Trachycephalus dibernardoi, Kwet & Solé, 2008

Kwet, Axel & Solé, Mirco, 2008, A new species of Trachycephalus (Anura: Hylidae) from the Atlantic Rain Forest in southern Brazil, Zootaxa 1947, pp. 53-67 : 54-61

Trachycephalus dibernardoi sp. nov.

( Figs. 1–3)

Phrynohyas imitatrix: Carrizo 1989: 9 ; Kwet 1997a: 66, 1997b: 20; Kwet & Di-Bernardo 1999: 40, 41; Lavilla & Cei 2001: 51; Lavilla et al. 2002: 103; Garcia & Vinciprova 2003: 161; Brusquetti & Lavilla 2006: 28.

Phrynohyas sp. ( aff. imitatrix ): Kwet 2001: 32, 45, 188.

Phrynohyas sp. : Kwet 2003: 41, 2004: 176.

Phrynohyas venulosa imitatrix “southern form”: Lutz 1973: 254, plate VII.

Trachycephalus imitatrix: Conte & Rossa-Feres 2006: 165 ; Conte & Rossa-Feres 2007: 1028.

Trachycephalus sp. : Machado & Maltchik 2007: 106.

Holotype. MCP 2422 , adult female, collected on 20 January 1996, at “Centro de Pesquisas e Conservação da Natureza” ( CPCN) Pró Mata (about 950 m a.s.l.), 29° 30´S, 50° 10´W, municipality of São Francisco de Paula , state of Rio Grande do Sul, Brazil, by Axel Kwet and Marcos Di Bernardo.

Paratypes. MCP 3693 , adult female, collected on 25 January 1999 ; MCP 7213 , adult male, collected on 30 December 2002 , MCP 6063 , adult male collected in stem-eclector between 15 February and 16 March 2002 , all specimens from the type locality. MCP 6584 , adult male, and MCP 6578–83 , 6585 , subadult and juvenile specimens, collected in September 2001 , UHE Machadinho (“usina hidroelétrica”), municipality of Machadinho, state of Rio Grande do Sul. MCN 5554, 5562–64, adult females, and MCN 5555, 5558, 5561, 5565, adult males, collected 1972 at Nova Teutônia , municipality of Seara, state of Santa Catarina .

Diagnosis. The new species is assigned to the genus Trachycephalus , due to the presence of paired lateral vocal sacks situated behind the angles of the jaws in males and the skin of nape and shoulder region thickened by well-developed glands producing an irrigating secretion ( Duellman, 1956; Trueb & Duellman, 1971; Tyler, 1971; Faivovich et al., 2005). A medium to large-sized species of Trachycephalus (SVL in females 73.3–84.4 mm, mean 77.6 mm; SVL in males 50.5–64.6 mm, mean 57.2 mm; see Table 1) which is characterised by (1) dorsal coloration green, bluish-green, yellowish-green, olive, or brown with a characteristic dorsal pattern of conspicuous dark ocelli and black spots, (2) limbs with broad, dark olive, black and white-edged transverse bands, (3) iris bright yellow or greenish-golden with contrasting black reticulated pattern forming a distinct, four radial symmetric network (a pattern of four light, petal-like spots), (4) adhesive disks on fingers and toes strongly developed and bright green or bluish-green in life; (5) unique advertisement call with dominant frequency spectrum ranging between 1100 and 1800 Hz.

