Scinax melanodactylus, Lourenço, Ana Carolina Calijorne, Luna, Maria Celeste & Pombal Jr, José P., 2014

Lourenço, Ana Carolina Calijorne, Luna, Maria Celeste & Pombal Jr, José P., 2014, A new species of the Scinax catharinae Group (Anura: Hylidae) from Northeastern Brazil, Zootaxa 3889 (2), pp. 259-276 : 261-269

Scinax melanodactylus sp. nov.

( Fig. 2–4 )

Scinax agilis— Faivovich, 2005. Herpetologica, 61: 77.

Scinax agilis— Pimenta et al. 2007. Zootaxa, 1441: 49 (part.)

Scinax agilis— Rocha et al. 2008. Brazilian Journal of Biology, 68: 104. Scinax agilis— Lourenço et al. 2009. Herpetologica, 65: 478 (part.)

Scinax agilis— Pombal et al. 2010. Zoologia, 27: 802 (part.)

Scinax agilis— Cruz et al. 2011. Zootaxa, 3096: 25 (part.)

Scinax agilis— Lima et al. 2011. Boletim do Museu Nacional, 529:6 (part.) Scinax agilis— Passos et al. 2012. Check List. Journal of Species Lists and Distribution, 8: 792 (part.)

Holotype. MNRJ 80145, an adult male collected in the road to Canavieiras (BA 001), district of Trancoso (16° 34' 5.80" S, 39° 11' 4.20" W; elevation 68 m), Municipality of Porto Seguro, State of Bahia, Brazil, in May, 2012 by T.S. Soares and P.V. Scherrer.

Paratypes. MNRJ 80141−80144, four adult males collected with the holotype; MNRJ 67838 an adult male collected on 6 to 15 June, 2010 by T.S. Soares and colleagues; CFBH 36877, an adult male collected on 17 April, 2014 by A.C.C. Lourenço, D. Baêta, A.F. Sabbag, and D. Morais; CFBH 36893, 36901−36903, four adult males, CFBH 36892, 36896−36899, five adult females, and CFBH 36894, 36895, 36900, three juveniles. All collected in Coroa Vermelha, Beira Mar Avenue (16º 22' 37.33" S, 39º 01' 12.24"W; elevation 5 m), Municipality of Porto Seguro, State of Bahia, Brazil, on 18 April, 2014 by A.C.C. Lourenço, A.F. Sabbag, D. Baêta, and D. Morais.

Referred specimens. All from Brazil. CFBH 1939 an adult male, CFBH 1940–1941 and 1943 three adult females collected at Municipality of Conceição da Barra, State of Espírito Santo; CFBH 7358–7361, four adult females collected at Municipality of Passo do Camaragibe, State of Alagoas; MZUSP 141339−141342, four adult males collected at Municipality of Passo do Camaragibe, State of Alagoas; MNRJ 46853 an adult female and MNRJ 46854 an adult male collected at Municipality of Belmonte, State of Bahia; MZUSP 88972−88974, three adult males collected at Municipality of Aracajú, State of Sergipe; UFBA 3739, an adult males collected at Municipality of Porto Seguro, State of Bahia; UFBA 3974, 4734−4736, 4931−4932, 4937, 4945, 4952, 6044−6045 adult males collected at Municipality of Mata de São João, State of Bahia; UFBA 3973, 3975−3981, 3983, 3985−3990, 3919, 3973, 4330−4333, 4394, 4934−4935, 4939, 4941−4942, 4944, 4948−4951, adult females collected at Municipality of Mata de São João, State of Bahia; UFBA 4396, adult male collected at Municipality of Camaçari, State of Bahia; UFBA 53130, adult male collected at Municipality of Santo Amaro das Brotas, State of Sergipe; MNRJ 75122−75126 and UFBA 10420, adult females collected at Municipality of Ilhéus, State of Bahia; UFBA 5915, 5947−5949, adult females collected at Municipality of Entre Rios, State of Bahia; UFBA 9605−9607, adult females collected at Municipality de Prado, State of Bahia.

