Philautus nianeae, Stuart, Bryan L., Phimmachak, Somphouthone, Seateun, Sengvilay & Sheridan, Jennifer A., 2013

Stuart, Bryan L., Phimmachak, Somphouthone, Seateun, Sengvilay & Sheridan, Jennifer A., 2013, A new Philautus (Anura: Rhacophoridae) from northern Laos allied to P. abditus Inger, Orlov & Darevsky, 1999, Zootaxa 3745 (1), pp. 73-83 : 75-80

Philautus nianeae sp. nov.

Holotype. NCSM 80038 (field tag BLS 15379), adult male ( Figure 2 ), Laos, Vientiane Province, Xaysomboun District, Nam Ngum River, 19.01807°N 102.87633°E, 490 m elev., coll. 10 May 2012 by Bryan L. Stuart, Somphouthone Phimmachak, and Niane Sivongxay.

Paratypes. Seven adult males: NUOL 0 0 0 0 4, NCSM 80039–41, same locality as holotype except 19.01622°N 102.87688°E, 493 m elev., coll. 11 May 2012. NCSM 80042, same data as holotype except Houay Men Stream, tributary of Nam Pha River, 19.04507°N 102.89150°E, 548 m elev., coll. 14 May 2012. NCSM 80043, same data as holotype except Houay Men Stream, tributary of Nam Pha River, 19.04620°N 102.89136°E, 530 m elev., coll. 14 May 2012. NCSM 80044, same data as holotype except Houay Men Stream, tributary of Nam Pha River, 19.04532°N 102.89143°E, 553 m elev., coll. 15 May 2012.

One adult female: NCSM 80690, Laos, Bolikhamxay Province, Viengthong District, Nam Kading National Protected Area, 18.42195ºN, 104.42139ºE, 471 m elev., coll. 3 March 2013 by Bryan L. Stuart, Niane Sivongxay, Sengvilay Seateun, and Jennifer A. Sheridan. Three juveniles: NCSM 80691, NUOL 0 0 0 11, same data as NCSM 80690. NCSM 80689, same data as NCSM 80690 except 18.42290ºN 104.42210ºE, 488 m elev., coll. 2 March 2013.

Three adult males: NCSM 80926, Laos, Khammouan Province, Boualapha District, Nakai-Nam Theun National Protected Area, Phou Ack Mountain, 17.64466ºN 105.73521ºE, 972 m elev., coll. 12 May 2013 by Bryan L. Stuart, Somphouthone Phimmachak, and Jennifer A. Sheridan. NCSM 80927, same data as NCSM 80926 except 17.64425ºN 105.73526ºE, 979 m elev., coll. 13 May 2013. NUOL 0 0 0 12, same data as NCSM 80926 except 17.64516ºN 105.73626ºE, 974 m elev., coll. 14 May 2013.

Etymology. The specific epithet is a matronym for Dr. Niane Sivongxay, Professor of Biology at the National University of Laos, co-collector of the species, and cherished friend and colleague of the authors.

Diagnosis. The new species is assigned to Philautus on the basis of its very close morphological similarity, and likely sister taxon relationship, to P. abditus , a species that is phylogenetically nested within a clade containing the generotype P. aurifasciatus (Schlegel 1837) (see Li et al. 2009; Pyron & Wiens 2011; Hertwig et al. 2012). The new species is a medium-sized Philautus having males with SVL 23.8–28.4, female with SVL 27.4; smooth skin, without spines or tubercles; tympanum completely hidden under skin; no nuptial pads; no dermal fringes or tubercles on limbs; extensive webbing on the foot; bronze iris; light-colored dorsal surfaces of discs on fingers and toes; ventral surfaces light gray with dark spotting; and large black spots on light background in inguinal region and hidden surfaces of hind limb.

Description of holotype. Habitus stocky. Head length subequal to head width. Snout rounded in dorsal and lateral views, a feeble prominence at tip; nostril as vertical slit, much closer to tip of snout than to eye, internarial shorter than interorbital distance; canthus rostralis distinct, rounded, constricted behind nares; lores oblique, concave; eye diameter greater than snout length, interorbital distance greater than upper eyelid width; tympanum not visible, hidden under skin; dentigerous process of vomer and vomerine teeth absent; choanae oval, separated by a distance equal to approximately four times horizontal diameter of choanae; tongue heart-shaped, deeply notched posteriorly.

