Hyloscirtus dispersus Varela-Jaramillo, Streicher, Venegas & Ron, 2025, sp. nov.
Creators: name: Varela-Jaramillo, Andrea
name: Streicher, Jeffrey W.
name: Venegas, Pablo J.
name: Ron, Santiago R.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Amphibia
Anura
Hylidae
Hyloscirtus
Hyloscirtus dispersus

description: Hyloscirtus dispersus sp. nov.
Figs 5, 7, 9, 10, 11, 20, 21, 22 Common name: Proposed standard English name: Dispersed stream frog Proposed standard Spanish name: Rana de Torrente dispersa
Type material.
Holotype. • QCAZ 52006 (Figs 20 – 22), field no. SC 38765, adult male from Ecuador, Provincia Tungurahua, Caserío Machay, 3 km E of Río Verde on the road to Puyo, (1.3923 ° S, 78.2801 ° W), 1349 m above sea level, collected by SRR, F. Ayala, T. Camacho, M. Yánez, D. Rivadeneira, S. Aldás and D. Pareja on 19 September 2011. A 3 D model of the holotype is available at Sketchfab platform (https://skfb.ly/oSqqI). Paratypes. • All collected in Ecuador. Provincia Sucumbíos: Río Azuela, Hostería El Reventador (0.0752 ° S, 77.5921 ° W), 1680 m, QCAZ 66709 –10, adult males, collected by G. Vaca, M. Mejía and D. Escobar on 26 February 2017; • Provincia Napo: Cocodrilos, on Baeza – Archidona road (0.6710 ° S, 77.7928 ° W), 1575 m, QCAZ 63488, adult male, collected by SRR, S. Guamán, M. J. Navarrete, B. Proaño and A. Achig on 23 June 2016; • Provincia Tungurahua: same locality, date, and collectors as for the holotype, (1.4002 ° S, 78.2807 ° W), 1244 m, QCAZ 52007, adult male; • Reserva Río Zuñac (1.3765 ° S, 78.1540 ° W), 1594 m, QCAZ 52458, 52462, adult males, collected by F. Ayala, D. Paucar, Y. Sagredo, J. P. Reyes, F. Recalde, L. Recalde and S. Recalde on 16 January 2011; • Provincia Pastaza: Reserva Comunitaria Ankaku, on Puyo – Tena road (1.2676 ° S, 78.0479 ° W), 1668 m, QCAZ 46297, adult male, collected by E. Tapia on 15 October 2009; • Parque Nacional Llanganates, Comunidad Zarentza (0.3524 ° S, 78.072 ° W), 1419 m, QCAZ 59819–21, adult males, collected by D. Rivadeneira, F. Mora, J. C. Sánchez, D. Velalcázar, D. Núñez and J. Pinto; • Provincia Morona Santiago: Chiguinda (3.2278 ° S, 78.7200 ° W), 1741, QCAZ 18275, collected by Í. Tapia and G. Onore on 27 December 2001; • 16 km N El Ideal, on the road to Cuenca from Gualaquiza (3.2425 ° S, 78.6725 ° W), 1600 m, QCAZ 23936, metamorph, QCAZ 23937, 23945, adult males, collected by SRR and G. Romero on 09 April 2003; • 8.6 km E 9 de Octubre, Guamote – Macas road (2.24774 ° S, 78.2069 ° W), 1671 m, QCAZ 32267, adult male, collected by M. Bustamante, J. Guayasamin, E. Bonaccorso and J. F. Freile on 19 July 2006; • 4 km from Limón (Leonidas Plaza Gutiérrez), on the road to Plan de Milagro (2.9969 ° S, 78.4550 ° W), 1373–1409 m, QCAZ 40878, adult male, collected by I. Tapia, D. Salazar, L. Coloma and SRR on 07 June 2008, QCAZ 41901 adult female, collected by D. Salazar, E. Lemmon and A. Lemmon on 06 August 2008; • Limón (Leonidas Plaza Gutiérrez), Río Napinaza (2.9230 ° S, 78.4080 ° W), 1430 m, QCAZ 42002, adult male, collected by D. Salazar, E. Lemmon and A. Lemmon on 13 August 2008, QCAZ 42047, adult male, collected by D. Salazar and N. Peñafiel on 28 February 2008; • Bosque Protector Abanico (2.2448 ° S, 78.2053 ° W), 1646, QCAZ 49032, adult male, collected by Y. Sagredo and R. Jarrín on 26 July 2010; • 9 de Octubre – Macas road (2.2351 ° S, 78.2167 ° W), 1683 m, QCAZ 57014–16, adult males, collected by F. Ayala, Y. Sagredo, S. Arroyo, S. Valverde and L. Cedeño on 02 March 2014; • Parque Nacional Sangay, Sardinayacu (2.0928 ° S, 78.1687 ° W), 1475–1735 m, QCAZ 58732–3, 58735, adult males, collected by D. Rivadeneira, D. Velalcázar, J. Pinto, F. Mora, D. Núñez, J. C. Sanchez and A. Correa between 16 January 2015 and 26 January 2015, QCAZ 59099, adult female, collected by SRR, D. Paucar, PJV, P. Baldeón, M. Caminer and K. Nusirquia on 28 February 2015; • Puchimi (2.7774 ° S, 78.1595 ° W), 1365–1450 m, QCAZ 69548, 69550, 69555, 69561–63, adult