Hyloscirtus maycu, Varela-Jaramillo & Streicher & Venegas & Ron, 2025

Hyloscirtus maycu sp. nov.

Figs 5 View Figure 5 , 7 View Figure 7 , 9 View Figure 9 , 10 View Figure 10 , 11 View Figure 11 , 16 View Figure 16 , 17 Common name: Proposed standard English name: Maycu stream frog Proposed standard Spanish name: Rana de torrente de Maycu View Figure 17

Type material.

Holotype. • QCAZ 67087 View Materials (Figs 16 View Figure 16 , 17 View Figure 17 ), field no. SC 56707, adult male from Ecuador, Provincia Zamora Chinchipe, Reserva Natural Maycu , plateau (4.2067 ° S, 78.6326 ° W), 882 m above sea level, collected by D. Almeida, K. Nusirquia, D. Núñez, D. Paucar, F. Hervas, J. Ortega, A. Achig, S. Pillajo, R. Gavilanez, and J. Mora on 27 February 2017. A 3 D model of the holotype is available at the Sketchfab platform (https://skfb.ly/oSqqr) GoogleMaps . Paratypes. • All from Ecuador, Provincia Zamora Chinchipe. Collected with the holotype, QCAZ 67081 View Materials , 67086 View Materials adult females, QCAZ 67082 View Materials adult male, QCAZ 67084 View Materials , 67085 View Materials juveniles, QCAZ 67083 View Materials tadpole, 959–1219 m of elevation, collected on 23 and 25 February 2017 and 01 March 2017 GoogleMaps . Nuevo Paraíso, camp near Río Nangaritza, Cordillera del Oso (4.4442 ° S, 78.8134 ° W), 1127 m, QCAZ 68055 View Materials adult male, collected on 16 May 2017 by K. Nusirquia, Darwin Núñez, Andrea Calispa GoogleMaps

Definition.

In this section, coloration and characters refer to preserved specimens unless otherwise mentioned. The definition and diagnosis are based on two adult females and three adult males. Hyloscirtus maycu sp. nov. can be diagnosed by the combination of the following characters: (1) mean SVL 33.4 mm in adult males (range 31.9–34.2; n = 3) and mean SVL 42.7 mm in adult females (range 41.7–43.7; n = 2; Suppl. material 1: table S 5; Fig. 7 View Figure 7 ); (2) white supralabial stripe present or absent; (3) tympanum round, inconspicuous in males and distinct in females; supratympanic fold inconspicuous and unpigmented; (4) white ulnar and tarsal folds inconspicuous or conspicuous; (5) subarticular tubercles conspicuous, round and single, in hands and feet; (6) supernumerary tubercles inconspicuous in hands and feet; (7) calcar tubercle absent; (8) pericloacal spots well-defined; (9) all surfaces plain cream with a combination of black and white spots in the dorsum; (10) in life, dorsal surfaces and flanks olive green to crete with white spots and minute or thick black spots scattered over the body; axillar and inguinal regions blueish or mongoose; venter and posterior surfaces of thighs yellow; other ventral surfaces silver or greenish; bones and articulations blue; unpigmented pericloacal spots; webbing yellow orange; iris clam shell with thick dark pinkish to leather reticulations; (11) the advertisement call consists of a single note, with duration of 0.053 s (n = 1) and a dominant frequency of 2343.8 Hz and fundamental frequency of 1171.90 Hz. The call can be repeated consecutively from 10–13 times in a series of calls.

Diagnosis.

Characters in this section pertain to preserved specimens unless otherwise noticed. Coloration refers to life specimens. The most similar species to H. maycu sp. nov. living in the Amazon basin are Hyloscirtus albopunctulatus , H. elbakyanae sp. nov., H. dispersus sp. nov., H. phyllognathus , and H. torrenticola . Hyloscirtus maycu sp. nov. differs by the absence of a supratympanic fold (present in H. albopunctulatus and H. dispersus sp. nov.), an inconspicuous tarsal fold (present and thick in H. albopunctulatus , H. phyllognathus , and H. torrenticola ), conspicuous subarticular tubercles in hands and feet (small to inconspicuous in hands and feet in H. albopunctulatus ; Fig. 11 View Figure 11 ), inconspicuous supernumerary tubercles in hands and feet (conspicuous in hands in H. dispersus sp. nov.), pericloacal spots ill-defined or absent (well-defined in H. albopunctulatus and H. phyllognathus ), an absent calcar tubercle (present in H. dispersus sp. nov. and H. phyllognathus ), and a clam iris with dark pinkish or leather reticulations (a clam shell iris with black or sand dune reticulations in H. albopunctulatus and a bronze iris in H. torrenticola , Fig. 12 View Figure 12 ). Although our sample size is small, the available evidence indicates that H. maycu sp. nov. differs from H. elbakyanae sp. nov. by its smaller size (Fig. 7 View Figure 7 ).

