Bioacoustics of Sigalegalephrynus gayoluesensis

Distribution and natural history. Sigalegalephrynus gayoluesensis sp. nov. is known only from rain forest flanking a stream adjacent to the Takengon-Blangkejeren road above the village Kenyaran Pantan Cuaca, in the Gayo Lues Regency of the province of Aceh , between 1787 and 1796 m a.s.l. ( Fig. 3 ). Both the holotype and paratype were found calling on broad smooth leaves, at 1.6 m and 3.8 m above ground, respectively. The call of the holotype was recorded. The call sounded similar to that of S. mandailinguensis at the time of recording. Both the holotype and paratype weighed 1.27 g . Our smallest juvenile of this species ( UTA A-65789) was less than 1 cm (SVL 8.0 mm) in SVL and weighed 0.05 g .

Description of holotype and variation of paratypes (in parenthesis). Body moderately robust; head longer than wide, HL/HW =1.14 (1.11, 1.07, 1.02); head length 33% (34%, 31%, 34%) of SVL; head width 29% (31%, 29%, 33%) of SVL; snout length 10% (10%, 10%, 11%) of SVL; canthus rostralis concave; loreal area without tubercles, concave; eye length 10% (12%, 10%, 9%) of SVL; pupil circular; snout truncate in dorsal view, protruding in lateral view, sloping back towards mouth; tympanum distinct and rounded, with annulus, but not surrounded by large tubercles; interorbital space flat; cranial crests absent; no teeth in jaws; tongue tip oval shaped and longer than wide; skin of dorsum finely shagreened, with few large and scattered tubercles; tubercles rounded, without keratinization; no dorsolateral, paravertebral, or occipital folds; skin on venter smooth with anastomosis; circumcloacal region is golden yellow. Arms robust; forearm length 31% (33%, 25%, 26%) of SVL; hand length 30% (31%, 26%, 27%) of SVL; relative length of Finger—I<II<IV<III; fingertips truncated and dilated; hands rudimentary webbed, hand webbing formula: I0-11/2II1-21/2III21/2-21/3IV (I[0]-[12/3–2]II[1–11/2]-[2–21/2]III[2–21/2]-[2–21/2]IV); skin of forearm with moderately developed tubercles; finger I with moderately developed inner metacarpal tubercle, smaller than the outer metacarpal tubercle; each finger with one poorly developed round subarticular tubercle; nuptial pads brownish-dark, glandular, dorsomedially extended; spicules of nuptial pads with black keratinized spicules. Thigh length 45% (44%, 44%, 44%) of SVL; tibia length 40% (43%, 39%, 41%) of SVL; tarsal length 25% (25%, 21%, 20%) of SVL; foot length 41% (42%, 42%, 39%) of SVL; relative lengths of toes—I<II<III<V<IV; toes bearing large pads; feet with moderate webbing ( Fig. 6B ), webbing formula for the feet: I0-1/2II0-1III1- 21/2IV23/4-2V (I[0]-[0–1/2]II[0]-[1]III[0–1/2]-[21/2]IV[21/2]-[12/3–2]V); heels without tubercles; inner and outer metatarsal tubercle moderately developed and elongate. Measurements (in mm). Holotype followed by paratype in parenthesis: SVL 26.49 (25.65, 26.07, 27.36); HL 8.72 (8.84, 8.06, 9.20); HW 7.67 (7.98, 7.53, 9.0); SNL 2.75 (2.5, 2.55, 3.0); ICD 4.30 (4.50, 4.50, 4.56); IND 2.20 (1.80, 2.0, 2.0); END 1.7 (1.8, 1.55, 2.12); NSD 0.25 (0.5, 0.5, 0.7); IOD 3.0 (3.5, 3.5, 4.0); EL 2.70 (3.0, 2.55, 2.55); TML 1.50 (1.55, 1.6, 1.47); FAL 8.24 (8.40, 6.5, 6.5); HAL 7.89 (7.86, 6.67, 7.5); THL 11.83 (11.34, 11.53, 12.07); TBL 10.68 (10.95, 10.29, 11.23); TRL 6.63 (6.48, 5.50, 5.50); FTL 10.83 (10.86, 10.90, 10.80); OMCL 1.0 (1.0, 10, 1.0); OMCW 1.0 (1.0, 1.0 1.0, 1.0); IMCL 0.75 (0.75, 0.65, 0.60); IMCW 0.50 (0.50, 0.50); IMTL 1.0 (1.0, 1.0, 1.0); IMTW 1.0 (1.0, 1.0, 1.0); F1L 1.5 (1.5, 1.5, 1.5); F2L 2.30 (2.25, 2.35 2.45); F3L 4.0(3.5, 3.5, 3.2); F4L 3.5 (3.0, 2.6, 2.55); T1L 2.0 (1.5, 1.5, 1.6); T2L 2.5 (2.0, 2.0, 2.0); T3L 3.2 (3.0, 3.3, 2.5); T4L 5.5 (5.0, 5.0, 4.5); T5L 4.0 (3.5, 3.5, 3.3); F3PD 1.25 (1.2, 1.0, 1.3); F3PB 1.0 (1.0, 0.9, 1.0). Color of holotype in life. ( Figs. 2D, 2E, 2F ). Dorsum predominantly brown, with suprascapular dark brown diamond-shaped marking encircled by light brown; flanks with alternate wide dark brown and narrow white stripes; wide whitish light-brown spot below eye; lore dark brown, with small light brown spot adjacent to anterior of orbit; iris golden yellow, heavily reticulated; dorsum of limbs dark brown, with dark-brown crossbars; large white tubercles present at point of posterior mandibular articulation; abdominal surface pink, with dark brown maculation; throat pinkish, with no maculation; underside of limbs pink, with dark brown maculation; iris golden yellow, with black reticulations. Color of holotype in preservative. In alcohol, pinkish coloration turned grey and venter whitish grey, maculated with dark brown blotches. Advertisement call. The call of the male holotype was recorded in the field and before collection. Ambient temperature at the time of recording was 17.2 ºC. The call is composed of 179 highly modulated notes given 0.245 seconds apart, on average (range, 0.140 –0.907 seconds, SD ± 0.148 seconds). On average, each note is 0.049 seconds (range, 0.24–0.93, SD ± 0.18 seconds) in length and is composed of one distinct pulse. The average fundamental and dominant frequencies of the vocalization are 2474.361 (range, 2368.652–2627.051 Hz, SD ± 85.86 Hz) Hz and 4948.722 Hz (range, 4737.305–5254.102 Hz, SD ±171.7309 Hz) respectively ( Fig. 7 ). Comparisons. Sigalegalephrynus gayoluesensis sp. nov. is likely restricted to the mountains of the Gayo Lues Regency of Aceh , Sumatera , and does not exist in sympatry with any other congener. Sigalegalephrynus gayoluesensis sp. nov. can be easily distinguished from S. mandailinguensis , S. minangkabauensis and S. harveyi sp. nov. by its smooth tubercles on the body (vs. sharp-tipped warty tubercles) and a diamond shaped marking on the dorsum (vs. hourglass in S. mandailinguensis , S. minangkabauensis and S. harveyi sp. nov. , no hourglass or diamond shape mark in S. burnitelongensis sp. nov. ). Sigalegalephrynus gayoluesensis sp. nov. can also be distinguished from S. burnitelongensis sp. nov. by its black anastomotic maculated throat and abdomen (vs immaculate throat and abdomen). Acoustic data is limited for Sigalegalephrynus species, the call of the holotype of S. gayoluesensis sp. nov. , differs from that of S. mandailinguensis in duration ( 46.448 s vs 17.27 s ), total number of notes (179 vs 62), notes per second (4 vs 6–7), average note length ( 0.49 s vs 0.029 s ), average pause length between notes ( 0.245 s vs 0.012 s ), and dominant frequency (4948.722 Hz vs 3400 Hz) ( Fig 5 ).