Scinax pyroinguinis, Chávez & Aznaran & García-Ayachi & Catenazzi, 2023

Chavez, German, Aznaran, Wilmar, Garcia-Ayachi, Luis A. & Catenazzi, Alessandro, 2023, Rising from the ashes: A new treefrog (Anura, Hylidae, Scinax) from a wildfire-threatened area in the Amazon lowlands of central Peru, Evolutionary Systematics 7 (1), pp. 183-194 : 183

Scinax pyroinguinis sp. nov.

Figs 3 , 4 , 5A, B

Type material.

Holotype. Peru • Adult male; Ucayali region, Coronel Portillo province, Quebrada Agua Blanca; 8°31'38.49"S, 74°39'36.63"W; 160 m; 29 Sep. 2022; G. Chávez, W. Aznaran leg.; CORBIDI 24669 (Figs 3 , 4A-D ). Paratopotype. Adult male (CORBIDI 24670, Fig. 4E-H ).

Diagnosis.

A medium-sized species of Scinax ; SVL of males 39.4-42.0 mm (n=2), females unknown; skin on dorsum tuberculate, tubercles large, spiculated; head rounded from dorsal and lateral view; nostrils protuberant, not projected from head contour in dorsal view; upper eyelid tubercles present, large, conical; tubercles on the lower jaw present, conical; vocal sac unpigmented; row of tarsal tubercles present; heel tubercle present, large, conical; row of ulnar tubercle present; a discrete anal flap present in males; a barely visible interorbital triangular mark pointed posteriorly; a large bright orange blotch on a dark background covering groin and anterior surface of thighs, bright orange spots on dark background covering posterior surface of thighs and shanks.

Comparisons.

Externally, the new species is easily differentiable from members of the Scinax catharinae clade and the S. ruber clade (except those included in the S. rostratus group) by having a row of tubercles on the lower jaw (see Fig. 4A, E ) and a snout projecting beyond the edge of the jaws (Fig. 5 ). Furthermore, it can be distinguished from the species in the S. rostratus group by the unique combination of lacking a tubercle or fleshy flap on the tip of the snout, having a snout rounded from dorsal view, conical tubercles on the upper eyelids and heels, dorsum skin strongly tuberculate, and having large bright orange blotches covering the groin, posterior surface of thighs and shanks (Figs 4 , 5A, B ). Specifically, Scinax pyroinguinis can be differentiated from S. boulengeri by having a head rounded from dorsal view (vs acuminate), nostrils not projected over the snout border on dorsal view (vs projected), and large conical tubercles on the heels (vs small); from S. constrictus by having a longer size with a maximum SVL in males (n = 2) of 42.2 mm (vs 28.4 mm), a head acutely rounded in dorsal view (vs pointed), and nostrils not projected over the snout border in dorsal view (vs projected); from S. garbei by having skin on dorsum tuberculate (vs smooth with scattered tubercles), a rounded head from dorsal view (vs acuminate), and nostrils not projected over the snout border in dorsal view (vs projected); from S. jolyi by having a rounded head from dorsal view (vs acuminate), nostrils not projected over the snout border in dorsal view (vs projected), a row of large conical tubercles on the lower jaw (vs absent), and large conical tubercles on the heels (vs small, low tubercles); from S. kennedyi by having skin on dorsum tuberculate (vs smooth), a row of large conical tubercles on the lower jaw (vs absent), large conical tubercles on the heels (vs small low tubercles); from S. nebulosus by having a longer size with a maximum SVL in males (n = 2) of 42.2 mm (vs 30 mm), a rounded head from dorsal view (vs acuminate), nostrils not projected over the snout border in dorsal view (vs projected), and lacking of tubercles on the tip of the snout (vs tubercle present); from S. pedromedinae by having a longer size with a maximum SVL in males (n = 2) of 42.2 mm (vs 29 mm), a rounded head from dorsal view (vs acuminate), nostrils not projected over the snout border in dorsal view (vs projected), and large conical tubercles on the upper eyelid (vs absent); from S. proboscideus by having a rounded head from dorsal view (vs pointed), a row of large conical tubercles on the lower jaw (vs small law tubercles), lacking a fleshy proboscis on the tip of the snout (vs present); from S. rostratus by having the skin on dorsum tuberculate (vs smooth with a few tubercles), a rounded head from dorsal view (vs acutely rounded), a row of large conical tubercles on the lower jaw (vs absent), and large conical tubercles on the heels (vs absent); finally from S. sugillatus by having a rounded head from dorsal view (vs acuminate), nostrils not projected over the snout border in dorsal view (vs projected), and lacking of tubercles on the tip of the snout (vs tubercle present). Moreover, Scinax pyroinguinis resembles S. acuminatus externally, but it can be distinguished by having a snout extending beyond the edge of the jaw (vs snout not projected beyond the jaws), a rounded head from dorsal view (vs acuminate), a row of large conical tubercles on the lower jaw (vs absent), conical tubercles on the heels (vs absent), and groin and posterior surface of thighs bright orange on a dark background (vs bluish-gray groins with black bands on the posterior surface of thighs).

