karst area of the Melinau Limestone Formation. I observed specimens only in the lowland, submontane, and montane karst forests in this particular area at elevations between 70 m and at least 1200 m ( Fig. 6 ). I never found the species nor heard its advertisement call in other forest types like alluvial forest, kerangas, or mixed dipterocarp forest in the GMNP. During an investigation of the amphibian assemblage of the lowland karst forest in the GMNP, I found K. calciphilus to be the second most common species after Pelophryne api (unpubl. data). It is one of only few anuran species in the GMNP whose call can also be heard during the day. Calling activity, however, is highest during the first half of the night. The tadpole and reproductive mode of this species remain unknown. As males are often found calling from the entrances of burrows in the ground and surface water bodies are absent in karst forests, I assume that breeding takes place underground inside these burrows. When handled, the species secretes a sticky mucus.