Allobates juami Simões & Gagliardi-Urrutia & Rojas-Runjaic & Castroviejo-Fisher 2018, sp. nov.

Allobates juami sp. nov.

Figures 2–7

Holotype. MCP 13287 (field code SCF 2027). An adult male collected by G. Gagliardi-Urrutia, F.J.M. Rojas- Runjaic, P.I. Simões and S. Castroviejo-Fisher on the 10th of February 2017, in an area of terra-firme forest on the east bank of the Juami River, within Estação Ecológica Juami-Japurá, State of Amazonas, Brazil (1.96455° S, 67.93579° W; ~ 87 m a.s.l.). Advertisement calls of the holotype were recorded at 17:10 h and 25.4°C.

Paratypes. MCP 13289, 13290, and 13292 (field codes SCF 2057, 2028, and 2016, respectively) adult males, MCP 13288, 13291, and 13293 (field codes SCF 2058, 2015, and 2017, respectively) adult females. Collected by G. Gagliardi-Urrutia, F.J.M. Rojas-Runjaic, P.I. Simões and S. Castroviejo-Fisher between 9–12 February 2017, same locality as the holotype.

Etymology. The specific epithet is a noun in singular nominative and refers to the species type locality, the forests alongside the Juami River, which is currently protected by the ESEC Juami-Japurá.

Generic placement. We assigned our new species to Allobates based on overall similarity with other species of the genus and presence of the following diagnostic phenotypic characters proposed by Grant et al. (2006): (1) Finger IV reaching distal half of distal subarticular tubercle of Finger III, (2) webbing absent on postaxial side of Toe I, (3) webbing absent on preaxial side of Toe II, (4) webbing absent on postaxial side of Toe II, (5) webbing absent on preaxial side of Toe III, (6) pale paracloacal mark present, (7) oblique lateral line absent or diffuse, (8) male abdomen pale, free or almost free of melanophores.

Definition. Allobates juami is characterized by: (1) skin texture of dorsum posteriorly granular, flat granules scattered from the level of tympanum to the urostyle region, more prominent from mid to posterior dorsum; (2) paired dorsal digital scutes present; (3) distal tubercle absent on Finger IV; (4) discs on fingers I–IV weakly expanded; (5) dermal lateral fringes and basal webbing absent on fingers; (6) metacarpal ridge absent; (7) Finger III not swollen in male or female specimens; (8) carpal pad absent; (9) male excrescences on thumbs absent; (10) thenar tubercle conspicuous; (11) black gland absent on arm; (12) tarsal keel present, tubercle-like, strongly curved; (13) disc on Toe I very weakly expanded; discs on toes II, III and V weakly expanded, discs on Toe IV greatly expanded; (14) basal webbing present between toes III and IV, rudimentary basal webbing present between toes II and III; (15) metartarsal fold absent; (16) cryptic external coloration; background color of dorsum solid dark brown, light tan brown on snout and on the urostyle region; large diamond, “X” or hourglass-shaped marks absent on dorsum; dorsal surface of thigh light brown in life, light brown in preserved specimens; a single transverse dark brown bar or spot may be present on dorsal surface of thigh; dorsal surface of arm cream to pale brown in life, yellow around arm-body insertion; dorsal surface of arm cream in preserved specimens; pale dorsolateral stripe present, wide and well defined; a dark brown lateral stripe surrounds the whole body, reaching leg-body insertion; pale oblique lateral stripe absent; pale ventrolateral stripe present, extending posteriorly from below the nostril to groin, with a diffuse lower margin from behind the eyes to groin, iridescent white in preserved specimens, bright yellow to iridescent white in live individuals; pale paracloacal mark present, diffuse distally, not crescent-shaped; (17) dark throat-collar absent; (18) throat marginally white, centrally translucent in preserved male specimens, uniformly white in preserved female specimens; (19) ventral surfaces uniformly yellow in life in male and female specimens, lighter yellow on abdomen; throat and vocal sac pinkish to translucent in live male specimens, uniformly yellow in female specimens; (20) iris dark with metallic gold flecks and a golden pupil ring; (21) large intestine unpigmented; (22) testis unpigmented; (23) mature oocytes pigmented, pigments black; (24) median lingual process absent; (25) tympanum inconspicuous to the naked eye; (26) vocal sac single; (27) maxillary teeth present; (28) habit is diurnal, males calling during daytime; (29) advertisement calls characterized by discrete trills of notes (2.5– 5.09 s) formed by approximately 60–73 short notes, emitted at an average rate of 13 notes per second; silent interval between notes 0.03 s in average; (30) snout-to-vent length (SVL), adult males 18.1 mm on average (range 17.9–18.2 mm), adult females 18.1 mm on average (range 17.5–18.5 mm).

