Scinax fuscomarginatus, (LUTZ, 1925)

Brusquetti, Francisco, Jansen, Martin, Barrio-Amorós, César, Segalla, Magno & Haddad, Célio F. B., 2014, Taxonomic review of Scinax fuscomarginatus (Lutz, 1925) and related species (Anura; Hylidae), Zoological Journal of the Linnean Society 171 (4), pp. 783-821 : 794-800

SCINAX FUSCOMARGINATUS ( LUTZ, 1925) REDESCRIPTION ( FIGS 4A , 5A , 6A )

Hyla fuscomarginata Lutz, 1925

Hyla parkeri Gaige, 1929 syn. nov.

Ololygon fuscomarginata – Fouquette & Delahoussaye, 1977

Ololygon parkeri – Fouquette & Delahoussaye, 1977 syn. nov.

Ololygon trilineata Hoogmoed & Gorzula, 1979 syn. nov.

Scinax fuscomarginata – Duellman & Wiens, 1992

Scinax trilineata – Duellman & Wiens, 1992 syn. nov.

Scinax parkeri – Duellman & Wiens, 1992 syn. nov.

Scinax fuscomarginatus – Köhler & Böhme, 1996

Scinax trilineatus – Köhler & Böhme, 1996 syn. nov.

Scinax lutzorum Cardoso & Pombal, 2010 syn. nov.

Scinax pusillus Pombal, Bilate, Gambale, Signorelli & Bastos, 2011 syn. nov.

Lectotype: AL-MN 845 designated by Cardoso & Pombal (2010). Belo Horizonte, Minas Gerais, Brazil, collect- ed by A. Lutz and J. Venâncio in November 1924 (specimen examined).

Paralectotypes: AL-MN 847–850 (specimens examined) and USNM 96964 (pictures) designated by Cardoso & Pombal (2010). Belo Horizonte, Minas Gerais, Brazil, collected by A. Lutz in November 1924 .

Diagnosis: Scinax fuscomarginatus is distinguished from all other species in the genus by the following combination of characters: (1) small size in males (SVL 15.7–26.7 mm); (2) subelliptical snout in dorsal view; (3) head longer than wide; (4) dorsal pattern with continuous divergent or parallel brown dorsolateral stripes on a light brown background; (5) uniform light brown colour on posterior surfaces of thighs; (6) immaculate or finely pointed chest and belly; (7) longitudinal dark stripes on forearm and shank external surface; (8) loreal region steep sloping toward lip; (9) diagonal stripes on dorsal surface of shank.

Redescription: Based on the lectotype ( ALMN 845 ) and material from Lagoa Santa, Minas Gerais, 35 km from the type locality ( CFBH 24356-64 ). A slender, smallsized frog (males SVL 20.2–21.8 mm), body width equal to head. Snout subelliptical in dorsal view and protruding in profile. Head longer than wide ( HW /HL 0.84). Nostrils protuberant, dorsolaterally located, IND 67% of IOD. Canthus rostralis rounded. Loreal region concave and steep sloping toward lip. Eye large, protuberant, 98% of IOD. Tympanum slightly distinct, small; tympanic annulus rounded with superior portion hidden by supratympanic fold. Supratympanic fold distinct from posterior corner of eye to arm insertion. In mouth corner a row of a variable number of tubercles with the first one bigger than the others. Vocal sac large, single, subgular, expanded externally, evident by the presence of loose skin with longitudinal folds, laterally reaching posterior region of mouth corner and ventrally the level of pectoral fold. Tongue ovoid, with lateral and posterior borders free, shallow notch in posterior region. Vocal slit longitudinal, from mediolateral portion of tongue to jaw angle. Vomerine dentigerous processes located medial and posterior to choanae, without contact between them, four to nine teeth each; choanae oval, slightly diagonal to sagittal axis .