Diagnosis and comparison with other species. The new species is included in the S. catharinae Group for having all phenotypic synapomorphies pointed out by Faivovich (2002) for this group (posterior part of the cricoid ring extensively elongated and curved; partial mineralization of intercalary elements between ultimate and penultimate phalanges; laterodistal origin of the m. extensor brevis distalis digiti III).

This new species is characterized by its small size (SVL males 12.0–16.0, n=11; SVL females 13.2–17.3, n=5); snout subovoid in dorsal view; canthus rostralis undifferentiated; loreal region concave and oblique; vocal slits present in males; males with vocal sac not expanded; males with hypertrophied forearms; absence of macroscopic glandular acini on the pectoral region; pectoral fold present; absence of macroscopic glandular acini on the medial region of the forearm; absence of macroscopic glandular acini on the dorsal region of the fingers II and III; dark colored and nonhypertrophied nuptial pad ( Fig. 4 ); interocular region with a thick, black longitudinal line or without markings; dorsolateral white band, dorsally bordered by dark brown stripe; skin on dorsum smooth; belly and throat beige; absence of bright coloration on inguinal region and hidden portions of the thigh and shank; absence of externally differentiated glands on the inguinal region of male; the interdigital membrane reaches the base of the disc on the medial margin of the toe V.

Scinax melanodactylus is distinguishable from all species of Scinax in possessing dark colored nuptial pads on digit II and it differs from all species of Scinax catharinae Group except S. agilis in possessing compound pectoral fold. Furthermore, Scinax melanodactylus presents a distinctive marking pattern and color on the body, which is characterized by the presence of a white dorsolateral band, dorsally bordered by dark brown strip, and by the presence of a black longitudinal line on the interocular region (variable in some specimens that do not have a line in this region). This feature helps differentiate the new species from all other of the S. catharinae Group except S. agilis .

In addition, Scinax melanodactylus differs from S. albicans ( Bokermann, 1967) , S. angrensis ( Lutz, 1973) , S. ariadne ( Bokermann, 1967) , S. aromothyella , S. berthae , S. brieni ( De Witte, 1930) , S. canastrensis ( Cardoso & Haddad, 1982) , S. carnevallii (Caramaschi & Kisteumacher, 1982) , S. catharinae ( Boulenger, 1888) , S. flavoguttatus ( Lutz & Lutz, 1939) , S. hiemalis ( Haddad & Pombal, 1987) , S. humilis ( Lutz, 1954) , S. jureia (Pombal & Gordo, 1991) , S. kautskyi ( Carvalho-e-Silva & Peixoto, 1991), S. littoralis (Pombal & Gordo, 1991) , S. longilineus ( Lutz, 1968) , S. luizotavioi ( Caramaschi & Kisteumacher, 1989) , S. muriciensis Cruz, Nunes & Lima, 2011 , S. obtriangulatus ( Lutz, 1973) , S. pombali Lourenço, Carvalho, Baêta, Pezzuti & Leite, 2013 , S. ranki ( Andrade & Cardoso, 1987) , S. rizibilis ( Bokermann, 1964) , S. skaios Pombal, Carvalho, Canelas & Bastos, 2010 , S. strigilatus ( Spix, 1824) , S. trapicheiroi ( Lutz, 1954) , and S. tripui Lourenço, Nascimento & Pires, 2009 by its smaller size (SVL of males in S. melanodactylus 12.0–16.0; combined SVL of males in these species 16.7–42.8; SVL of female in S. melanodactylus 13.2–17.3; combined SVL of females in these species 19.5–47.0); from S. heyeri ( Weygoldt, 1986) by the smaller size of males only (combined SVL of males in S. heyeri 21.1–24.4); from S. argyreornatus ( Miranda-Ribeiro, 1926) and S. machadoi ( Bokermann & Sazima, 1973) by the smaller size of females only (combined SVL of females in these species 18–25.1).