Description of holotype. Adult male of SVL = 18.0 mm in good state of preservation, with a piece of muscle ventrally cut and preserved as tissue sample (Fig. 2). Measurements of the holotype are presented in Table 1. Body robust, head wider than long (HL/HW = 0.98), head length 0.37 times the SVL (Fig. 2). Eye diameter larger than distance from anterior corner of the eye to nostril (EN/ED = 0.37) (Fig. 3). Nares located posterolaterally to tip of snout, directed laterally, visible in ventral, lateral and anterior views. Distance between nostrils 0.36 times the HW. Canthus rostralis slightly convex from tip of snout to nostril, straight from nostril to anterior corner of the eye. Loreal region vertical. Tympanum round, 0.59 times the maximum diameter of the eye. Margins of tympanum indistinct to the naked eye (but visible under magnification), more conspicuous ventrally, at the level of pale ventrolateral stripe (Fig. 3). Maxillary teeth present, concealed by inner surface of upper lip, detectable only under 30X magnification or by moving a wire probe along the maxillary surface. Tongue longer than wide, with anterior third attached to the mouth floor. Median lingual process absent. Choanae round, positioned anteriorly to eye bulge. Vocal sac single, covering most of the medial and posterior portions of the subgular region. Lateral vocal slits conspicuous.

Palmar tubercle round to slightly elliptical. Thenar tubercle present, oval, evident in ventral view, flattened and less conspicuous in profile. Maximum diameter of thenar tubercle 71% of maximum diameter of palmar tubercle (Fig. 4). Subarticular tubercles of fingers III and IV round, small, never exceeding the width of phalanges. Subarticular tubercle on Finger II elliptical, protuberant, 1.2 times larger than thenar tubercle in maximum diameter. Subarticular tubercle on Finger I very protuberant, elliptical to almost rectangular, 1.3 times wider than thenar tubercle in maximum diameter. Distal subarticular tubercle absent on Finger IV. Supernumerary tubercles absent. Metacarpal ridge absent. Finger fringes and hand webbings absent. Length of Finger II equivalent to approximately 90% of Finger I’s length. Tip of Finger IV does not reach distal subarticular tubercle of Finger III when fingers are juxtaposed. Relative lengths of fingers: IV <II <I <III. Finger III not swollen. Discs of fingers I– IV weakly expanded, width of discs corresponding to 1.6, 1.5, 1.6 and 1.6 times the width of their respective adjacent phalanges (Fig. 4).

Tibia length corresponding to approximately half the SVL (TL/SVL = 0.55). Tarsal keel present, tubercle-like, strongly curved at its proximal end, flattening and straightening towards metatarsal tubercle, but not reaching it (Fig. 4). Preaxial edge of tarsus smooth, with no fringe. Metatarsal fold absent. Basal webbing present between toes III and IV. Basal webbing present but shorter between toes II and III. Relative lengths of toes: I <II <V <III <IV. Disc of Toe I very weakly expanded, width 1.2 times the width of adjacent phalanx. Discs of toes II, III and V weakly expanded, width of discs 1.8 times the width of adjacent phalanges. Discs of Toe IV greatly expanded, width of disc about 3.0 times the width of adjacent phalanx (Fig. 5).

Skin on dorsum moderately granular, with low granules scattered from urostyle region to about mid body. Low granules present on inguinal region, absent from other lateral surfaces. Skin smooth ventrally. Dermal flap absent above cloaca (Fig. 2).

Color in alcohol of holotype. Dorsal surface of body predominantly dark brown, but conspicuously lighter from tip of snout to the level of the eyes and posteriorly on the urostyle region (Fig. 2). A pale, light brown dorsolateral stripe is present, characterized by a broad line (~ 1.2 mm wide at mid-dorsum level) where density of brown melanophores is reduced, extending from behind the dorsal surface of orbital region to about the level of urostyle region; inner and outer edges of pale dorsolateral stripe are well marked, not diffuse. Dorsal surface of urostyle region light brown, same color as snout, darker only at the tips of larger skin granules. Lateral surface of body characterized by a solid dark brown stripe, darker than brown shades on dorsum, extending from tip of snout to groin, surrounding the body. Pale ventrolateral stripe present, narrower than dorsolateral stripe, iridescent white, extending from snout to groin, solid and continuous anteriorly from tip of snout to the level of arm insertion, with lower margins more diffuse from arm-insertion level to groin, where it merges with the white color of abdomen (Fig. 3). Ventral surfaces white to translucent, with evenly scattered white iridescent patches on chin and from pectoral region to posterior abdomen. White iridescent patches absent on throat. Tongue is cream-colored.

Arms cream to pale brown in dorsal view, melanophores generally evenly scattered on upper and forearm, more densely grouped on wrist. Hands cream colored, with melanophores absent on proximal dorsal surface of metacarpal region. Tips of fingers brown. Paired scutes on discs of fingers I, II and III white, black on Finger IV. Upper arm white to translucent in ventral view, continuous with color pattern of abdomen. Outer lateral edge of forearm light brown. Carpal and metarcarpal regions brown, densely pigmented in ventral view (Fig. 4A).