Arm more slender than forearm. Row of unpigmented flat tubercles in external surface of forearm. Fingers short; finger discs elliptical, wider than long, disc of finger I markedly smaller than the others; webbing reduced to a fringed in proximal and distal margins of fingers II and III, absent in the others. Ulnar ridge present. Palmar tubercle bifid. Subarticular tubercles of fingers I and II conical, of finger III rounded, and of finger IV with distal margin truncated. Thenar tubercle large, occupying much of the base of finger I; a pad between subarticular tubercle of finger I and palmar tubercle. Unpigmented nuptial pad occupying posterior region of the base of finger I and posterodorsal region until distal margin of subarticular tubercle. Supernumerary tubercles rounded. Hind limbs slender, shank 51% and thigh 43% of SVL. A row of unpigmented flat tubercles on external surface of tarsus. Toes slender. Elliptical discs, wider than long, those of toes I and II smaller than the others. Inner metatarsal tubercle oval. Outer metatarsal tubercle rounded, half the size of inner metatarsal tubercle, located with proximal margin at the level of distal margin of inner metatarsal tubercle or slightly passing it. A cutaneous ridge on proximal margin of toe I from inner metatarsal tubercle to subarticular tubercle. Cutaneous ridge on external margin of the base of toe V. Supernumerary tubercles rounded, located at the base of toes. Webbing formula I 2–2 II 11/2 –2 III 1 or 11/2 –2 IV 2–1 or 11/2 V. Tarsal fold absent.

Preaxillar pectoral fold distinct. Dorsolateral region of body, dorsal region of head, upper eyelid, and dorsal region of hind limbs covered with rounded pustules; gular region smooth; chest and belly granular; ventral surface of thighs shagreen.

Colour in preservative: General colour light brown with continuous dark brown dorsolateral stripe from upper eyelid to inguinal region, where it is more diffuse; considering the pair of stripes, they are divergent; supratympanic fold with same coloration as dorsolateral stripe; between dorsolateral stripe and inferior border of tympanum level a wide, light brown stripe (with lower chromatophore density than dorsolateral stripe); from supratympanic fold to inguinal region, tympanic membrane of same colour as adjacent region (sometimes with slightly lower chromatophore density); dark brown stripe on canthus rostralis; loreal region with scattered chromatophores, at lowest density on the upper lip; between eye and upper lip only a few chromatophores or absence of them; a median line from internostril region to sacral region, wider between eyes and nostrils, in the portion between eyes, in median region of dorsum, and in sacral region; a wide, dark brown transversal interocular stripe; finger discs darkly pigmented, dorsal surface of hands with dark brown dots and transversal stripes on fingers III and IV, like those on forearms. A longitudinal dark brown stripe on external margin of finger IV to elbow; dorsal surface of legs with diagonal dark brown stripes, with one on heel and three on shank; external surface of thigh and tarsus with a longitudinal dark brown stripe; ventrally, external borders of the gula, shoulders, and borders of belly finely spotted, immaculate on rest of belly and chest; hidden and posterior parts of thigh and inguinal region uniform light brown.

Variation: Measurements and body proportions are given in Table 2. All of the analysed specimens show a subelliptical snout in dorsal view but with some variation related to the tip shape, ranging from rounded to slightly pointed tips. We found great variation in the development of toe webbing, mainly between toes II and III. Small specimens (SVL <17 mm) show a trend for less developed toe webbing. The webbing formula ranges from I 2–2 II 11/2 –2 III 1–2 IV 2–1 V to I 2–2 II 2–3 III 11/2 –3 IV 3– 11/2 V. The dorsal pattern varies with respect to the median line, interocular stripe, and dorsolateral stripe (see intrapopulational variation in Fig. 7 ). Some individuals have a longitudinal marbled stripe on the dorsal shank surface instead of diagonal stripes. In general, darker individuals have the lateral part of the body more spotted, finely dotted on chest and in some cases with dark brown pigmentation between the glands that form the nuptial pad. The longitudinal dark stripe on the external surface of the shank is present in a great percentage of our sample (91%). Most of the specimens that do not present the longitudinal stripe are noticeably faded.

Advertisement call: The advertisement call of S. fuscomarginatus has been described in several works and from different localities ( Duellman & Pyles, 1983; De la Riva et al., 1994; Pombal, Bastos & Haddad, 1995a; Toledo & Haddad, 2005a; Pombal et al., 2011). All variation is given in Table 3. The advertisement call of S. fuscomarginatus (N = 56 males) is constitut- ed by a single multipulsed note with modulated frequency. On average, note duration is 0.54 s (SD = 0.20; range = 0.27−0.92), dominant frequency is 3776.10 Hz (SD = 325.04; range = 2960.40–4593.80), and pulse rate is 172.49 pulses/s (SD = 23.22; range = 113.42– 271.74).

