Phyzelaphryne nimio, Simões & Costa & Rojas-Runjaic & Gagliardi-Urrutia & Sturaro & Peloso & Castroviejo-Fisher, 2018

Simões, Pedro Ivo, Costa, João Carlos Lopes, Rojas-Runjaic, Fernando J. M., Gagliardi-Urrutia, Giussepe, Sturaro, Marcelo José, Peloso, Pedro L. V. & Castroviejo-Fisher, Santiago, 2018, A new species of Phyzelaphryne Heyer, 1977 (Anura: Eleutherodactylidae) from the Japurá River basin, with a discussion of the diversity and distribution of the genus, Zootaxa 4532 (2), pp. 203-230 : 216-224

Phyzelaphryne nimio sp. nov.

Figures 5–10 , 12

Holotype. MCP 13719 (field code SCF 1846 ). An adult female, collected by G. Gagliardi-Urrutia, F.J.M. Rojas- Runjaic, P.I. Simões and S. Castroviejo-Fisher on 5 February 2017, in an area of terra-firme forest on the west bank of the Juami River ( Canal da Inveja ), within Estação Ecológica Juami-Japurá, state of Amazonas, Brazil (1.75834° S, 67.61532° W; ~ 67 m a.s.l.).

Paratypes. Thirty-three adult specimens, 16 females and 18 males. Females: MCP 13683–13697 , 13720 (field codes SCF 1877 , 2003 , 1968 , 1969 , 1967 , 1973 , 1907 , 1775 , 1972 , 1970 , 1908 , 1875 , 1820 , 1743 , 1847 , 1971 , respectively). Males: MCP 13698–13715 (field codes SCF 1910 , 1959 , 1909 , 1964 , 1974 , 1965 , 1912 , 1744 , 1745 , 1961 , 1962 , 1960 , 1849 , 1966 , 1876 , 1848 , 1742 , 1911 , respectively). All collected by G. Gagliardi-Urrutia, F.J.M. Rojas-Runjaic, P.I. Simões and S. Castroviejo-Fisher between 2–9 February 2017 at the same site as the holotype and at a second sampling site within EEJJ ( Igarapé da Fartura ), on the east bank of the middle course of the Juami River (1.96063° S, 67.93694° W, ~ 71 m a.s.l.) .

Referred specimens. MCP 13716, 13717 and 13718 (field codes SCF 1913 , 1963 and 1978 respectively), all juvenile specimens, collected at Igarapé da Fartura sampling site, between 6–8 February 2017, same collectors as the paratypes . MCP 13725 (field code SCF 1975 ), three eggs laid by female paratype MCP 13688 on 0 8 February 2017 .

Etymology. The specific epithet nimio is a Spanish masculine adjective derived from the Latin word nimius (“abundant” or “plentiful”). The Spanish term keeps this meaning but has also received the additional meaning of “insignificant” and “very small” ( Real Academia Española 2014). The dual meaning of nimio alludes simultaneously to the abundance of the new species in the two localities where it was collected and to its very small body size, and is used in apposition to the genus.

Generic placement. We assign this new species to Phyzelaphryne based on its phylogenetic position using molecular data, and on the presence of the following diagnostic phenotypic characters, proposed by Hoogmoed & Lescure (1984): (1) Digits round in cross section; (2) discs on fingers and toes small, not expanded to moderately expanded, pointed at their tips; (3) discs of fingers III and IV and discs of toes I–V with distinct lateral grooves, interrupted only at the tip; (4) number of phalanges in fingers I–IV: 2-2-3-3; (5) number of phalanges in toes I–V: 2-2-3-4-3; (6) terminal phalanges in most fingers and toes with T-shaped tips; (7) tongue with a narrow anterior stem, widening into a large subcircular shape posteriorly; (8) a well-defined oblique subtympanic glandular ridge, not in contact with the tympanic annulus; (9) inguinal black spot absent.

