Allobates brunneus

Lima, Albertina P., Caldwell, Janalee P. & Strussmann, Christine, 2009, Redescription of Allobates brunneus (Cope) 1887 (Anura: Aromobatidae: Allobatinae), with a description of the tadpole, call, and reproductive behavior, Zootaxa 1988, pp. 1-16: 4-8

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Allobates brunneus


Redescription of Allobates brunneus 

( Figures 1–2View FIGURE 1View FIGURE 2)

Adult definition and diagnosis: A small-sized Allobates  (mean adult male SVL 16.7 mm; mean adult female SVL 18.3 mm); dorsum granular, heaviest posteriorly; Finger I slightly longer than Finger II, Finger II longer than Finger IV; Finger III on males not swollen ( Fig. 3View FIGURE 3 A). Dorsolateral stripe absent in both sexes; ventrolateral stripes absent in preserved specimens, present in life; oblique lateral stripe present but diffuse ( Figs. 1View FIGURE 1 C and 1 F; Figs. 2View FIGURE 2 A, 2 B, and 2 C); finger discs expanded; no webbing on hands ( Fig. 3View FIGURE 3 A); lateral fringes on fingers and toes absent ( Figs. 2View FIGURE 2 A and B); basal webbing present between Toes II and III and Toes III and IV ( Fig. 3View FIGURE 3 B); median lingual process absent ( Grant et al. 1997); black arm-band absent ( Grant & Castro 1998); white (unpigmented) testes extending half the length of the kidney; mature oocytes pigmented; teeth imperceptible under microscope at 50 X magnification.

Comparison with other species: Forty-four species are currently placed in the genus Allobates  , many of which are known only from the vicinity of their type localities or have restricted ranges. We distinguish A. brunneus  from other species that occur in the Amazon region of Brazil or in southern Brazil. Allobates brunneus  has a distinct dark hourglass pattern on the dorsum, which distinguishes it from A. caeruleodactylus ( Lima & Caldwell 2001)  , A. conspicuus  ( Morales 2002 “ 2000 ”), A. fuscellus  ( Morales 2002 “ 2000 ”), A. marchesianus  ( Melin 1941; Caldwell et al. 2002 b), A. masniger  ( Morales 2002 “ 2000 ”), A. nidicola ( Caldwell & Lima 2003)  , A. subfolionidificans ( Lima et al. 2007)  , A. sumtuosus  ( Morales 2002 “ 2000 ”), and A. vanzolinius  ( Morales 2002 “ 2000 ”), all of which have plain dorsa. It is distinguished from two other Amazonian species of Allobates  that have hourglass patterns on the dorsum by the following characters: A. crombiei  has Fingers II and IV equal in length, a distinct dorsolateral stripe, no oblique lateral or ventrolateral stripes, and throat dark gray in males ( Morales 2002 “ 2000 ”); A. gasconi  is smaller than A. brunneus  , dorsolateral and ventrolateral stripes are present, oblique lateral stripe is absent, and males have a swollen third finger and gray throat ( Morales 2002 “ 2000 ”). Allobates olfersioides  (including synonyms A. alagoanus  , A. capixaba  and A carioca  ; Lutz 1925; Verdade & Rodrigues 2007) differs from A. brunneus  in having a pattern of intercrossing Xs on the dorsum (dark hourglass pattern in A. brunneus  ) and no oblique lateral stripe (diffuse oblique lateral stripe extending from groin to near midbody in A. brunneus  ).