The new species differs from T. atlas , T. jordani , and T. nigromaculatus by the lack of an occipital crest, and from all other taxa in this genus (formerly treated in the genus Phrynohyas ) by its unique greenish-brown and ocellated dorsal pattern. Compared with the four species of Trachycephalus occurring in the Atlantic Rain forest biome, T. dibernardoi differs as follows: (1) from T. imitatrix by its larger size (SVL in females 58.7– 70.0 mm, mean 64.3 mm, n = 2; SVL in males 50.3–50.9 mm, mean 50.6 mm, n = 2, in T. imitatrix ; own measurements), by the different head profile (head broader than long with short snout in T. dibernardoi , whereas snout longer and head about long as broad in T. imitatrix ), and by the presence of a distinct pattern of ocelli and dark spots on the dorsum not extending to the head (distinct ocellus pattern absent in T. imitatrix , which instead presents a large, brown, black bordered, partly spotted parallelogram on the anterior part of the dorsum extending from between the eyes to the sacral region, sometimes followed by a single ocellus and/or several small spots on the region between anus and sacrum; Figs. 4A, C; see also Cochran, 1955; Lutz, 1973); (2) from T. lepidus by the larger size (SVL of single female 58.7 mm; of single male 49.1 mm; see Pombal et al. 2003), the more extensively webbed toes and fingers, and the absence of an extensive axillary membrane; (3) from T. mesophaeus by the larger size (SVL in females 64.1–69.4 mm, mean 66.3 mm, n = 3; SVL in males 54.2–63.8 mm, mean 59.4 mm, n = 8, in T. mesophaeus ; own measurements), by the different iris coloration with a petal-like pattern (iris with a few irregular zig-zag veins in T. mesophaeus ), by the presence of broad, distinct cross-bars on limbs (absent in T. mesophaeus ), and by a distinct ocellus pattern on dorsum (absent in T. mesophaeus , which is characterized by a large, uniform, dark brown dorsal fleck from between the eyes down to the anus, bordered by broad, yellowish lateral stripes; see Figs. 4B, C); (4) from the southern populations of T. venulosus in Misiones ( Argentina) and Paraná state (near the distribution range of T. dibernardoi ), which were formerly referred to the subspecies Phrynohyas venulosa hebes , by the distinct sexual size dimorphism in T. dibernardoi (males with mean SVL of 57.2 mm are considerably smaller than females with mean SVL of 77.6 mm, whereas in T. venulosus the SVL of females with 69.1–85.2 mm, mean 77.3 mm, n = 15, is similar to that of males with 59.4–86.2 mm, mean 72.7 mm, n = 18; own measurements), by the different ground coloration (greenish with distinct ocellus pattern in T. dibernardoi , brown to gray without ocelli in T. venulosus ), by the interspace width between dark transverse bands on shanks (dark bands usually as broad as, or broader, than interspace between these band in T. venulosus , narrower in T. dibernardoi ), and by the very thick, highly glandular dorsal and ventral skin including a well-developed parotoid in the head and neck region in T. venulosus .

Description of holotype. Adult female, MCP 2422 ( Figs. 1, 2A, B), for measurements see Table 1. Robust, medium to large-sized hylid with broad and flattened head, slightly wider than long. Snout short and blunt, nearly rounded in dorsal profile and truncate in lateral profile ( Fig. 1B). Canthus rostralis distinct and rounded, the loreal region concave. Lips flared, nostrils protuberant and laterally directed. The eye-nostril distance is about two times the distance of the nostril to the tip of the snout and somewhat larger than the internarial distance. Internarial region slightly depressed. The eyes are sited laterally, directed anteriorly, with diameters of about 1/4 of head length. The pupils are horizontal and the iris shows a radial symmetric pattern of contrasting black reticulations forming a conspicuous pattern of four light, petal-like spots ( Fig. 2B). The tympanum is large and distinct, its size being approximately the same as the eye diameter; the supratympanic fold is distinct extending from the posterior corner of the eye over the tympanum to the arm insertion. The tongue is large, broadly cordiform, covering approximately 4/5 of the mouth floor; it is barely free and poste- riorly notched. The vomerine teeth are small and indistinct (between 8–10 very small dentigerous processes at each side), situated on two slightly curved ridges between the relatively large internal nares. The dorsal skin texture is smooth with scattered small pustules ( Fig. 1A), and highly glandular (white venomous skin secretion when stressed; see Fig. 2C); the skin on the under surface is anteriorly smooth and posteriorly granular ( Fig. 1C). Arms are short and moderately robust; without axillary membranes or ulnar folds; the large hands with short and moderately robust fingers have large, distinct finger discs with diameters equal to, or slightly smaller than, the tympanum diameter on fingers II–IV and about two thirds of tympanum diameter on finger I ( Fig. 1D). The distinct inner metacarpal tubercle is large and elliptical being visible from dorsal view, with its distal end slightly pointed and its proximal end blunt; an outer metacarpal tubercle is present but small and indistinct. The distinct subarticular tubercles are single and round on fingers I-III, and oval, slightly bilobate on finger IV; supernumerary tubercles are not evident. Relative finger length is I <II <IV <III; the fingers are slightly webbed, except the web between the first and second digits which is rudimentary; the hand webbing formula is I basal – II 2 - – 3 - III 2 + – 2 IV. Legs are robust, with thighs and shanks each reaching about half of SVL. There is no inner tarsal fold, and the discs of the toes are well developed and large. The inner metatarsal tubercle is large and elliptical; the outer metatarsal tubercle is very small and indistinct ( Fig. 1E). Subarticular tubercles are large, prominent and subconical; small supernumerary tarsal tubercles are indistinct but present. Relative toe length is I <II <V = III <IV, the foot webbing formula is I 1 1/2 – 2 - II 1 - – 2 + III 1 - – 2 IV 2 – 1 1/2 V.

