Boana hobbsi ( Cochran & Goin, 1970 )

De Almeida, Alexandre P., Moraes, Leandro J. C. L., Rojas, Rommel R., Roberto, Igor J., Carvalho, Vinicius Tadeu De, Ávila, Robson W., Frazão, Luciana, Silva, Ariane A. A., Menin, Marcelo, Werneck, Fernanda P., Hrbek, Tomas, Farias, Izeni P. & Gordo, Marcelo, 2021, Phylogenetic relationships of the poorly known treefrog Boana hobbsi (Cochran & Goin, 1970) (Anura: Hylidae), systematic implications and remarks on morphological variations and geographic distribution, Zootaxa 4933 (3), pp. 301-323 : 306-311

Boana hobbsi ( Cochran & Goin, 1970)

Holotype. MCZ 28052, from Caño Guacayá , a tributary of the Rio Apaporis, Amazonas, Colombia.

Morphological variation. Morphometric data analysis of the newly collected B. hobbsi series showed measurements contained within the described variation of the species ( Table 3). Other morphological data observed in preserved specimens include: (1) slender body with smooth to weakly shagreened dorsum skin fully covered by melanophores, and a finely granular ventral surface skin; (2) dark brown to pale yellowish dorsum with scattered black spots throughout the dorsal surfaces of body, arms, and shank ( Figs. 2A, 2C, 2E ); (3) white to cream dorsolateral stripe varying in evidence, beginning at the tip of the snout, crossing the upper eyelid, reaching the sacrum and ending just anterior to the groin ( Figs. 2A, 2C, 2E ); (4) greenish white to cream belly, with concentration of melanophores on the ventral surfaces of hands, forearms, and feet ( Figs. 2B, 2D, 2F ); (5) head truncate in lateral view and round in dorsal view, snout truncate in lateral and dorsal views ( Figs. 3A, 3B ), with an evident mental gland ( Fig. 3C ); (6) evident prepollex with no spine protruding out of the skin; (7) palmar tubercle rounded; (8) relative length of fingers I <II <IV <III, almost unwebbed (I–II 2 - –3 - III 3 - –3 - IV) ( Fig. 3D ); (9) subarticular tubercle rounded in fingers I and II, bifid in fingers III and IV ( Fig. 3D ); (10) supernumerary tubercles absent; (11) relative length of toes I <II <III <V <IV, fully webbed (I1 + –1 - II 1 + –3 - III 1 + – 11/2 IV 2 + –0 V) ( Fig. 3E ). Coloration patterns of B. hobbsi in life ( Fig. 4 ) include: (1) dark brown to pale green dorsum, with scattered blackish spots; light yellow flanks, fingers, toes and ventral surfaces of forearm and shank; (2) a cream stripe varying in evidence across the dorsolateral regions of head and body; (3) iris golden-yellow, bordered by an intense black ring, with black thin reticulation near the border of the eyelid and a reddish-brown pigmentation around the pupil ( Fig. 4 ). Although analyzed specimens were collected from geographically distant localities (nearly 300 km apart), we did not notice any significant difference in morphological characteristics associated with the distinct sampling localities. Our morphological results indicate that despite its relatively wide geographic distribution, the species overall morphology is conserved throughout its range of occurrence.

Comparisons. Data from all other species of the B. benitezi group are provided in parenthesis except Boana pulidoi , which was recently synonymized. In living and in preserved specimens, B. hobbsi differs from all other species of the B. benitezi group by the presence of scattered black spots on the dorsal surfaces of body, arms and thighs (absent in all other species), and by a larger body size with mean SVL 41.14 mm (mean SVL <40.0 mm). By exhibiting a brown dorsal color pattern with a cream dorsolateral stripe, B. hobbsi differs from B. benitezi (brown, with brown transverse bars varying in width and dorsolateral stripes absent), B. jimenezi (green, with large spots in limbs and forearms), B. lemai (light yellow to reddish-brown, with dark transversal stripes and eventually with white dorsolateral stripes), B. microderma (light yellow to orange-brown, with light brown transversal bars), B. nympha (bright yellowish green to reddish brown), B. ornatissima (green, with an elaborated ornamentation in the center of the dorsal surface), B. rhythmica (reddish brown, with fine black reticulation or black transverse lines, eventually with white dorsolateral stripes), B. roraima (light brown with irregular dark brown markings and eventually with middorsal dark stripes), and B. tepuiana (in life varying from bright yellow with brown marks, to brown with gray markings, and to dark brown with cream dorsolateral stripes; in preserved specimens a reticulated pattern can also be observed). By its greenish cream-colored ventral surface in living specimens, B. hobbsi also differs from B. benitezi (bright orange or white) and B. ornatissima (varying from greenish yellow to translucid blue). Male specimens of B. hobbsi also have an evident mental gland that differs from the condition observed in B. jimenezi (absent). In life, B. hobbsi can also be distinguished by a unique iris color, with its golden-yellow background, black reticulation and reddish-brown pigmentation around the pupil, from B. benitezi (varying from light brown to dark brown), B. jimenezi (silvery with a dark brown rim around the pupil and a fine dark reticulation), B. lemai (pale green to gray), B. microderma (cream to pale yellow with a black peripheric mark), B. nympha (varying from cream to creamy-golden with a black peripheric mark), B. ornatissima (varying from silver to gray-green background with a reddish-brown area around pupil), B. rhythmica (golden without reticulation), B. roraima (varying from pale green to yellow without reticulation and a black peripheric mark), and B. tepuiana (silvery-gray to dark brown).