males, collected by D. Almeida, D. Núñez, K. Nusirquia and J. Mora on 09 July 2017; • Comunidad Shuar Kunkuk, base of Cordillera del Cóndor mountain range (3.3302 ° S, 78.1972 ° W), 1521 m, QCAZ 71029, adult female, collected by D. Almeida, D. Núñez, K. Nusirquia and R. Gavilanes on 01 March 2018; • Cordillera de Cutucú, Carlos Hurtado’s house surroundings (2.7818 ° S, 78.1604 ° W), 1380 m, QCAZ 71428, adult male, collected by D. Almeida, D. Paucar, D. Núñez, K. Nusirquia and R. Gavilanes on 29 January 2018; • Provincia Zamora Chinchipe: Miazi Alto (4.2502 ° S, 78.6174 ° W), 1250 m, QCAZ 41031, adult female, 41032, male, collected by E. Tapia and J. Guayasamín on 12 April 2009, QCAZ 41554, adult male, collected by J. Guayasamín, E. Tapia and H. Braun on 07 April 2009, QCAZ 41649, adult female, collected by S. Aldás, J. Guayasamín and E. Tapia on 12 April 2009; • Los Encuentros (3.7568 ° S, 78.6457 ° W), QCAZ 47074, juvenile, 47110 female, collected by A. Almendáriz on 23 June 2009; Nuevo Paraíso, 700 m NO on the road to Las Tres Aguas (4.8710 ° S, 78.9757 ° W), 1742 m, QCAZ 57099–100, adult females, collected by D. Paucar, D. Almeida, G. Galarza and D. Pareja on 10 April 2014; • Reserva Numbami, 18 km on Zamora-Romerillos road (4.1760 ° S, 78.9561 ° W), 1434–1583 m, QCAZ 57664, 57667, adult males, 57665–66, adult females, collected by SRR, D. Paucar, PJV, D. Almeida, D. Velalcázar, M. J. Navarrete, S. Arroyo, N. Páez and Z. Lange on 11 July 2014; • Parque Nacional Podocarpus, Bombuscaro (4.1344 ° S, 78.9938 ° W), 1443 m, QCAZ 60688, 60692, adult males, 60694–95, adult females, collected by D. Rivadeneira, F. Mora, J. C. Sánchez, D. Velalcázar, D. Núñez, J. Pinto, K. Cruz and L. Tipantiza on 24 March 2015; • Concesión Mirador ECSA, Río Wawayme basin, towards Canales (3.59145 ° S, 78.4212 ° W), 1637 m, QCAZ 66050–52, adult males, collected by R. Betancourt, M. Cajamarca and L. Pandiguana on 23 November 2016; • Nuevo Paraíso, Ciudad Perdida (4.4803 ° S, 78.8294 ° W), 1334 m, QCAZ 68056, adult female, collected by F. Ayala, K. Nusirquia, D. Núñez and A. Calispa on 13 May 2017.
Definition.
In this section, coloration and characters refer to preserved specimens unless otherwise mentioned. The Definition and Diagnosis are based on 11 adult females and 36 adult males. Hyloscirtus dispersus sp. nov. can be diagnosed by the combination of the following characters: (1) mean SVL 34.1 mm in adult males (range 31.3–38.7; n = 36) and mean SVL 41.1 mm in adult females (range 35.4–45.2; n = 11; Suppl. material 1: table S 5, Fig. 7); (2) white supralabial stripe present or absent; (3) tympanum rounded, inconspicuous to conspicuous in males and conspicuous in females; supratympanic fold present and unpigmented; (4) white ulnar and tarsal folds; (5) subarticular tubercles conspicuous in hands and feet; (6) supernumerary tubercles inconspicuous in feet and conspicuous in hands: (7) calcar tubercle present; (8) pericloacal spots well-defined; (9) all surfaces plain cream with a combination of scattered large or minute black spots and with white spots or flecks varying from ill-defined to large on the dorsum; (10) in life, dorsal surfaces and flanks yellowish green, olive green, dull green, brownish green or greyish green, with barely visible to thick white spots and minute or thick black spots or flecks, scattered throughout the body; venter yellow, gold, whitish, brownish green, grayish green, or dark pinkish; axillar and inguinal regions and ventral surfaces yellow, blueish, greenish, silver, brownish green or dark pinkish; pericloacal spots yellow, white or unpigmented; webbing yellow, yellow orange, whitish or dark pinkish; iris pearl or pinkish with leather reticulations; (11) the advertisement call consist of a single note, with a mean duration of 0.11 ± 0.015 s and a mean dominant frequency of 2795.4 ± 138.68 Hz and a fundamental frequency of 2700.63 ± 195.66 Hz. The call can be repeated in a series of 1 to 8 calls.
