Sigalegalephrnnus mandailinguensis, Smart & Sarker & Arifin & Harvey & Sidik & Hamidy & Kurniawan & Smith, 2017

Smart, Utpal, Sarker, Goutam C., Arifin, Umilaela, Harvey, Michael B., Sidik, Irvan, Hamidy, Amir, Kurniawan, Nia & Smith, Eric N., 2017, A New Genus and Two New Species of Arboreal Toads from the Highlands of Sumatra with a Phylogeny of Sundaland Toad Genera, Herpetologica 73 (1), pp. 63-75 : 63-75

Sigalegalephrŋnus mandailinguensis sp. nov.

Holotype. —Museum Zoologicum Bogoriense Amphibian Collection, MZB 25736 (field number ENS 15697; Fig. 3 ), an adult male from above the village of Sibanggor Tonga on the northeast slope of Gunung Sorikmarapi , Kecamatan Panyabungan Selatan , Kabupaten Mandailing Natal , Provinsi Sumatera Utara, Indonesia, 0.70164°N, 99.55262°E, 1383 m (in all cases, datum ¼ WGS84), collected by U. Smart, I. Sidik, and E.N. Smith on 25 January 2014.

Paratypes (3). — UTA 63561 (field number ENS 16709), adult male from trail between the Tano Bato to Sapo Tinjak road and Lake Saba Begu , Batang Gadis National Park , Kecamatan Batang Natal , Kabupaten Mandailing Natal, Provinsi Sumatera Utara, Sumatra, Indonesia 0.70845°N, 99.51899°E at 1299 m . UTA 63562 (field number ENS 16936) and MZB 25737 (field number ENS 16937), adult males from the same locality as previous paratype but at 1297 m 0.70866°N, 99.51953°E. All paratypes collected by U. Smart, S. Handayani, and I. Sidik on 26 January 2014.

Diagnosis. —The following combination of characters is unique to Sigalegalephrŋnus mandailinguensis : (1) This medium-sized (males 30.6–38.0 mm SVL) slender toad lacks parotoid glands. (2) The tympanum is visible. (3) The nares are closer to the tip of the snout than to the eye. (4) The fingertips are truncated and expanded. (5) The toe tips are truncated but not expanded. (6) The webbing is rudimentary in the hands and moderate in the feet. (7) The dorsal coloration consists of white and brown with a thin stripe extending from the tip of the snout to the vent at midline. (8) A dark band above orbits is joined medially, and extends as an interrupted medial track to the sacrum. (9) Alternate black–dark brown and white marks on the upper lip. (10) The flanks have a stroke of brown extending from the orbit to the inguinal area. (11) The dorsal surface is moderately tuberculate. (12) The surface of the abdomen is uniformly tuberculate, with small, smooth, and round tubercles.

Description of holotype and variation. — Holotype (adult male) followed by variation of three adult male paratypes in parentheses (UTA 63561; UTA 63562; MZB 25737). The specimen has SVL of 38.0 mm (30.6, 32.29, 32.75); head length 11.34 mm (9.5, 9.73, 10.19); head width 11.3 mm (9.65, 10.27, 10.22); snout length 5.0 mm (4.0, 3.6, 3.5); internarial distance 3.0 mm (2.5, 2.68, 2.75); eye length 3.3 mm (2.8, 3.1, 3); interocular distance 4 mm (3.5, 3.5, 3.7); intercanthal distance 5.7 mm (4.4, 5.0, 5.5); tympanum width 2.1 mm (1.5, 1.8, 1.8); hand length 11.2 mm (9.4, 9.1, 9.8); forearm length 11.5 mm (10, 9.6, 10.3); femur length 15.85 mm (13.46, 12.88, 13.38); tibia length 17.0 mm (13.86, 13.1, 14.02); tarsus length 9.0 mm (7.3, 7.2, 7.5); foot length 16.37 mm (13.58, 13.04, 13.68); width of fingertip pads for Finger I 0.10 mm (0.09, 0.08, 0.09), Finger II 0.13 mm (0.11, 0.10, 0.11), Finger III 0.14 mm (0.11, 0.11, 0.13), Finger IV 0.14 mm (0.10, 0.11, 0.13); width of toe pads for Toe I 0.09 mm (0.07, 0.07, 0.07), Toe II 0.09 mm (0.08, 0.08, 0.08), Toe III 0.11 mm (0.08, 0.08, 0.09), Toe IV 0.12 mm (0.09, 0.09, 0.10), Toe V 0.12 mm (0.09, 0.09, 0.11).