The new species is most similar to Scinax agilis but differs from it by the presence of dark colored nuptial pad in males. Also, it differs from S. rizibilis in having nonhypertrophied nuptial pad.

Scinax melanodactylus differs from S. agilis , S. albicans , S. angrensis , S. argyreornatus , S. berthae , S. canastrensis , S. carnevallii , S. centralis (Pombal & Bastos, 1996) , S. flavoguttatus , S. heyeri , S. hiemalis , S. humilis , S. kautskyi , S. littoralis , S. machadoi , S. muriciensis , S. pombali , S. ranki , S. skuki Lima, Cruz & Azevedo, 2011, S. strigilatus , S. trapicheiroi , and S. tripui in having hypertrophied forearms in males.

The new species differ from the most species of the S. catharinae Group except S. canastrensis , S. centralis , S. longilineus , S. machadoi , S. pombali , S. rizibilis , and S. skaios by its subovoid snout in dorsal view (sub-elliptical in S. aromothyella and S. berthae ; rounded in S. ariadne , S. catharinae , S. brieni , S. obtriangulatus , and S. ranki ; rounded with a mucronate tip in S. albicans , S. angrensis , S. flavoguttatus , S. hiemalis , S. heyeri , S. humilis , S. littoralis , S. muriciensis , S. strigilatus , S. trapicheiroi , and S. tripui ; mucronate in S. carnevallii and S. kautskyi ; sub-elliptical with acute tip in S. jureia and S. luizotavioi ; mucronate or sub-elliptical in S. argyreornatus and S. skuki ).

Scinax melanodactylus differs from S. angrensis , S. ariadne , S. brieni , S. canastrensis , S. carnevallii , S. catharinae , S. centralis , S. flavoguttatus , S. kautskyi , S. heyeri , S. hiemalis , S. humilis , S. jureia , S. littoralis , S. longilineus , S. luizotavioi , S. muriciensis , S. obtriangulatus , S. pombali , S. skaios , S. strigilatus , S. trapicheiroi , and S. tripui in having poorly marked canthus rostralis.

The presence of vocal slits differentiates the new species from S. ariadne and S. skaios (vocal slits absent). The new species is distinguished from S. aromothyella , S. berthae , and S. rizibilis by its vocal sac in males not externally expanded (notably expanded in these species)

The new species differs from S. canastrensis , S. carnevallii , S. flavoguttatus , S. kautskyi , S. longilineus , S. machadoi , S. muriciensis , S. skaios , S. strigilatus , and S. tripui by the absence of glandular acini on the medial region of forearm (glandular acini present).

The lack of glandular acini on the dorsal region of the fingers II and III distinguish the new species from S. albicans , S. angrensis , S. brieni , S. canastrensis , S. catharinae , S. carnevallii , S. flavoguttatus , S. humilis , S. kautskyi , S. littoralis , S. longilineus , S. luizotavioi , S. machadoi , S. obtriangulatus , S. trapicheiroi , and S. tripui (glandular acini present).

Scinax melanodactylus differs from almost all species of the S. catharinae Group except S. aromothyella and S. berthae in having smooth skin on dorsum (rough in S. ariadne , S. canastrensis , S. longilineus , S. pombali and S. skaios ; covered by scattered tubercles in the remaining species).

The lack of an externally differentiated inguinal gland distinguishes S. melanodactylus from S. ariadne , S. brieni , S. canastrensis , S. catharinae , S. centralis , S. flavoguttatus , S. jureia , S. hiemalis , S. longilineus , S. luizotavioi , S. obtriangulatus , S. ranki , S. rizibilis , S. skaios , and S. tripui (particularly hypertrophied in S. centralis and externally well differentiated in the other species, often enclosed by a fold).

Scinax melanodactylus presents a white dorsolateral band, dorsally bordered by dark brown stripe, and a black longitudinal line on the interocular region (or without markings in this region). This pattern is unique to this species and S. agilis among all species of the S. catharinae Group.

