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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 spinulifer

The tadpole inhabits clear, rocky lowland streams, occurring in moderate currents, riffles, and on coarse gravel and rocky substrates. It feeds on algal growth rasped from the substrate while remaining attached by the oral sucker. Tadpoles are active during the day but may be more active at night.
  • Family:
    Bufonidae
  • Genus:
    Ansonia
  • Ecomorph:
    exotrophic, lotic, rheophilous, suctorial
  • Waterbody Type:
    flowing
  • Water Column:
    rock surface
  • Feeding Type:
    feeding, hard surface grazer, omnivorous, rasping
  • Size:
    20 mm
  • Development:
    larva, tadpole
  • Adult:
    Ansonia
    spinulifer

Coloration

Dorsum dark brown to black, with the snout and areas below the eye dusted with golden pigment cells, visible only at high magnification. Additional scattered golden pigment (iridocytes) occurs on the lower flank and extends slightly onto the belly. The venter is unpigmented and translucent, with internal organs visible. Lateral pigmentation ends abruptly ventrally, forming a sharp boundary in ventral view, with concentrations of golden pigment posterolateral to the oral sucker and lateral to the gut coils. Dark body pigmentation extends onto the muscular portion of the tail. Tail fins bear scattered dark pigment cells along the margins; fin bases mostly unpigmented.

Snout

Body broadly expanded in dorsal view, forming a smooth arch; profile long, sloping, and streamlined.

Oral Disc

Ventral sucker as wide as maximum body width. Marginal papillae present on the lower lip; upper lip with a circumferential rim-like bulge. Two distinct rows of flat submarginal papillae on the lower lip. Keratodont rows undivided, two on the upper lip and three on the lower lip (LTRF 2/3). Upper keratodont rows do not laterally wrap around the lower rows. