Description
Scinax montivagus have an average snout-vent length in males of 28.0 ± 1.1 mm with a range of 25.9 mm to 30.0 mm. Females have an average snout-vent length of 30.1 ±1.5 mm with a range of 28.9 mm to 32.2 mm. Scinax montivagus has a slender body with a head that has a greater length than width. In both the dorsal view and profile, the snout is rounded. The nostrils are protruding and located anterolaterally. The eyes are also protruding. The canthus rostralis is straight. The loreal region has a concave shape. A distinct, nearly circular tympanic ring is present. The well-developed supratympanic fold extends from the posterior corner of the eye to the shoulder. The fold covers the upper border of the tympanum. These frogs have a single median, subgular vocal sac. However, the vocal sac does not reach the pectoral fold, which is compound and just observable. The vocal silts are situated on the mouth floor laterally. The tongue is elliptical and located laterally, but is not completely free from behind. The elliptical-shaped choanae is in front of the vomerine teeth, which are arranged in two transverse series. Dispersed granules are present on the dorsal region. The ventral and inferior regions of the thigh possess granulations as well. The skin of the gular region, under the arms, and tibia is smooth. The forearms are robust, whereas the upper arms are slim. The slim fingers are poorly fringed and have elliptical disks. Finger I lacks pigmented spicules. In breeding males, the dorsal surface of metacarpal I is nearly covered with nuptial pads. The lengths of the fingers increase from I < II ≤ IV < III. There is a single oval inner metacarpal tubercle. The outer metacarpal tubercles are separated into two round parts. Simple, round subarticular tubercles are present. The supernumerary tubercles are round. They have robust legs and their toes have elliptical disks. The toes increase in length from I < II < V < III < IV. Webbing on the toes is variable with a modal webbing formula of I 2⁺ – 2^1/2 II 1^1/2 – 2^- III 1 –3 IV 2^1/2 – 1^1/2 V. A single, ovoid inner metatarsal tubercle is present. The outer metatarsal tubercle is simple and round. Both the subarticular and supernumerary tubercles are single and round. The tarsus has a longitudinal skin fold. The calcar is proximal to the tubercle (Juncâ et al. 2015).

From the dorsal view, the larval body appears oval and from the lateral view, it appears triangular. The height is about 90% of the length of the body and the height is almost equal to the width. The body height and width range from 5.6 mm to 7.0 mm. The body length ranges from 8.6 mm to 10.0 mm, which is approximately 35% of the total length. The average total length is 27.0 ± 1.9 mm, ranging from 23.7 mm to 30.0 mm during developmental stages 33 - 34. The oral disc is trapezoidal and has a width that is equal to the 50% of the body width. It is not emarginated, but is subterminal. The marginal papillae are round and in one row. Additionally, they have a short dorsal gap. Only the middle portion of the anterior labium lacks submarginal papillae. Otherwise, submarginal papillae are randomly spread out on lateral regions of the disc in one row on the posterior labium, next to a row of marginal papillae. The upper jaw sheath is definitely jagged and has extensive keratinization. A middle lateral process is present. The lower jaw sheath is similar to the upper jaw sheath, but it is V-shaped. The posterior rows of teeth are shorter than the anterior rows and there is a reduction in the third row of teeth. The labial tooth formula is 2(2)/3(1). In the lateral view, the snout is reduced and in the dorsal view, it is round. The nostrils are dorsolateral and are situated further away from the eyes than the snout. The snout has a round opening with a diameter measuring about 6% of the body width. The distance between the nostril and snout is about 20% of the body length. The eyes are located laterally and the diameter is about 30% of the body width. The interorbital distance is about 59% of the body width. The spiracle is found below the lateral midline near the middle third of the body length and it is sinistral and short. The vent tube is positioned on the dextral side, over the ventral fin margin. The tail is relatively long compared to body height and possesses adequate musculature. The maximum ventral fin height is less than or equal to the maximum dorsal height. The dorsal fin begins to curve from the posterior third of the body. It then rises steadily and at the middle third of the tail, reaches a maximum height, at which point it starts to decrease. For the ventral fin, which begins at the ventral end of the body, the maximum height is at the posterior third of the tail, and from there it decreases (Juncâ et al. 2015).

Scinax montivagus is a member of the Scinax ruber clade but adults can be differentiated from most members by its moderate snout-vent length, shape of the snout, straight and well-marked canthus rostralis, modal toe webbing, tarsal fold and tubercle, dorsal patterning, beige surfaces of the thigh and groan, lack of transverse brown bars on the limbs, and advertisement call. The tadpoles can be differentiated based on mouth parts.

More specifically, adult S. montivagus are smaller than S. acuminatus, S. castroviejoi, S. dolloi, S. eurydice, S. fuscovarius, S. granulatus, S. hayii, S. iquitorum, S. perereca, S. sateremawe, S. similis, and S. x-signatus. They are larger than S. auratus, S. cabralensis, S. cardosoi, S. cuspidatus, and S. exiguous. The presence of a vocal sac that does not reach the pectoral fold differentiates S. montivagus from S. baumgardenri, S. exiguus, S. fuscomarginatus, S. madeira, S. manriquei, S. villasboasi and S. wandae. The fact that the vocal sac is single, subgular, and laterally unexpanded differentiates S. montivagus from S. camposseabrai. A rounded snout and a heel without a pointed tubercle differentiates S. montivagus from S. boulengeri, S. garbei, S. jolyi, S. kennedyi, S. nebulosus, S. pedromedinae, S. proboscideus, S. rostratus, and S. sugillatus. A sharp canthus rostralis and presence of tarsal folds and tubercles differentiates S. montivagus from S. blairi and S. quinquefasciatus. The tarsal folds alone distinguish S. montivagus from S. cretatus. A grayish-red iris differentiates S. montivagus from S. cretatus, S. cruentommus, S. pinima, S. rupestris, and S. uruguayus. The dorsal patterning of S. montivagus differentiates it from S. altae, S. alter, S. auratus, S, blairi, S. cabralensis, S. caldarum, S. cardosoi, S. chiquitanus, S. cretatus, S. crospedospilus, S. curicia, S. cuspidatus, S. danae, S. daurtei, S. imbegue, S. juncae, S. lindsayi, S. maracaya, S. oreites, S. quinquefasciatus, S. rogerioi, S. ruber, S. squalirostris, S. staufferi, S. tigrinus, S. tymbamirim, and S. wandae. The lack of flash coloring on the hidden surfaces of the thigh and groin, and the lack of brown transvers limb bars differentiate S. montivagus from S. nasicus, S. iquitorum, and S. x-signatus. Toe webbing formulas distinguish S. montivagus from S. similis. Various features of the advertisement call allow differentiation of S. montivagus from S. alter, S. boesemani, S. cabralensis, S. chiquitanus, S. crospedospilus, S. cruentommus, S. elaeochrous, S. eurydice, S. ictericus, S. juncae, S. lindsayi, S. maracaya, S. manriquei, S. nasicus, S. perereca, S. rogerioi, S. rupestris, and S. squalirostris (Juncâ et al. 2015).

Adult S. montivagus closely resembles S. cabralensis and S. rupestris. Scinax montivagus males have snout-vent lengths between 25.9 mm and 30.0 mm, while S. cabralensis males have smaller snout-vent lengths ranging from 22.5 mm to 25.0 mm. The scapula region of S. montivagus has an inverted parenthesis created by fragmented brown marks and the sacral region has two incomplete brown longitudinal marks, while S. cabralensis has scattered marks or spots on the dorsal region. The call duration of S. montivagus (0.14 s – 0.24 s) is shorter than the call duration of S. cabralensis (0.31 s – 1.01 s). Scinax cabralensis has a pointed snout and a round canthus rostalis, while S. montivagus has a round snout and a straight canthus rostralis. Scinax montivagus has a distinct supratympanic fold, whereas S. cabralensis has a rudimentary one. The vocal sacs of S. cabralensis are more developed than S. montivagus. The finger disks are small and round in S. montivagus unlike S. cabralensis, which have large and oval disks. Scinax montivagus possesses a tarsal fold and tarsal tubercles, whereas S. cabralensis has a smooth tarsus (Juncâ et al. 2015).