Forelimb slender. Finger tips with round discs having circummarginal grooves; fingers moderately slender; relative finger lengths I <II <IV <III; outer three fingers with rudiment of web at base; subarticular tubercles conspicuous, surfaces rounded, formula 1, 1, 2, 2; two oval, outer palmar tubercles in contact, lateral largest, surfaces flat; oval, thenar tubercle, surface flat; round, indistinct supernumerary tubercles.

Hindlimb slender. Toe tips with round discs having circummarginal grooves, diameter of discs subequal to those of fingers; toes moderately slender; relative toe lengths I<II<III<V<IV; web on toe I and preaxial side of toe II to level of distal margin of subarticular tubercle, on postaxial side of toe II to base of tip, on preaxial side of toe III to level of proximal subarticular tubercle, on postaxial side of toe III to base of tip, on preaxial and postaxial sides of toe IV to level of penultimate subarticular tubercle and continuing as a fringe to base of tip, and on toe V to level of distal margin of subarticular tubercle; weak dermal fringe on outer margin of toe V from base of foot to base of tip; subarticular tubercles conspicuous, surfaces rounded, formula 1, 1, 2, 3, 2; inner metatarsal tubercle oval, surface flat; outer metatarsal tubercle absent.

Skin smooth dorsally and laterally; weak tubercles on dorsal surface of head and near vent; curved supratympanic fold; venter finely granular; no dermal fringes, flaps, or tubercles on limbs.

Nuptial pads absent; elongated vocal sac openings near corner of mouth; vocal sac median; testes mature.

Color of holotype in life. Iris bronze; white line extending from under eye to corner of mouth, with irregular white bars on upper lip; dorsum, flank, and dorsal surfaces of forelimbs, thigh and shank brown; indistinct black Xshaped marking on back extending to near groin; irregular black cross bar between eyelids; broad black crossbands on dorsal surfaces of limbs; axillary region white; inguinal region, anterior surface and poster surfaces of thigh, ventral surfaces of shank, and dorsal surface of foot white or light gray with large black spots, often formed by terminus of black crossband on limb; dorsal surfaces of discs on fingers and toes white and brown; throat, belly, and ventral surfaces of forelimb and thigh light gray with dark gray, brown and black spotting.

Color of holotype in preservative. Gray on throat and belly faded to light brown.

Variation. Paratypes closely resemble the holotype, varying mostly in the presence and number of large black spots on the ventral surface of the shank. The holotype, NCSM 80039, NCSM 80690, and NUOL 0 0 0 0 4 have one large black spot on each shank, NCSM 80926 has one spot on the right shank but none on the left, NCSM 80040 and NCSM 80043 have two spots on the right shank but none on the left, NCSM 80041 and NCSM 80927 have two spots on each shank, NUOL 0 0 0 12 has three spots on each shank, and NCSM 80042 and NCSM 80044 have none on either shank. A single female (NCSM 80690) with developing, pigmented ova is similar in size to mature males (Table 1). Measurements are summarized in Table 1.

Molecules: Ten paratypes of P. nianeae sampled among the three Laos localities (NCSM 80039, NCSM 80043–44, NCSM 80689–91, NCSM 80926–27, NUOL 00011–12) have uncorrected pairwise distances of 0.00– 0.97% in the 16S gene fragment, but have uncorrected pairwise distances of 2.77–3.26% in the same gene fragment to a near topotype of P. abditus from Gia Lai Province, Vietnam (ROM 33145), 3.49–3.78% to two specimens of P. abditus from Quang Nam Province, Vietnam (AMS R 171540–41) and 2.52–2.61% from a specimen of P. abditus from Ratanakiri Province, Cambodia (MVZ 258310; Table 2).

Advertisement call. Call description is based on a single recording of paratype NCSM 80926, recorded at 22.8º C ambient temperature, 88.8% relative humidity, and 902.0 hPa atmospheric pressure at 2000 h. The recording contained six calls with an inter-call interval of mean ± SD 49.38 ± 5.23 s. Calls consisted of two notes ( Figure 3 ). The first note had 1–3 (2 ± 0.89) pulses and the second note had 10–15 (12 ± 1.67) pulses. Pulse rate for the second note was 4.57 ± 0.07 pulses per second. Call duration was 4.15 ± 0.42 s, with dominant frequency of 2.6 ± 0.0 kHz for the first note, and 2.5 ± 0.1 kHz for the second note.