The pale belly and throat differentiate the new species from S. ariadne , S. brieni , S. catharinae , S. flavoguttatus , S. jureia , and S. tripui ( S. ariadne , S. flavoguttatus , and S. tripui have irregular beige spots on brown background in this region; S. brieni , S. catharinae , and S. jureia have irregular lines and dots equally distributed on beige background in this region).

The new species has no flash color on the inguinal region and hidden areas of the thigh and shank, unlike S. ariadne (light brown irregular blotches on violet or pink background; personal observation), S. aromothyella (dark yellow; Faivovich 2005), S. berthae (“irregular yellow-orange spots”; Barrio 1962), S. brieni (“pale bluish color on the concealed areas”; B. Lutz 1973), S. canastrensis (“yellow”; Cardoso & Haddad 1982), S. catharinae , S. humilis , and S. trapicheiroi (dark brown blotches on light blue or white background; personal observation), S. centralis (“yellow on dark brown background”; Pombal & Bastos 1996), S. flavoguttatus and S. heyeri (brown blotches on orange backgroud; personal observation), S. hiemalis (“black blotches on green background”; Haddad & Pombal 1987), S. longilineus and S. machadoi (vermiculate spots on yellow or pale background; personal observation) S. obtriangulatus (“dull grayish violet”; B. Lutz 1973), S. pombali (irregular brown blotches on yellow background; personal observation) S. ranki (dark brown blotches on greenish background; personal observation), S. skaios (vermicularis dark brown spots on light green background; personal observation), S. strigilatus (“concealed surfaces of flanks and thighs greenish”; Pimenta et al. 2007), and S. tripui (irregular brown blotches on light green background; personal observation).

Description of the holotype. Small sized (SVL 13.1). The snout is subovoid in dorsal view and protruding in profile. Nostril elliptical, located laterally, immediately before the tip of snout, opening directed dorso–laterally. Canthus rostralis undifferentiated. Loreal region oblique and concave. Eye large, diameter 50% of head width. Interorbital and internostril distance 41.3% and 28.3% of head width respectively. Tympanum rounded, annulus tympanicus well defined, its diameter 39% of eye diameter. Supratympanic fold present, well evident, extending from posterior corner of eye to just anterior to shoulder. Tongue unattached on the posterior and laterally borders. Vocal slits present, originating on the side of the tongue and running to the posterolateral corner of the mouth. Choanae elliptical. Vomerine teeth in two contiguous convex series of three teeth each, positioned between choanae. Vocal sac not expanded externally. Forearms longer than arms, hypertrophied in males.

Pectoral area and medial region of the forearm without macroscopic glandular acini. Outer margin of forearm and tarsus smooth. Outer metacarpal tubercle bifid. Inner metacarpal tubercle single and elliptical. Subarticular tubercles single and rounded. Supernumerary tubercles small and rounded. Dorsal region of the fingers II and III without macroscopic glandular acini. Webbing absent between fingers II and III and basal between other fingers. Discs on fingers elliptical, wider than long. Relative finger length II<III=V<IV. Glandular area on medial margin of Finger II develop to form a distinct dark colored nuptial pad.

Foot 40% of snout vent length. Inner metatarsal tubercle single and elliptical, larger than outer, which is single, rounded and very little. The subarticular tubercles are single and rounded. Inner metatarsal tubercle single and rounded, larger than the outer that is rounded and very small. Supernumerary tubercles rounded and distributed across the plantar surface. Relative toe length: I<II<V<III<IV. Webbing formula I — II1 1/2 — 3 III1 1/2 — 3 IV3 — 1 1/ 2V (basal between toes I and II). Discs elliptical, wider than long.

Externally differentiated inguinal gland absent. The pectoral region has compound folds, that is, when folds has both pre-axillary and post-axillary elements (see character 3, state 0 in Faivovich, 2002). Cloacal opening at upper level of thighs. Skin on dorsum smooth; granular on throat, belly, and undersurfaces of thigh.

Measurements of the holotype. SVL 13.1; HW 4.42; HL 5.1; END 1.26; IND 1.34; ED 2.32; IOD 1.88; TD 0.8; TL 6.64; THL 6.76; FL 5.12.