Area immediately around vent light brown. Pale paracloacal mark is diffuse, perceptible only as an unpigmented region adjacent to vent (Fig. 2). Pale paracloacal mark is not flanked by dark transverse stripes. Thigh uniformly light brown in dorsal view. A single brown spot is present dorsally on the right thigh (see Variation in type series below). Inner dorsolateral surface of thigh dark brown. Outer dorsolateral surface of thigh light brown, same color of dorsal surface. Dorsal surface of shank same color as thigh, with a single dark brown blotch present medially on each leg. Dorsal surface of tarsal region lighter than overall color of legs, uniformly light brown to cream. Toes brown, with irregularly distributed melanophores. Paired scutes on toes white on toes I, II, III and IV, black on Toe V. Ventral surfaces of thigh and shank cream to translucent. Ventral surfaces of tarsal and metatarsal regions uniformly dark brown. Toes brown, densely pigmented in ventral view (Fig. 5).

Variation in type series. Variation in morphometric measurements of male and female types are presented in Table 1. Thigh length is longer than tibia length in three paratypes (LL/TL = 1.02, 1.05 and 1.10 in MCP 13289, 13291, 13293, one male and two females, respectively). Throat of preserved female specimens is white, the underlying parietal peritoneum visible through translucent skin. A solid transverse brown stripe is present medially on dorsal surface of thigh of a female paratype (MCP 13288) (Fig. 2). The same transversal brown stripe is present but interrupted on thighs of two paratypes (MCP 13292, 13293) (Fig. 6). A solid transverse brown stripe is absent on dorsal surface of shanks on paratype MCP 13289. Brown transversal stripes are absent on dorsal surface of thigh in the remaining specimens, including the holotype. Color of paired scutes on Finger IV and Toe V variable, black, gray or white.

Color in life. Description is based on field observations and photographs of specimens forming the type series. Dorsum centrally dark brown, tan brown anteriorly, from tip of snout to the level of the eye, and posteriorly, on the urostyle region. Iris golden copper with dark brown reticulation. Pale dorsolateral stripe evident and broad, pale brown (Fig. 7A–C). Lateral surface of body surrounded by a uniformly dark brown stripe from tip of snout to groin. A few faint spots may be present postlaterally on the dark brown stripe about the inguinal region, but never forming a pale oblique lateral line. Thin iridescent white ventrolateral stripe present along the lower border of dark brown stripe from the level of the eye to groin. Lower border of ventrolateral stripe is more diffuse from behind arm-body insertion to groin, merging with the yellow ventral color laterally, towards the abdomen (Fig. 7A–B). Ventrolateral stripe extending from the level of the eye to tip of snout white to bright yellow, evidenced by a continuous line of iridophores underlying the yellow skin. Throat uniformly yellow in female specimens (Fig. 7D). Throat and vocal sac pinkish to translucent in live male specimens (Fig. 7E). Remaining ventral surfaces of body uniformly yellow, paler medially on the abdomen, where underlain by peritoneum. Vocal sac of males cream to translucent when inflated.

Dorsal surface of upper and forearm uniformly cream to pale brown, yellowish only around arm-body insertion. Isolated brown irregular spots may be present dorsally or laterally on forearm. Upper arm yellow, same color as chest, in ventral view. Forearm, carpal and metacarpal regions brown in ventral view. Fingers brown in ventral and dorsal views, darker in ventral view. Paired scutes on finger discs iridescent white, sometimes black.

Surfaces immediately adjacent to vent pale brown with isolated and irregular brown spots. Light cream paracloacal mark present, short, diffuse distally, merging with the color of dorsal surface of thigh. Dorsal surface of thigh uniformly light brown. A single dark brown blotch may be present medially on dorsal surface of thigh, sometimes extending laterally and forming a transverse dark brown stripe. Dorsal surface of shank same color as thigh, with a medial transverse dark brown stripe. Ventral surface of thigh and shank solid yellow to ocher, darker than yellow shades of abdomen. Dorsal surface of tarsal region light brown, with a medial transverse dark brown stripe. Tarsal and plantar regions brown in ventral view. Toes with ocher and brown patterning. Paired scutes on toe discs iridescent white, sometimes black.

Call description. Advertisement calls of Allobates juami are formed by the emission of short notes arranged in trills (Fig. 8A). The average duration of trills among all males recorded was 4.51 ± 0.37 (2.50–5.09) s. The average rate of note emission was 13.75 ± 0.35 (13–14) notes/s and each note trill contained an average of 65 ± 4 (60–73) notes. Average note duration was 0.038 ± 0.006 (0.026–0.055) s. Notes have an ascending frequency modulation (Fig. 8B). Average peak frequency was 5.19 ± 0.24 (4.59–5.47) kHz. Lower frequency of notes was 4.60 ± 0.13 (4.20–4.83) kHz on average, and average upper frequency was 5.59 ± 0.17 (4.94–5.77) kHz. Average duration of silent intervals between notes was 0.032 ± 0.007 (0.020–0.050) s. The fundamental frequency was observed between 2.40–2.80 kHz only in spectrograms of calls emitted by the holotype, which contained less background noise.