Coloration in live. The dorsal coloration in life consists of olive to greenish-brown tones, with a distinct pattern of several large and small, dark olive ocelli and a few black spots ( Figs. 2A, B). The irregularly formed, variably sized ocelli have black outer lines and are bordered by a whitish zone; centrally they present the same tone as the dorsal ground coloration, but slightly darker. The holotype has two large-sized ocelli located centrally on each side of the dorsum, roughly between the insertions of fore and hind limbs. Two larger ocelli are presented on the sacral region, and several small ocelli and dark spots are located laterally and on the posterior region of the dorsum. The upper surfaces of the limbs have the same ground coloration as the dorsum with dark olive to brown tones and are characterized by a distinct pattern of dark, transverse bands with the same coloration as the ocelli (dark brown with black and whitish margins). The hind limbs are characterized by two transverse bands on each femur, thigh, and tarsus; these bands are narrower than the width of their interspaces. The fore limbs present one transverse band on each upper arm and under arm. The ventral surface is yellowish-white with a greenish hint, immaculate except a few small, dark brown spots in the gular region and laterally near the flanks ( Fig. 1C). Adhesive disks on fingers and toes are bluish-green to greenishbrown. The iris is golden to bright yellow with a contrasting dark radial symmetric network-pattern forming the petal-like pattern described above.

Coloration in preservative. The dorsum turned to brownish-gray presenting the distinct pattern of variable ocelli on dorsum and transverse bands on limbs as described above. The ventral surface is whitish, but the bluish-green hints, especially of the adhesive disks on fingers and toes, turned to brown.

Variation. Measurements and proportions of the female paratypes are similar to the holotype ( Table 1), but males are considerably smaller in SVL than females; females have more extensive webbing than males and slightly larger fingers and toes. Calling males have dark, paired, lateral vocal sacs and dark callosities at the base of the first finger. The dorsal ground coloration in life varies from greenish-olive (holotype), bright yellowish-green ( MCP 3693 ), bluish-green (most of the smaller specimens), to dark brown ( Figs. 2C–F). There is a considerable variation in the pattern of dorsal ocelli and blotches, which is illustrated in Figs. 3A, B. Most specimens have a distinct, symmetrical pattern of one or two large, mid-dorsally located ocelli and several smaller ocelli especially on the sacral region, and a few dark spots scattered over the dorsum. The outer lines of these ocelli might be interrupted or not, and some specimens present a much reduced dorsal pattern (e.g. MCP 6581 ) consisting only of a few small spots on dorsum and transverse lines on limbs instead of the prominent ocellus and bar pattern. MCP 3693 presents a more diffuse, spot-like pattern on dorsum. The number and shape of the dark transverse bands on hind limbs also show some variation, but the interspace width is usually larger than these bands varying between one and twice the width of the bands .

Advertisement call. The advertisement call of T. dibernardoi ( Fig. 5) consists of a long series of single notes with differing note intervals between 0.8- 3.0 s and note repetition rates of about 24-36 per min; the call series could comprise over 30 consecutive notes lasting more than 1 min. We analyzed 25 consecutive notes of the advertisement call from one male (voucher specimen MCP 7213). Each call lasted on average 604 ms (range 470–760 ms) and consisted of a series of 31–49 pulses (mean 37.6 pulses). Pulse duration was 6–7 ms with varying pulse intervals of about 9.5 ms (range 5–18 ms); pulse intervals were slightly larger at the beginning of the note (12–18 ms) than at the end (5–12 ms), and the pulse repetition rates varied from about 25 pulses per s at the beginning of the note to 80 pulses per s at the end. The dominant frequency spectrum ranged between 1100–1800 Hz, with a peak at about 1550 Hz, slightly increasing towards the end of the note. The fundamental frequency was from around 600–900 Hz, and a third frequency with detectable energy ranged from 2800–3400 Hz, but the call did not show harmonic structure.

