Ansonia kyaiktiyoensis, Quah & Grismer & Wood & Thura & Oaks & Lin, 2019

Quah, Evan S. H., Grismer, L. Lee, Wood, Perry L., Thura, Myint Kyaw, Oaks, Jamie R. & Lin, Aung, 2019, Discovery of the westernmost population of the genus Ansonia Stoliczka (Anura, Bufonidae) with the description of a new species from the Shan Plateau of eastern Myanmar, Zootaxa 4656 (3), pp. 545-571 : 555-561

Ansonia kyaiktiyoensis sp. nov.

Suggested common name: The Golden Rock Slender Toad

Fig. 2A , 3 & 4B .

urn:lsid:zoobank.org:act:34555D1C-97E2-41BD-8552-68347BFCCC3F

Holotype. Adult female ( LSUHC 14066 ) collected on 4 November 2018 in proximity of a stream below the Kyaiktiyo Pagoda, Mon State, Myanmar (97.099379 N, 17.478863 E, 1033 m in elevation) by Perry L. Wood, Jr., Myint Kyaw Thura, L. Lee Grismer, Jamie R. Oaks, Evan S.H. Quah, and Aung Lin.

Paratype. Sub-adult male ( LSUHC 14067 ) bearing the same collection data as the holotype .

Diagnosis. Ansonia kyaiktiyoensis sp. nov. is recognised as a member of the genus Ansonia based on the molecular phylogenetic analyses ( Fig. 1 ) and a combination of the following morphological characters: small body size (maximum SVL 24.0 mm in males and females); long slender limbs bearing long slender digits with bulbous tips; absence of parotoid glands; weak subarticular tubercles; and membranous foot webbing ( Chan et al. 2014; Davis et al. 2016; Grismer et al. 2016; Inger 1960, 1966, 1992; Wilkinson et al. 2012). It can be differentiated from all congeners by the following combination of characters: SVL 24.0 mm in the single male and female; snout projecting beyond lower jaw; tympanum visible; absence of interorbital and tarsal ridges; first finger shorter than second; finger and toe tips bulbous; approximately 1.5 phalanges free of web on fifth toe; presence of a yellow rictal tubercle at the angle of jaw; distinct dorsal tubercles; abdomen coarsely granular; absence of oblique flaps of skin on each side of vent; absence of wide, light-coloured patch below eye; presence of light-coloured interscapular spot; presence of large, discrete, bright-yellow submandibular spots; presence of markings on the snout consisting of streaks below the eye to the lip, and on the canthus rostralis to the nostril; dorsum grey-brown with a dark-brown, X-shaped marking on the back surrounding the interscapular spot; dark coloured markings on the rump; dorsum and flanks covered in orange-beige spots; a thin, dark dorsolateral stripe; iris yellow-gold; fore and hind limbs bearing orange-beige crossbars; and venter light-grey with yellow spots, especially near the flanks and the underside of the hind limbs.

Description of holotype. Adult female, SVL 24.0 mm; head longer than wide (HL/ HW =1.04); snout shorter than wide (SL/ SW =0.89), projecting beyond lower jaw, dorsally convex with a midline depression, truncate in dorsal view, truncate and sloping in lateral view; canthus rostralis distinct, lores vertical, slightly concave; nares open laterally just below canthus, nearly terminal on snout; distance between nares smaller than snout length ( IND /SL=0.62) and snout width ( IND / SW =0.55); eyes large, slightly protruding beyond labials in dorsal view, diameter less than snout length ( ED /SL=0.64) and interorbital distance ( ED / IOD =0.76); pupils horizontal; interorbital region flat, distance smaller than snout width ( IOD / SW =0.75) and snout length ( IOD /SL=0.85); tympanum distinct, oval, taller than wide, with horizontal axis less than eye diameter ( TD / ED =0.39); choanae subcircular, separated by a distance larger than their diameter; vomerine ridge and teeth absent; tongue narrow, ending in median point, posterior one-half free.

Forelimbs and fingers long and slender; finger length from shortest to longest: I<II<IV<III; basal webbing not extending beyond proximal subarticular tubercle; fingertips bulbous, slightly dilated but not forming discs; subarticular tubercles indistinct; inner and outer metacarpal tubercles distinct, oval, raised, inner smaller than outer; supernumerary tubercles absent. Hind limbs and toes long and slender (CL/ SVL =0.42), foot shorter than tibia ( PL / CL=0.75); toe length from shortest to longest: I<II<V<III<IV; webbing formula: I ½–1.5 II ½– 3 III 1.5– 3 IV 3–1.5 V; toe tips bulbous, slightly dilated but not forming discs; subarticular tubercles indistinct; inner metatarsal tubercle oval, slightly raised; outer metatarsal tubercle raised, rounded, slightly smaller than inner.

Upper eyelid, interorbital region, dorsal part of snout and canthus covered with small, flat tubercles bearing brown, keratinized tips; interorbital ridges absent; few randomly dispersed tubercles present on lores; single row of small spinules on upper lip and outer margin of upper eyelid; rictal tubercle at the corner of the jaw; supratympanic fold and parotoid gland absent; back, flanks and dorsal part of limbs bearing irregularly spaced large and small tubercles bearing brown keratinized spinules, larger tubercles often have more than one spinule; concentration of larger tubercles above tympanum and in scapular region forming an indistinct dorsolateral row posterior to eye and tympanum, extending to insertion of hind limbs; a series of brown or white conical, keratinized tubercles along edges of underside of mandible that are most dense near snout and corners of jaw, becoming randomly distributed in gular region; abdomen coarsely granular; all ventral surfaces except for manus and pes covered with coarse, evenly spaced tubercles, and the tubercles are largest and most dense on abdominal region of flanks and underside of thigh, becoming more finely granular in pectoral and gular regions; ventral and lateral surfaces of limbs bearing randomly distributed large and small conical tubercles, most terminating in keratinized tips. All measurements of the type series are presented in Table 4 .

Colouration in life ( Fig. 2A & 3 ). Dorsum and flanks grey-brown and peppered with orange-beige spots; a dark-brown, X-shaped marking on the back starting behind the eyes and the lower arms of the X bordering the light- coloured, orange-beige insterscapular spot; another dark-brown arched marking across the sacrum that joins with the dark, posterior border of the interscapular spot on the midline of the back; and another dark-coloured marking on the urostyle; a narrow dorsolateral stripes runs from the posterior corner of the eyes, above the tympanum and ap- proximately halfway down the body between the forelimb and hind limb insertions before arching along the flanks to the anterior margin of the hind limb at its insertion point on the body; tips of tubercles on the dorsum and flanks orange-beige; colour of the iris is yellow-gold; a dark-coloured streak extends from below the eye to the lips, and another from the canthus rostralis to the nostril; yellow rictal tubercle at the corner of the jaw present; fore and hind limbs with orange-beige crossbars; venter light-grey with yellow spots that are more prominent on the flanks and the underside of the thighs; large, discrete, bright-yellow submandibular spots along the underside of lower jaw.

Colouration in preservative. Dorsum and flanks grey with lighter grey interscapular spot and dull orange- brown tubercles; markings on back and flanks dark-grey; venter light-grey with the yellow spots of the venter and submandibular spots turning cream.

Variation ( Fig. 3 ). The paratype closely resembles the holotype in most aspects of colouration and morphology except for having more prominent yellow spotting on the underside of the jaws and venter that forms a reticulated pattern on the flanks and underside of the thighs. Similar to the holotype, it has the prominent markings on the snout that consist of streaks below the eye to the lip, and on the canthus rostralis to the nostril ( Fig 4B ). Measurements are presented in Table 4 .

14067

Distribution ( Fig. 5 ). Ansonia kyaiktiyoensis sp. nov. is only known from the forested hills ( Fig. 2B ) near the Kyaiktiyo Pagoda in Mon State, Myanmar.

Natural history. The holotype and paratype were collected at night between 2000–2200 h in hill forest approximately 15–20 meters away from a stream. Both specimens were found sitting on top of leaf litter along the trail. The female holotype was not gravid and the male paratype did not possess any secondary sexual characteristics (nuptial pads, distended vocal sacs, etc.), which indicates that the month of November may be outside the breeding season for the species. Other species of anurans found in the vicinity were Megophrys sp., Sylvirana nigrovittata , Ingerana cf. tenasserimensis , Limnonectes cf. limborgi , L. cf. taylori, Philautus sp., Polypedates cf. leucomystax and Rhacophorus bipunctatus .

Etymology. The specific epithet kyaiktiyoensis is in reference to the type locality of this species near the Kyaiktiyo Pagoda.

Comparison. Ansonia kyaiktiyoensis sp. nov. is distinguished from A. mcgregori (Taylor) and A. muelleri (Boulenger) by the presence of a visible tympanum. From A. fuliginea (Mocquard) , A. guibei Inger , and A. latidisca Inger it can be distinguished by its snout projecting beyond the lower jaw. Ansonia kyaiktiyoensis sp. nov. can be distinguished from A. glandulosa Iskandar & Mumpuni , A. latidisca , A. latirostra Grismer, A. mcgregori , A. vidua Hertwig, Pui, Haas & Das and some specimens of A. leptopus , A. longidigita and A. spinulifer (Mocquard) by the absence of interorbital tubercle ridges. It can be further differentiated from A. leptopus and A. longidigita along with A. glandulosa , A. guibei , A. latiffi Wood, Grismer, Ahmad & Senawi , A. platysoma Inger and A. spinulifer by the tip of its first finger not reaching the disc of the second finger. The absence of a tarsal ridge in A. kyaiktiyoensis sp. nov. differentiates it from A. albomaculata Inger , A. jeetsukumarani Wood, Grismer, Ahmad & Senawi , A. khaochangensis Grismer, Wood, Aowphol, Cota, Grismer, Murdoch, Aguilar & Grismer , A. latiffi , A. mcgregori , A. minuta , A. muelleri and A. penangensis . Finger tips that are bulbous versus expanded and spatulate differentiate A. kyaiktiyoensis sp. nov. from A. hanitschi , A. latidisca , A. minuta Inger , A. platysoma , A. torrentis Dring and A. vidua . The absence of an enlarged row of dorsolateral tubercles in Ansonia kyaiktiyoensis sp. nov. differentiates it from A. echinata Inger & Stuebing , A. glandulosa , A. latirostra , A. pilokensis Matsui, Khonsue & Panha , A. spinulifer , A. thinthinae and some specimens of A. guibei and A. lumut Chan, Wood, Anuar, Muin, Quah, Sumarli & Grismer. The coarsely granular abdomen of A. kyaiktiyoensis sp. nov. differentiates it from A. echinata , A. latiffi , A. longidigita , A. lumut , A. phuketensis Matsui, Khonsue & Panha , A. siamensis Kiew and A. vidua .

The presence of large, discrete, bright-yellow, submandibular spots along the underside of the lower jaw ( Fig. 3B ) distinguishes A. kyaiktiyoensis sp. nov. from all its congeners except the Thai and Burmese species; A. inthanon , A. pilokensis , A. phuketensis , A. siamensis and A. thinthinae . The presence of a light spot between the scapulae further differentiates A. kyaiktiyoensis sp. nov. from A. albomaculata , A. echinata , A. fuliginea , A. guibei , A. hanitschi Inger , A. khaochangensis , A. latidisca , A. leptopus , A. longidigita , A. mcgregori , A. minuta , A. meulleri , A. platysoma , A. sia- mensis, A. tiomanica Hendrickson , A. torrentis , A. vidua and some specimens of A. endauensis Grismer , A. latirostra , A. lumut , A. penangensis Stoliczka and A. smeagol Davis, Grismer, Klabacka, Muin, Quah, Anuar, Wood & Sites. The yellow-gold coloured iris further separates it from A. endauensis , A. jeetsukumarani , A. khaochangensis , A. latidisca , A. latiffi , A. latirostra , A. lumut , A. mcgregori , A. muelleri , A. penangensis , A. smeagol , A. teneritas Waser, Schweizer, Haas, Das, Jankowski, Pui & Hertwig , A. tiomanica , A. torrestis and A. vidua that have iris colours ranging from reddish gold to black. The absence of a wide, light-coloured patch below the eye separates A. kyaiktiyoensis sp. nov. from A. albomaculata , A. pilokensis , A. phuketensis , A. teneritas , A. thinthinae and some specimens of A. endauensis , A. hanitschi , A. kraensis , A. latirostra , A. malayana Inger , A. minuta , A. penangensis , A. platysoma and A. tiomanica .

Ansonia kyaiktiyoensis sp. nov. most closely resembles A. kraensis and A. inthanon in morphology but can be distinguished from the former by having yellow spots and blotches on the venter that are especially prominent near the flanks ( Fig. 3B ) as opposed to the venter being silvery white and mottled in dark-brown ( Matsui et al. 2005: Fig. 1B ). From its sister species A. inthanon , it can be distinguished by the presence of dark markings on the snout and lips ( Fig. 4 ), a dark dorsolateral stripe, and less extensive webbing on the toes ( Table 3 ; Matsui et al. 1998). A. kyaiktiyoensis sp. nov. differs from A. inthanon in the number of free phalanges on the second toe (0.5–1.5 vs. 0.5–1); third toe (1.5–2.5 or 3.0 vs. 0.5–2.00); fourth toe (3 vs. 2.66–2.75); and fifth toe (1.5 vs. 0.5) ( Table 4 & 5 ). Other diagnostic characters that separate Ansonia kyaiktiyoensis sp. nov. from the other nominal species of Ansonia are summarized in Table 5 .

Figures

FIGURE 1. Maximum likelihood (ML) phylogram for species of the genus Ansonia. Nodal support is indicated by Bayesian posterior probability (BPP) / Ultrafast bootstrap (UFBOOT). Black circles represent nodes supported by a BPP and UFB of 1.00 and 100, respectively. Blue node indicates the Thai-Malay Peninsula clade and red node indicates the Thai-Burmese clade. Species outside of the Thai-Malay Peninsula clade are represented by single tip labels for their lineages.

FIGURE 2. (A) Paratype of Ansonia kyaiktiyoensis sp. nov. (LSUHC 14067). (B) Hill forest habitat of Ansonia kyaiktiyoensis sp. nov. at Kyaiktiyo, Mon State, Myanmar.

FIGURE 3. Dorsum (A) and venter (B) of type series of Ansonia kyaiktiyoensis sp. nov. Paratype (LSUHC 14067) on the left and holotype (LSUHC 14066) on the right.

FIGURE 4. (A) Calling adult male Ansonia inthanon from Doi Inthanon, Chiang Mai, Thailand. (B) Close-up of head of para- type of Ansonia kyaiktiyoensis sp. nov. (LSUHC 14067). Note the markings on the snout and under the eye as indicated by the arrows. (C) Close-up of head of A. inthanon from Doi Inthanon, Chiang Mai, Thailand. Note the absence of markings on the head. (Photographs by Ian Dugdale [A & C] and Evan Quah [B]).

FIGURE 5. Distribution of Ansonia species along the Myanmar-Thai border and the type locality of Ansonia kyaiktiyoensis sp. nov. Star = type locality.