The advertisement call of H. maycu sp. nov. has a rise time of 0.8 s (longer in H. albopunctulatus with 2.28 ± 0.80 s and shorter in H. elbakyanae sp. nov. with 0.57 ± 0.05 s and in H. torrenticola with 0.16 ± 0.017 s), a dominant frequency of 2343.8 Hz and a fundamental frequency of 1171.9 Hz (higher dominant frequency in H. dispersus sp. nov. of 2795.41 ± 138.68 Hz and fundamental frequency of 2700.63 ± 195.66 Hz). Hyloscirtus torrenticola also has a higher dominant frequency of 2743.79 ± 48.22 Hz and a fundamental frequency of 2743.75 ± 48.16 Hz. Hyloscirtus maycu sp. nov. has a call duration of 0.053 s (longer in H. dispersus sp. nov. of 0.11 ± 0.015 s) (Table 4 View Table 4 , Fig. 9 View Figure 9 ; Melin 1941; Duellman and Altig 1978; Rivera-Correa 2016).

Additionally, H. maycu sp. nov. inhabits elevations between 882 and 1183 m, while H. elbakyanae sp. nov. lives lower between 214 and 622 m and in wetter and warmer environments (Figs 5 View Figure 5 , 10 View Figure 10 ).

Description of the holotype.

Description of characters based on the preserved specimen. Adult male (Figs 16 View Figure 16 , 17 View Figure 17 ). Measurements (in mm): SVL 34.1; foot length 13.9, head length 9.7, head width 10.2, eye diameter 3.0, tympanum diameter 2.0, tibia length 17.2, femur length 17.2, internarial distance 3.1, inter-orbital distance 4.9. Head wider than long; body slender; snout rounded in dorsal and lateral view; distance from nostril to eye same as diameter of eye; canthus rostralis distinct; loreal region convex; internarial region slightly curved; top of the head slightly concave; nostrils not protuberant, round, directed anterolaterally; lips rounded, not flared; interorbital area slightly concave, longer than upper eyelid; tympanum and tympanic fold inconspicuous; tympanic annulus absent; tympanic membrane absent; mental gland present, diamond-shaped, well defined, extending ~ 1 / 3 the size of the head; dentigerous processes of vomers slightly curved, transversal and posterior to ovoid choanae, each process narrowly separated from each other and bearing five teeth each; tongue cordiform, widely attached to mouth floor; vocal slits and subgular 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 + — 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 1 – — 2 – II 1 + — 2 – III 1 + — 2 – IV 2 – — 1 + V; outer tarsal fold present; tarsal tubercles absent; calcar tubercle absent; subarticular tubercles conspicuous, round and single; supernumerary tubercles inconspicuous; inner metatarsal tubercle present and round, outer absent. Skin on dorsum, flanks, dorsal and ventral surfaces of limbs, thighs, and venter smooth; cloacal opening directed posteriorly at upper level of thighs; cloacal fold thick.

Color of holotype in preservative

(Fig. 16 View Figure 16 ). Dorsal surfaces of the head, dorsum, flanks, and limbs cream with few minute black and white spots scattered through the body. Venter, throat, and ventral surfaces of limbs plain cream. Mental gland pale cream. White supralabial stripe absent. Ulnar, tarsal, and cloacal folds white. Webbing cream. Other details are shown in Fig. 16 View Figure 16 .

Color of holotype in life

(Fig. 17 View Figure 17 ). Based on digital photographs. Dorsal surfaces and flanks olive green with white spots and minute black spots and a few dispersed black marks. Head darker brown, probably because of the high accumulation of minute black spots. Venter and posterior surface of thighs yellow. Axillar and inguinal regions and other ventral surfaces greenish white. Yellowish mental gland. Ulnar, tarsal, and cloacal folds white. Webbing yellow orange. Iris clam shell with leather reticulations.

