Kalophrynus calciphilus, Dehling, Maximilian, 2011

Dehling, Maximilian, 2011, A new karst-dwelling species of Kalophrynus (Anura: Microhylidae) from Gunung Mulu National Park, Borneo, Malaysia, Zootaxa 2737, pp. 49-60 : 51-58

Kalophrynus calciphilus sp. n.

Limestone Sticky Frog ( Figs. 1–4 )

Synonymy: Kalophrynus punctatus (nec Calophrynus punctatus Peters, 1871 )

Dring 1983: 112 (partim); Kiew 1984a: 151; Dring 1987: 44; Inger and Stuebing 1992: 45, 47; Dehling 2010: 66.

Holotype: NMBE 1056261, adult male, collected close to the northern entrance of Gua Bulansusu (Moonmilk Cave) on Batu Bungan, ca. 200 m a.s.l., Gunung Mulu National Park, Sarawak, Malaysia, on 25 December 2007 at 23:40 h by J. M. Dehling.

Paratypes: NMBE 1056262, adult male, collected along the Pinnacles Trail, ca. 550 m a.s.l., northern slope of Gunung Api , Gunung Mulu National Park, Sarawak, Malaysia, on 23 October 2007 at 22:45 h by J. M. Dehling; NMBE 1056263, adult female, collected on Batu Bungan, ca. 130 m a.s.l., Gunung Mulu National Park, Sarawak, Malaysia, on 20 December 2007 at 2:15 h by J. M. Dehling; BMNH 1978.1612, adult female, collected at 900 m a.s.l. on Gunung Api , Gunung Mulu National Park, Sarawak, Malaysia, in 1977 by J. C. M. Dring; BMNH 1978.1611, subadult female, collected at 800 m a.s.l. on Gunung Api , Gunung Mulu National Park, Sarawak, Malaysia, in 1977 by J. C. M. Dring; BMNH 1978.1613–1615, three juveniles, collected at 600, 200, and 800 m a.s.l., respectively, on Gunung Api , Gunung Mulu National Park, Sarawak, Malaysia, in 1977 by J. C. M. Dring; FMNH 171777, juvenile, collected on Ulu Tutoh, near Melinau Gorge, Gunung Mulu National Park, Sarawak, Malaysia, in September 1970 by P. Lehmann.

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.

Comparisons. Species of the genus Kalophrynus are difficult to distinguish because morphological characters are quite uniform within the genus. Many morphological characters, such as toe webbing, snout shape, leg length, relative finger and toe length, and aspects of colouration like dorsal and ventral colouration and presence or absence of a dorsolateral line, show little intraspecific variation and thus can be used for species differentiation. In the following, Kalophrynus calciphilus is compared to all other species of Kalophrynus , listing only opposed characters. The lists of characters are not exhaustive and for two poorly known species which have been characterised very briefly in their original descriptions, only few characters are stated.

The other members of the genus Kalophrynus can be distinguished from Kalophrynus calciphilus (characters given in parentheses) by the following characters:

Kalophrynus baluensis Kiew, 1984 : body larger, SVL of adult males up to 36 mm (vs. 30.1 mm), of adult females up to 47 mm (vs. 38.8 mm); snout sharply pointed in dorsal view (obtusely pointed); one or two large yellow ocelli present in inguinal region (absent); ventral side whitish grey, speckled with dark spots (black on chin and chest fading to dark grey on abdomen, speckled with white dots); iris greyish golden (red or reddish orange).

Kalophrynus bunguranus ( Günther, 1895) : body smaller, SVL of males up to 23 mm (vs. 29.7–30.1 mm), of females up to 27 mm (vs. 35.5–38.8 mm); dark spots in light inguinal area (no spots in dark inguinal area); combined length of forearm and hand relatively shorter with ARM/SVL 0.41–0.44 (vs. 0.49–0.52); Finger IV reduced to knob lacking subarticular tubercle (one subarticular tubercle present), its free portion being wider than long (much longer than wide), lateral surfaces of thighs rose-coloured in life (dark brown).

Kalophrynus eok Das and Haas, 2003 : body smaller, SVL of only known specimen, a male, 26.6 mm (vs. 29.7– 30.1 mm); dorsum brick red, with dark interorbital bar (dark brown or black without interorbital bar); upper jaw edentate (with dentition); skin fringes present on inner and outer margins of Finger IV (absent); smooth nuptial pads present on upper surfaces of fingers II and III (absent).

Kalophrynus heterochirus Boulenger, 1900 : body smaller, SVL of adult males to 24 mm (vs. 29.7–30.1 mm), of adult females 27–32 mm (vs. 35.5–38.8 mm); large, bright spots in inguinal region and on lateral surfaces of thighs (absent); Finger IV reduced to knob, its free portion being wider than long and lacking subarticular tubercle in males (longer, free portion much longer than wide, one subarticular tubercle present).