Distribution and natural history. Philautus nianeae is known from three localities in Vientiane, Bolikhamxay, and Khammouan Provinces in northern Laos ( Figure 1 ). In Vientiane Province, males were found during mid-May calling at night (2015–2130 h) on vegetation within 2 m of the ground and within 5 m of streams and riverbanks in disturbed semi-evergreen forest, sometimes mixed with bamboo, at 490–548 m elevation. In Bolikhamxay Province, a female and three juveniles were found during early March on rainy nights (1912–1952 h) 1 m above the ground on sapling leaves and palm fronds within 3 m of small rocky streams in semi-evergreen forest at 471–488 m elevation. In Khammouan Province, males were found during mid-May calling at night (2000– 2110 h) on vegetation 1.5–4 m above the ground in semi-evergreen mixed with pine forest near the edge of open grassland at 972–979 m elevation. The Nam Ngum River at the type locality in Vientiane Province is under concession for a hydroelectric power project, making the persistence of the species at the type locality uncertain.

Comparisons. The combination of having a hidden tympanum and large black spots on hidden surfaces of the hind limbs distinguishes P. nianeae from all other species of Philautus except P. abditus . Philautus nianeae differs from P. abditus by having a bronze iris ( P. abditus with red iris); the throat, belly, and ventral surfaces of forelimb and thigh light gray with dark spotting ( P. abditus with throat, belly, and ventral surfaces of forelimb and thigh dark gray or black); considerably less contrast between large black spots and light background in inguinal region and hidden surfaces of hindlimbs ( P. abditus having strongly contrasting large black spots with sharp borders on an immaculate white background in inguinal region and hidden surfaces of hindlimbs); and light-colored dorsal surfaces of discs on fingers and toes ( P. abditus with dark-colored dorsal surfaces of discs on fingers and toes).

Two additional species of Philautus occur in the vicinity of Laos, P. maosonensis Bourret 1937 from northern Vietnam and P. cardamonus Ohler, Swan & Daltry 2002 from southwestern Cambodia. Philautus nianeae further differs from these two species by having smooth skin ( P. maosonensis males with distinct conical tubercles on head; Orlov et al. 2004), lacking yellow fingertips (present in P. maosonensis ; Bain & Nguyen 2004), lacking a greenish-yellow belly and ventral surface of limbs (present in P. cardamonus ; Ohler et al. 2002), and lacking nuptial pads (present in P. cardamonus ; Ohler et al. 2002). Theloderma petilum (Stuart & Heatwole 2004) new comb., known only by its female holotype from northern Laos, was provisionally placed in Philautus in its original description (as P. petilus ). However, this species is almost certainly related to a suite of species also having a slender habitus, dorsal dermal asperities, distinct tympanum, and no finger webbing, including T. nebulosum Rowley, Le, Hoang, Dau & Cao 2011 , T. palliatum Rowley, Le, Hoang, Dau & Cao 2011 , T. rhododiscus (Liu & Hu, 1962), and T. truongsonense (Orlov & Ho 2005), that have been recently placed (either as newly described species or transferred from Philautus ) into an expanded Theloderma Tschudi 1838 on the basis of molecular phylogenetic analyses (Yu et al. 2008; Rowley et al. 2011).

Figures

FIGURE 1. Map illustrating the type locality (white star) of Philautus nianeae sp. nov. in Xaysomboun District, Vientiane Province, Laos; the paratype localities (white circles) of P. nianeae sp. nov. in Viengthong District, Bolikhamxay Province, Laos and Boualapha District, Khammouan Province, Laos; the type locality (black star) of P. abditus in An Khe District, Gia Lai Province, Vietnam (Inger et al. 1999); and all other reported localities (black circles) of P. abditus in Kon Plong District, Kon Tum Province, Vietnam (Nguyen et al. 2009), Phuoc Son District, Quang Nam Province, Vietnam (this study), and Veunsai District, Ratanakiri Province, Cambodia (Stuart et al. 2010).

FIGURE 2. (A) Philautus abditus in life from Quang Nam Province, Vietnam. Photograph by J. J. L. Rowley. (B) Holotype NCSM 80038 of P. nianeae sp. nov. in life. Photograph by B. L. Stuart. (C) Paratype NCSM 80926 of P. nianeae sp. nov. in life. Photograph by B. L. Stuart. (D) Dorsal, (E) ventral, and (F) lateral views of holotype NCSM 80038 of P. nianeae sp. nov. immediately prior to preservation. (G) Dorsal and (H) ventral views of paratype NCSM 80042 of P. nianeae sp. nov. immediately prior to preservation. (I) Ventral view of P. abditus from Quang Nam Province, Vietnam immediately prior to preservation. Photograph by J. J. L. Rowley.

FIGURE 3. (Above) Waveform and (below) spectrogram of an advertisement call of paratype NCSM 80926 of Philautus nianae sp. nov. obtained during a 5 - minute recording at an ambient air temperature of 22.8 º C.