Pristimantis symptosus, Köhler & Castillo-Urbina & Aguilar-Puntriano & Vences & Glaw, 2022

Koehler, Joern, Castillo-Urbina, Ernesto, Aguilar-Puntriano, Cesar, Vences, Miguel & Glaw, Frank, 2022, Rediscovery, redescription and identity of Pristimantis nebulosus (Henle, 1992), and description of a new terrestrial-breeding frog from montane rainforests of central Peru (Anura, Strabomantidae), Zoosystematics and Evolution 98 (2), pp. 213-232 : 213

Pristimantis symptosus sp. nov.

Holotype.

MUSM 40256 (FGZC 6207), adult male, from a point along the road 18A, approximately 5.5 km airline distance northeast of the Carpish Tunnel (9.67744°S, 76.07313°W, 2360 m a.s.l.), Cordillera de Carpish, Departamento Huánuco, Peru, collected on 4 November 2019 by E. Castillo-Urbina, F. Glaw, and J. Köhler.

Diagnosis.

A medium-sized species of the Pristimantis conspicillatus species group (based on molecular relationships and morphological similarity), with 27.6 mm SVL in adult male, characterised by: (1) skin on dorsum tuberculate, with a pair of enlarged scapular warts; flanks tuberculate; throat smooth, venter weakly areolate; discoidal fold conspicuous; dorsolateral folds distinct, but low; dorsal folds absent; three prominent postrictal conical tubercles present; upper eyelid lacking tubercles and granules; posterior surfaces of thighs smooth; (2) tympanic membrane and annulus distinct, slightly higher than long, their length less than half of eye diameter; supratympanic fold long, prominent, almost straight, not covering upper tympanum or annulus; (3) head longer than wide; snout subacuminate in dorsal view, bluntly rounded in lateral profile; canthus rostralis straight in dorsal view, sharp in profile; (4) cranial crests absent; (5) dentigerous process of vomers prominent, elongate, oblique, situated posteromedial to choanae; (6) males with vocal slits, single subgular vocal sac, and nuptial asperities on dorsal surface of thenar tubercle; (7) hands with long and slender fingers, first finger equal in length to second; subarticular tubercles subconical, prominent; supernumerary tubercles absent; palmar tubercle bifid, flat; thenar tubercle prominent, elongated; terminal discs of inner two fingers enlarged and round, those of external fingers enlarged, ovate, about twice the width of digit proximal to disc; circumferential grooves conspicuous, ungual flap very slightly indented; lateral fringes on fingers absent; basal webbing between fingers absent; (8) ulnar tubercles absent; (9) tubercles on heel and tarsus absent, tarsal fold absent; (10) inner metatarsal tubercle ovate, prominent; outer metatarsal tubercle round, flat; supernumerary tubercles absent; (11) toes long and slender (FootL 54% SVL); narrow lateral fringes weakly expressed, trace of basal toe webbing present; toe V reaching distal level of penultimate subarticular tubercle of toe IV; toe V slightly longer than toe III; tips of toes rounded to slightly ovate, enlarged; circumferential grooves conspicuous; (12) in life, dorsal colouration brown to tan with dark brown chevrons and flecks on dorsum; dark brown bars on dorsal surfaces of arms and legs; dark brown interorbital bar; a pair of black spots, surrounding prominent conical scapular warts: broad black supratympanic stripe; black canthal stripe; belly cream; throat densely mottled with dark brown; ventral surfaces of thighs and shanks orange tan; posterior surface of thighs orange-brown with irregular cream spotting; plantar and palmar surfaces yellowish-brown, densely covered with dark brown mottling; iris copper, with black reticulation; posterior iris periphery pale blue; bones white; (13) advertisement call consisting of a single pulsed note of 132-186 ms duration, emitted at regular succession (see below).

Comparison.

