Boana geographica (Spix, 1824)

Schiesari, Luis, Rossa-Feres, Denise De Cerqueira, Menin, Marcelo & Hödl, Walter, 2022, Tadpoles of Central Amazonia (Amphibia: Anura), Zootaxa 5223 (1), pp. 1-149 : 44

Boana geographica

External morphology. Description based on five tadpoles between Stages 37 to 39 (LCS 433, 441, 616). Total length 51.0 ± 2.8 mm (N = 5). Body elongate oval in dorsal view and globular/depressed in lateral view ( Fig. 19A, B ). Snout rounded in dorsal and lateral views. Eyes small, dorsolaterally positioned and laterally directed. Nostrils small, oval, dorsolaterally positioned, near to eyes, with opening anterolaterally directed, with a small projection on the marginal rim. Oral disc ( Fig. 19C ) anteroventral, ventrolaterally emarginate; marginal papillae conical, biseriate and alternate, with a dorsal gap. Submarginal papillae present laterally. LTRF 3(Ae1,3)/5-6(1); Ae1, A1 and A2 of the same length; P2 slightly longer than P1; P3, P4, P5 and P6 slightly shorter than P2. Anterior jaw sheath moderately wide, posterior jaw sheath narrow, both finely serrated; anterior jaw sheath arch-shaped, posterior jaw sheath V-shaped. Spiracle single, sinistral, conical, short, and wide posterodorsally directed, opening in the medial third of the body, with the centripetal wall fused to the body wall and of the same length as the external wall. Vent tube medial, fused to the ventral fin, with a dextral opening. Caudal musculature of moderate width; in lateral view gradually tapering to a pointed tip. Dorsal and ventral fins high and convex; dorsal fin originating on the posterior third of the body. Tail tip rounded. Lateral line visible.

Colour. In preservative body and tail dark brown; venter nearly transparent with gut perfectly visible; tail musculature cream-colored; fins opaque grey, translucent to transparent. In life body and tail black; fins dull gray. Tadpoles at Stage 25 have transparent ventral skin and tail fins; ventral skin and tail fins translucent between Stages 26 and 29; fins opaque dark grey after Stage 29, gut visible through the ventral skin.

Variation. LTRF 1/3(1), 2(2)/3, or 2(2)/3(1) at Stage 25.

Metamorphs. Body dark grey to black; limbs dark brown ( Fig. 19D ).

Natural history. Eggs and tadpoles are found in streams, streamside ponds and lakes in terra-firme forest, forest edge and várzea floodplains. Clutches contain 2,500 ( Lima et al. 2012) or 2.979 eggs (this study) pigmented eggs. Tadpoles are found in all months of the year. Tadpoles form conspicuous size-structured, compact, nonpolarized schools containing up to 3,000 individuals; tadpoles move continuously from the periphery toward the middle of the school, presumably to lower individual predation risk; schooling behavior is observed throughout the entire premetamorphic development; schools with actively swimming tadpoles are observed both by day and night ( Caldwell 1989). Tadpoles graze on periphyton and bob air in the water surface (this study). Development appears to be comparatively slow (this study) and tadpoles reach 90+ mm in total length ( Caldwell 1989). Eggs are preyed upon by the turtle Platemys platycephala (Albertina Lima, pers. comm. in Hero, 1991). Tadpoles are preyed upon by the snake Helicops angulatus ( Martins & Oliveira 1998) and parasitized by the parasitic crustacean Argulus (this study). In experiment eggs were found to be avoided by fish but consumed by dytiscid beetles and oophagous tadpoles; B. geographica tadpoles are themselves moderately oophagous ( Magnusson & Hero 1991). Tadpoles are unpalatable to fish and the black coloration is presumably aposematic.

Comments. Tadpoles from Trinidad were described by Kenny (1969), from Ecuador by Duellman (1978), from Peru by Duellman (2005), from Bolivia by Schulze et al. (2015), and tadpoles from Central Amazonia were illustrated by Hero (1990). LTRF 2(2)/3 is the only morphological difference between tadpoles from Trinidad and those herein characterized. Tadpoles from Ecuador and from Bolivia differ from those herein characterized by presenting body ovoid. Those from Ecuador also differ from those herein characterized by presenting oral disc laterally emarginate, LTRF 2(2)/4, and dorsal fin not extending onto the body ( Duellman 1978). Tadpoles characterized by Hero (1990) and Duellman (2005) differ from those herein characterized by presenting LRTF 2-3[1] [3]/3-5 [1]. Moreover, those from Hero (1990) differ from those herein characterized by presenting a dorsal fin originating at the body-tail junction and those from Peru by presenting a dorsal fin originating on the tail (although Fig. 13.14C shows a tadpole with dorsal fin originating at the body-tail junction), oral disc laterally emarginate, submarginal papillae absent, LTRF 2(1)/4, and tail tip pointed ( Duellman 2005). Tadpoles from Bolivia ( Schulze et al. 2015) differ from those herein characterized by presenting snout oval in dorsal view, nostrils rounded, marginal papillae uniseriate anteriorly and irregularly biseriate laterally and posteriorly, lower jaw sheath U-shaped, LTRF 2(2)/4(1), spiracle centripetal wall free from body in its second half, ventral fin parallel to longitudinal axis of tail. These tadpoles were characterized as Osteocephalus taurinus by Duellman & Lescure (1973), and they differ from those characterized herein just by dorsal fin originating on the tail-body junction.

Figures

FIGURE 13. Tadpole of Ceratophrys cornuta (MNRJ s/n) at Stage 38: (A) lateral view, (B) dorsal view (scale = 10 mm), and (C) oral disc (scale = 1 mm).

FIGURE 19. Tadpole of Boana geographica (LCS 616) at Stage 37: (A) lateral view, (B) dorsal view (scale = 10 mm), and (C) oral disc (scale = 1 mm). (D) Dorsolateral view of newly metamorphosed froglet.