Definition. Phyzelaphryne nimio is characterized by: (1) small body size, males 11.2 to 15.2 mm and females 13.2 to 15.9 mm in SVL; (2) skin on dorsum shagreened; ventral surfaces smooth, finely tuberculate only on thighs; (3) snout sub-acuminate in dorsal view, protruding in lateral view; (4) tympanum round and small, horizontal diameter approximately 30 % of eye diameter; tympanic annulus concealed dorsally by a skin fold; (5) subtympanic glandular ridge present from the mouth rictus to approximately the insertion of upper arm; (6) two or three pentagonal, trapezoid or ellipsoid supernumerary tubercles of which the one at the base of finger III is much larger than the others; (7) when conspicuous, supernumerary tubercle at the base of finger IV is ellipsoid, fused laterally with tubercle at the base of finger III; (8) thenar tubercle fused with subarticular tubercle on finger I; (9) inner metatarsal tubercle fused with subarticular tubercle of toe I; (10) cryptic body coloration, background color of dorsum tan or dark brown with darker brown mottling and small light brown or white spots, flanks tan or dark brown with white or light cream spots, ventral surfaces of body and limbs grayish brown, darkest on chest, with white blotches or spots; (11) iris golden copper with black reticulations and a bright red pupil ring.

Description of holotype. Adult female (SVL = 15.3 mm) in good state of preservation, with a piece of muscle ventrally cut from the right thigh and preserved as tissue sample ( Fig. 5 ). Measurements of the holotype are in Table 1. Body robust, head wider than long (HL/HW = 0.9), head length 0.3 times the SVL. Eye length greater than distance from anterior corner of eye to nostril (EN/EL = 0.7). Nares located posterolaterally to tip of snout, directed laterally. Nares opening laterally, visible in lateral view, but not distinct in ventral or dorsal views. Internasal distance 0.3 times HW. Snout sub-acuminate in dorsal view, protruding in lateral view. Canthus rostralis distinct, sharply angular from anterior corner of the eye to nostril, rounded from nostril to tip of snout. Loreal region slightly concave. Interorbital distance only slightly greater than internasal distance (IO/IN = 1.1). Distance between orbits 1.1 times the maximum width of eyelids, when measured dorsally ( Fig. 5 ). Tympanum round, 0.3 times maximum length of eye. Tympanum distinct to the naked eye, tympanic annulus present, well-defined, one fourth of right tympanum concealed posterodorsally ( Fig. 6 ), one third of left tympanum concealed dorsally.

Tympanum separated from posterior corner of the eye by a distance of 0.5 times the maximum horizontal diameter of tympanum. Subtympanic glandular ridge present from the mouth rictus to approximately the insertion of the upper arm. Subtympanic glandular ridge not contacting the tympanic annulus. Anterior 25 % of tongue attached to the mouth floor, forming a narrow stem. Tongue widening into a subcircular shape posteriorly. Choanae round, positioned anteriorly to prevomerine processes and eye bulge. Dentigerous processes straight, not in contact, sharply separated, forming a transverse row, located between the choanae and the eye bulge. Vomerine teeth present, not visible under maximum (60 X) magnification but detectable by moving a wire probe along the vomerine surface.

Lengths of upper arm and forearm 0.2 and 0.3 times the SVL. Palmar tubercle round to slightly elliptical. Thenar tubercle present, oval, slightly pointed distally, fused with subarticular tubercle of finger I. Maximum diameter of thenar tubercle 62 % of maximum diameter of palmar tubercle ( Fig. 7 ). Three supernumerary tubercles present at the bases of fingers II, III and IV. Supernumerary tubercle at the base of finger III pentagonal, about the same diameter as palmar tubercle, 1.3 times size of pentagonal supernumerary tubercle at the base of finger II. Supernumerary tubercle at the base of finger IV small, ellipsoid, flat and fused laterally with supernumerary tubercle at the base of finger III. Subarticular tubercles on fingers I to IV one, one, two and one respectively. Subarticular tubercles generally round, protuberant, slightly exceeding the width of phalanges. Subarticular tubercle on finger I elliptical, distally acuminate. Fingers unwebbed. Tip of Finger IV reaching the center of distal subarticular tubercle of Finger III when fingers are juxtaposed. Relative lengths of fingers: IV <II = I <III. Fingers with mucronate, abruptly pointed tips. Discs of fingers I and II not expanded, never exceeding the width of phalanges. Discs of fingers III and IV weakly expanded, width of discs corresponding to 1.0 and 1.1 times the width of their respective adjacent phalanges ( Fig. 7 ).

