Dendropsophus bilobatus, Ferrão & Moravec & Hanken & Lima, 2020

Ferrao, Miqueias, Moravec, Jiri, Hanken, James & Lima, Albertina Pimentel, 2020, A new species of Dendropsophus (Anura, Hylidae) from southwestern Amazonia with a green bilobate vocal sac, ZooKeys 942, pp. 77-104 : 77

publication ID

https://dx.doi.org/10.3897/zookeys.942.51864

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persistent identifier

https://treatment.plazi.org/id/18906B0C-5EEA-416B-A672-FF8AD98DA448

taxon LSID

lsid:zoobank.org:act:18906B0C-5EEA-416B-A672-FF8AD98DA448

treatment provided by

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scientific name

Dendropsophus bilobatus
status

sp. nov.

Dendropsophus bilobatus sp. nov. Figures 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , Table 2, 3

Material.

Holotype. INPA-H 41300 (field number APL 19703; GenBank accession number MN977837), an adult male from the RAPELD Jaci-Novo sampling site (09°24'45"S, 64°26'33"W; 117 m a.s.l.), flooded forest at the west bank of the Jaci-Parana River (east tributary of the upper Madeira River), municipality of Porto Velho, district of Jaci-Parana, state of Rondônia, Brazil, collected on 26 March 2013 by Albertina P. Lima.

Paratopotypes. Five males: INPA-H 41302 (field number APL 19442), 41303 (field number APL 19443; GenBank accession number MN977835), 41304 (field number APL 19444), 41305 (field number APL 19445; GenBank accession number MN977836), and 41306 (field number APL 19446), collected on 15 February 2013 by Albertina P. Lima.

Paratypes. Two males: INPA-H 41301 (field number APL 19419; GenBank accession number MN977834) and 41307 (field number APL 19448), from the RAPELD Jaci-Direito sampling site (09°27'44"S, 64°23'32"W; 121 m a.s.l.), east bank of the Jaci-Parana River (an east tributary of the upper Madeira River), municipality of Porto Velho, district of Jaci-Parana, state of Rondônia, Brazil, collected on 14 and 15 February 2013, respectively, by Albertina P. Lima.

Referred material. Three males: INPA-H 41308 (field number APL 16652) and 41309 (field number APL 16653), from the RAPELD Jirau-Direito sampling site (09°21'43"S, 64°41'31"W; 131 m a.s.l.), east bank of the upper Madeira River, municipality of Porto Velho, state of Rondônia, Brazil, collected on 20 January 2011 by Albertina P. Lima; and INPA-H 41310 (field number APL 16428), from the RAPELD Morrinhos sampling site (09°04'34"S, 64°14'46"W; 95 m a.s.l.), municipality of Porto Velho, state of Rondônia, Brazil, collected on 13 January 2011 by Albertina P. Lima.

Generic placement.

We assign this species to Dendropsophus based on our molecular phylogenetic analysis (Fig. 2 View Figure 2 ) and on its general morphological similarity to other members of the genus.

Diagnosis.

A species of the Dendropsophus microcephalus species group, distinguished from other species of Dendropsophus by the following combination of characters: (1) small size, SVL 18.8-20.8 mm (N = 8) in males (females unknown), head slightly wider than body; (2) snout short, truncate in dorsal and lateral views; (3) tympanum evident, round, about one third of eye diameter, tympanic annulus distinct anteriorly, ventrally and partly posteriorly; supratympanic fold barely evident; (4) dentigerous processes of vomers small, barely prominent, and separated medially between posterior halves of choanae; (5) skin on dorsal surfaces smooth; (6) tarsal fold and tubercles on outer edge of tarsus absent; ulnar folds and tubercles absent; (7) axillary membrane extensively developed; (8) fingers about half webbed; toes about three-fourths webbed; (9) bifid distal subarticular tubercle under fourth finger; (10) pectoral glands absent; (11) generally darker coloration of the loreal-tympanic region contrasts sharply with the lighter dorsal head coloration, one or two white spots below the eye; (12) in life, ground coloration of dorsum light brown; head greenish brown laterally; flanks ventrally and posteriorly a translucent pinkish white without chromatophores; hidden surfaces of thighs yellow without melanophores; (13) in life, throat green in males; belly yellowish-white in pectoral and central parts, translucent pinkish-white in posterior and lateral parts; ventral surfaces of thighs translucent pinkish white; (14) in life, iris pale to dark brown with barely visible tiny brown veins, iris periphery dark brown to black; bones white; (15) advertisement call consisting of 1-4 notes (usually 1-2 notes), emitted regularly in series of 7-35 calls; high-pitched, monophasic, pulsed notes (3-8 pulses) with a duration of 12-24 ms and a dominant frequency of 8,979-9,606 Hz.