Description of the holotype.

Head slightly longer than wide (HW/HL = 0.95, HL = 36% of SVL, HW = 35% of SVL); snout elongate, rounded in dorsal view (Fig. 3E ) and acutely rounded in lateral view (Fig. 3F ); nostrils not projected from head contour in dorsal view, projected in lateral view; canthus rostralis concave from dorsal view; ED 52% of END, 22% of HL, 23% of HW; internarial region depressed; upper eyelid conical tubercle present, higher than rest of tubercles on the same region; tympanum evident, circular, 87% of ED; supratympanic fold evident; tongue slightly cordiform, free behind; vomerine teeth in two small groups between choanae; single subgular vocal sac; five tubercles along the edge of the lower jaw at each side. Upper arm robust, with 3 tubercles on outer side; fingers size I<II~IV<III (Fig. 3C ); fingers I to IV basally webbed; nuptial pads absent; outer metacarpal tubercle cordiform, inner metacarpal tubercle oval; subarticular tubercles rounded; finger discs wider than long; toes size I<II<V~III<IV (Fig. 3D ). Hind limb long; tibia longer than femur, TL 61% of SVL, THL 50% of SVL; FL 45% of SVL; foot webbing formula I 2-2+ II 1-1+ III 0-2- IV 2-0 V; inner metatarsal tubercle rounded, the outer with ⅔ the size of the inner; subarticular tubercles rounded; supernumerary tubercles discrete on hands and feet; outer margin of tarsus with a ridge of tubercles; calcar tubercle conical; a discrete anal flap formed by two enlarged tubercles; a dermal groove from the cloaca to the center of ventral surface of thighs. Skin of dorsum and head tuberculate with many small ridges, conical and rounded tubercles; flanks and shoulders shagreened with numerous smaller tubercles; body not bearing any constriction; dorsal surfaces of arms and legs with scattered tubercles; venter areolate; throat granular; ventral surfaces of legs and arms smooth.

Coloration of the holotype in life

(Fig. 4A-D ). Background coloration of dorsal surfaces of head, body, and limbs dark brown with olive-green fine blotches. Dorsal pattern consisting of a greenish-brown triangle-like inter-orbital mark pointed distally, loreal region darker, numerous greenish brown blotches distributed randomly on dorsal surfaces of limbs. Fingers and toes brown, distal surfaces of disc brown with cream bars or blotches; toe webbing creamy yellow with brown reticulations. Axillary region dark brown with a bright orange blotch; flanks creamy yellow with brown reticulations; groins dark brown with a large irregular bright orange blotch that reaches the medial part of the anterior surface of thighs, the right with a small orange spot above the blotch; posterior surfaces of thighs dark brown with two large bright orange spots; posterior surface of shanks and tarsus dark brown with bright orange blotches. Throat and chest creamy yellow with brown reticulations; belly creamy yellow. Ventral surfaces of hands brown; supernumerary tubercles cream; ventral surface of feet dark brown. Iris creamy yellow with a brown transversal stripe crossing the iris horizontally, uncomplete vertical black stripes above and below the pupil, and some fine black reticulations above and below the pupil.