Among the now 42 recognised species in the P. conspicillatus species group ( Padial et al. 2014, 2016; de Oliveira et al. 2017, 2020; Taucce et al. 2020), 13 species, including P. symptosus , exhibit dorsolateral folds ( Duellman and Lehr 2009; Padial et al. 2016). Among these, P. adiastolus mainly differs from P. symptosus by more prominent and longer dorsolateral folds, finger I slightly shorter than finger II, and skin on dorsal surfaces shagreen ( Duellman and Hedges 2007); P. avicuporum mainly differs by the presence of an interocular dermal fold, fingers bearing lateral fringes, and finely shagreen dorsal skin ( Duellman and Pramuk 1999; Duellman and Lehr 2009); P. buccinator mainly differs by continuous and prominent dorsolateral folds, an X-shaped or V-shaped dorsal fold and presence of an interorbital dermal ridge ( Rodríguez 1994); P. condor mainly differs by larger male size (SVL 32.1-39.5 mm) and finger I distinctly longer than finger II ( Lynch and Duellman 1980); P. conspicillatus mainly differs by finger I being distinctly longer than finger II, fingers bearing lateral keels, and dorsal skin finely shagreen ( Duellman and Lehr 2009); P. iiap mainly differs by upper eyelid bearing small granules, skin on dorsum coarsely shagreen, basal toe webbing absent, presence of a tarsal fold, and advertisement call ( Padial et al. 2016); P. malkini mainly differs by finger I distinctly longer than finger II and more extensive webbing between toes ( Lynch 1980; Duellman and Lehr 2009); P. meridionalis mainly differs by finger I being shorter than finger II, dentigerous processes of vomers small and round, and fingers bearing lateral fringes ( Duellman and Lehr 2009); P. peruvianus mainly differs by very prominent and long dorsolateral folds, finger I distinctly longer than finger II, and fingers bearing lateral fringes ( Köhler 2000; Padial and De la Riva 2009); P. skydmainos mainly differs by more prominent and continuous dorsolateral folds, finger I being shorter than finger II, and a black mid-dorsal tubercle ( Flores and Rodríguez 1997; Padial and De la Riva 2005). The closely related P. nebulosus mainly differs by skin on dorsum and flanks shagreen, curved supratympanic fold, relatively longer legs (TL/SVL 0.64 versus 0.60), presence of a tarsal fold, presence of basal webbing between fingers II and III, bronze-coloured iris in life, advertisement call (see below), and divergence in the mitochondrial 16S gene (p-distance 4.1%). The sister species P. bipunctatus is most similar to P. symptosus in sharing similar adult male size, finger I about equal in length to finger II, tarsus lacking a tarsal fold, fingers lacking lateral keels or fringes, a pair of enlarged scapular warts, and a similiar colour pattern. However, P. bipunctatus (Fig. 7 ) differs by skin on dorsum and flanks finely shagreen (tuberculate), bluntly rounded snout in dorsal view (subacuminate), basal webbing between toes IV and V (basal webbing between all toes) ( Duellman and Hedges 2005; Duellman and Lehr 2009), and considerable divergence in the mitochondrial 16S gene (p-distance 3.3-4.1%). The advertisement call of P. bipunctatus remains unknown. Individuals of the recently described species P. pictus , P. pluvian and P. moa from Amazonian Brazil may sometimes exhibit weakly developed dorsolateral folds, but all differ from the new species by shagreen dorsal skin (versus tuberculate) and advertisement call ( de Oliveira et al. 2020).

Description of the holotype.

An adult male, in good state of preservation (Fig. 8 ), with subgular vocal sac and vocal slits. Head longer than wide (HL/HW = 1.2); snout subacuminate in dorsal view, bluntly rounded in profile; nostrils oriented posterolaterally; canthus rostralis straight in dorsal view, sharp in profile; loreal region straight; lips not flared; upper eyelid without tubercles; cranial crests absent. Supratympanic fold prominent, long, almost straight, not covering upper tympanic membrane or annulus; tympanic membrane and annulus distinct; tympanic membrane nearly slightly higher than long, its length slightly less than half the eye diameter; three prominent postrictal tubercles, conical. Choanae not concealed by palatal shelf of the maxillary arch when roof of mouth is viewed from below; choanae large, round, separated by distance equal to six times diameter of a choana; dentigerous process of vomers prominent, elongate, not in contact, oblique, situated posteromedial to choanae, bearing vomerine teeth; tongue removed for tissue sample; vocal sac subgular, vocal slits placed posterolaterally. Skin on dorsum tuberculate, with a pair of prominent conical scapular warts; dorsal surfaces of hind limbs tuberculate, dorsal surfaces of forearms and flanks tuberculate; skin on throat and chest smooth, that on belly areolate; occipital folds absent; dorsolateral folds distinct, but low; discoidal fold conspicuous. Arm without ulnar tubercles; palmar tubercle bifid, flat, equal in size to elongate thenar tubercle; supernumerary tubercles absent; subarticular tubercles prominent, subconical; fingers long and slender; finger tips enlarged, rounded on inner two fingers, on two outer fingers ovate, their width about twice the width of digit proximal to disc; circumferential grooves conspicuous, ungual flap very slightly indented on outer fingers; lateral fringes and keels on fingers absent; basal webbing between fingers absent; relative length of fingers III> IV> II = I; nuptial pad present on dorsal surface of thumb. Toes long and slender (FootL 54% of SVL); heel and tarsus lacking tubercles; tarsal fold absent; inner metatarsal tubercle ovate, prominent, larger than outer; outer metatarsal tubercle round, flat, about one third the size of outer; tarsal fold absent; supernumerary tubercles absent; subarticular tubercles prominent, subconical; narrow lateral fringes on toes weakly expressed, traces of basal toe webbing present; toe tips enlarged, rounded to slightly ovate, their width about 1.5 times the width of toe proximal to disc; circumferential grooves conspicuous; relative length of toes IV> V> III> II> I; toe V reaching distal level of penultimate subarticular tubercle of toe IV. Tibiotarsal articulation reaches slightly beyond tip of snout when hind limb flexed parallel to axis of body; heels overlapping when hind limbs flexed perpendicular to axis of body.

Measurements (in mm): SVL 27.6; TL 16.8; HL 11.9; HW 9.9; IOD 3.4; ED 3.9; TD 1.7; E-N 3.1; HandL 7.9; FootL 14.8.