Comparisons.

Dendropsophus bilobatus sp. nov. is readily distinguished from all congeners by having a green bilobate subgular vocal sac (some members of the D. marmoratus species group have a bilobate vocal sac, but not green) and a monophasic advertisement call with a remarkably high dominant frequency (8,979-9,606 Hz). Below we describe additional important differences between the new species and other members of the D. microcephalus species group (sensu Faivovich et al. 2005) that occur in Brazilian Amazonia and surrounding areas of Bolivia, Colombia, Peru and Ecuador. Characters of D. bilobatus are set in parentheses if not otherwise stated.

Three species of the Dendropsophus microcephalus species group have advertisement calls with a high dominant frequency: D. meridianus (Lutz, 1954), D. minusculus , and D. ozzyi . However, D. meridianus differs from D. bilobatus in having a snout slightly acuminate in lateral view (truncate), a single subgular yellow vocal sac (bilobate, green), dark dorsal lines or stripes on the dorsum (absent), absence of white subocular spots (present; Lutz 1973), and the dominant frequency of the advertisement call reaches 8,000 Hz (it reaches 9,606 Hz in D. bilobatus ; Lutz 1973, Pombal and Bastos 1998); D. minusculus can be distinguished by its yellow single subgular vocal sac (bilobate, green) and by the absence of white subocular spots (present; Zina et al. 2014); and D. ozzyi differs in its single subgular transparent vocal sac (bilobate, green), absence of white subocular spots (present), vivid orange palmar end plantar surfaces (palmar surface greenish yellow, plantar surface orange), webbing formula of feet I 2-2+ II 1+-3- III 1+-2+ IV 2+-1+ V (I 1+-2- II 1+-11/2 III 11/2-2- IV 2--1+ V), presence of glandular structures restricted on toes III and IV (glandular structures present also on toes II and V), and in single notes of the advertisement call (pulsed notes; Orrico et al. 2014).

The dark-greenish-brown coloration of the loreal-tympanic region of Dendropsophus bilobatus , which sharply contrasts with the light brown dorsal head coloration, resembles the head color pattern of D. coffea ( Köhler, Jungfer & Reichle, 2005), D. cruzi (Pombal & Bastos, 1998), D. studerae (Carvalho-e-Silva, Carvalho-e-Silva & Izecksohn, 2003), D. juliani , D. meridianus , D. microcephalus (Cope, 1886), D. minusculus , D. shiwiarum Ortega-Andrade & Ron, 2013, D. tintinnabulum (Melin, 1941), and D. reichlei , but the new species is easily distinguished from each named species as follows (species already distinguished above are not listed here): D. coffea lacks white subocular spots (present) and has dark brown dorsal stripes (absent; Köhler et al. 2005); in D. cruzi , the thigh is longer than the tibia (tibia longer than thigh; Pombal and Bastos 1998); D. studerae has tuberculate dorsal skin (smooth; Carvalho-e-Silva et al. 2003); D. juliani has an acutely rounded snout in dorsal view (truncate), absence of white subocular spots (present), and greenish yellow plantar surfaces (orange; Moravec et al. 2006); D. microcephalus has maximum male SVL 24.5 mm (20.8 mm), an acutely rounded snout in dorsal view (truncate), an ovoid tongue (cordiform), and a weak tarsal fold (absent; Duellman 1970); D. shiwiarum has the discs of finger III and toe IV with pointed tips (pointed tips absent), a prominent conical tubercle on the dorsal surface of fingers III and IV (tubercle absent), both palmar and plantar surfaces unpigmented (palmar surface greenish yellow, plantar surface orange), and a lower dominant frequency of the advertisement call (3,984-5,254 Hz in D. shiwiarum vs. 8,979-9,606 Hz in D. bilobatus ; Ortega-Andrade and Ron 2013); D. tintinnabulum has a triangular-to-rounded snout in dorsal view (truncate) and orange palmar surfaces (greenish; Teixeira and Giaretta 2017), and lacks white subocular spots (present); and D. reichlei has a rounded snout in dorsal view (truncate) and a distinct canthus rostralis (absent), and lacks a glandular nuptial pad (present; Moravec et al. 2008).

In our phylogenetic analysis, the clade that contains Dendropsophus bilobatus is closely related to D. bipunctatus (Spix, 1824), D. meridianus and D. berthalutzae (Bokermann, 1962) from the southern and southeastern Brazilian coast (Fig. 2 View Figure 2 ). In addition to differences in shape and color of the vocal sac and in advertisement call, these three species can be distinguished from D. bilobatus as follows: D. bipunctatus has a granulate dorsum (smooth), maximum SVL in males 25 mm (maximum male SVL 20.8 mm) and several small spots surrounded by a dark network that are distributed across the subocular area and lateral snout (spots only on subocular area and are not surrounded by dark network; Lutz 1973); D. berthalutzae has a snout that is slightly mucronate in dorsal view (truncate) and longer than eye diameter (snout shorter than eye diameter), and a minute outer metatarsal tubercle (absent; Lutz 1973).

Nine other small Amazonian species have been associated with the Dendropsophus microcephalus species group. These species differ from D. bilobatus in having the following combinations of characters: D. joannae ( Köhler & Lötters, 2001) has tuberculate dorsal skin (smooth), a red inner iris in life (iris light to dark brown), and uniform head coloration without white subocular spots (coloration of loreal-tympanic region sharply outlined, subocular spots present; Köhler and Lötters 2001); D. leali (Bokermann, 1964) has a uniform ground head coloration without white subocular spots (coloration of loreal-tympanic region sharply outlined, subocular spots present: Köhler and Lötters 2001) and a biphasic call (monophasic; A. P. Lima personal data); D. haraldschultzi (Bokermann, 1962), D. nanus (Boulenger, 1889), D. sanborni (Schmidt, 1944) and D. walfordi (Bokermann, 1962) have a more pointed snout (snout short, truncate in dorsal and lateral views), a more or less conspicuous pattern of numerous thin brown lines on a yellowish dorsum (lines absent) and a biphasic call (monophasic; Hödl 1977; Teixeira et al. 2016; Missassi et al. 2017); D. mathiassoni (Cochran & Goin, 1970) has dorsolateral lymphatic sacs (absent; Cochran and Goin 1970); D. rhodopeplus ( Günther, 1858) has a yellow dorsum with bright purple or red marks (purple or red marks absent; Duellman 2005); and D. riveroi (Cochran & Goin, 1970) has a canthus rostralis (absent) but lacks glandular nuptial pads in males (present; Ortega-Andrade and Ron 2013).

Ten other small Amazonian species belong to the Dendropsophus rubicundulus clade of the D. microcephalus species group (sensu Faivovich 2005). These species can be distinguished from D. bilobatus as follows: D. anataliasiasi (Bokermann, 1972), D. araguaya (Napoli & Caramaschi, 1998), D. cerradensis (Napoli & Caramaschi, 1998), D. jimi (Napoli & Caramaschi, 1999), D. rhea (Napoli & Caramaschi, 1999), D. rozenmani , D. rubicundulus (Reinhardt & Lütken, 1862) and D. tritaeniatus (Bokermann, 1965) lack white subocular spots (present) and have conspicuous dark brown stripes or small dark brown spots arranged in longitudinal lines on the dorsum (dorsum with irregular pattern of irregular yellow spots or small dark brown dots; Martins and Jim 2004, Teixeira et al. 2013, Teixeira and Giaretta 2015, Jansen et al. 2019); and D. cachimbo (Napoli & Caramaschi, 1999) and D. elianeae have a uniformly green or yellowish green dorsum (dorsum light brown with irregular pattern of yellow spots or small dark brown dots) and lack white subocular spots (spots present; Jansen et al. 2019).