Coloration of the holotype in alcohol

(Fig. 3 ). Dorsal surfaces of head, body, and limbs dark brown; throat and chest creamy white with brown reticulations; belly and ventral surface of limbs creamy white. Groins, axilla, posterior surface of thighs and shanks dark brown with white blotches or large spots.

Variation.

Paratype CORBIDI 24670 shows a greener canthus rostralis and paler dorsum. Also, it has a more reticulated iris. Variation in body measurements and proportions are given in Table 1 .

Etymology.

The specific epithet pyroinguinis is an adjective that means "groins of fire", and is formed from the combination of the Greek prefix “pyro” (=fire) and the Latin name “inguen” (=groin). The name refers to the striking orange blotched groins of the new species which remind us the flames of the wildfires threatening its habitat.

Distribution and natural history.

Scinax pyroinguinis sp. nov. is only known from the type locality, in the Ucayali River basin (Fig. 2 ). The type locality is a remnant patch of forest surrounded by farms where vegetation has been burnt or converted to pastures (Fig. 6A, B ). Vegetation in the area is represented primarily by cecropia trees ( Cecropia spp.) up to 15 m tall, scattered bushes, and ferns. The ground is well covered by leaf litter and some fallen trunks, also some epiphytes and lichens are present on trunks. A 3 m width stream bordering the edge of the forest has banks covered by clay or sand (Fig. 6A ). We observed individuals of S. pyroinguinis perched on leaves of bushes along the stream and at the edge of the forest, about 1 m above the ground, at night. During our fieldwork, we did not notice any calls and our search for tadpoles was unsuccessful. Additionally, we observed the following sympatric species: Boana lanciformis , B. cinerascens and S. ruber .

Figures

Figure 2. Maximum Likelihood consensus tree for Scinax (new species in bold) and related species Scarthyla ostinodactyla and Sphaenorhynchus lacteus (as outgroup terminals) included in this study based on a 590 - bp fragment of the 16 S rRNA gene in IQ-TREE (posterior probabilities are indicated at each node). Consensus tree was constructed from 1000 bootstrap trees (log-likelihood of consensus tree: - 3243.3050, SE 139.8126). Branch lengths are optimized by maximum likelihood on original alignment.

Figure 3. Preserved male Holotype (CORBIDI 24669, SVL = 42.0 mm) of Scinax pyroinguinis sp. nov. A. Dorsal view of the body; B. Ventral view of the body; C. Ventral view of the right hand; D. Ventral view of the right foot; E. Dorsal view of the head; F. Lateral view of the head. Scale bar: 10 mm.

Figure 4. Color pattern of the type series of Scinax pyroinguinis sp. nov. in life. A-D. Holotype (CORBIDI 24669, SVL = 42 mm); E-H. Paratopotype (CORBIDI 24700, SVL = 39.4 mm).

Figure 5. Dorsal (left column) and ventral (right column) coloration in life of some species of the Scinax rostratus group (A-F) vs a representative of the Scinax ruber clade not included in the S. rostratus group (G-H). A, B. Scinax pyroinguinis sp. nov.; C, D. Scinax garbei (SINCHI 00712), E-F) Scinax pedromedinae (CORBIDI 18210); G, H. Scinax ruber (SINCHI 00416). Arrows show the differences between the edge of the maxilla and the tip of the snout. Green arrows pointed on the maxillary edge; Red arrows pointed on the tip of the snout.

Figure 6. Habitat of Scinax pyroinguinis sp. nov. A. Wildfire in the vicinity of the type locality during our fieldwork; B. Stream and surrounding vegetation in Quebrada Blanca, where specimens of the new species were caught; Ucayali, central Peru. Photos by: A Luis A. Garcia-Ayachi; B Pavel Cartagena.