In comparison to the S. rupestris, S. montivagus have more slender bodies. Scinax montivagus can be differentiated from S. rupestris because S. rupestris have small round and asymmetrical dark marks that are dispersed on the dorsal region. Scinax montivagus possess a straight canthus rostralis and a smooth vocal sac, and not a convex canthus rostralis and a granular vocal sac like S. rupestris. The iris of S. montivagus is gray-red in color, while the iris of S. rupestris is beige in color and possesses a diagonal dark brown bar. Larvae of S. montivagus have triangular bodies and larvae of S. rupestris have ovoid bodies. The advertisement call of S. montivagus consists of a single note with multiple pulses and the call duration is between 0.14 s and 0.24 s. In contrast, the advertisement call of S. rupestris had multiple notes and pulses and the call duration varies from 0.29 s and 0.42 s. Aside from the first two and last pulses, the pulses of S. montivagus are of comparable amplitudes, whereas the last pulses of each note of S. rupestris increase in amplitude (Juncâ et al. 2015).

The submarginal papillae on the lower lip can differentiate tadpoles of S. montivagus from S. auratus, S. caldarum, S. crospedospilus, S. curicica, S. duartei, S. eurydice, S. funereus, S. fuscovarious, S. hayii, S. ictericus, S. juncae, S. maracaya, S. oreites, S. pachycrus, S. perereca, and S. ruber. Scinax montivagus has a different tooth row formula than S. pachycrus. The lack of keratinized plates besides the lower jaw sheath distinguishes S. montivagus from S. uruguayus. Scinax montivagus tadpoles do not have a posterior third tooth row at the end of a labial arm, which differentiates it from S. alter, S. auratus, S. crospedospilus, S. cuspidatus, S. juncae, and all the known tadpoles of the S. rostratus group. A pair of pigmented keratinized spurs located behind the lower jaw sheath distinguishes S. montivagus from S. ictericus. Having a subterminal instead of terminal oral disc differentiates S. montivagus from S. acuminatus and all known tadpoles of the S. rostratus group. Body size, rounded dorsal fin, and posteriorly directed spiracle differentiate S. montivagus from S. oreites and S. similis. The preserved body color and patterning differentiates S. montivagus from S. elaeochrous. And lastly, the triangular body shape of S. montivagus differentiates it from S. rupestris (Juncâ et al. 2015).

In life, the ground color of adult S. montivagus on the dorsal surface is golden. A marble green coloration is evident on the upper eyelids and thighs. The posterior margin is jagged and a brown trapezoid-shaped mark is divided and inverted in the interorbital region. The scapular region has an inverted parenthesis-shaped mark and the sacral area had two divided brown longitudinal marks. The dorsal surfaces, forelimbs and hind limbs have some scattered brown spots. A dark brown stripe is present along the supratympanic fold. Spots and marks are absent from both the inguinal region and posterior surface of the thigh. The nuptial pads are lightly colored. The ventral surface is cream in color, while the chest, hind limbs and forelimbs are red. The iris is a gray-red color marked with a distinct lattice pattern that is dark-brown. The lower hemisphere is gray and a dark-brown bar is present in the medial portion. In alcohol, the colors appear faded, but the pattern remains intact (Juncâ et al. 2015).

In life, S. montivagus larvae have some gray-brown blotches present on the yellow-cream colored body and tail of the larvae. The spiracles appear transparent, while the fins are translucent. Their fins are light yellow in color, possessing some dark brown spots as well as a few veins. The venter wall is also translucent, but has a slight lustrous color. In preservative, the body and tail are more cream colored with some gray-brown blotches. The spiracles are transparent, but the venter wall is sheer. The fins are also sheer, but have some dark brown spots and a few small veins (Juncâ et al. 2015).

In comparison to the holotype, the nostrils can be located slightly higher in paratypes. Differences in the number of supernumerary tubercles may exist. Toe webbing is also variable. Females are generally larger than the males. The ground color on the dorsal region can be brown and a faded interorbital mark may be present in a few fixed specimens. There may also be more prominent scapular and sacral stripes (Juncâ et al. 2015).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Brazil

View distribution map in BerkeleyMapper.