Body slender; head almost as long as wide; head length 30% (31%, 30%, 31%) of SVL; head width 30.0% (32%, 32%, 31%) of SVL; snout length 13% (13%, 11%, 11%) of SVL; canthus rostralis concave; loreal area slightly tuberculate and concave; eye length 8.7% of SVL; pupil horizontal; snout slightly sloping back toward mouth; snout mucronate and with prominent median keel, in dorsal view; tympanum distinct, with moderately developed supratympanic fold; interorbital space flat; cranial crests absent; no teeth in jaws; tongue tip oval-shaped and longer than wide; skin of dorsal surfaces rough to finely shagreen with few large, scattered tubercles; tubercles small, rounded, and almost without keratinization; no dorsolateral, paravertebral, or occipital folds; skin on venter smooth with very fine warts; forearm length 30.3% (32.7%, 29.7%, 31.5%) of SVL; hand length 29.5% (30.7%, 28.2%, 29.9%) of SVL; relative length of Finger I <II <IV <III; fingers bearing large, expanded pads; webbing formula for hand: I1 3 / 4 –2II1 3 / 4 –2 1 / 2 III2 1 / 3 – 2IV (I[2–2], [2–2], [13 / 4 –2] II[13 / 4 – 21 / 2], [13 / 4 – 21 / 2], [13 / 4 – 2 1 / 2]III[2 1 / 5 –2 1 / 5], [2 3 / 4 –2], [2 1 / 2 –2 1 / 4]IV); skin of forearm with tubercles; Finger I with elongate inner metacarpal tubercle, as large as outer metacarpal tubercle; each finger with one poorly developed round subarticular tubercle; nuptial excrescence brownish-dark, glandular, and dorsomedially extended with keratinized spicules present at the base of Finger I; femur length 41.7% (44%, 39.9%, 40.9%) of SVL; tibia length 44.8% (45.3%, 40.6%, 42.8%) of SVL; tarsal length 23.7% (23.9%, 22.3%, 22.9%) of SVL; foot length 43.1% (44.4%, 40.4%, 41.8%) of SVL; relative lengths of toes I <II <III <V <IV; toes bearing large pads; feet with moderate webbing, webbing formula for the feet: I0– 1 1 / 3 II0–1 3 / 4 III2–2 1 / 5 IV2 1 / 5 –1 2 / 3 V (I[0–1], [1–1 1 / 2], [0– 1 1 / 4]II[1–2], [1–2], [1–2]III[1 1 / 3 –3], [1 1 / 2 –2 1 / 3], [1– 2 3 / 4]IV[2 2 / 3 –2], [2 2 / 3 –1 2 / 3], [2 2 / 3 –1 3 / 4]V); heels without tubercles; inner metatarsal tubercle moderately developed and elongate; outer metatarsal tubercle absent; one moderate subarticular tubercle present at the base of first phalanx on each toe; toes without toe pads.

Color in life. —Distinct light brown spot on each side of lore and distinct whitish spot on upper jaw just below posterior end of orbit; dorsum brown with light chamoisbrown-colored hourglass marking; distinct darker spots dorsolateral of sacral and iliac joint; alternate black and brown bands on dorsal side of limbs; in lateral flanks, skin with distinct blackish stripe extending from posterior end of eyes through top of humeral–ulnar joint to inguinal area; short, black dorsal stripe on each side of pubic junction; venter yellowish-white maculated with black blotches; chest and ventral surface of limbs light tea-rose orange with few sparsely located yellowish dots; tips of fingers and toes tearose orange-colored without dots; iris bright gold with black reticulations.

Color in preservative. —In preservative the color of the animal differs slightly from that in life. The dorsum has a very light hourglass marking. The venter is whitish grey maculated with dark brown blotches.

Etymology. —The specific epithet is an adjective referring to the Mandailing Batak ethnic region and Kabupaten (regency) where the new species was found.

Common name. —Mandailing Puppet Toads.

Distribution and natural history. — Sigalegalephrŋnus mandailinguensis is known only from rainforests on the slopes of Gunung Sorikmarapi in southern Sumatera Utara from 1297 m to 1383 m ( Figs. 4 and 5 ). The holotype was found at 1830 h inactive on a cave wall, ~ 2 m from the entrance and below ground level. The paratypes were active on vegetation 0.5 m, 2 m, and 3 m (on a liana) above ground between 1930 and 2115 h. The two individuals higher above the ground were vocalizing using a series of high-pitched ticks. The holotype weighed 2.5 g, and the paratypes 1.4, 1.7, and 1.8 g.

Call. —The advertisement call of Sigalegalephrynus mandailinguensis is best described as a rapid succession of regularly placed, shrill ticks. A single call 17.27 s in length was recorded at 2156 h. The call begins with infrequent, lowamplitude ticks, which progressively get louder and attain a uniform pulse rate during the main calling period that, in our recording, lasted ~ 15 s. During this time, the tonal pulses were organized in a discreet series repeated at a moderately high rate of 6 times/s. Each individual pulse lasted about 29 ± 4 ms ( Fig. 6 ) intersected by pauses ~ 12 ± 9 ms long. These pulses were relatively narrow band (<500 Hz). The average dominant frequency of pulses was 3.4 ± 0.04 Hz.

Figures

FIG. 3.—(A) Lateral, (B) dorsal, and (C) ventral view of the adult male holotype of Sigalegalephrŋnus mandailinguensis from Gunung Sorikmarapi, Sumatera Utara Province, Sumatra (MZB 25736). A color version of this figure is available online.

FIG. 4.—Map of Sumatra with topographical relief showing localities where members of the new genus of toad (Sigalegalephrŋnus) were found.

FIG. 5.—Habitat of Sigalegalephrŋnus mandailinguensis—a view of the rainforest at the edge of an inactive solphatara field on the northeastern slope of Gunung Sorikmarapi where the holotype was found (upper); and first author at the entrance of the subterranean hollow where the holotype was collected (lower).

FIG. 6.—Advertisement call of Sigalegalephrŋnus mandailinguensis. (A) oscillogram (relative amplitude vs. time) and (B) spectrograms (energy in each frequency vs. time) of a single pulse; (C) power spectra. A color version of this figure is available online.