Adult description: Females are slightly larger than males ( Table 1). Average female SVL is 1.5 mm greater than male SVL, but males have relatively wider heads [head wider than long; male HW 39 % of SVL in males, 37 % of SVL in females (t = 2.8, df = 36, P = 0.005)]. Snout blunt, broadly rounded to nearly truncate in dorsal view ( Figs. 1View FIGURE 1 A and 1 D) and acutely rounded in lateral view ( Figs. 1View FIGURE 1 C and 1 F), extending past lower jaw ( Figs. 1View FIGURE 1 B and 1 E). Male SL 46 % and female SL 47 % of HL; IN in males and females 38 % of HW; EN in males 74 % and in females 73 % of HW; tympanic membrane inconspicuous, round, TYM 46 % of EL in both sexes; posterodorsal part of tympanum partially concealed by slip of m. depressor mandibulae; tongue attached anteriorly, longer than wide, slightly rounded posteriorly, median lingual process absent; teeth on premaxilla and maxilla imperceptible under light microscope at 50 X magnification; dorsal skin granular, heavier posteriorly; dorsolateral stripe absent; ventrolateral stripe present in life, absent in preserved specimens; oblique lateral stripe present, consisting of a broad, diffuse area that interrupts the lateral dark brown band in several positions, most obvious from groin to midbody but extending to forearm in some specimens ( Figs. 1View FIGURE 1 and 2View FIGURE 2).

Forearm slightly longer than upper arm; ulnar fold absent; HAND III length in males 19.5 % and females 18.4 % of SVL; Finger I slightly longer than Finger II when fingers appressed; Finger III>I>II>IV ( Fig. 3View FIGURE 3 A); finger webbing absent; palmar tubercle nearly round, diameter 0.65 ± 0.08 mm in females, 0.56 ± 0.06 mm in males, 14.1 % of HL in both sexes; thenar tubercle elliptic, one-third diameter of palmar tubercle ( Fig. 3View FIGURE 3 A); one subarticular tubercle present on Fingers I, II, and IV, two subarticular tubercles present on Finger III ( Fig. 3View FIGURE 3 A); basal subarticular tubercles on Fingers I and II largest, nearly equal in size, basal subarticular tubercle on finger IV very small; basal and distal subarticular tubercle on Finger III smaller, subequal. No fringes on fingers; all discs on fingers expanded; Finger III not swollen, width of disc on Finger III 0.55 mm, disc 62 % wider than width of finger (hand characters in Fig. 3View FIGURE 3 A).

Hindlimbs robust; TL 50.4 % of SVL. Ratio of foot length to SVL in males (mean 0.47 ± 0.02 mm) significantly greater than in females (mean 0.45 ± 0.03 mm; t = 3.05, df = 36, P = 0.005); foot length 45 % of SVL in males and 47 % in females; relative length of toes IV>III>V>II>I; basal webbing between Toes III and IV present in all specimens; rudimentary webbing present between Toes III and IV only in 5 of 38 specimens; lateral fringes absent on all toes; Toe I reaching distal edge of subarticular tubercle of Toe II when appressed; discs on Toes I, II, III, and IV larger than adjacent phalanges; disc on Toe V nearly same width of phalanges; width of disc on toe IV 0.68 mm in adults; inner metatarsal tubercle oval; outer metatarsal tubercle round; medial metatarsal tubercle absent; metatarsal fold weak, present in 33 and absent in 5 specimens; tarsal keel distinct, short and curved; one subarticular tubercle on Toes I and II; two on Toes III and V; Toe IV with three subarticular tubercles, basal subarticular tubercle poorly defined in 33 and absent in 5 specimens (foot characters in Fig. 3View FIGURE 3 B).

Color in life: Ground color of dorsum generally varies from light grayish brown to orange brown with one to three dark brown, sometimes diffuse, triangular, diamond, or hourglass markings from between the orbits extending to the sacral region ( Fig. 2View FIGURE 2 A– 2 C). Upper surface of arm light orange-brown; upper surfaces of legs light gray with dark brown transverse bands on thigh, shank and foot in most specimens. Adult males with greenish-yellow throats with melanophores evenly dispersed on vocal sac; chest and belly lemon yellow to light lemon yellow; adult females yellow on outer edge of throat becoming white on central part of throat, blending with white chest and belly ( Fig. 2View FIGURE 2 D). Flank and undersurface of thigh greenish yellow; undersurface of leg and foot light gray; lower surface of arm light brown. Dorsolateral stripe absent; oblique lateral stripe pale tan to light orange brown, forming diffuse area variously extending from groin to midbody or sometimes to arm insertion; ventrolateral stripe consisting of a series of irregular, elongate white spots, extending from the anterior corner of eye to groin. Upper part of iris and pupil ring metallic gold with fine black reticulations; remainder of iris brown.