Diagnosis.
Characters in this section pertain to preserved specimens unless otherwise noticed. Coloration refers to life specimens. The most similar species to Hyloscirtus dispersus sp. nov. living in the Amazon basin are Hyloscirtus albopunctulatus (sympatrically distributed, Fig. 5), H. maycu sp. nov., H. elbakyanae sp. nov., H. phyllognathus, and H. torrenticola. Hyloscirtus dispersus sp. nov. differs by having a supratympanic fold (absent in H. maycu sp. nov., H. elbakyanae sp. nov., H. phyllognathus, and H. torrenticola), an inconspicuous tarsal fold (thick in H. albopunctulatus, H. phyllognathus, and H. torrenticola), conspicuous subarticular tubercles in hands and fee (inconspicuous in hands and feet in H. albopunctulatus, Fig. 11), conspicuous supernumerary tubercles in hands (inconspicuous in hands and feet in H. albopunctulatus, H. maycu sp. nov., and H. elbakyanae sp. nov.), well-defined pericloacal spots (ill-defined or absent in H. maycu sp. nov. and H. elbakyanae sp. nov.), a calcar tubercle present (absent in all species except for H. phyllognathus), and an iris pearl or pinkish with leather-colored reticulations (clam shell with black or sand dune reticulations in H. albopunctulatus and a bronze iris in H. torrenticola, Fig. 12).
The advertisement call of Hyloscirtus dispersus sp. nov. differs by having a call duration of 0.11 ± 0.015 s (shorter in H. albopunctulatus with 0.051 ± 0.005 s and in H. torrenticola with 0.03 ± 0.001 s), a dominant frequency of 2743.79 ± 48.22 Hz (lower in H. albopunctulatus with 2149.84 ± 137.36 Hz and in H. elbakyanae sp. nov. with 2321.29 ± 127.86 Hz) and a fundamental frequency of 2700.63 ± 195.66 Hz (lower in H. albopunctulatus with 1214.12 ± 184.71 Hz and in H. elbakyanae sp. nov. with 1184.35 ± 30.48 Hz). Hyloscirtus dispersus sp. nov. has an intercall duration of 0.33 ± 0.044 s (shorter in H. phyllognathus with 0.06 s and in H. torrenticola with 0.07 ± 0.007 s) (Table 4, Fig. 9; Melin 1941; Duellman and Altig 1978; Rivera-Correa 2016). Moreover, all males of H. dispersus sp. nov. have been found calling while perching on vegetation over streams (n = 14; Pontificia Universidad Católica del Ecuador 2024), while all males of H. albopunctulatus were registered calling from under the rocks next to streams (n = 5; Pontificia Universidad Católica del Ecuador 2024).
Finally, H. dispersus sp. nov. inhabits elevations between 879 and 1807 m, while Hyloscirtus elbakyanae sp. nov. lives lower between 214 and 622 m and in warmer and wetter environments (Figs 5, 10).
Description of the holotype.
Description of characters based on preserved specimen. Adult male (Figs 20 – 22). Measurements (in mm): SVL 32.7; foot length 13.6, head length 9.6, head width 9.5, eye diameter 2.9, tympanum diameter 1.5, tibia length 15.8, femur length 14.3, internarial distance 2.7, interorbital distance 4.8. Head slightly longer than wide; body slender; snout rounded in dorsal view and slightly truncated in lateral view; distance from nostril to eye shorter than diameter of eye; canthus rostralis distinct, slightly convex; loreal region slightly concave; internarial region and top of the head flat; nostrils not protuberant, round, directed anterolaterally; lips rounded, not flared; interorbital area flat, longer than upper eyelid; tympanum round, with upper and posterior margins covered by a curved unpigmented supratympanic fold, reaching anterior margin of insertion of arm; tympanic annulus absent; tympanic membrane absent; mental gland present, oval-shaped, barely defined, extending ~ 1 / 3 the length of head; dentigerous processes of vomers straight, between round choanae, narrowly separated from each other, with five (right) and four (left) teeth; tongue slightly cordiform, widely attached to mouth floor; vocal slits and vocal sac present.