Tibia length half SVL (TL/SVL = 0.5). Keels or tubercles absent on tarsal region. Inner metatarsal tubercle elliptical, fused with subarticular tubercle of toe I. Outer metatarsal tubercle small and round, its maximum diameter equal to 0.4 of maximum diameter of inner metatarsal tubercle ( Fig. 8 ). Metatarsal region smooth, with no folds, ridges or additional tubercles. Toes unwebbed. Relative lengths of toes I <II <V <III <IV. Toes with mucronate, abruptly pointed tips. Discs of toes I and V not expanded, not exceeding the width of adjacent phalanges. Discs of toes II, III and IV moderately expanded, width of discs 1.1, 1.4 and 1.6 times the width of adjacent phalanges. One, one, two, three and two subarticular tubercles are present on toes I to V, respectively. Dorsal skin shagreened. Ventral skin smooth, finely tuberculate only medially on thigh.

Color of holotype in preservative. Dorsum tan brown with scattered irregular dark brown spots and mottling. Dorsum grayish dark brown on supraorbital region and laterally, from snout to shortly posterior to the level of upper arm insertion ( Fig. 5 ). Flanks the same color pattern as dorsum, with large dark brown areas from tip of snout to anterior corner of the eye, from posterior corner of the eye to shortly posterior to upper arm insertion (above tympanum and upper arm insertion) and on inguinal region ( Fig. 6 ). A transverse pale stripe is present ~ 1.5 mm posterior to upper arm in right lateral view. The same region is uniformly dark brown in left lateral view. Upper and lower lips with irregular white blotches, larger at the level of the eye than anteriorly. White blotches appear ventrolaterally, merging with color pattern of abdomen. Ventral surfaces with cream round marks on brown background. Density of melanophores variable longitudinally, rendering the brown background to be lighter on throat and abdomen and darker on chest ( Fig. 5 ). Tongue is pale cream.

Arm pale cream with irregular dark brown blotches along their outer edge and on wrist in dorsal view. Hand pale cream, with brown areas on proximal dorsal surface of metacarpal region and on fingers. Tips of fingers brown, Finger III pale brown at tip. Ventral upper arm pale cream to translucent with a few melanophores scattered laterally. Forearm brown with pale cream blotches ventrally. Carpal and metarcarpal regions gray to translucent, with scattered brown pigments visible through skin in ventral view ( Fig. 7 ).

Area immediately around vent uniform dark brown. A pale transverse bar flanks the dark brown area surrounding vent on the proximal region of thigh, in posterior view. Dorsal surface of thigh tan brown with dark brown marks forming incomplete transverse bars. Thigh ventrally light brown with cream round marks. Inner and outer lateral surfaces of thigh dark brown with pale cream dots. Dorsal surface of shank same color as thigh, with larger irregular dark brown blotches present medially. Ventral surface of shank uniformly tan. Dorsal surface of tarsal region and foot same color as dorsal surface of shank. Tarsal and palmar regions dark brown with a few pale cream blotches. In dorsal view, toes with an alternating dark brown/pale cream pattern. Toes uniformly dark brown in ventral view ( Fig. 8 ).

Osteology of fingers and toes. From examination of cleared and stained female paratype (MCP 13720), the number of phalanges in fingers I–IV of Phyzelaphryne nimio are 2-2-3-3, respectively ( Fig. 9 ). Tips of terminal phalanges of fingers II, III and IV are T-shaped. Tip of terminal phalanx of finger I is blunt. The number of phalanges in toes I–V are 2-2-3-4-3 ( Fig. 9 ). Tip of terminal phalanges of all toes are T-shaped.

