Bioacoustics of Pristimantis marmoratus

Diagnosis Pristimantis marmoratus ( Boulenger, 1900 ) has historically been assigned to the polyphyletic “ unistrigatus species group” ( sensu Hedges et al. 2008 ), which is mainly characterized by having Finger I shorter than II, Toe V longer than III, extending to the distal edge of the distal subarticular tubercle of Toe IV when toes are adpressed, and by the absence of cranial crests and the presence of vomerine teeth. Pristimantis marmoratus is characterized by the following unique combination of characters: (1) body small, adult males 17.6–20.4 mm SVL (n = 5), adult female 27.9 mm SVL (n = 1); (2) dorsal skin granular/ pustulate, usually with distinctly enlarged tubercles (less pustulate in female), belly skin granular (granules not as closely set as in areolate skin sensu Duellman & Lehr 2009 ), sometimes becoming smooth in preservative; (3) presence of well-developed oblique scapular ridges in males (less prominent in female); (4) tympanum present, tympanic membrane not or only poorly differentiated, and tympanic annulus only partially visible externally, obscured by supratympanic fold, TYM 22–34% of EL; (5) small pharyngeal ostia present; (6) TIL 1.9–2.0 times HAND; (7) snout rounded to subovoid in dorsal view, slightly sloping in profile, canthus rostralis nearly straight in dorsal view, rounded in cross section, loreal region concave, flaring slightly at upper lip; (8) upper eyelid granular, with 1–3 distinctly enlarged tubercles on each eyelid; (9) choanae small, round, dentigerous processes of vomers small, sometimes barely visible or even not detectable, slightly oblique, ovoid, posterior and medial to choanae, each bearing 3–5 teeth when present; (10) presence of vocal slits in male, vocal sac single, subgular; (11) tongue cordiform; (12) one unpigmented whitish nuptial pad located on the preaxial side of the thenar tubercle on each thumb in male, a second pad is sometimes present (on one thumb or on both) on the preaxial side of the first subarticular tubercle; (13) Finger I shorter than II, FI 75–83% of FII in males, 86% of FII in female; (14) fingers basally webbed, with moderately developed lateral fringes, usually more conspicuously developed preaxially on Finger II; (15) palmar tubercle V-shaped, often broken in three distinct tubercles; (16) axillary tubercles ( sensu Myers & Donnelly 2001 ) absent; (17) small ulnar tubercles present, in line; (18) small tarsal tubercles present, 1–3 slightly enlarged calcar tubercles present; (19) inner metatarsal tubercle oval, about 3–4 times the size of the round, projecting outer metatarsal tubercle; (20) Toe V longer than III, extending to the distal edge of the distal tubercle on Toe IV when toes are adpressed; (21) toes with lateral fringes, best developed preaxially on Toes II–IV, webbing basal between Toes II–V; (22) discs broadly expanded, elliptical; (23) in life, main dorsal colour pattern ranges from large, weakly visible, dark brown or grey-brown blotches to nearly uniformly brownish grey, ventral colouration ranges from whitish to grey or dark brown with series of tiny, dark brown punctuations and light grey flecking; (24) in preservative, main dorsal colour pattern similar to when alive, but with the melanin more prominent, revealing large, indistinct blotches or more or less uniformly distributed medium brown colour, ventral colouration consists in a uniformly distributed series of tiny, warm brown punctuations on the chin, belly and undersurfaces of the legs, feet and toes; (25) in life, anterior and lower posterior surfaces of thighs brown to dark brown with light grey flecking (brown with white flecking in preservative); (26) in life, diffuse yellow or pale green wash (white in preservative) on groin and absence of flashy colour on axillary /pre-axillary region; (27) in life, iris pale gold to bronze with fine black reticulations, a median horizontal brown to reddish brown bar, and a vertical streak running across the iris; (28) advertisement call consists in a single note repeated at a rate of ca 11 calls/ min with a dominant frequency ranging from 2756 to 3101 Hz; (29) males call exclusively at dusk, usually upside down on mossy tree trunks of low diameter; (30) known elevational distribution ca 600 to 1800 m .

