A new stream treefrog of the genus Hyloscirtus (Amphibia, Hylidae) from the Rio Negro-Sopladora National Park, Ecuador Author Sanchez-Nivicela, Juan C. https://orcid.org/0000-0001-7971-1216 Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biologicas y Ambientales COCIBA, Instituto de Biodiversidad Tropical IBIOTROP, Laboratorio de Zoologia Terrestre, Museo de Zoologia, Quito 170901, Ecuador & Universidad Nacional de Colombia, Facultad de Ciencias, Grupo de Investigacion Evolucion y Ecologia de Fauna Neotropical, Bogota D. C., Colombia & Instituto Nacional de Biodiversidad, Division de Herpetologia, Quito, Ecuador Author Falcon-Reiban, Jose M. https://orcid.org/0000-0003-1588-9044 Universidad Complutense de Madrid, Facultad de Ciencias Biologicas, Madrid, Espana Author Cisneros-Heredia, Diego F. https://orcid.org/0000-0002-6132-2738 Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biologicas y Ambientales COCIBA, Instituto de Biodiversidad Tropical IBIOTROP, Laboratorio de Zoologia Terrestre, Museo de Zoologia, Quito 170901, Ecuador & Instituto Nacional de Biodiversidad, Division de Herpetologia, Quito, Ecuador diegofrancisco.cisneros@gmail.com text ZooKeys 2023 2023-01-19 1141 75 92 http://dx.doi.org/10.3897/zookeys.1141.90290 journal article http://dx.doi.org/10.3897/zookeys.1141.90290 1313-2970-1141-75 1E409C8A53714330ACCDC1F02E06037C 438276C9DC2C5C48B0D5EEDDD17EA7FF Hyloscirtus tolkieni sp. nov. Figs 2 , 3 , 4 , 5o , 6o , 7o English common name: Rio Negro Stream Treefrog Spanish common name: Rana de Torrente de Rio Negro Holotype (Figs 2 - 4 ) ZSFQ-4142 (field number JCS-1613), adult female collected at Puente de Piedra ( 2°47'13"S , 78°36'16"W ; 3190 m), Parque Nacional Rio Negro-Sopladora, provincia de Morona Santiago, Republica del Ecuador, by Jose M. Falcon-Reiban , Juan C. Sanchez-Nivicela , and Tarquino Valverde, on 5 February 2020. Figure 2. Holotype of Hyloscirtus tolkieni sp. nov. (SVL = 64.9 mm) in life: a fronto-lateral view b lateral view of head c frontal view d dorso-lateral view. Photographs by Juan C. Sanchez-Nivicela . Figure 3. Holotype of Hyloscirtus tolkieni sp. nov. in preservative a dorsal view b ventral view c lateral view. Scale bar: 1 cm. Figure 4. Details of Hyloscirtus tolkieni sp. nov. in preservative a lateral view of head b dorsal view of head c ventral view of hand d ventral view of foot. Scale bar: 1 cm. Diagnosis. Hyloscirtus tolkieni differs from other congeneric species by the following combination of characters: large body size (64.9 mm SVL in a single adult female); broad dermal fringes in fingers and toes; discs slightly expanded; head 7% wider than long; snout truncate in dorsal and lateral view; tympanic membrane and annulus evident, partially covered by supratympanic fold; dentigerous process of vomers slightly separated, with 9-13 vomerine teeth; forearm robust and slightly thicker than arm; discs slightly expanded; broad dermal fringes in fingers and toes; prepollex enlarged, hidden under thenar tubercle and not projected into a prepollical spine; subarticular tubercles on hands and feet rounded and poorly projected; calcar tubercle present; dorsum greyish-green, with paler-hued reticulum, yellow spots and black speckles; throat, venter, flanks and hidden surfaces of limbs yellow with large black blotches and spots; fingers, toes and webbing yellow with black bars and spots; iris pale pink with black periphery, sclera greyish-blue, and nictitating membrane yellow (Figs 2 - 4 ). Hyloscirtus tolkieni is readily distinguishable from all other species of Hyloscirtus by its greyish-green dorsum with paler reticulations, yellow spots, and black speckles. Based on its colouration pattern, Hyloscirtus tolkieni (characteristics in parentheses) is easily differentiated from all other species of the northern clade of the Hyloscirtus larinopygion species group (Figs 5 - 7 ) as follows: Dorsal surfaces of H. antioquia , H. caucanus , H. criptico , H. larinopygion , H. lindae , H. pacha , H. pantostictus , H. princecharlesi , H. psarolaimus , H. ptychodactylus , H. sethmacfarlanei and H. staufferorum are dark or light brown or black with or without paler or darker marks, H. sarampiona is pale olive green with orange spots, and H. tigrinus is green or yellow with thick black reticulum or stripes (greyish-green dorsum with paler reticulum, yellow spots and black speckles). Flanks of H. antioquia , H. caucanus , H. criptico , H. lindae , H. pacha , H. pantostictus , H. princecharlesi , H. ptychodactylus , H. sarampiona , H. sethmacfarlanei and H. staufferorum are dark brown or black with or without paler or darker marks; bluish grey or cream with dark bars, blotches, or spots in H. larinopygion and H. psarolaimus ; and yellow or green with thick black stripes or reticulum in H. tigrinus (yellow flanks with large black blotches and spots). Fingers, toes and discs are dark brown in H. criptico and H. staufferorum ; dark brown with orange discs in H. lindae ; bluish grey with dark bars in H. larinopygion ; dark brown with pale bars in H. pacha ; black with pale discs in H. caucanus and H. pantostictus ; black with orange or red spots in H. princecharlesi and H. sethmacfarlanei ; cream with dark marks in H. psarolaimus ; black with reddish-brown marks in H. ptychodactylus ; dark olive green with orange dots in H. sarampiona ; and yellow or green with black marks in H. tigrinus (yellow with black marks). Irises of H. criptico , H. pacha , H. pantostictus , H. princecharlesi , and H. staufferorum are dark grey or brown without reticulations; grey with dark grey reticulations in H. sethmacfarlanei ; grey with burgundy reticulations in H. antioquia ; pale yellow with brown reticulations in H. caucanus ; golden with black reticulations in H. larinopygion ; dark brown with minute grey flecks in H. lindae ; dull bronze with black reticulations in H. psarolaimus ; pale blue in H. ptychodactylus ; gold with black reticulations in H. sarampiona ; and light grey or yellow with black reticulations in H. tigrinus (pale pink with very thin, almost imperceptible, reticulations). Snout rounded in dorsal view in H. antioquia , H. caucanus , H. larinopygion , H. lindae , H. pacha , H. pantostictus , H. psarolaimus , H. sarampiona , H. staufferorum , and H. tigrinus (truncated). Vomerine teeth 12-20 in H. antioquia and 21-25 in H. staufferorum (9-13). Calcar tubercles absent in H. princecharlesi (present). Figure 5. Dorsal colouration patterns in species of the northern clade of the Hyloscirtus larinopygion species group a H. antioquia b H. caucanus c H. criptico d H. larinopygion e H. lindae f H. pacha g H. pantostictus h H. princecharlesi i H. psarolaimus j H. ptychodactylus k H. sarampiona l H. sethmacfarlanei m H. staufferorum n H. tigrinus o H. tolkieni sp. nov. Illustrations by Jose M. Falcon-Reiban . Figure 6. Ventral colouration patterns in species of the northern clade of the Hyloscirtus larinopygion species group: a H. antioquia b H. caucanus c H. criptico d H. larinopygion e H. lindae f H. pacha g H. pantostictus h H. princecharlesi i H. psarolaimus j H. ptychodactylus k H. sarampiona l H. sethmacfarlanei m H. staufferorum n H. tigrinus o H. tolkieni sp. nov. Illustrations by Jose M. Falcon-Reiban . Figure 7. Flank colouration patterns in species of the northern clade of the Hyloscirtus larinopygion species group: a H. antioquia b H. caucanus c H. criptico d H. larinopygion e H. lindae f H. pacha g H. pantostictus h H. princecharlesi i H. psarolaimus j H. ptychodactylus k H. sarampiona l H. sethmacfarlanei m H. staufferorum n H. tigrinus o H. tolkieni sp. nov. Illustrations by Jose M. Falcon-Reiban . Hyloscirtus tolkieni has non-protruding prepollex and narrower head (HW/HL = 1.07), more vomerine teeth (9-13), and thinner forearms than species of the southern clade of the H. larinopygion species group (including H. condor , H. diabolus , H. hillisi and H. tapichalaca ), which have protruding prepollical spines, wider heads (HW/HL ≥ 1.10), less vomerine teeth (2-6), and hypertrophied forearms. Also, all species of the southern clade of the H. larinopygion species group are dark-coloured dorsally and ventrally. Hyloscirtus tolkieni differs from species of the H. armatus species group by the absence of clusters of keratinised spines on the prepollex and the proximal ventral surface of the humerus (present in H. armatus and H. charazani ), non-expanded prepollex (expanded in H. armatus and H. charazani ), robust but not hypertrophied forearms (hypertrophied in H. armatus and H. charazani ), and absence of a skin fold in the proximoventral portion of upper arm (present in H. armatus , H. charazani , and H. chlorostea ). Hyloscirtus tolkieni differs from species of the H. bogotensis species group, including H. albopunctulatus and H. phyllognathus that inhabit the eastern Andes of Ecuador, and from H. jahni , single member of its homonym group, by its larger body size with 64.9 mm in SVL (smaller in the H. bogotensis and H. jahni species groups with SVL<36 mm), greyish-green dorsum with paler reticulum, yellow spots and black speckles (green or brown dorsum with or without pale or dark spots and speckles and pale lines in the H. bogotensis and H. jahni species groups), ventral surfaces yellow with large black blotches and spots (venter cream or yellowish without dark marks in the H. bogotensis and H. jahni species groups). Description of the holotype. Adult female (Figs 2 - 4 ), 64.9 mm SVL, body robust. Head wider than long (HW/HL = 1.07, HW/SVL = 0.31, HL/SVL = 0.29); snout truncate in dorsal and lateral view; canthus rostralis rounded, distinct; loreal region slightly concave, nearly vertical; lips rounded, slightly flared; nostrils slightly protuberant, openings directed anterolaterally, located at level of anterior margin of lower jaw, area between nostril slightly concave; dorsal surface of internarial region concave; interorbital distance shorter than eye (IOD/ED = 0.91); eye prominent (ED/HL = 0.37, ED/EN = 1.33); tympanic membrane and annulus evident (TD/ED = 0.41); supratympatic fold prominent, extending from below eye across upper and posterior margins of tympanum towards posterior end of mouth and down to arm insertion; region between head and suprascapula slightly depressed; dentigerous processes of vomer prominent, oval, in transverse position, between choanae, narrowly separated, left process with 9 vomerine teeth and right one with 13; choanae small, rounded, separated about 4 x their maximum diameter; tongue cordiform, broad, attached to 80% of mouth floor; mental gland absent (Figs 2 - 4 ). Skin on dorsum shagreen, throat slightly granular, flanks and venter granular, posterior surfaces of limbs strongly granular; pectoral fold absent; cloacal opening directed posteroventrally at upper level of thighs; supracloacal flap present; two pairs of swollen, thick, vertical, pericloacal folds. Forearms robust, slightly thicker than arms, not hypertrophied; axillary membrane absent; ulnar fold present, covering dorsal surface of forearms; fingers long, with thick lateral fringes; discs round, slightly expanded; all discs with rounded pads, circumferential groove of each disc clearly defined; disc on Finger III wider than tympanum (Fin3DW/TD = 1.11); relative lengths on fingers I<II<IV<V; webbing formula: III 3--3- IV ; palmar surface with deep grooves; subarticular tubercles round and poorly projected, distal tubercles larger; supernumerary tubercles small, rounded; thenar tubercle large, elliptical; palmar tubercle flat, bifid, same length as thenar; broad elliptical prepollex hidden under thenar tubercle (Figs 2 - 4 ). Hindlimbs robust (TL/SVL = 0.48, FL/SVL = 0.48); small calcar tubercle present; short and thin inner tarsal fold; without outer tarsal fold or tubercles; inner metatarsal