Color of holotype in preservative. Overall dorsal coloration brown. The upper lip is white with brown dots. The interocular region has a black longitudinal line. The lateral region has a white stripe dorsally bordered by a brown line, originates on the posterior region of eye and reaches the inguinal region. The dorsum presents two longitudinal brown lines that reach the inguinal region, and three other lines that are clearer and disrupted in some points, interspersing the first two. The dorsal region of hindlimbs is pale and has brown dots. Canthus rostralis with a black line. Iris gray. The inguinal region is fully pale. The belly and throat are pale.

Color in life (based on type series). The same as in preservative, except by the brighter and sharper intensity of color and by the brown colored iris. The inguinal region shows no vivid color.

Variation among paratypes and referred specimens. Some measurements are shown on Table 1 . Males are more robust and smaller than females. The forearms of females are not hypertrophied as in males. Males and females have variable toe webbing formula: I — II1 1/2 — 3(3+) III1 1/2 — 3-(3) IV2 1/2(3) — 1 1/ 2V in males and I — II1 1/ 2 — 3(3+) III11/2 (1+) — 3+(3 1/2) IV3 (2 1/2) — 1 1/2(1)V in females (rudimentary between fingers I and II). Some specimens may have four vomerine teeth (n=4), in some others the vomerine teeth seemed damaged (n=6), so they were not counted. Some specimens have no interocular line (n=6). The longitudinal lines on dorsum are absent in some specimens (n=4); others specimens have only the two darker lines (n=3) or have three to five longitudinal lines, disrupted (n=4) or complete (n=3).

Structure of the nuptial pad ( CFBH 36902). The surface of the nuptial pad is easily distinguishable from the rest of the skin by the presence of numerous dark colored epidermal projections (EPs). The space between EPs is not colored. The nuptial pad covers dorsally the base of the first digit reaching the proximal margin of the basal phalanx and, ventrally, nearly half of the inner metacarpal tubercle ( Fig. 5 A–B). The scanning electron microscopy (SEM) observations show epidermal surface specializations on the pad area ( Fig. 5 C). The EPs are irregular in size, and show ornamentations covering the surface of each EP. These ornamentations are made by multiple projections, which are radially distributed over the EPs and have a sharpened distal end ( Fig. 5 D–E).

Comparison between nuptial pad structures. Nuptial pads of all other species of the S. catharine Group are whitish when are observed with a stereomicroscope (e.g. Scinax agilis , Fig. 5 F). The SEM observations show differences in the development of epidermal modifications. Nuptial pads of S. agilis show not distinctively area ( Fig. 5 G–H). The nuptial pads of other species show EPs covering the nuptial pad area (e.g. Scinax berthae Fig. 5 I). Detail view of the EPs of S. berthae show the smoothness of the surface of each EP ( Fig. 5 J), differing from the presence of conspicuous ornamentations in the new species.

Distribution and natural history. Scinax melanodactylus is found in Brazilian coastal sandbanks and in forest areas near these environments, occurring from northern of Espírito Santo State to Sergipe State ( Fig. 6 ). Individuals of this species were observed on leaves and stems of vegetation, especially in bromeliads, in the margins of temporary and permanent water bodies, both streams as swamps. Males were not heard calling, but the species is apparently abundant in the places visited. One female has 133 oocytes (CFBH 36868).

Recently, the geographical distribution of S. agilis was expanded in some studies. Perhaps, the specimens of these studies may actually be S. melanodactylus . For instance, Toledo (2005) registered S. agilis in Municipality of Passo do Camaragibe, State of Alagoas. In our analysis we identified specimens of S. melanodactylus from the same Municipality. However, we examined the specimens collected by this author (CFBH 7358–7361) and all are females. As the diagnostic character that distinguishes S. melanodactylus from S. agilis is only observed in males, we cannot confirm assuredly the identity of specimens collected by Toledo (2005). In the other study, Nunes et al. (2007) described the vocalization of two specimens of S. agilis from Municipality of Camaçari, State of Bahia. In accordance with the distribution of the new species presented herein, these specimens can be actually S. melanodactylus . However, the identity of these specimens cannot be verified because they were not collected. Similarly, Peixoto et al. (2003) registered S. agilis in Municipality of Prado, State of Bahia. The specimens collected by these authors are also probable S. melanodactylus , considering its distribution. Nevertheless, we did not analyze these specimens and its identity could not be verified.