Comparisons: Males of S. fuscomarginatus have a smaller body size (SVL 15.7–26.7 mm) compared with males of the following species: S. acuminatus (SVL 39–45 mm; Lutz, 1973), Scinax boesemani ( Goin, 1966) (28.4–31.8 mm; Duellman, 1986), Scinax camposseabrai ( Bokermann, 1968) (SVL 28.9–33.5 mm; Caramaschi & Cardoso, 2006), Scinax castroviejoi De la Riva, 1993 (SVL 41.9 mm; De la Riva, 1993), Scinax chiquitanus ( De la Riva, 1990) (SVL 33.3 mm; De la Riva, 1990), Scinax dolloi ( Werner, 1903) (SVL 34.9 mm; Pugliese, Baêta & Pombal, 2009), Scinax eurydice ( Bokermann, 1968) (SVL 44– 52 mm; Bokermann, 1968), Scinax funereus ( Cope, 1874) (SVL 28.7–35.1 mm; Duellman, 1971), Scinax fuscovarius ( Lutz, 1925) (SVL 41–44 mm; Cei, 1980), Scinax hayii ( Barbour, 1909) (SVL 39–43 mm; Heyer et al., 1990), Scinax iquitorum Moravec et al., 2009 (35 mm; Moravec et al., 2009), Scinax manriquei Barrio-Amorós, Orellana & Chacón-Ortiz, 2004 (SVL 27.7 mm; Barrio-Amorós et al., 2004), Scinax perereca Pombal, Haddad & Kasahara, 1995b (SVL 34–38.5 mm; Pombal et al., 1995b), Scinax similis (SVL 29.4–34.7 mm; Caramaschi & Cardoso, 2006), and Scinax x-signatus ( Spix, 1824) (SVL 29.1–39.1 mm; Caramaschi & Cardoso, 2006).

By its uniform light brown colour on the posterior surfaces of the thigh, S. fuscomarginatus can be differentiated from Scinax caldarum ( Lutz, 1968) , Scinax cardosoi ( Carvalho-e-Silva & Peixoto, 1991), Scinax curicica Pugliese, Pombal & Sazima, 2004 , Scinax duartei ( Lutz, 1951) , Scinax granulatus ( Peters, 1871) , Scinax hayii , Scinax maracaya ( Cardoso & Sazima, 1980) , Scinax nasicus , S. similis (all with yellow flash colour on posterior surface of thigh), and Scinax rogerioi Pugliese et al., 2009 (brown spots on posterior surface of thigh; Pugliese et al., 2009).

By its dorsal pattern with a continuous brown dorsolateral stripe from the upper eyelid to the inguinal region S. fuscomarginatus differs from S. acuminatus , Scinax baumgardneri ( Rivero, 1961) ( Duellman, 1986) , S. boesemani ( Duellman, 1986) , Scinax cabralensis Drummond, Baêta & Pires, 2007 ( Drummond et al., 2007), S. camposseabrai , Scinax crospedospilus ( Lutz, 1925) , Scinax danae ( Duellman, 1986) , S. eurydice , Scinax lindsayi Pyburn, 1992 ( Pyburn, 1992) , S. maracaya (all without dorsolateral stripe); from S. alter , Scinax auratus ( Wied-Neuwied, 1821) , Scinax ED , eye diameter, measured horizontally; EN, eye−nostril distance, from distal corner of orbit to proximal margin of external nostril; ESD, eye−snout distance, from tip of the snout to distal corner of the eye; FAL, forearm length, from elbow to the proximal margin of the thenar tubercle; HL, head length; HW, head width; IND, internostril distance, between the interior margins of the nostrils; IOD, interorbital distance; SHL, shank length; SVL, snout−vent length; TAL, tarsus length, from the tibiotarsal articulation to the proximal margin of the internal tarsal tubercle; TD, tympanum diameter, measured horizontally; THL, thigh length.

cretatus Nunes & Pombal, 2011 ( Nunes & Pombal, 2011), Scinax exiguus ( Duellman, 1986) , S. squalirostris , Scinax wandae ( Pyburn & Fouquette, 1971) (all with dorsolateral light stripe); from S. caldarum and S. duartei (with dorsal stripe from between eyes and connected with a interocular blotch); from Scinax pachycrus ( Miranda-Ribeiro, 1937) (with a lateral dark subcantal stripe from corner of eye to inguinal region); from Scinax cuspidatus ( Lutz, 1925) (with irregular stripe or inverted parenthesis on thoracic region; Lutz, 1973); and from S. cruentommus (with irregular longitudinal marks; Duellman, 1972).