tubercle large, ovoid; outer metatarsal tubercle indistinct; toes long, with thick lateral fringes, bearing discs slightly smaller than those on fingers; relative lengths of toes: I<II<III=V<IV; Toe I with last phalange twisted inside on both feet; webbing formula: I 2-2 II 1⅔- 21/2 III 2-3- IV 3-2- V . Subarticular tubercles large, round; supernumerary tubercles low, round, and sparse (Figs 2 - 4 ). Colouration in life. Dorsal surfaces of head, body and limbs greyish-green, with thick paler-hued reticulum, yellow spots, and black speckles; head with a light greyish-green medial line; throat, venter and flanks yellow (more intense on the throat and turning greyish towards posterior end of venter) with large black blotches and spots; hidden surfaces of limbs yellow with transversely distributed black oval dots; fingers, toes and webbing yellow with black bars and spots; iris pale pink with black periphery, sclera greyish-blue, and nictitating membrane yellow (Fig. 2 ) Colouration in preservative. Same colouration patterns as described for the colouration in life, but greyish-green dorsal areas turned darker grey, yellow on venter and flanks turned golden-grey to grey (Figs 3 - 4 ). Measurements of the holotype (in mm). SVL=64.9, HL=18.8, HW=20.2, IND=4.6, IOD=6.3, EW=4.9, EN=5.2, ED=6.9; TD=2.8, TL=31.2, FL=30.9, Fin3DW=3.1. Etymology. The specific epithet Hyloscirtus tolkieni is in honour of the writer, poet, philologist, and academic John Ronald Reuel Tolkien (J.R.R. Tolkien, 1892-1973), creator of Middle-earth and author of fantasy works like "The Hobbit" and "The Lord of the Rings". The amazing colours of the new species evoke the magnificent creatures that seem to only exist in fantasy worlds. Distribution, natural history, and conservation status. Hyloscirtus tolkieni is only known from its type locality on the southeastern slopes of the Cordillera Oriental of the Andes of Ecuador, at 3190 m elevation, in the Rio Negro-Sopladora National Park, province of Morona Santiago (Fig. 8 ). The ecosystem in the area is High Montane Forest of the Eastern Cordillera of the Southern Andes of Ecuador (MAE et al. 2013). The holotype was active at night at 20:30 amidst tree branches, c. 5 m above ground and 8 m from the nearest stream (Fig. 9 ). It was found in sympatry with an undescribed species of Pristimantis . Figure 8. Map showing the type locality of Hyloscirtus tolkieni sp. nov. at the Rio Negro-Sopladora National Park, province of Morona Santiago, Republic of Ecuador. Figure 9. Habitat of Hyloscirtus tolkieni sp. nov. General landscape (above, red arrow pointing to collection site); and at the collection site inside the forest (below). Photographs by Juan C. Sanchez-Nivicela . Very few herpetological surveys have been conducted in the region, with James A. Peters being one of the few herpetologists that visited the area ( Peters 1973 ). Our surveys were carried out over 13 effective days, and we could not detect additional individuals of H. tolkieni , despite focalised searches. The type locality of H. tolkieni is officially protected as part of the Rio Negro-Sopladora National Park, a protected area created in 2018 where little habitat loss has occurred. Large, forested areas remain unstudied in the national park, and the species may have a wider distribution beyond the immediate surrounding of its type locality. In the absence of sufficient information to evaluate the conservation status and extinction risk of H. tolkieni , we propose that it be classified under the Data Deficiency category until more data is obtained ( IUCN 2012 , 2017 ; Ortega-Andrade et al. 2021 ). Urgent research and monitoring actions should be established to study its life history and ecology, population size and trends, survey new sites where additional populations may exist and evaluate if threats are impacting its long-term conservation, such as invasive species, emerging diseases, or climate changes.