Kalophrynus interlineatus (Blyth, 1855) : body larger, SVL of males 37.4–47.7 mm (vs. 29.7–30.1 mm); snout sharply pointed in dorsal view (obtusely pointed); legs shorter, tibio-tarsal articulation reaching between shoulder and posterior border of tympanum (to posterior border of eye); dorsal pattern consisting of longitudinal stripes on the back and oblique transverse bars across the femur and tibia (absent or consisting of reticulated markings); ocellar spot present on the groin (absent).

Kalophrynus intermedius Inger, 1966 : body larger, SVL of adult females 37–41 mm (vs. 35.5–38.8 mm); venter cream-coloured (black on chin and chest fading to dark grey on abdomen); light dorsolateral line absent (present); tympanum larger with TD/ED 0.68–0.79 (vs. 0.51–0.58); feet relatively longer with FOT/TFL 0.87–0.92 (vs. 0.81–0.86); thick gland on side of head much larger.

Kalophrynus menglienicus Yang and Su, 1980 : body smaller, SVL of males 19.8–23.4 (vs. 29.7–30.1 mm); toe webbing absent (present).

Kalophrynus minusculus Iskandar, 1998 : body smaller, SVL of males up to 25 mm (vs. 29.7–30.1 mm); dorsal pattern consisting of several parallel black stripes (absent or consisting of reticulated markings).

Kalophrynus nubicola Dring, 1983 : body much smaller, SVL of adult males 14.4–24.4 mm (vs. 29.7–30.1 mm); snout truncate in profile (pointed); Toe V relatively longer, equal or subequal to Toe III (shorter than Toe III); subarticular tubercles on fingers and toes very low, reduced to pads of thickened skin (prominent); metacarpal tubercles absent (present); throat and chest orange, heavily mottled with dark brown (dark brown or black, mottled with white); abdomen and lateral surfaces of thighs with large rounded pastel-blue spots in a brown setting (abdomen white, lateral surfaces of thighs black).

Kalophrynus palmatissimus Kiew, 1984 : body larger, SVL of males 31.2–38.8 mm (vs. 29.7–30.1 mm); dorsum light brown to reddish brown in life (dark brown to black); snout sharply pointed in dorsal view (obtusely pointed); interorbital distance greater, about twice the width of upper eyelid (smaller, 1.42-1.58 times the width of upper eyelid); Finger IV relatively longer, its tip reaching between subarticular tubercles of Finger III (reaches to proximal tubercle only); toe webbing more extensive, formula being I 0.5–(1.5–2-) II 0.5–(1.5–2) III 0.5– 2 IV 2–0.5 V (vs. I 1 –2.5 II 2 - –3+ III 2– 4 IV 4– 1 V); Toes III and V relatively longer, reaching beyond median and proximal subarticular tubercle of Toe IV, respectively (reaching to median and proximal tubercle, respectively); outer metatarsal tubercle smaller, reduced to small and low thickened layer of skin (more prominent).

Kalophrynus pleurostigma Tschudi, 1838 : body much larger, SVL of males to 50 mm, females to 57 mm (vs. 30.1 and 38.8, respectively), black ocellus in inguinal region (absent); webbing on toe IV to median subarticular tubercle (to proximal tubercle); snout sharply pointed in dorsal view (obtusely pointed); tympanum larger, TD/ED 0.63–0.75 (0.51–0.58); diffuse nuptial pads on dorsal surface of Toes I, II, and III in males (absent).

Kalophrynus punctatus Peters, 1871 : body slightly smaller, SVL of adult males 22–28.3 mm (vs. 29.7–30.1 mm); head narrower in males, HW/SVL 0.31 in the holotype (vs. 0.36); tibiofibula shorter in adult males, TFL/ SVL 0.39–0.41 (vs. 0.42–0.43); Finger IV relatively longer, subequal to Finger II, its tip reaching to centre of distal subarticular tubercle of Finger III (shorter than Finger II, tip not reaching beyond proximal subarticular tubercle of Finger III); Toe V relatively longer, equal or longer than Toe III, its tip reaching to centre of median subarticular tubercle of Toe IV (shorter than Toe III, tip not reaching beyond proximal subarticular tubercle of Toe IV); sides of head and body without a light lateral line (dorsolateral white line present, running from tip of snout to groin); dorsum dark brown with pattern consisting of black spots (dorsum black, lightening to dark brown during the day, pattern absent or consisting of reticulated markings).