Forearms slender; axillary membrane absent; fingers bearing dermal fringes and rounded discs; relative lengths of fingers I <II <IV <III; webbing formula I basal II 2—3 + III 2 1 / 2 —2 + IV; subarticular tubercles prominent, round, single; supernumerary tubercles small; thenar tubercle absent, palmar tubercle small; prepollex present, not modified as a spine; nuptial pads absent; ulnar tubercles absent; outer ulnar fold present. Hindlimbs slender; toes bearing dermal fringes and rounded discs; relative length of toes I <II <III <V <IV; extensive toe webbing, formula I 2 – — 1 + II 1 + — 2 – III 1 + — 2 + IV 2 + — 1 – V; outer tarsal fold present; tarsal tubercles absent; calcar tubercle small, pinkish white; subarticular tubercles conspicuous, round and single; supernumerary tubercles inconspicuous in feet and conspicuous in hand; inner metatarsal tubercle present and ovoid, outer absent. Skin on dorsal surfaces and flanks smooth; venter finely granular; cloacal opening directed posteriorly at upper level of thighs, round tubercles below; cloacal fold present, thick.
Color of holotype in preservative
(Fig. 20). Dorsal surfaces of the head, body, limbs, and flanks cream densely covered with minute black spots, bigger black spots dispersed on the head and anterior part of the body. Very few, barely visible, white spots scattered on the posterior dorsum and hindlimbs. Venter, throat, and ventral surfaces of limbs cream. Mental gland cream. White supralabial stripe. White ulnar fold. Pinkish white cloacal and tarsal folds with black spots. Webbing cream.
Color of holotype in life
(Figs 21, 22). Based on digital photographs. Dorsal surfaces and flanks pale brownish green with minute black spots in the anterior part of the body and arms and white spots scattered throughout the body and limbs. Belly and other ventral surfaces are reddish brown. Tympanum and throat greenish. Mental gland yellowish green. Webbing reddish brown. Iris pinkish with leather reticulations.
Variation.
Dorsal and ventral variation of adult specimens is illustrated on Figs 20 – 22. In preservative (Fig. 20), dorsal background coloration varies from darker and brownish cream to pale cream. Background coloration has a variable pattern of white spots distributed throughout the body and limbs with minute black spots scattered in the body (e. g., QCAZ 41901), minute and thick brownish black spots (e. g., QCAZ 57100), few black marks scattered in the dorsum (e. g., QCAZ 60695) or without black spots (e. g., QCAZ 69550), to barely visible white spots in the body with minute black spots dispersed in the body (e. g., QCAZ 66710), minute and thick black or brownish black spots covering half the body or the entire body and limbs (e. g., QCAZ 41554, 69548), covering half the body (e. g., QCAZ 66052, 66709), with dark marks and flecks across the body and limbs (e. g., QCAZ 66051, 52458) and big white marks with thick brownish spots in the body (e. g., QCAZ 41649) and barely visible black spots (e. g., QCAZ 60694). Ventral surfaces vary from pale cream (e. g., QCAZ 57100) to cream (e. g., QCAZ 66051), without any pattern. Throat cream or whitish cream, with or without minute black spots (e. g., 66709). Mental gland varies from cream (e. g., QCAZ 69548) to whitish cream (e. g., QCAZ 41554). Cloacal fold varies from white (e. g., QCAZ 60695), pinkish white (e. g., QCAZ 69550), to pinkish white with black spots (e. g., QCAZ 69561). White supralabial stripe varies from absent (e. g., QCAZ 69548), inconspicuous (e. g., QCAZ 66051) to conspicuous (e. g., QCAZ 66710).