In life (Fig. 9 ), dorsal ground colour brown to tan, with dark brown chevrons and irregular dark brown blotches on dorsum, most of them finely outlined with cream; dark brown bars on dorsal surfaces of arms and legs; dark brown interorbital bar, extending to upper eyelids; a pair of black spots surrounding prominent scapular warts; broad black supratympanic stripe; broad blackish canthal stripe; lips dark brown to black, barred with cream; flanks brown with irregular dark brown markings; belly cream; throat and chest orange-brown with dense black mottling; ventral surfaces of thighs and shanks orange tan; posterior surface of thighs orange-brown with irregular cream spotting; plantar and palmar surfaces yellowish-brown, densely covered with dark brown mottling; iris copper, with black reticulation; posterior iris periphery pale blue; bones white. After two years in preservative (Fig. 7 ), the general colour pattern remains the same as in life. Brown ground colouration turned to greyish-tan, with brown flecks, bars and chevrons; black colour of canthal and supratympanic stripes faded to anthracite; chest and ventral surfaces of thighs yellowish-cream; belly cream; throat cream with grey mottling.

Natural history.

The forest at the type locality constitutes upper montane rainforest at the transition zone to cloud forest, growing on steep slopes (Fig. 10 ), with trees not exceeding 20 m height ( Jiménez and Pacheco 2016). Males were calling from a low position in shrub vegetation along the road during a foggy night and light rain. The holotype was sitting on a leaf approximately 25 cm above the ground. Pristimantis sp. ( Pristimantis lacrimosus group) and P. sp. ( Pristimantis aff. rhabdocnemus ) were found at nearby sites. Nothing else is known.

Vocalisation.

Calls were recorded at the type locality of P. symptosus on 4 November 2019 (estimated air temperature 16 °C). Calling males were easily disturbed and stopped calling when being approached at distances of less than 10 m. Therefore, recordings are of poor quality, as the recorded individual was calling at considerable distance (estimated> 15 m) and there is considerable background noise in the recording. A call voucher could not be collected, but the male holotype was caught at a spot from where the same type of call was emitted (although the individual could not be directly observed calling), making it very probable that the calls described here belong to P. symptosus . Although the poor recording quality hampers access to some call parameters (i.e. pulse structure and exact rate), the call can be described as follows. The advertisement call consists of a single, short, pulsed note, repeated at regular succession (Fig. 11 ). Calls (= notes) exhibit a very slight upward frequency modulation and are clearly pulsed, although the poor recording quality prevents any reliable counting of pulses; however, it can be estimated from some sections of the calls that pulse rate is greater than 200 pulses/second. Numerical parameters of 23 analysed calls are as follows: call duration (= note duration) 132-186 ms (151.3 ± 14.1 ms); inter-call interval 804-1041 ms (882.3 ± 79.5 ms); dominant frequency 1442-1507 Hz (1468 ± 25 Hz), with a second peak in call energy of similar intensity at around 2800-2930 Hz; prevalent bandwidth 1200-4000 Hz; calls were repeated at a rate of 52-63 call/minute.

Distribution.

Pristimantis symptosus is only known from its type locality and possibly endemic to the Cordillera de Carpish.

Etymology.

The specific epithet is a Latinised adjective derived from the Greek σύμπτωση (symptosi) meaning ‘coincidence’. It refers to the fact that we only discovered the new species by coincidence on an unplanned return to the Cordillera de Carpish after forgetting part of our expedition gear there.

Figures

Figure 7. Pristimantis bipunctatus (MUSM 31120; GenBank accession number KY 006089) from Yanachaga-Chemillen National Park, 2290 m a. s. l., Departamento Pasco, Peru, in life: a. Dorsolateral view; b. Ventral view. Photographs by J. Moravec.

Figure 8. Preserved male holotype of Pristimantis symptosus sp. nov. (MUSM 40256, FGZC 6207) from the Cordillera de Carpish, 2360 m a. s. l., in a. dorsal, and b. ventral views; c. Palmar surface of left hand; d. Head in lateral profile (mirrored). Note prominent scapular tubercle surrounded by black spot.

Figure 9. Male holotype of Pristimantis symptosus sp. nov. (MUSM 40256, FGZC 6207) from the Cordillera de Carpish, 2360 m a. s. l., in life: a. Dorsolateral view of left body side; b. Dorsolateral view of right body side; c. Ventral view. Note tuberculate skin on dorsum, flanks and forearm.

Figure 10. View of the forest along the road 18 A close to the type locality of Pristimantis symptosus sp. nov. in the Cordillera de Carpish, Departamento Huanuco, Peru, at approximately 2450 m a. s. l. Photo taken on 4 November 2019.

Figure 11. Audiospectrogram and corresponding oscillogram of one advertisement call allocated to Pristimantis symptosus sp. nov. from Cordillera de Carpish, 2360 m a. s. l., Peru, at 1000 ms time scale. Recording band-pass filtered at 850 - 6500 Hz.