From the most similar species S. madeirae and Scinax villasboasi sp. nov., S. fuscomarginatus differs by its subelliptical snout in dorsal view (rounded in S. madeirae and S. villasboasi sp. nov.); head much longer than wide (head nearly as wide as long in S. madeirae and S. villasboasi sp. nov.); loreal region steep sloping toward lip (softly in S. madeirae and S. villasboasi sp. nov.); longitudinal dark stripe on external surface of shank (absent in S. madeirae and S. villasboasi sp. nov.; Fig. 8 ); oblique stripes on dorsal surface of shank (transversal in S. madeirae and in S. villasboasi sp. nov.; Fig. 9 ). Scinax fuscomarginatus differs from S. madeirae by an unpigmented or finely spotted area on upper lip (strongly spotted, forming patches in S. madeirae ; Fig. 10 ); lateral part of body immaculate or finely spotted (strongly spotted in S. madeirae ; Fig. 10 ); and dorsolateral stripes divergent or parallel (convergent in S. madeirae ).

Figures

Figure 4. Dorsal and lateral views of the head of A, Scinax fuscomarginatus (CFBH 24364, Lagoa Santa, Minas Gerais, Brazil); B, Scinax madeirae (CFBH 25469, topotype); C, Scinax villasboasi sp. nov. (CHUNB 40156, holotype).

Figure 5. Hand (left) and foot (right) of A, Scinax fuscomarginatus (CFBH 24364, Lagoa Santa, Minas Gerais, Brazil); B, Scinax madeirae (CFBH 25469, topotype); C, Scinax villasboasi sp. nov. (CHUNB 40156, holotype).

Figure 6. Dorsal and ventral views of A, Scinax fuscomarginatus (CFBH 24364, Lagoa Santa, Minas Gerais, Brazil); B, Scinax madeirae (CFBH 25470, topotype); C, Scinax villasboasi sp. nov. (CHUNB 40156, holotype).

Figure 7. Scinax fuscomarginatus intrapopulation dorsal variation (vertebral line, interocular stripe, and dorsolateral stripes). Letters represent different populations: A, Lagoa Santa, Minas Gerais, Brazil; B, Reserva Mabarakajú, Canindeyú, Paraguay; C, Parque Nacional Cerro Corá, Amambay, Paraguay; D, Chapada dos Guimarães, Mato Grosso, Brazil; E, Altamira, Pará, Brazil; F, Passo de Camarajibe, Alagoas, Brazil; G, Formoso de Araguaia, Tocantins, Brazil; H, Porto Nacional, Tocantins, Brazil; I, Isla Yasyretá, Itapúa, Paraguay; J, Estancia Pirá Potrero, Amambay, Paraguay; K, Fazenda Lazer, Porto Nacional, Tocantins, Brazil.

Figure 8. External view of tibia. A, with a longitudinal dark stripe (CFBH 24362; Scinax fuscomarginatus, Lagoa Santa, Minas Gerais, Brazil); B, lacking longitudinal dark stripe (CFBH 25469; Hyla madeirae, topotype).

Figure 9. Dorsal view of tibia showing the striped pattern. A, transversal stripes (CFBH 24362; Scinax fuscomarginatus, Lagoa Santa, Minas Gerais, Brazil); B, perpendicular stripes (CHUNB 9939; Scinax madeirae, Vilhena, Rondônia).

Figure 10. Lateral view showing the upper lips and lateral patterns. A, finely spotted (CFBH 24364; Scinax fuscomarginatus, Lagoa Santa, Minas Gerais, Brazil); B, conspicuously spotted, forming patches (CFBH 25469; Hyla madeirae, topotype); and C, (CHUNB 40157; Scinax villasboasi sp. nov., paratype). Scale bar = 5 mm.