Odorrana aureola Stuart, Chuaynkern, Chan-ard, and Inger, 2006

Ampai, Natee, Rujirawan, Attapol, Arkajag, Jirachai, Mcleod, David S. & Aowphol, Anchalee, 2015, Description of the tadpoles of two endemic frogs: the Phu Luang cascade frog Odorrana aureola (Anura: Ranidae) and the Isan big-headed frog Limnonectes isanensis (Anura: Dicroglossidae) from northeastern Thailand, Zootaxa 3981 (4), pp. 508-520 : 510-513

Odorrana aureola Stuart, Chuaynkern, Chan-ard, and Inger, 2006

Specimens examined. A single tadpole of O. aureola (ZMKU AM 01138) was collected from Kok Huai Toey Stream, Phu Luang Wildlife Sanctuary, Loei Province (17°19'20.9"N 101°31'21.6"E, 1246 m ASL) by Attapol Rujirawan and Natee Ampai on 19 September 2013 (2052 hr). A single adult specimen (ZMKU AM 01137; Fig. 2 A) was collected at the same location ( Fig. 2 B) by Anchalee Aowphol, Attapol Rujirawan, Natee Ampai and Somphouthone Phimmachak on 28 July 2013 (2100 hr).

Identification. Sequence data from the tadpole (ZMKU AM 01138) and adult (ZMKU AM 01137) were 100% identical over a fragment of 553 bp. Morphology of the adult specimen of O. aureola matched the original description ( Stuart et al. 2006a).

Measurement of tadpole. Morphometric measurements (in mm) at Gosner (1960) developmental stage 30 ( Table 1 ): BH = 3.5; BL = 8.8; BW = 4.7; IND = 1.8; IOD = 2.8; IOS = 1.5; MTH = 4.3; ODW = 2.5; SS = 6.6; TAL = 20.9; TL = 29.7; TMH = 2.7; TMW = 2.4; HUF = 1.5; HLF = 1.2.

Species Odorrana aureola Limnonectes isanensis Description of tadpole. Body small and streamlined ( Figs. 3 , 4 ). From above, body oval, wider anteriorly than posteriorly, snout acutely rounded; in profile body dorsoventrally depressed, snout rounded, sloping gently from the plane of the eyes, oral disc anteroventral. Nares small with elevated rim, anterodorsally positioned, closer to snout than eye. Eyes positioned at the anterior one-third of the body, dorsolateral, not visible from ventral view. Interorbital distance almost twice internarial distance. Single, sinistral, tubular spiracle opening just below body axis posterior to midpoint of body ( Fig. 4 C); SS = 6.6 mm. Vent tube dextral, opens midway between muscle and edge of ventral fin. Tail musculature well developed, round shaped, end rounded. Fin beginning at root of tail, margin of dorsal fin higher than ventral fin and slightly convex, ventral fin parallel to caudal fin, fin tapering to pointed tip, TMH = 2.7 mm.

Color pattern. Color in life (Stage 30, Fig. 4 ): body brown to russet with dense dark brown pigmentation on the dorsum from snout to distal third of tail, clusters of melanophores become less dense towards the venter giving the sides of body and tail a spotted appearance. Dorsum, sides of body and tail flecked with small golden spots arranged almost linearly. Distal third of tail musculature dark brown, tip transparent. Fins flecked with dark brown pigment near musculature, fading to transparent at margins and distal tip of tail. Oral disc pale white. Venter translucent revealing internal organs and centro-sinistral intestines. Coloration in preservative similar to that in life with dark brown pigmentation remaining the same, but body pale grayish, and spots pale golden.

Oral disc. Oral disc ( Fig. 3 B) anteroventral, emarginated with uniserial array of blunt marginal papillae and 5– 6 submarginal papillae at intersection of anterior and posterior labia. Upper and lower jaw sheathes medium and serrated with black margins, LTRF: 5(2–5)/4(1).

Ecology. The tadpole was discovered at the bottom of a small, shallow pool in a permanent stream with an accumulation of dead leaves and rocks <40 cm in diameter ( Fig. 2 B). The tadpole was buried within the gravel substrate on the bottom of the pool. Sampling area in the stream was 2.4 m 2 with a maximum depth of 16 cm water. Tadpole was collected at 2052 hr on 19 September 2013. Ambient air temperature = 21.4°C, relative humidity = 85.9%, surface water temperature = 19.8°C, water temperature at 16 cm = 18.9°C, and stream current was slow (0.2 m /s). Stream pH taken at 1036 hr on 20 September 2013 was 8.6 (weak base), ambient air temperature = 22.8°C, water temperature was not collected. No egg masses were found during the surveys. When disturbed, the tadpole moved quickly and hid within gravel, rock crevices, and dead leaves. Adult males of O. aureola were often found 20–30 cm above the water perched on large rocks. When disturbed, adult frogs escaped to other rocky perches or took cover at the bottom of the stream.