Although aforementioned comparisons show that B. hobbsi is easily distinguished from congeneric species of the B. benitezi group, this species shares greater morphological affinity with this group than when compared to congeneric species of the B. punctata group. These morphological similarities include a brown dorsal surface of the body, eventually with highly contrasting white or cream dorsolateral stripes, as observed in B. lemai , B. tepuiana and B. benitezi ; and the dense matrix of chromatophores in the dorsal surface and eventual presence of highly contrasting whitish-cream dorsolateral stripes shared with the greenish colored B. jimenezi . These similarities clearly reflect the closer phylogenetic relationships among species found in our molecular analysis (i.e. the highly supported clade containing B. hobbsi , B. tepuiana , B. lemai and B. jimenezi ). With remaining members of B. benitezi group, Boana hobbsi shares a slender body and limbs, eyes bordered by an intense dark ring, and the presence of a mental gland (also present in B. lemai and B. benitezi ).

Geographic distribution. New sampling localities filled relevant knowledge gaps in the geographic range of B. hobbsi ( Fig. 5 ). One of these localities is a small stream inside the forest on the right bank of the Japurá River, near to Vila Bittencourt (1.845994° S, 69.029466° W), located 117 km east of the nearest record on the Caquetá River, and 185 km from the type locality (Caño Guacayá, a tributary of the Río Apoporis, in Amazonas, Colombia—Co-chran & Goin [1970]). The second locality is a stream at the road to Cucuí village in the vicinity of S„o Gabriel da Cachoeira (0.130547°S, 67.038947°W), located 160 km south of the nearest record at Cerro de la Neblina base camp, Venezuela, and 390 km from the type locality ( Fig. 5 ). Our record at S„o Gabriel da Cachoeira, along with the Cerro de la Neblina Venezuelan record, and the first Brazilian record at Japurá River, all represent the easternmost known limits of geog raphic ra nge of B. hobbsi .

Figures

FIGURE 2. Dorsal and ventral views of newly collected preserved specimens of Boana hobbsi (Cochran & Goin, 1970). (A, B) adult male, with dark brown dorsum and little evident dorsolateral stripe (CZPB-AA 1658, SVL= 46.2 mm); (C, D) adult female, with dark brown dorsum and evident dorsolateral stripe (CZPB-AA 1660, SVL= 43.5 mm); (E, F) adult male, with yellowish dorsum and evident dorsolateral stripe (CZPB-AA 1657, SVL= 33.7 mm).All specimens were collected on the right bank of the Japurá River, near to the city of Japurá, state ofAmazonas, Brazil.

FIGURE 3. Morphological details of newly collected preserved specimens of Boana hobbsi (Cochran & Goin, 1970). (A–C) lateral, dorsal and ventral views of the head of an adult male (CZPB-AA 1658, SVL= 46.2 mm), highlighting the presence of an evident mental gland (red arrow). (D, E) ventral surfaces of the hands and feet of an adult female of B. hobbsi (CZPB-AA 1659; SVL = 45.8 mm).

FIGURE 4. Dorsolateral views of newly recorded living specimens of Boana hobbsi (Cochran & Goin, 1970): (A) adult female from the right bank of the Japurá River, near to Vila Bittencourt, Amazonas, Brazil (Photo: APA); (B) adult male from the municipality of of S„o Gabriel da Cachoeira, Amazonas, Brazil (Photo: LJCLM); (C, D) adult and juvenile males from Japurá River, showing variations in dorsal coloration, from tan, to dark brown, to a pale green-grayish, respectively (Photo: VTC).

FIGURE 5. Known geographic distribution of Boana hobbsi (Cochran & Goin, 1970) in the northwestern Amazonia. White circles indicate the historical localities of occurrence in Colombia, Venezuela and Brazil (Cochran & Goin 1970; Pyburn 1978; McDiarmid et al. 1988; Ruiz-Carranza et al. 1996; Acosta-Galvis 2000; Lynch 2005, 2007; Suárez-Mayorga & Lynch 2017; Acosta-Galvis 2018; Barrio-Amorós et al. 2019; Simıes et al. 2019). Yellow circles on the Brazilian territory indicate new distribution records reported at Japurá and Negro river basins. The red star indicates type locality at Caño Guacaya, Apaporis River, Colombia (Cochran & Goin 1970).