Diagnosis

Chiromantis inexpectatus is distinguishable from its congeners by the combination of the following characters: (1) size small, SVL 22.2–22.4 mm in males, (2) dark stripes absent, but dark spots present on dorsum, (3) a dark-brown lateral band present from snout tip to half of body, bordered below by white stripe, (4) third and fourth fingers less than half webbed (III 2–2.5 IV), (5) third finger disk wider but toe disks narrower than tympanum diameter, (6) inner metatarsal tubercle present.

Etymology

The specific name is a Latin adjective, referring to the fact that the occurrence of the genus on the island of Borneo, where the new species was found, was unexpected.

Fig. 2.

(A) Male holotype (BORNEENSIS 22421) and (B) male paratype (BORNEENSIS 22420) of Chiromantis inexpectatus in life, showing different color phase.

Fig. 3.

(A) Dorsal, (B) ventral, and (C) lateral views of male holotype (BORNEENSIS 22421) of Chiromantis inexpectatus after preservation. Scale bar = 10 mm.

Holotype

BORNEENSIS 22421, adult male, collected by Tomohiko Shimada on 9 March 2005 from Camel Trophy field station (4°54' N, 116°53' E; ca. 1050 m a.s.I.) of the Maliau Basin Conservation Area, Sandakan Division, Sabah, East Malaysia.

Paratypes

BORNEENSIS 22419, metamorphosing young, and BORNEENSIS 22420, adult male, same collection details as for holotype.

Description of holotype

Adult male; SVL 22.2 mm; head longer (HL 38.7% SVL) than wide (HW 36.9% SVL), wider than body, relatively flat; snout truncated in lateral view, length (SL 14.9% SVL) subequal to eye length (EL 14.4% SVL), sloping anteroventrally, projecting beyond mouth; canthus rostralis rounded; loreal region vertical and concave; nostril nearer to tip of snout (SNL 8.1% SVL) than to eye (N-EL 9.0% SVL); internarial distance (IND 12.4% SVL) less than interorbital distance (IOD 14.9% SVL), which in turn nearly twice as wide as upper eyelid (UEW 7.9% SVL); eye large, protuberant; tympanum distinct, subcircular, diameter (TD 5.4% SVL) three-eighths of eye length and separated from eye by one-eighth of tympanum diameter (T-EL 0.7% SVL); vomerine teeth absent; choana oval; tongue notched posteriorly; single median vocal sac; vocal slits on floor of mouth well anterior to jaw commissure on both sides.

Forelimb long (FLL 67.1% SVL); hand and forearm long (LAL 56.3% SVL) and relatively robust; finger length formula: I < II < IV < III; expanded disks each with a circummarginal groove and a transverse ventral groove; disks on third and fourth fingers (3FDW 6.1% SVL) only slightly wider than those on second (2FDW 6.0% SVL) and first (1FDW 5.9% SVL), all wider than tympanum; no webbing between first and second fingers; second and third fingers, and third and fourth fingers less than half webbed (II 3–3 III 2–2.5 IV); inner two fingers widely separated from outer two fingers (opposable); subarticular tubercle between penultimate and adjoining proximal phalange on third and fourth fingers indistinct; inner palmar tubercle flat (IPTL 5.4% SVL), outer one absent; nuptial pad absent.

Fig. 4.

Ventral views of (A) left hand and (B) right foot of male holotype (BORNEENSIS 22421) of Chiromantis inexpectatus after preservation. Scale bar = 10 mm.

Fig. 5.

(A) Dorsal and (B) ventral views of juvenile paratype (BORNEENSIS 22419) of Chiromantis inexpectatus in anesthesized condition. Scale bar = 5 mm.

Hindlimb relatively short (HLL 159.9% SVL); tibiotarsal articulation extends to anterior corner of eye when fully stretched leg adpressed to body; heels touching each other when thigh (THIGH 54.7% SVL) and tibia (TL 54.5% SVL) placed at right angle to body; foot (FL 41.9% SVL) much shorter than tibia; toe length formula I<II<III<V< IV; toes bearing expanded disks each with a circummarginal groove and a transverse ventral groove, width of fourth toe disk (4TDW 4.7% SVL) much narrower than those of finger disks; webbing formula I 2–2 II 1¹/₂–2 III 1¹/₂–2 IV1¹/₂–1¹/₂ V; subarticular tubercles oval, poorly developed; inner metatarsal tubercle small (IMTL 3.6% SVL) and flat, about onethird length of first toe (1TOEL 11.5% SVL); no outer metatarsal tubercle.

Dorsal surface nearly smooth, sparsely scattered with minute, blunt asperities between shoulder and sacral regions; supratympanic fold weak, continued as glandular fold to shoulder; skin of lower jaw posterolateral^ forming a short fold at anterior base of upper arm; ventral surface composed of flat granules; skin of ventral surface of foot smooth, with longitudinal folds.

Color

The color changes in life: when captured, the dorsal ground color was whitish-yellow on body and pinkish on limbs, but later changed to light brown (Fig. 2). Dorsum scattered with vaguely defined small dark-brown spots; a darkbrown lateral band extending from tip of snout, through lower eyelid, upper half of tympanum, to fade one-half way down body, bordered ventrally by a narrower white stripe extending from snout tip below canthus, through lower eyelid and tympanum; venter immaculate creamy white, semitransparent.

Table 2.

Measurements (in mm) of types of Chiromantis inexpectatus. See text for abbreviations.

In alcohol, all dorsal and ventral surfaces faded to beige, but dark-brown and white stripes remained.