Variation in type series. Variation in morphometric measurements of female and male types are presented in Table 1. SVL of females generally larger than males (female SVL: mean = 13.2 mm, range 13.2–15.9; male SVL: mean = 12, range = 11.2–15.2). SVL of three juvenile specimens for which sex could not be determined were 10.7, 10.7 and 10.5 mm. Body proportions of adults (HL/SVL, HW/SVL, HL/HW, SL/SVL, TYM/SVL, FAL/SVL, TL/ SVL) overlapping between sexes.

Canthus rostralis in cross section varying from angular to nearly rounded between anterior corner of the eye to nostril in cross section, concave in dorsal view. Vocal sac of males subgular, single and small, not extending onto chest or arm insertion ( Fig. 5 ), sometimes forming wrinkles on the surface of throat. Vocal slits flanking tongue at its posterior third, with darkly pigmented borders. Dentigerous process slightly convex in specimens MCP 13690 and MCP 13715. One third of tympanum dorsally concealed in 65 % and one fourth of tympanum dorsally concealed in 35 % of specimens.

Supernumerary tubercle at the base of finger IV conspicuous in all female specimens and in 50 % of male specimens, inconspicuous in the remaining males. When conspicuous, supernumerary tubercle at the base of finger IV is fused with the one at the base of finger III. Supernumerary tubercles pentagonal or trapezoid ( Fig. 7 ).

Color in life. Description is based on field observations and photographs of specimens forming the type series. Coloration is variable among type specimens, but not sexually dimorphic ( Fig. 10 ). Juvenile specimens have the same color pattern as adults.

Dorsum tan, brownish orange or brownish yellow, with variable dark brown mottling. Scattered small white dots present on dorsum in some individuals. Flanks same color as dorsum, with dark brown areas extending from behind the eye to above upper arm insertion. Large dark brown patches generally present ventrolaterally. Bright white spots present ventrolaterally on flanks and on upper and lower lips, generally more evident below the eye. Lateral bright spots whitish yellow in some individuals. Venter grayish brown, darker anteriorly. Irregular bright white spots present on all ventral surfaces, dense on throat and chest, sparse on posterior abdomen. Spots frequently with a darker grayish brown margin.

Dorsal surface of upper and forearm dark yellow with dark brown mottling, denser on forearm. Isolated bright white spots sometimes present on dorsal surface of forearm. Ventral surface of upper arm yellow to translucent. Forearm, carpal and metacarpal regions and fingers gray ventrally, gray with bright white spots dorsally.

Area immediately adjacent to vent uniform dark brown. Inner lateral surface of thigh dark brown with scattered irregular white spots, varying in shape, size and density among individuals. Dorsal surfaces of thigh and shank same color as dorsum, generally with dark brown mottling, sometimes forming irregular transverse dark brown bars. Venter of thigh grayish brown with bright white spots, same color as anterior ventral surfaces of body. Ventral surface of shank solid grayish brown. Dorsal surface of tarsal region same color as thigh and shank, with alternating transverse pale (tan brown, light brown or white) and dark brown blotches. Ventral surfaces of tarsal and plantar regions solid dark gray in ventral view. Toes with alternating transverse white and dark brown blotches ventrally. Iris is golden copper with black reticulations and a bright red pupil ring.

Natural history. Phyzelaphryne nimio is a very small nocturnal and hemiedaphic frog that inhabits the leaf litter of terra-firme rainforests ( Fig. 11 ) at EEJJ. None were detected in flooded forest areas or at channel or river edges. The species is very abundant at the two localities where it was collected (Canal da Inveja and Igarapé da Fartura), but can go unnoticed due to its secretive habits, small size and cryptic coloration. When leaf litter is removed and they jump to escape, they can be easily mistaken for crickets. Despite their small size their jumps can reach approximately one meter, more than 60 times their mean SVL. Phyzelaphryne nimio was hardest to detect during nocturnal searches after a rain; the largest numbers of individuals were detected on dry nights. We detected a high number of specimens during our nocturnal surveys by careful removal of leaf litter using feet or sticks. Phyzelaphryne nimio was more abundant in areas where the forest floor was covered by a deep layer of leaf litter, ca. 25–40 cm. At least 15 specimens were detected by leaf litter removal with a stick in about 20 minutes in an area of ca. 10 m 2, near the basecamp of Igarapé da Fartura at 22:00 h on 0 8 February 2017. In spite of the abundance of this species and the great sampling effort at the two localities, no calling males were detected. At least eight of the adult females collected were ovate (MCP 13684, 13686, 13687, 13688, 13690, 13691, 13692, 13720); two or three very large eggs were evident through the translucent skin on their flanks. An amplectant couple (male MCP 13702; female MCP 13688; Fig. 12 ) was found in cephalic amplexus on the leaf litter at 22:10 h on 0 8 February 2017 in the vicinity of the basecamp of Igarapé da Fartura. During transport to the camp, the female laid three large eggs on the leaf litter in the transporting bag. Eggs were 3.9, 4.0 and 4.3 mm in maximum diameter and their yolk was uniformly white ( Fig. 12 ). Juveniles were very uncommon in our sample, with only three juvenile specimens collected (MCP 13716, 13717 and 13718).