The two unnamed forms of Dendropsophus in the D. microcephalus species group from the west bank of the upper Madeira River ( D. sp. A and D. sp. B) differ from D. bilobatus in having a single yellow subgular vocal sac (bilobate, green) and pointed discs on toes and fingers (rounded).

Five Dendropsophus species distantly related to the D. microcephalus species group are reported from the area of the upper Madeira River (A. P. Lima personal data): D. kamagarini Rivadeneira, Venegas & Ron, 2018, D. koechlini (Duellman & Trueb, 1989), D. leucophyllatus (Beireis, 1783), D. minutus (Peters, 1872) and D. sarayacuensis (Shreve, 1935). These species differ clearly in their larger size and coloration (Rodriguez and Duellman 1994, Peloso et al. 2016, Caminer et al. 2017, Rivadeneira et al. 2018).

Currently, Dendropsophus amicorum (Mijares-Urrutia, 1998), D. battersbyi (Rivero, 1961), D. bromeliaceus Ferreira, Faivovich, Beard, & Pombal, 2015 and D. yaracuyanus (Mijares-Urrutia & Rivero, 2000) are not assigned with certainty to any species group. However, Dendropsophus bilobatus differs from D. amicorum , D. battersbyi and D. yaracuyanus by the SVL in males of 18.8-20.8 mm in males (SVL 22.8 mm in the male holotype of D. amicorum , SVL 33 mm in the male holotype of D. battersbyi , SVL 28.5-30.4 mm in males of D. yaracuyanus ; Rivero 1961, Mijares-Urrutia 1998, Mijares-Urrutia and Rivero 2000); from D. bromeliaceus by the presence of subocular spots and webbing formula of fingers I 2+-2 II 11/2-22/3 III 2- -2 IV (subocular spots absent, I trace II 2--3- III 3+-3+ IV; Ferreira et al. 2015). Although Dendropsophus minimus (Ahl, 1933) was placed in the D. minimus species group (sensu Faivovich et al. 2005), this species has never been included in a phylogenetic analysis and its group membership is uncertain. Dendropsophus bilobatus can be distinguished from D. minimus by having a visible tympanum and by the absence of tarsal fold (concealed tympanum and presence of tarsal fold; Ahl 1933).

Holotype description.

INPA-H 41300. Adult male (Figs 3 View Figure 3 , 4A, B View Figure 4 ), SVL 18.8 mm; body moderately robust; head slightly wider than long (HW/HL = 1.08); snout truncate in dorsal and lateral views; snout short, eye-nostril distance shorter than eye diameter (END/ED = 0.68); canthus rostralis rounded in dorsal and lateral views; loreal region slightly concave; internarial area slightly depressed; nostrils barely protuberant, directed dorsolaterally; interorbital area flat, slightly depressed in the central portion; interorbital distance equal 34% of head width; eyes large, strongly protuberant, ED/TD = 3.30, ED/HL = 0.42; tympanic membrane small, round, clearly distinct, its diameter 30% of eye diameter and 13% of head length; tympanic annulus distinct ventrally and anteriorly; supratympanic fold barely evident, slightly obscuring the upper edge of the tympanum. Arms slender and not hypertrophied; ulnar tubercles and fold absent; axillary membrane reaches the second third of the upper arm; hand relatively long, about 30% of SVL, approximately the same size as the forearm; fingers long, slender, bearing small discs; finger III twice as wide medialy than anteriorly; relative length of fingers I<II<IV<III; discs rounded on fingers; diameter of disc on finger III about the size of the tympanum; subarticular tubercles of fingers I and IV medium to large-sized, round, prominent, bifid in finger IV; subarticular tubercles of fingers II-III small, round, prominent; supernumerary tubercles barely evident; palmar tubercle small, flat, oval, barely evident proximally; prepollical tubercle large, flat, ovoid; nuptial pad white, glandular, covering the dorsolateral portion of the thumb but not reaching the ventral surface; webbing formula of fingers I 2+-2 II 11/2-22/3 III 2- -2 IV. Legs moderately long, slender (THL/SVL = 0.55; TL/SVL = 0.56); tibia slightly longer than thigh (TL/THL = 1.02); tarsal fold and tarsal tubercles absent; calcar tubercles absent; toes moderately long, bearing discs slightly smaller than those on fingers; toe IV length equals 60% of foot length; relative length of toes I<II<III<V<IV; toes I, II and V slender; toes III and IV widened by elongated flat glandular structures on both sides, glandular structures forming a continuous elongated glandular patch along toe IV, small glandular aggregations present also on fingers II and V; discs rounded on toes; diameter of the disc on toe IV equals diameter of the disc on finger III; subarticular tubercles round, prominent, penultimate tubercle on toe V bifid; supernumerary tubercles on toes III-IV small, round, barely evident; inner metatarsal tubercle elliptical, flat; outer metatarsal tubercle barely distinct; webbing formula of toes I 1+-2- II 1+-11/2 III 11/2-2- IV 2--1+ V.

