Barbour’s Thin-toed Frog, Leptodactylus insularum

Identification: Dorsal skin smooth; a pair of dorsolateral folds extend from the upper eyelid back to the groin (rarely, a second pair of folds is present); overall brown with a dark triangular blotch between the eyes, pointing backwards; surfaces of limbs barred. Ventral skin smooth with a discoidal fold on belly; white-cream. Snout truncated in profile and blunt from above. Distinct tympanum about three-quarters of eye diameter. Breeding males have enlarged forearms. Fingers free, toes slightly webbed and fringed; no adhesive discs.

Vocalization: A loud repeated ‘bloop, bloop’. After very wet days, choruses may continue through the night until dawn. Similar species: The large size of adults distinguishes this frog from all other leptodactylids in Trinidad. The single dorsolateral fold on each side, extending back from the upper margin of the eyes also separates this species from other leptodactylids. Distribution and habitat: Barbour’s Thin-toed Frog ranges from Costa Rica south into Colombia and east into Venezuela, with the Trinidad population the most easterly known. In Trinidad it has been recorded only from the southwest and central portions of the island; it has not been recorded from Tobago. This is a lowland species, from forest and swamp margins.

Biology: Diet not recorded. Mating pairs generate large foam nests, up to 30 cm across, at the edges of water and usually hidden under vegetation. Pools seasonal, but not the small shallow pools used by some species, since insularum tadpoles grow to a large size and need several weeks. Nests contain several thousand black/grey eggs, hatching after 1-2 days. Tadpoles form tight shoals. There is evidence, though not from Trinidad, that females guard their nests and tadpole shoals. Tadpoles form tight shoals, moving together through and up/down in the water column. Tadpoles reach about 50 mm in total length after several weeks. Body wider then deep and overall grey-brown, including the tail and tail fins. Tail tapered. Newly metamorphosed individuals are about 19 mm SVL and look like miniature adults.

Conservation status: Not assessed by IUCN whose species list does not yet recognize L. insularum. Leptodactylus bolivianus is listed as Least Concern on account of its wide distribution, tolerance of a wide range of habitats and presumed large population. Since the range of L. insularum is large, this status is unlikely to change.

Heyer WR, de Sa RO 2011 Variation, systematics, and relationships of the Leptodactylus bolivianus complex (Amphibia: Anura: Leptodactylidae). Smithsonian Contrib Zoology 635:1-58.