Diagnosis. Because Phyzelaphryne and Adelophryne share a very similar external morphology, we compare the new species with all currently recognized Amazonian Phyzelaphryninae . Character states in species other than P. nimio are described in parentheses.

Phyzelaphryne nimio is most easily distinguished from Phyzelaphryne miriamae Heyer, 1977 by the morphology of the carpal and metacarpal ventral surfaces. Phyzelaphryne nimio differs from P. miriamae by the presence of three pentagonal, trapezoid or ellipsoid supernumerary tubercles (three round to elliptical supernumerary tubercles in P. miriamae ). Supernumerary tubercle at the base of finger III 1.3–1.4 times larger in maximum diameter than the supernumerary tubercles at the base of fingers II or IV, respectively (supernumerary tubercles only slightly variable in maximum diameter). Supernumerary tubercle at the base of finger IV not protuberant, sometimes inconspicuous (supernumerary tubercle at the base of finger IV protuberant, always conspicuous). When conspicuous, supernumerary tubercle at the base of finger IV is fused with tubercle at the base of finger III (supernumerary tubercles separated by a conspicuous gap). Thenar tubercle fused with subarticular tubercle on finger I (thenar tubercle and subarticular tubercle on finger I separated by a conspicuous gap). Inner metatarsal tubercle and subarticular tubercle of toe I fused (inner metatarsal tubercle and subarticular tubercle of toe I not fused, separated by a short, but conspicuous gap). Male P. nimio generally smaller than male P. miriamae , although the ranges of their SVL overlap (male P. nimio = 11.2–15.2 mm; male P. miriamae 14.6–16.2 mm). Female P. nimio much smaller than female P. miriamae (SVL range in female P. nimio 13.2–15.9 mm; SVL range in female P. miriamae 19.4–20.0 mm).

Phyzelaphryne nimio differs from all Amazonian species of Adelophryne in having cylindrical digits in cross section (digits flattened), by the presence of distinct, round subarticular tubercles on fingers (indistinct subarticular tubercles), by having a large subcircular tongue (tongue narrow, not expanding into a subcircular shape posteriorly) and by the presence of a small subgular vocal sac, indistinct in preserved male specimens (subgular vocal sacs large, conspicuous as skin folds, commonly extending to the level of chest or that of the upper arm insertion). It also differs in having tympanum separated from eye by a distance much less than the maximum horizontal diameter of tympanum (tympanum separated from eye by a distance equal to or slightly less than horizontal diameter of tympanum).

Phyzelaphryne nimio differs from Adelophryne adiastola Hoogmoed & Lescure, 1984 in having three phalanges on finger IV (two phalanges on finger IV), in having white or cream spots on flanks (white or cream spots absent on flanks) and in having a brown dorsum with dark brown mottling and with small cream or white spots (dorsum uniformly brown).

Phyzelaphryne nimio differs from Adelophryne gutturosa Hoogmoed & Lescure, 1984 in having tips of fingers III and IV weakly expanded into discs (no discs on tips of fingers) and by venter grayish brown, darkest on chest, with scattered white spots (venter dark brown, darkest on throat, with small white dots).