Etymology. The species name melanodactylus is derived from the Latin melano (=black) + dactylus (=finger). The name is an allusion to the black nuptial pad, a so far exclusive feature among all known species of Scinax .

Figures

FIGURE 2. Dorsal and ventral views of Scinax melanodactylus sp. nov., holotype (MNRJ 80145). Scale bar = 5 mm.

FIGURE 3. Scinax melanodactylus sp. nov., holotype (MNRJ 80145). (A) dorsal and (B) lateral views of the head; (C) palmar view of the hand and (D) plantar view of the foot. Scale bar = 5 mm.

FIGURE 4. Left hand of Scinax melanodactylus sp. nov., holotype (MNRJ 80145) in dorsal and ventral view. See the black nuptial pad on finger II. Scale bar = 1 mm.

FIGURE 5. Nuptial pad of Scinax melanodactylus sp. nov. (CFBH 36902). (A) Dorsal view of finger II. (B) Ventral view of finger II. (A – B) Scale bar = 500 µm. (C – E) Scanning electron micrographs of nuptial pad. (C) General view of finger II. Notice the epidermal modification of the nuptial pad area. Scale bar = 100 µm. (D) Higher magnification of nuptial pad viewed from above showing the irregularly EPs, scale bar = 20 µm. (E) Detailed view of a single EP, scale bar = 5 µm. (F-H) Nuptial pad of Scinax agilis. (F) Dorsal view of finger II. Scale bar = 500 µm. (G) Scanning electron micrographs of finger II. Note the absence of a distinctively area. Scale bar = 200 µm. (H) Detail of the area delimited in (G) showing absence of EPs. Scale bar = 20 µm. (I- J) Nuptial pad of Scinax berthae. (I) Scanning electron micrographs of finger II. Note the presence of EPs. Scale bar = 200 µm. (J) Detail of the area delimited in (I) showing smooth EPs. Scale bar = 50 µm.

FIGURE 6. Geographical distribution of Scinax melanodactylus sp. nov. in southeastern and northeastern Brazil (the star represents district of Trancoso, Municipality of Porto Seguro, Bahia, the type locality). AL = State of Alagoas; SE = State of Sergipe; BA = State of Bahia; MG = State of Minas Gerais.

Tables

TABLE 1. Recorded measurements (in mm) of the adult paratypes of Scinax melanodactylus. Ranges followed by means and standard deviation in parentheses.

	Males (n=11)	Females (n=5)
SVL	12.0–16.0 (13.5±0.9)	13.2–17.3 (16.3±1.2)
HL	4.3–6.0 (5.3±0.5)	5.6–6.3(6.0±0.2)
HW	4.0–5.6 (4.6±0.4)	5.0–5.9(5.5±0.3)
END	1.2–2.3 (1.5±0.2)	1.1–2.3 (1.8±0.3)
IND	1.1–1.6 (1.3±0.1)	1.4–1.7 (1.6±0.1)
ED	2.2–2.9 (2.3±0.1)	2.3–2.9 (2.6±0.2)
IOD	1.7–2.3 (1.9±0.2)	2.0–2.3 (2.8±0.2)
TD	0.7–1.1 (0.9±0.1)	0.8–1.1 (1.0±0.1)
THL	5.8–8.2 (6.8±0.6)	8.0–8.7 (8.4±0.3)
TL	6.7–8.6 (7.3±0.5)	7.7–9.2 (8.7±0.5)
FL	4.0–6.1 (5.4±0.4)	10.0–11.5 (10.6±0.5)