Skin on head, dorsum, dorsal surfaces of limbs and flanks smooth; vocal sac and ventral surfaces of arms smooth; belly smooth laterally, coarsely granular medially; lower surfaces of thighs and surroundings of cloaca slightly granular. Cloacal opening directed posteroventrally at midlevel of thigh, covered dorsally by a wide cloacal sheath. Choanae small, vertically oval; dentigerous processes of vomers small, three vomerine teeth present on the right process, absent on the left process. Tongue cordiform, posterior third not attached to the floor of the mouth. Vocal slits long, extending from the midlateral base of the tongue to the angle of the jaw; anterior part covered by the lateral margin of the tongue. Vocal sac bilobate, subgular (Figs 3A View Figure 3 , 4A, C, D View Figure 4 ).

In life (Fig. 4A, B View Figure 4 ), the dorsum and dorsal surfaces of the limbs are light brown with an irregular pattern of yellow spots; the head has a large triangular yellow blotch that extends from the tip of the snout to the anterior interorbital region, including the anterior margin of the upper eyelids; the lateral sides of the head are greenish brown with two white horizontally elongate subocular spots on the left side and one elongate and one round white spot on the right side. The iris is pale to dark brown with barely visible tiny brown veins; its outer edge is brown to black. Proximal dorsal surfaces of fingers I-III are greenish white to yellowish white; the proximal dorsal surface of finger IV is brown; distal dorsal surfaces of the fingers are yellowish orange; nuptial pads are white. The upper part of the flanks is a light pinkish brown; the posterior part of the flanks and the groin are pinkish white. Hidden dorsal surfaces of the thighs are yellow. The vocal sac is green when deflated but translucent greenish white when inflated. The chest and belly are yellowish white medially but translucent pinkish white laterally and posteriorly. Ventral surfaces of arms and legs are translucent pinkish white; the anteroventral side of the thigh is yellow, the posteroventral side is pinkish white; palmar surfaces are greenish yellow; plantar surfaces are orange. Bones are white.

In alcohol (Fig. 3 View Figure 3 ), the head and dorsum are cream to brown with numerous tiny black melanophores and irregular white spots and blotches; dorsal surfaces of the limbs are light cream or translucent; ventral surfaces are translucent to cream, the chest and medial area of the belly are white. Bones are white.

Holotype measurements (in mm): SVL, 18.8; HL, 6.1; HW, 6.6; EN, 1.7; ED, 2.5; IOD, 2.3; TD, 0.8; 3FD, 0.8; 4TD, 0.8; TL, 14.4; THL, 10.3; TAL, 5.6; FL, 14.1.

Variation.