Color in preservative: Ground color of dorsum uniform light brown with 1 to 3 chocolate brown triangular, diamond-shaped, or hourglass markings extending from between the orbits to the sacral region ( Figs. 1View FIGURE 1 A and 1 D); upper surface of arms cream to yellowish in 35 specimens, brown in 3; posterior surfaces of arms and legs light brown with dark brown flecks. In 35 specimens, upper surfaces of leg light brown with a dark brown band on thigh, shank, and foot; in 3 specimens these bands diffuse. Dark brown band extending from the snout laterally around the body, to midbody in 35 specimens, or nearly to arm insertion in 3 specimens; this lateral dark brown band narrows before and after eye. Ventrolateral stripe not visible in preserved specimens; pale oblique lateral stripe interrupts lateral dark brown band at midbody in 32 specimens; in 6 specimens it consists of diffuse pale cream spots imbedded in the dark brown lateral band at level of groin ( Fig. 1View FIGURE 1 C and 1 F, 2 A– 2 C). Flank, belly, and upper lip plain white or very light yellow; adult male throat cream to yellowish with rows of spots formed by melanophores around lips; widely dispersed melanophores visible only under microscope on remainder of throat; chest and belly cream to yellowish ( Fig. 1View FIGURE 1 B). Female throat, chest, and belly cream ( Fig. 1View FIGURE 1 E); palms of hands and soles of feet brown; paracloacal mark absent ( Fig. 1View FIGURE 1 A– 1 F).

TABLE 1. Measurements (in mm) of adult males and females of Allobates brunneus collected from near the type locality. Abbreviations are defined in the text. Values are means ± standard deviation; maximum and minimum values are in parentheses.

Character Male (n = 20) Female (n = 18)
SVL 16.7 ± 0.8 (14.8–18.3) 18.3 ± 1.2 (15.8–19.8)
HL 4.6 ± 0.2 (42.2–5.0) 5.0 ± 0.4 (4.2–5.6)
HW 6.5 ± 0.5 (5.6–7.0) 6.8 ± 0.4 (5.7–7.3)
SL 2.1 ± 0.2 (1.8–2.3) 2.4 ± 0.2 (1.9–2.7)
EN 1.6 ± 1.0 (1.4–1.7) 1.7 ± 0.1 (1.5–1.8)
IN 2.4 ± 1.0 (2.3–2.7) 2.6 ± 0.1 (2.3–2.9)
EL 2.1 ± 0.2 (1.9–2.5) 2.3 ± 0.2 (2.0–2.6)
IOD 5.1 ± 0.3 (4.6–5.7) 5.5 ± 0.3 (5.0–6.0)
TYM 1.0 ± 0.1 (0.8–1.1) 1.0 ± 0.1 (0.9–1.2)
FAL 4.0 ± 0.3 (3.3–4.5) 4.1 ± 0.2 (3.7–4.5)
HAND I 3.3 ± 0.33 (2.6–4.1) 3.3 ± 0.2 (2.9–3.7)
HAND II 3.1 ± 0.3 (2.2–3.4) 3.2 ± 0.2 (2.9–3.6)
HAND III 4.2 ± 0.4 (3.2–4.7) 4.4 ± 0.3 (3.7–5.0)
HAND IV 2.8 ± 0.1 (2.6–3.0) 2.9 ± 0.2 (2.6–3.1)
WFD 0.5 ± 0.1 (0.4–0.6) 0.6 ± 0.1 (0.4–0.7)
FL 7.9 ± 0.5 (6.8–8.7) 8.1 ± 0.5 (7.4–9.2)
WTD 0.7 ± 0.1 (0.5–0.8) 0.7 ± 0.1 (0.6–0.8)
TIL 8.6 ± 0.5 (7.8–9.6) 9.0 ± 0.2 (8.5–9.7)
AL 3.7 ± 0.3 (3.2–4.2) 3.9 ± 0.3 (3.5–4.3)