Phyzelaphryne nimio differs from Adelophryne patamona MacCulloch, Lathrop, Kok, Minter, Khan & Barrio- Amorós, 2008 by ventral color in life: grayish brown, darker on chest, with irregular bright white spots dense on throat and chest, sparse on posterior abdomen (throat, chest and underside of upper arms dark gray with white or pale blue spots; posterior abdomen and underside of legs reddish brown with white or pale blue spots).

Geographic distribution. Phyzelaphryne nimio is currently known from terra-firme forests in the Juami River basin, south of the Japurá River, Amazonas, Brazil ( Fig.1 ). Two other nearby sites were searched: 1) riverside environments and on small islands at the confluence of Juami and Japurá rivers (1.73946° S, 67.60149° W, 44 km from the type locality, and 2) north bank of the Japurá River (Comunidade de Barreirinha, 1.64137° S, 67.70606° W, 43 km from type locality). No specimens of P. nimio were found in these locations.

Figures

FIGURE 1. Geographic location of study areas in Brazilian Amazonia (Estação Ecológica Juami-Japurá and Parque Nacional do Jaú) and known localities of Phyzelaphryne based in Hoogmoed & Lescure (1984), Fouquet et al. (2012) and the results of this study. Lighter green shades correspond to Brazilian conservation units and black dots mark type localities. Pentagons, P. nimio sp. nov.; circles, P. miriamae; Triangles and square, Phyzelaphryne sp. (C1) and Phyzelaphryne sp. (C2), respectively, two candidate new species.

FIGURE 5. Dorsal and ventral views of preserved specimens of Phyzelaphryne nimio sp. nov. Left: Holotype adult female (MCP 13719). Right: Paratype adult male (MCP 13715).

FIGURE 6. Lateral view of type specimens of Phyzelaphryne nimio sp. nov. Top: Holotype adult female (MCP 13719). Bottom: Paratype adult male (MCP 13715).

FIGURE 7. Ventral view of the left hand of preserved type specimens of Phyzelaphryne miriamae (A, B) and P. nimio sp. nov. (C–F). (A) Holotype adult female (MZUSP 49894). (B) Paratype adult male (MZUSP 49895). (C) Paratype adult female (MCP 13691). (D) Paratype adult male (MCP 13715). (E) Holotype adult female (MCP 13719). (F) Paratype adult male (MCP 13711). Scale bars = 1.0 mm.

FIGURE 8. Ventral view of the left foot of preserved type specimens of Phyzelaphryne miriamae (A, B) and P. nimio sp. nov. (C–F). (A) Holotype adult female (MZUSP 49894). (B) Paratype adult male (MZUSP 49895). (C) Paratype adult female (MCP 13691). (D) Paratype adult male (MCP 13711). (E) Holotype adult female (MCP 13719). (F) Paratype adult male (MCP 13715). Scale bars = 1.0 mm.

FIGURE 9. Dorsal view of the cleared and stained hand (top) and ventral view of foot (bottom) of a female paratype (MCP 13720) of Phyzelaphryne nimio sp. nov. Note T-shaped tips of terminal phalanges on fingers II, III and IV and toes I–IV. Tip of toe V is indistinct in this view, but it is also T-shaped.

FIGURE 10. Color variation in life in Phyzelaphryne nimio sp. nov. (A, B) Adult female paratype MCP 13696; (C, D) male paratype MCP 13714; (E, F) gravid female paratype MCP 13690, with egg visible through translucent skin on the posterior right flank (F).

FIGURE 11. (A) Canal da Inveja, a black water watercourse at Estação Ecológica Juami-Japurá (EEJJ), state of Amazonas, Brazil. In this conservation unit, terra-firme forests such as the type locality of Phyzelaphryne nimio sp. nov. are accessed from water channels and creeks. (B) Habitat of P. nimio at EEJJ.

FIGURE 12. (A) Cephalic amplexus of Phyzelaphryne nimio sp. nov. male paratype MCP 13702 (SVL = 11.9 mm) and female paratype MCP 13688 (SVL = 14.0 mm). (B) Eggs laid by MCP 13688. Diameter of eggs ranged between 3.9 and 4.3 mm.