Rhacophorus chuyangsinensis, ORLOV, NGUYEN & HO, 2008

REDESCRIPTION OF RHACOPHORUS CHUYANGSINENSIS ORLOV, NGUYEN & HO, 2008

In the following we provide a detailed morphological description of R. chuyangsinensis based on 15 adult males and two adult females from Lam Dong and Khanh Hoa Provinces , southern Vietnam (for measurements see Table 1).

Head approximately as long as wide; snout slightly pointed in dorsal view, pointed and slightly exceeding to mouth in profile; nostril round, and closer to tip of snout than to eye; canthus rostralis distinct; eye diameter 0.7–0.9 times of snout length; interorbital region flat, wider than internarial distance and as large as or little bit larger than width of upper eyelid; tympanum round, not raised above temporal region, with a slightly elevated rim; diameter of tympanum 0.4–0.5 times of eye diameter, distance between eye and tympanum 0.3–0.4 times the tympanum diameter; supratympanic fold distinct, from behind of eye to beyond level of axilla; choanae small, round; vomerine teeth grouped in two oblique rows, beginning nearby anterior edges of the choanaes, closer to choanae than to each other; tongue bifid at rear.

Limbs slender; relative lengths of fingers I<II<IV<III; tips of fingers flat, enlarged into round discs with circummarginal grooves; disc of third finger as large as or little larger than the tympanum diameter; fingers incompletely webbed, formula I(1) IIi(1)e(0.5) IIIi(1.5)e(1) IV(1); narrow, smooth flap of skin present along outside of fourth finger and lower arm, ending at elbow; subarticular tubercles on fingers and toes round, prominent and conspicuous; nuptial pad distinct in males, located on lateral and dorsal aspect of first finger, from near its base to proximal end of penultimate phalanx; length of nuptial pad slightly larger than that of the first finger; discs of toes round with circummarginal grooves, smaller than those of fingers; relative lengths of toes I<II<V<III<IV; toes broadly webbed, formula I(0) IIi(1)e(0.5) IIIi(1)e(0) IVi(0.5)e(0.5) V(0.5); dermal fringe along outside of fifth toe and foot narrower than that along outside of fourth finger and lower arm, and ending at tibiotarsal articulation with a long, pointed projection; inner metatarsal tubercle flat, oval, its length about one-third to half of that of first toe; outer metatarsal tubercle absent; heels overlapped when legs are held at right angles to body; tibiotarsal articulation extending to anterior edge of eye or between eye and tip of snout.

Skin smooth on dorsal body, head, and limbs; throat, chest, and lower part of flank slightly granular; belly and ventral surface of thigh coarsely granular; posterior cloacal appendix present.

Coloration in preservative. Dorsal surfaces of body and limbs ground yellow to dark brown; dorsal pattern which is yellow in life becomes creamish-white in preservative; nuptial pad white; surfaces of belly, limbs, discs and webbings whitish-cream; the blue color surrounding the black patches on flanks and upper arms is only slightly discernible if at all.

Coloration in life. Back and upper surfaces of limbs pale green or dark brown, with many small white or yellow spots; ventral surface bright yellow without small spots; thin, light stripes present along canthus rostralis, from tip of snout to middle of the eye; flanks, anterior and posterior surfaces of limbs yellow to orange; axilla, groin, anterior surface of upper arm and thigh, and posterior surfaces of thigh and tibia usually with large, black patches that vary in size and shape; these patches are sometimes surrounded by bright blue color and are more obvious in females (more details are given in the discussion of the sexual dimorphism); webbings on fingers and toes yellow or orange, sometimes with black pattern at base; discs of fingers and toes yellow to orange; posterior cloacal appendix white; long, pointed projection at the heel of the same color as dorsal surface of thigh or yellow; pupil horizontal, black; iris brown, fading into red-orange at the upper and lower parts and surrounded by an inner black and outer blue circle (Fig. 2). Dorsum of some males (UNS00506–00508; ZFMK91517–91519) reddish brown, with two yellow dorsolateral stripes stretching from posterior corner of eye to groin and a medium third yellow stripe extending from behind the middle of the back towards cloaca; in such coloured specimens, also the light snout stripes are more distinctly developed, and sometimes a light stripe between eyes is present, forming a triangle on the dorsal surface of head (UNS00506 & ZFMK91519) (Fig. 2 E & F).

Sexual dimorphism. Female size on average is 1.6 times larger than that of males. The females also differ from males by their flank pattern, which consists of the

FIG. 2

Different color patterns of Rhacophorus chuyangsinensis in life. (A-B) female (VNMN965) at day and night time. (C-F) males (C: UNS00500, D: UNS00508, E: ZFMK91518, and F: UNS00506).

same colour than the dorsal pattern, viz. dark reddish brown or ground brown, with many small whitish spots (versus bright yellow flanks in males without small whitish spots). In females the bright bluish color on axilla, groin and front of the forearm is also more obvious and furthermore may even extend towards the middle of the flanks and cover nearly the whole anterior surface of the forearm (Figs 2A, 2B). In addition, the posterior surface of the thigh and tibia of females is covered with large black, elongated patches.

EXTENDED DIAGNOSIS (AFTER ORLOV ET AL. 2008, COMBINED WITH OUR NEW DATA)

A small rhacophorid species with 35.1–44.15 mm SVL in adult males, and 58. 0–60.2 mm in adult females; body depressed; head wide and flat, approximately as long as wide; snout somewhat pointed; diameter of the eye 0.7–0.9 times of snout length; iris brown to red-orange at the upper and lower parts, surrounded by inner black and outer blue circle; pupil black, horizontal; tympanum round, small but clearly visible; supratympanic fold extending just beyond level of axilla; back and dorsal surfaces of limbs smooth; throat slightly granulated, belly and ventral surface of thigh coarsely granular; vomerine teeth in two oblique ridges that reach the upper part of the rounded choanas; discs of fingers and toes flat, large, round, with circummarginal grooves; discs on fingers larger than toe discs; fingers incompletely webbed (formula: I(1) IIi(1)e(0.5) IIIi(1.5)e(1) IV(1)); toes extensively webbed (formula: I(0) IIi(1)e(0.5) IIIi(1)e(0) IVi(0.5)e(0.5) V(0.5)); dermal fringe along the outside of the fourth finger and lower arm present; similar ridge of skin present along the outside of the fifth toe and foot, ending at heel, which bears a long, pointed projection; back and dorsal surfaces of limbs pale green to dark green or dark brown, with many small white or yellow spots; belly yellow without spots; webbings on fingers and toes yellow to orange; posterior cloacal appendix white.

NATURAL HISTORY

The new records of Rhacophorus chuyangsinensis from Bi Doup-Nui Ba National Park (Lam Dong Province) and Hon Ba Nature Reserve (Khanh Hoa Province) were made nearby or within rocky streams in evergreen forests at elevations between 1,320–1,600 m a.s.l. The frogs were observed during evening and night time sitting on high branches of trees along the streams, approximately 1.5–2 m above the ground. Sometimes these trees were up to 5 m distant from water sources (Fig. 3). On 22 May 2010, we measured environmental temperatures of 19.2–19.5°C, and humidities of 92.4–93.6% at the sites where the frogs were found. One female (UNS00509), which was collected during dry season on 18 March 2010, was gravid and contained large eggs up to 3 mm diameter.