Kalophrynus robinsoni Smith, 1922 : body much smaller, SVL of males 16.9–17.7 mm (vs. 29.7–30.1 mm), of female 18 mm (vs. 35.5–38.8); Finger IV reduced to knob, its free portion wider than long (longer, free portion much longer than wide); dorsum light brown in life with X-shaped dark brown marking (black or dark brown, without pattern or with reticulated markings); venter yellowish with brown spots (black on chin and chest fading to dark grey on abdomen); dorsolateral line absent (present); subarticular tubercles on fingers and toes very low, reduced to pads of thickened skin (prominent); nuptial excrescences in form of comb-like rows of very large, conical tubercles on dorsal surface of Fingers I–III (absent).

Kalophrynus subterrestris Inger, 1966 : body smaller, SVL of males 21.0– 23.4 mm (vs. 29.7–30.1 mm), of females up to 27 mm (vs. 35.5–38.8 mm); dorsolateral line absent (present); Finger IV very short, reduced to knob, lacking subarticular tubercle, its free portion being wider than long (longer, one subarticular tubercle present, free portion much longer than wide); proximal subarticular tubercles on Toes III and IV small and low (prominent).

Kalophrynus yongi Matsui, 2009 : arm very stout with strongly developed humeral spine in males (arm slender, humeral spine absent); nuptial pads present on dorsal surfaces of Fingers I–III, bearing prominent excrescences in form of comb-like rows of large, conical tubercles (nuptial pads and excrescences absent); foot relatively longer, FOT/SVL 0.37–0.44, median 0.42 (vs. 0.34–0.36) and FOT/TFL 1.01 (vs. 0.81–0.86); upper jaw edentate (with dentition); metacarpal tubercle between subarticular tubercle of Finger IV and palmar tubercle absent (present); subarticular tubercles on Toe V distinct (reduced to layer of thickened skin); dark inguinal spot present (absent); iris colour golden with black pigmentation (red to reddish-orange).

In addition to the morphological differences, the advertisement call of Kalophrynus calciphilus differs from all known advertisement calls of other species of the genus. So far, the advertisement calls of five species of Kalophrynus have been described in detail and analysed ( Dring 1983, Malkmus & Riede 1996, Matsui et al. 1996, Matsui 2009). The call of Kalophrynus pleurostigma consists of a series of unpulsed notes emitted at a rate between 0.70 and 2.99 per second (single pulsed note, repeated at rate of 0.18–0.53/s), and the energy maximum varies between 420 and 650 Hz (vs. 2110–2650 Hz) ( Matsui et al. 1996). The calls of K. baluensis and K. yongi consist of single, unpulsed notes (pulsed), repeated in series. The call of K. yongi is slightly frequency-modulated (no modulation) and the dominant frequency is at 1300–1800 Hz (vs. 2110–2650 Hz) ( Matsui 2009). The call repetition rate is lower in call series of K. baluensis with 0.10–0.12 calls/s (vs. 0.18–0.53/s) ( Malkmus & Riede 1996, own data). The advertisement calls of K. interlineatus and K. nubicola consist of single, pulsed notes like the call of K. calciphilus . The call of K. interlineatus is a long trill, lasting 843 ± 110 ms (vs. 161 ± 4 ms) and consisting of 23–41 pulses (vs. 7, rarely 8), and the energy maximum is at 743 ± 19 Hz (vs. 2459 ± 82 Hz) ( Matsui et al. 1996). Although recorded at lower temperatures (17–20 °C), the pulse repetition rate is much higher in both call types of K. nubicola with 93–100 pulses/s (vs. 43 [38–67]/s) ( Dring 1983).

Figures

FIGURE 1. Lateral view (top), dorsal view (bottom left), and ventral view (bottom right) of the holotype of Kalophrynus calciphilus sp. n. (NMBE 1056261) in life.

FIGURE 2. Volar view of left hand (left) and plantar view of left foot (right) of the preserved holotype of Kalophrynus calciphilus sp. n. (NMBE 1056261). Marker represents 1 mm.

FIGURE 3. Profile of the head of a male paratype of Kalophrynus calciphilus sp. n. (NMBE 1056262) life. Note the daytime-colouration of the dorsum.

FIGURE 4. Female paratype of Kalophrynus calciphilus sp. n. (NMBE 1056263) in life, showing the dorsal colouration during daytime (left) and night (right).

FIGURE 5. Oscillogram (top) and audiospectrogram (bottom) of an advertisement call of the holotype of Kalophrynus calciphilus sp. n. (NMBE 1056261).

FIGURE 6. Karst forest at 600 m elevation on Gunung Api, Gunung Mulu National Park, Sarawak, Malaysia. Habitat of Kalophrynus calciphilus sp. n.