Scinax montivagus is only known from in the State of Bahia, Brazil, specifically in the Chapada Diamantina ecoregion, which is a part of the Espinhaço Range. These frogs have been found in various habitats in rock fields. In a study conducted by Juncâ et al. (2015), 12% of the specimens were discovered away from water bodies, while 24% were found next to water bodies. Additionally, 14% were observed in semi-deciduous forest areas that contained dense vegetation and rapidly moving freshwater. Areas with multiple features were where the other 50% of the specimens were found. Features included open land containing herbaceous plants and exposed rocks as well as riparian areas (Juncâ et al. 2015).

Life History, Abundance, Activity, and Special Behaviors
The majority of S. montivagus are found near herbaceous plants and exposed rocks in open lands and riparian areas. Some are found near lotic water bodies in semi-deciduous forests that contain compact vegetation. They can also inhabit areas distant and adjacent to water bodies (Juncâ et al. 2015).

Scinax montivagus males generally call during the rainy season, which occurs between November and January. While calling, males sit on vegetation near small streams and temporary ponds. In the type locality, one note of an advertisement call of S. montivagus consists of 9 to 15 pulses, with an average of 12.65 pulses. The call duration lasts between 0.14 and 0.24 s, with an average of 0.20 seconds. The note pulse rate is between 53.42 and 64.10 pulses/s, with an average of 60.60 pulses/s. The time between calls ranges from 0.70 and 6.86 s, with an average of 2.22 s. Frequencies between 0.8 and 2.7 kHz represent the lowest-pitch harmonic, whereas the frequencies between 3.0 and 5.6 kHz represent the highest-pitch harmonic. The call’s dominant frequencies are between 1.54 and 1.84 Hz, which are characterized as the lowest-pitch harmonic. The second or third quartile of each pulse of a note is more intense in energy. Besides the first two, less intense pulses, the sound intensity of the pulses is similar. The last pulse may also be less intense in energy than the previous pulse. Scinax montivagus in the Municipality of Mucugê, State of Bahia, Brazil have similar advertisement calls. The average number of pulses is 14.16 pulses, the average call duration is 0.22 s, the average note pulse rate is 63.61 pulses/s and the average time between calls is 2.81 s. However, their call dominant frequencies could be either in the lowest-pitch harmonic (1.72 to 1.90 kHz) or the highest-pitch harmonic (3.79 to 4.35 kHz) (Juncâ et al. 2015).

Comments
The species authority is: Juncâ, F. A., Napoli, M. F., Nunes, I., Mercês, E. A., and Abreu, R. O. (2015). “A New Species of the Scinax ruber Clade (Anura, Hylidae) from the Espinhaço Range, Northeastern Brazil.” Herpetologica, 71(4), 299-309.

Scinax montivagus is a member of the Scinax ruber clade. However, more phylogenetic work was needed at the time of S. montivagus’ description to place it more specifically within the clade (Juncâ et al. 2015).

The species name "montivagus" is derived from the Latin words, “monti” meaning “mountain” and “vagus” meaning “errant” (Juncâ et al. 2015).

Ten species from the S. ruber clade can be found in the Espinhaço Range: S. auratus, S. cabralensis, S. curicica, S. eurydice, S. fuscomarginatus, S. fuscovarius, S. maracaya, S. pachycrus, S. squalirostris, and S. x-signatus. Only S. eurydice is can be found in both the north and the south. Scinax cabralensis, S. curicica, S. fuscovarius, and S. marcaya are only found in the southern region of the range. The other species have ranges beyond the Chapada Diamantina. The first endemic species to the northern region of the Espinhaço Range from the S. ruber clade is S. montivagus (Juncâ et al. 2015).

References

Juncâ, F. A., Napoli, M. F., Nunes, I., Mercês, E. A., Abreu, R. O. (2015). ''A New Species of the Scinax ruber Clade (Anura, Hylidae) from the Espinhaço Range, Northeastern Brazil.'' Herpetologica, 71(4), 299-309.

Species Account Citation: AmphibiaWeb 2018 Scinax montivagus <https://amphibiaweb.org/species/8396> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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