Comparisons. The external morphology of some tadpoles in the genus Odorrana has been described previously. Inthara et al. (2005) reported LTRF 5(2–5)/4(1) for Odorrana livida from Loei Province but did not address other oral features. Songchan (2007) described coloration and body morphology of a Gosner stage 35 tadpole of O. livida from Chiang Dao, Chiang Mai Province, northern Thailand and reported a LTRF consistent with Inthara et al. (2005). Unfortunately, these studies are confounded by the taxonomic confusion over the identity of O. livida complex members and the fact that some species occur in sympatry in Thailand. The lack of genetic data in Inthara et al. (2005) and Songchan (2007) precludes the use of molecular sequence homology to validate the identification. We found the labial tooth row formula of O. aureola to be the same as that of O. livida in Songchan (2007) and Inthara et al. (2005), but we found marginal papillae arranged in a single row not two rows as described by Inthara et al. (2005) and Songchan (2007). A distinctive larval feature of O. aureola appears to the presence of small golden spots arranged almost linearly along the entire brown to russet colored body. This is differs from previous descriptions of O. livida tadpoles, which are described as having scattered small golden or yellow flecks on a gray or dark colored body with some dark spots on the tail muscle. We suggest that the tadpoles described by Inthara et al. (2005) and Songchan (2007) may be those of O. chloronota , but additional studies are required to confirm this.

Figures

FIGURE 2. (A) Adult male of the Phu Luang cascade frog, Odorrana aureola and (B) The habitat of O. aureola at Phu Luang Wildlife Sanctuary, Loei Province.

FIGURE 3. Odorrana aureola tadpole (ZMKU AM 01138; Gosner stage 30); (A) lateral view, (B) oral disc. Scale bar = 1 mm.

FIGURE 4. Odorrana aureola tadpole (ZMKU AM 01138; Gosner stage 30) in life; (A) Dorsal view, (B) ventral view, and (C) lateral view. Scale bar = 1 mm.

Tables

TABLE 1. Morphometric measurements (mm) of Odorrana aureola tadpole (ZMKU AM 01138; n = 1) and morphometric variations of Limnonectes isanensis tadpole series (ZMKU AM 01140; n = 3, ZMKU AM 01141; n = 1, and ZMKU AM 01142; n = 1) from Phu Luang Wildlife Sanctuary, Loei Province, northeastern Thailand.

ZMKU number	ZMKU AM 0 1138	ZMKU AM 0 1140	ZMKU AM 0 1141	ZMKU AM 0 1140	ZMKU AM 0 1142
Gosner stage Number of tadpole (n) Body height (BH)	30 n=1 3.5	30 n=1 3.8	32 n=1 5.6	35 n=2 5.9±0.1	38 n=1 5.9
Body length (BL) Body width (BW) Internarial distance (IND)	8.8 4.7 1.8	9.6 6.0 1.5	12.5 7.4 2.4	12.8±0.8 7.8±0.1 2.5±0.1	13.4 7.9 2.8
Interorbital distance (IOD) Distance from IOD to IND (IOS)	2.8 1.5	3.0 1.7	3.8 2.5	3.4±0.7 2.5±0.1	4.0 2.6
Maximum tail height (MTH) Width of oral disc (ODW)	4.3 2.5	5.2 2.0	6.2 2.2	6.3±0.1 2.5±0.1	6.8 2.4
Distance of snout to spiracle (SS) Tail length (TAL) Total length (TL)	6.6 20.9 29.7	6.2 17.6 27.1	7.2 19.2 31.7	7.6±0.1 19.5±0.1 32.3±0.2	7.7 26.9 40.3
Tail muscle height (TMH) Tail muscle width (TMW) Height of upper tail fin (HUF)	2.7 2.4 1.5	2.2 1.9 1.9	2.9 2.3 1.9	3.0±0.1 2.8±0.1 2.1±0.1	3.1 3.2 2.2
Height of lower tail fin (HLF)	1.2	1.1	1.3	1.4±0.1	1.5