The morphology of paratypes and paratopotypes does not deviate from that of the holotype. Morphometric measurements of all type specimens are shown in Table 3 View Table 3 . Dendropsophus bilobatus sp. nov. exhibits two dorsal color patterns. The pattern of the holotype, while less common, is shared with two other specimens (INPA-H 41306 and 41307). The second and most common pattern is characterized by the dorsum and dorsal surfaces of the limbs being light brown with small irregularly distributed brown dots (Fig. 5A, B View Figure 5 ). Different from the holotype’s pattern (Fig. 5C View Figure 5 ), the limit between the pinkish flanks and the light brown dorsum is well marked (Fig. 4C View Figure 4 ). The number of subocular light spots is variable in both patterns, ranging from 1 to 3 spots. White nuptial pads are conspicuous in all specimens but absent in paratopotype INPA-H 41306. Ventral color is similar in all specimens, as well as the color of the bilobate vocal sac. Females are unknown.

Call description.

The advertisement call of Dendropsophus bilobatus (Fig. 6 View Figure 6 ) consists of single- or multiple-note calls emitted regularly in series of 7-35 calls (19 ± 9, N = 12). The most common arrangements are the single-note call (N = 181) and the two-note call (N = 58), while the rarest are the three-note (N = 1) and four-note calls (N = 1). Single-note calls have a call duration of 12-24 ms (8.2 ± 3, N = 30), an inter-call interval of 483-1,284 ms (751 ± 201, N = 30), and a call period of 503-1,302 ms (769 ± 202, N = 30). Two-note calls have a call-duration of 155-199 ms (171 ± 13, N = 22), an inter-call interval of 437-1,347 ms (816 ± 196, N = 19), and a call period of 612-1,542 ms (985 ± 198, n = 19). Notes in the two-note calls have a note duration of 12-22 ms (17 ± 3, N = 44) and an inter-note interval of 126-165 ms (137 ± 11, N = 22).The notes of both single- and multiple-note calls consist of 3-8 pulses (5 ± 1, N = 74). Pulse duration is 1-2 ms (1.2 ± 0.4, N = 30), inter-pulse intervals are 1-2 ms (1.5 ± 0.4, N = 30). The high-pitched calls are emitted with a dominant frequency of 8,979-9,606 Hz (9,274 ± 195, N = 52) and have a bandwidth of 7328-11517 Hz (N = 33).

Distribution and natural history.

Our research team has sampled frogs at more than 150 permanent sampling sites distributed on both banks of the upper Madeira River and along the Purus-Madeira Interfluve. Yet, we have only observed Dendropsophus bilobatus in the lowland ombrophilous open forest on the east bank of the upper Madeira River. This area is close to the border between Brazil and Bolivia, and we expect that the new species also occurs in Bolivian lowland ombrophilous open forest, as do other anuran species that are known exclusively from the east bank of the upper Madeira River (e.g., Hydrolaetare caparu [Jansen, Gonzales-Álvarez & Köhler, 2007] and Hamptophryne alios [Wild, 1995]; Simões et al. 2011, Ferrão et al. 2014).

To date, specimens of Dendropsophus bilobatus have been observed only in the rainy season (early November to late March), which coincides with the species’ breeding season. Calling males were observed in flooded areas connected to rivers of moderate (Jaci-Parana River) to large size (Madeira River). Males typically call in a large chorus while perched on leaves and tiny trunks that range in height from just a few centimeters above the water surface to ~ 2 m high. Males start calling in the crepuscule (~ 18:00 hs) and call activity has been observed at least to approximately midnight. When call activity ends remains unknown. Amplexus has not been observed. Other sympatric frogs include Rhaebo guttatus (Schneider, 1799), Boana cinerascens (Spix, 1824), B. lanciformis (Cope, 1871), Scinax sp. 6 (sensu Ferrão et al. 2016) and an uncollected Scinax with an advertisement call that resembles that of S. garbei (Miranda-Ribeiro, 1926).

Etymology.

The specific name bilobatus is derived from the Latin noun bilobate. The name refers to the characteristic bilobate shape of the vocal sac of males of the new species.

Kingdom

Animalia

Phylum

Chordata

Class

Amphibia

Order

Anura

Family

Hylidae

Genus

Dendropsophus