Variation.

Dorsal and ventral variation of adult specimens is illustrated on Fig. 16 View Figure 16 (in preservative) and Fig. 17 View Figure 17 (in life). In preservative, dorsum varies from cream with white spots scattered throughout the body and limbs with minute and thick darker brownish black spots scattered across the entire body and limbs (e. g., QCAZ 67081 ) or accumulated in the anterior part of the body (e. g., QCAZ 67086 ) to darker cream with scattered spots dispersed in the body and limbs and minute black spots covering the dorsum (e. g., QCAZ 67082 ) or barely visible minute black spots and a few black marks in the anterior part of the body (e. g., QCAZ 68055 ). Venter varies from paler (e. g., QCAZ 67086 ) to darker cream (e. g., QCAZ 68055 ). White supralabial stripe varies from absent (e. g., QCAZ 67082 ), ill-defined (e. g., QCAZ 67081 ) to well-defined (e. g., QCAZ 67086 ).

In life (Fig. 17 View Figure 17 ), dorsum varies from olive green with scattered white spots throughout the body and limbs with thick black spots in the body and limbs (e. g., QCAZ 67081 ) or few black marks in the body (e. g., QCAZ 67082 ) to paler olive green with spread white marks covering the entire body and limbs and few black marks in the mid part of the body (e. g., QCAZ 67086 ). Axillar and inguinal regions vary from blue (e. g., QCAZ 67081 ) to whitish. Ventral surfaces besides venter and posterior thighs vary from greenish (e. g., QCAZ 67081 ) to whitish (e. g., QCAZ 67082 ). A white supralabial stripe is present (e. g., QCAZ 67086 ) or absent (e. g., QCAZ 67082 ). Iris varies from clam shell with thin leather reticulations (e. g., QCAZ 67086 ), thick pinkish reticulations (e. g., QCAZ 67081 ) or thick leather reticulations (e. g., QCAZ 67082 ).

Distribution and natural history.

Hyloscirtus maycu sp. nov. is known only from its type locality in Provincia Morona Santiago and one locality in Provincia Zamora Chinchipe (airline distance 32 km), at elevations between 882 and 1183 m, on the foothills of Cordillera del Cóndor, in Ecuador (Fig. 5 View Figure 5 ). Biogeographic region is Eastern Lower Montane Forest ( Ron et al. 2022). This species lives in primary and secondary forests. They are nocturnal and associated with ravines and streams. Males call from vegetation up to 2 m high, on the edge of the streams. One individual was recorded calling under a rock, and another on a rock in a ravine with low flow. A metamorph was found (in March) on an island of rock in the middle of a stream, suggesting that its tadpoles develop in streams, like other Hyloscirtus . A tadpole ( QCAZ 67083 ) was found on a pool next to a stream in February.

Advertisement call.

We analyzed five calls from one individual ( QCAZ 67087 ) from Reserva Natural Maycu, Provincia Zamora Chinchipe, 27 February 2017, recorded by J. Ortega. The advertisement call consists of a single tonal note, repeated 10–13 times in a series of calls (Fig. 9 B View Figure 9 ). Average call duration is 0.053 s with an average inter-call interval of 0.09 s. The average dominant frequency of the call is 2343.8 Hz. Other call parameters are listed in Table 4 View Table 4 .

Conservation status.

The distribution polygon of H. maycu sp. nov. is 54.8 km 2 (based on two localities). Its distribution range is small but overlaps with a protected area, Reserva Natural Maycu; however, it is also found in Cordillera del Cóndor, an area severely fragmented by deforestation due to agriculture, cattle raising, and threatened mining activities. In response to its distribution range being less than 20000 km 2 and by having less than 10 known localities, we propose assigning H. maycu sp. nov. to the Red List category Vulnerable c (VU B 1 a).

Etymology.

The specific epithet maycu is used as a noun in apposition and refers to the type locality of the species, a protected area in Ecuador named Reserva Natural Maycu, managed by the NGO Naturaleza y Cultura Internacional. “Maycu” seems to be a derivation of the Shuar word “Maycua” or “Maycuwa”, which the Shuar people use to refer to some species of small trees of the genus Brugmansia (angel’s trumpet). The southern border of the Reserve has been invaded by illegal miners and provides an additional example of the threat that mining represents for biodiversity conservation (F. Serrano, in litt.).