The advertisement calls of the morphologically similar T. imitatrix and from T. lepidus from the Atlantic rain forest are not yet described, but the published call of T. mesophaeus occurring sympatrically with T. dibernardoi is very different ( Fig. 6; Carvalho e Silva et al., 2002; Prado et al. 2003). It consists of much shorter notes (note length about 0.18– 0.27 s), has a different dominant frequency and presents distinct fre- quency modulation (descending frequency towards the end of the note). The published calls from the other taxa in the former genus Phrynohyas are also completely different, i.e. the calls of T. coriaceus , T. resinifictrix , and T. venulosus , which are available on commercial CDs and/or tapes from various countries like Panama, French Guyana, Peru, Ecuador, Bolivia, and Argentina. Due to zoogeographical reasons and geographical proximity, the advertisement calls of T. venulosus from Brazil (Goiás; Guimarães et al., 2001), Argentina (audiotape by Straneck et al., 1993), and Bolivia ( De la Riva et al., 1995; CD by Márquez et al., 2002) are most interesting for bioacoustic comparisons. However, all these analyzed calls of T. venulosus are composed of more pulses per note (about 60–70, versus 30–50 in T. dibernardoi ) with slightly shorter note lengths (between 350–550 ms, versus 470–760 ms), and they also differ in higher dominant frequencies (between 1800–2500 Hz, versus 1100–1800 Hz) with the energy more broadly distributed throughout the frequency spectrum.

Etymology. The species name honours the late Brazilian herpetologist Marcos Di-Bernardo, our good friend and outstanding colleague, in recognition of his valuable contributions to the knowledge of the herpetofauna of Rio Grande do Sul. Marcos’ tragic death (see obituary in Kwet, 2006) prevented our plans to describe this new species together with him.

Distribution. Trachycephalus dibernardoi is described from three localities on the Araucaria Plateau in extreme north-eastern and northern Rio Grande do Sul (municipalities of São Francisco de Paula, 950 m a.s.l., and Machadinho, 760 m a.s.l.) and western Santa Catarina (municipality Seara, 550 m a.s.l.). Material from El Soberbio (department Guaraní, 190 m a.s.l.) in the Argentinean province Misiones, cited as P. imitatrix by Carrizo (1989), Lavilla & Cei (2001), and Lavilla et al. (2002), is also referred to T. dibernardoi , due to the characteristic dorsal pattern shown in the drawing by Carrizo (1989) which is different from that of T. imitatrix (which shows a large parallelogram extending from the anterior corner of each eyelid to the sacrum; see Figs. 4A, C). Brusquetti & Lavilla (2006: 28) cited “a probable occurrence of T. imitatrix in the woodland formation of south and south-eastern Paraguay ”, but this citation must be yet verified and would also refer to T. dibernardoi . In all cases, T. dibernardoi should have a wider distribution than currently acknowledged occurring in the whole range of the Serra Geral and adjacent regions of northern and north-eastern Rio Grande do Sul, Santa Catarina, Paraná ( Brazil, see Discussion), and eastern Misiones province at altitudes from about 150–1100 m a.s.l.

Conservation status. Trachycephalus dibernardoi seems to be a very rare species throughout its distribution range and may be sensitive for habitat disturbance. Unless more distributional data are available, this frog should be classified as “Data Deficient” according to the criteria established for the Global Amphibian Assessment ( IUCN et al., 2006). In the current version of GAA, the species is still included as “Least Concern” under the taxon name T. imitatrix , a species which is abundant in south-eastern Brazil. In the red list of the amphibians of Rio Grande do Sul ( Garcia et al., 2003), T. dibernardoi is listed (as Phrynohyas imitatrix ) in the category “Espécies com Dados Insuficientes”, and Lavilla et al. (2002) listed this species as “Insuficientemente Conocida” in Argentina (both categories meaning “Data Deficient”).

Natural history. Trachycephalus dibernardoi is a poorly known arboreal frog of mountainous and submountainous ranges, which we found in primary and secondary subtropical rainforests and forest edges including Araucaria forests. The breeding time seems to be highly correlated with heavy rain in the warm summer months from about December to February. The new species is a nocturnal explosive breeder which we found spawning in still permanent water bodies in the forest or at the forest edge; it might be easily overlooked when not breeding. Both the female holotype (MCP 2422) and a female paratype (MCP 3693) were run over by car on a puddle road in the Pró Mata reserve during severe rainfall in January. The male paratype, MCP 7213, was observed on 30 December 2002 in Pró Mata calling at night from a small shrub at about 1 m height near a small pond on the edge of the Araucaria forest. Eggs and larvae of the new species are not yet known.