Variation

Morphometric variation is shown in Table 2. The male paratype (BORNEENSIS 22420) is generally similar with the holotype in general morphology and coloration, but has more isolated, clearer dark spots. Another paratype (BORNEENSIS 22419) is a metamorphosing juvenile with a tail stub of 0.1 mm and lacks a visible tympanum. Darkbrown lateral band is indistinct and ventral white stripe is not recognizable.

Range

Known from the type locality, Camel Trophy of the Maliau Basin Conservation Area, Sandakan Division, State of Sabah, Malaysian Borneo.

Natural history

In the type locality, Camel Trophy, two adult males and a metamorphosing juvenile of the type series were simultaneously found at night perching each on a leaf of low trees (< 1 m) extending above the surface of a shallow pool (3–5 m × 10 m). The air temperature before the time of finding was 24°C. No tadpoles were found in the pond nor eggs on overhanging leaves of trees. Early March may not be a breeding season since males were not calling, but is surely in the season of metamorphosis as evidenced by the presence of a juvenile with a degenerating tail. Frogs found together with the new species included Rhacophorus borneensis, Kurixalus appendiculatus, Polypedates macrotis (Boulenger, 1891), and Microhyla petrigena Inger and Frogner, 1979.

Comparisons

Chiromantis inexpectatus is distinguished from C. cherrapunjiae (Roonwal and Kripalani, 1966) from northern India by light brown or yellowish brown dorsum with dark-brown spots, dark-brown dorsolateral stripe bordered below by white stripe, and the presence of inner metatarsal tubercle (vs. dorsum pale green to dark green and inner metatarsal tubercle absent in C. cherrapunjiae: Chanda, 1994; Mathew and Sen, 2010); from C. doriae from northern India through Myanmar, Thailand, Laos, Cambodia, and Vietnam to China, by the absence of dark dorsal stripes and presence of external vocal sac (vs. dark dorsal stripe present and external vocal sac absent in C. doriae); from C. dudhwaensis (Ray, 1992) from northern India by the possession of dorsum with dark-brown spots, and third finger disk larger than tympanum (vs. dorsum with dark stripe, and disk on third finger smaller than tympanum in C. dudhwaensis); from C. hansenae from Thailand by dark-brown dorsolateral stripe bordered below by white streak on anterior half of flank, and clearly webbed second to fourth fingers (vs. dorsolateral stripe cream bordered with violet streaks on each edge to groin, and webs on hand rudimentary in C. hansenae: Taylor, 1962); from C. marginis Chan et al., 2011 from the Malay Peninsula by dorsolateral stripe dark-brown, bordered below by white streak, both of which not continuous but fading one-half way down body, webbing between third and fourth fingers not extensive (III 2–2.5 IV), and disk on third finger larger than tympanum (vs. dark-brown dorsolateral stripe bordered above by white stripe, both of which continuing to groin, extensive webbing between third and fourth fingers [III 1.5–IV], and third finger disk smaller than tympanum in C. marginis: Chan et al., 2011); and from C. nongkhorensis from Myanmar, Thailand, Laos, Cambodia, Vietnam, and Malaysia, by smaller body size, relatively small eye shorter than snout, possession of clear dorsolateral stripes and dorsum speckled with small dark-brown spots (vs. body larger, SVL 29–32 mm in males, eye longer than snout, dorsolateral stripes absent, and distinct dark dorsal markings between orbital and sacral regions in C. nongkhorensis).

The new species also differs from the following species morphologically: from C. punctatus (Wilkinson et al., 2003) from Myanmar by dorsum scattered with vaguely defined small dark-brown spots, and dark-brown dorsolateral stripe bordered ventrally by narrow white stripe extending from snout tip below canthus, through lower eyelid to one-half way down body (vs. dorsum with many clearly defined darkbrown spots, and wide white dorsolateral stripe running from snout above canthus rostralis through upper eyelid to groin, bordered ventrally by narrow dark stripe in C. punctatus); from C. samkosensis Grismer et al., 2007 from Cambodia by the dorsal ground color of yellow to light brown, distinct white streak below canthus, and possession of disk on third finger larger than tympanum (vs. ground color of dorsum lime-green, no white streak below canthus, and third finger disk slightly smaller than tympanum in C. samkosensis: Grismer et al., 2007); from C. senapatiensis (Mathew and Sen, 2009) from northern India by the absence of dark dorsal stripe and presence of clear webs on second to fourth fingers (vs. dark middorsal stripe present and webs on hand rudimentary in C. senapatiensis: Mathew and Sen, 2010); from C. shyamrupus (Chanda and Ghosh, 1989) from northern

India by the absence of dark dorsal stripes, and presence of clear webs on second to fourth fingers and inner metatarsal tubercle (vs. a dark middorsal stripe present, fingers free of web, and inner metatarsal tubercle absent in C. shyamrupus: Chanda, 1994; Mathew and Sen, 2010); from C. simus (Annandale, 1915) from northern India by the smaller body size (male SVL 22 mm) and the absence of uniform tuberculation and dark stripes on dorsum (vs. body larger, SVL 30 mm, and dorsum uniformly tuberculate with dark stripes in C. simus: Ahmed et al., 2009); and from C. vittatus from northern India through Myanmar, Thailand, Laos, Cambodia, and Vietnam to China, by the smaller body size and presence of dark-brown dorsolateral stripe bordered below by white streak on anterior half of flank (vs. size larger, males 26–28 mm in SVL, and dorsolateral stripe bordered above by white stripe running to groin in C. vittatus).

The African species, C. kelleri Boettger, 1893 from Ethiopia and Somalia through Kenya to Tanzania, C. petersii Boulenger, 1882 from Kenya and Tanzania, C. rufescens from West Africa, and C. xerampelina from Kenya, Angola and Namibia to South Africa, are all much larger (SVL 35–80 mm: Liem, 1970) than the present new species (ca. 22 mm).