In life, dorsal background coloration varies from yellowish green, pale olive green, olive green, brownish green, darker brownish green, greyish green to lemon grass (Figs 21, 22). Background coloration has a variable pattern of white spots scattered throughout the body and limbs with minute and thick black spots or marks scattered across the body (e. g., QCAZ 52463, 58732), accumulated in the anterior part (e. g., QCAZ 60694), accumulated in the entire body (e. g., QCAZ 69563), with black flecks (e. g., QCAZ 41031) or without black spots or any marks (e. g., QCAZ 57100, 69546) to barely visible or absent white spots without any dark spots or marks (e. g., QCAZ 49032, 66710). Additionally, the dorsum can be covered by thick white marks (e. g., QCAZ 57666, 60694). Venter and posterior tights vary from yellow (e. g., QCAZ 41031, 57666 – less common), greenish (e. g., QCAZ 57099, 59099), lemon grass (e. g., QCAZ 58732), brownish (e. g., QCAZ 52463, 69550), silver (e. g., QCAZ 59821) or white (e. g., QCAZ 69546). Ventral axillar and inguinal surfaces vary from yellow (e. g., QCAZ 41031) to green (e. g., QCAZ 59099) or white (e. g., QCAZ 69456). Throat white (e. g., QCAZ 41031), green (e. g., QCAZ 63488), or brownish (e. g., QCAZ 52463). White supralabial stripe varies from present (e. g., QCAZ 57100) to absent (e. g., QCAZ 66710). Iris varies from pearl with barely visible reticulations (e. g., QCAZ 69546) or leather reticulations (e. g., QCAZ 59821) to pinkish with leather reticulations (e. g., QCAZ 69563). Webbing matches ventral coloration.
Distribution and natural history.
Hyloscirtus dispersus sp. nov. is known from more than 25 localities from northern to southern Ecuador in the eastern Andean slopes, at elevations between 879–1807 m (Fig. 5). From the species analyzed in this study, this is the most widespread and its biogeographic regions are Eastern Lower Montane Forest and Eastern Montane Forest (Ron et al. 2022). This species lives in hillside forests, frequently found in secondary forest and artificial open areas. They are nocturnal and associated with streams of running water and ravines. Males call perched on riparian vegetation up to 2.5 m above the ground. It also occurs close to lagoons and small waterfalls. Perching sites include plants of Araceae, bromeliads, cedars, and ferns (Pontificia Universidad Católica del Ecuador 2024). This species has not been found living or calling under rocks. It is known to live in sympatry with Hyloscirtus albopunctulatus and potentially with H. maycu sp. nov.
Advertisement call.
We analyzed 60 calls from 14 individuals. QCAZ 52006 from Caserío Machay, Provincia Tungurahua, 19 September 2011, recorded by SRR. QCAZ 59820 from Comunidad Zarentza, Llanganates National Park, Provincia Pastaza, 23 February 2015, air temperature 18 ° C recorded by D. Rivadeneira. QCAZ 63488 from Cocodrilos, Provincia Napo, 23 June 2016, recorded by SRR. KU 164338 and one unvouchered specimen from 2 km SW of Río Reventador, Provincia Napo, 19 March 1975, temperature 18 ° C, recorded by W. E. Duellman. USNM 286338, Río Reventador, Provincia Napo, recorded by R. McDiarmid. USNM 286349 from Baeza – Lago Agrio Road, Provincia Napo, 22 February 1985, recorded by R. McDiarmid. USNM 284316 from Cascada San Rafael, Provincia Napo, recorded by M. Foster. Two unvouchered specimens from San Rafael, Provincia Napo, recorded by R. McDiarmid. One unvouchered specimen from Sangay National Park, Provincia Morona Santiago, recorded by D. Batallas. Two unvouchered specimens from Río Azuela, Provincia Napo, 23 October 1971, temperature 18–19 ° C, and one from Cordillera del Dué, Provincia Sucumbíos, recorded by W. Duellman. The advertisement call consists of a single note, repeated in series of 1–8 calls (Fig. 9 E). Average call duration is 0.11 ± 0.015 s with an average inter-call interval of 0.33 ± 0.044 s. Mean dominant frequency is 2795.41 ± 138.68 Hz. Other call parameters are listed in Table 4.
Conservation status.
The distribution polygon of H. dispersus sp. nov. is 26,296 km 2. Its distribution range overlaps with many protected areas. Its presence in secondary forests and artificial open areas indicates that it can withstand anthropogenic habitat change. Therefore, we propose assigning H. dispersus sp. nov. to the Red List category Least Concern.
Etymology.
The specific epithet comes from the Latin word dispersus in reference to the wide distribution range of this species, extending from north to south of the eastern Andes of Ecuador and probably with a wider unknown distribution that includes neighboring countries, Colombia, and Peru.
description: Published as part of Varela-Jaramillo, Andrea, Streicher, Jeffrey W., Venegas, Pablo J. & Ron, Santiago R., 2025, Three new species of torrent treefrogs (Anura, Hylidae) of the Hyloscirtus bogotensis group from the eastern Andean slopes and the biogeographic history of the genus, pp. 233-292 in ZooKeys 1231 on pages 233-292, DOI: 10.3897/zookeys.1231.124926