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Frogs of Borneo

Frogs of Borneo

Frogs of Borneo

Frogs of Borneo

Frogs of Borneo

Frogs of Borneo

Frogs of Borneo

Frogs of Borneo

Frogs of Borneo

Frogs of Borneo

Frogs of Borneo

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Ansonia leptopus

A small tadpole inhabiting lowland to mid-elevation streams. Tadpoles occur on or among leaf drift, plant material, or rocks, where they clasp onto the substrate or swim freely. They avoid fast-flowing water and aggregate in quiet sections of streams. Individuals may be encountered both during the day and at night. Locally and seasonally, tadpoles can be abundant.
  • Family:
    Bufonidae
  • Genus:
    Ansonia
  • Ecomorph:
    clasping, exotrophic, lotic
  • Waterbody Type:
    flowing
  • Water Column:
    rock surface
  • Feeding Type:
    feeding, hard surface grazer, omnivorous, rasping
  • Size:
    10 mm
  • Development:
    larva, tadpole
  • Adult:
    Ansonia
    leptopus

Coloration

Ground color pale cream with distinct black markings on the body and tail. Abdominal flanks black. A median dorsal stripe extends from the snout to the tail. A dark stripe originates at the snout and curves below the eye to the posterior portion of the head. The muscular portion of the tail bears a dorsal and lateral stripe. Ventral surfaces unpigmented, with internal organs visible.

Snout

In dorsal view, snout broadly rounded; oral disc may protrude slightly from beneath the snout laterally. In lateral profile, snout steeply sloping, nearly obtuse.

Oral Disc

Oral disc ventral in position and narrower than the maximum body width. Lower lip not flattened or sucker-like. Lower lip margin and lateral portions of the upper lip margin papillated; papillae absent from the medial third of the upper lip, which instead bears a soft bulge. Submarginal papillae present on both upper and lower lips. Two undivided labial keratodont rows on the upper lip and three on the lower lip (LTRF 2/3). Upper rows do not extend laterally around the lower rows. Upper beak divided; lower beak undivided.

Body

Body oval, wider than high. Spiracle attached to the body wall, positioned low on the flank.

Eyes & Nostrils

Eyes dorsolateral. Iris and sclera black. In dorsal view, nostrils positioned closer to the eyes than to the tip of the snout.

Tail

Tail comprising two thirds or less of the total length. Muscular portion moderately developed. Dorsal fin slopes gradually along the proximal third of the tail, then rises more abruptly at the beginning of the second third, terminating in a rounded tip.

Similar Species

The color pattern of Ansonia leptopus tadpoles is unique within the genus. Ansonia longidigita also exhibits sharply delimited black markings on a light background; however, the pattern differs distinctly from that of A. leptopus. In various publications, Inger referred to these tadpoles as “cruciform,” in reference to the crossing black bars. At present, these two species are the only known Ansonia with strongly contrasting black-and-white tadpoles. Notably, A. leptopus tadpoles are exceptionally small.

Literature

Males call from the ground, on sandy stream banks or rocks. Often groups of dozens of males congregate at a stretch of a slowly moving stream. The call is a soft highpitched trill.
Inger, R.F. (1985) Tadpoles of the forested regions of Borneo. Fieldiana Zoology new series 26: 1–89.

Inger, R.F. (1992) Variation of apomorphic characters in streamdwelling tadpoles of the bufonid genus Ansonia (Amphibia: Anura). Zoological Journal of the Linnean Society 105: 225–237.