Natural history All specimens were found in undisturbed submontane or montane rainforest ( Fig. 9 ), active on small trees 50–300 cm above the ground, exclusively at dusk. Pristimantis marmoratus is not a common species; only a few specimens have been found at each locality of occurrence. Males were found calling (in June and November) upside down from mossy tree trunks of low diameter (< 10 cm ) between 120 and 300 cm above the ground, except one male (IRSNB 14473), which was calling from the top of a green leaf 50 cm above the ground. The “upside down” call posture is also found in the closely related P. sp. 1 of Fouquet et al . (2013) (as recovered in our preliminary molecular phylogenetic analysis, see below), and in P. espedeus and P. inguinalis . In June 2012 , which corresponds to the rainy season in the area, a cluster of four Pristimantis marmoratus eggs ( Fig. 6B ) was found by one of us (DBM) attached to the inside part of a leaf of a bromeliad, Guzmania cf. sphaeroidea (André) André ex Mez ( Fig. 6A ), 150 cm above the ground, on Mount Kopinang, Wokomung Massif, near the top of Kamana Falls at about 1600 m elevation ( 04°59′58″ N , 59°52′49″ W ). Molecular analyses confirmed conspecificity of these eggs with P. marmoratus (Appendix 3). The large, white eggs did not have visibly developed embryos. After photographing and preserving the eggs, the small plant was investigated for inhabitants of the aquatic portion of the phytotelmata. Immediately a small frog jumped out and disappeared into the deep ground litter, and eggs and tadpoles of Anomaloglossus beebei (Noble, 1923) were found in the water of the phytotelmata of the same small bromeliad and in the water of five other bromeliads nearby (egg /frog identifications confirmed by molecular analyses). Pristimantis marmoratus and Anomaloglossus beebei thus share the same bromeliad as an oviposition site on the Wokomung Massif ( Fig. 6C ). Other Pristimantis species found in syntopy with P. marmoratus were P. dendrobatoides (above 1600 m elevation), P. jester (above 1300 m elevation), P. saltissimus (above 1000 m elevation), and P. pulvinatus (above 1000 m elevation).

Advertisement call Temporal structure The advertisement call of Pristimantis marmoratus consists of a single, unpulsed (tonal) note repeated at a rate of 11.25–11.87 calls /min. Mean call duration is 0.0184 ± 0.002 s (0.016– 0.023 s ). The intercall silent interval is relatively uniform and has a mean of 6.011 ± 0.9 s and a range of 5.023– 7.958 s ( Figs 7–8 ). Spectral structure Four to five harmonics are developed, with the dominant frequency located in the first (fundamental) harmonic (mean: 3047 ± 121 Hz; range: 2756–3101 Hz) ( Figs 7–8 ). Calls show a downward followed by a slightly upward frequency modulation ( Fig. 8 ). Comparison with other Pristimantis calls in the Guiana Shield uplands and highlands To the best of our knowledge, only three uplands /highlands Pristimantis species for which documented calls are known produce a single note per call: P.aureoventris from above 2200 m elevation onWei-Assiputepui and on the highest slopes of Mt. Roraima ( Kok et al. 2011 ), P. muchimuk Barrio-Amorós, Mesa, Brewer-Carías & McDiarmid, 2010 from above 2300 m elevation on Churí-tepui, and P. yuruaniensis Rödder & Jungfer, 2008 from above 2300 m on Yuruaní-tepui. The call of P. aureoventris mainly differs in having a lower dominant frequency (2180–2430 Hz vs 2756–3101 Hz in P. marmoratus ), and a higher call rate (18 calls /min vs ca 11 calls / min in P. marmoratus ). The call of P. muchimuk is longer (0.027– 0.062 s vs 0.016– 0.023 s in P. marmoratus ) and emitted at a much faster pace (> 100 calls/ min vs ca 11 calls/ min in P. marmoratus ). The call of P. yuruaniensis is longer (0.093– 0.139 s vs 0.016– 0.023 s in P. marmoratus ) and the dominant frequency is at 1980 Hz (2756–3101 Hz in P. marmoratus ). Interestingly, the call of Pristimantis marmoratus is extremely similar to the call of P. inguinalis (Parker, 1940) , a species known from the lowlands of the eastern Guiana Shield, east of the Essequibo River. Both species have an unpulsed single note call with a dominant frequency within the same range. Based on our analysis of a call of P. inguinalis provided in Marty & Gaucher (1999) and partial data from Fouquet et al. (2013) , the only differences found are (1) a slightly longer call length in P. inguinalis (0.023– 0.032 s vs 0.016– 0.023 s in P. marmoratus ); (2) a slightly higher call rate in P. inguinalis (17.91 calls/ min vs 11.25–11.87 calls/ min in P. marmoratus ); and (3) a slightly shorter inter-call silent interval in P. inguinalis (3.16– 3.85 s vs 5.02– 7.96 s in P. marmoratus ). See Discussion for further comments about distribution and phylogenetic relationships; see also fig. 6 in Fouquet et al. (2013) for comparison.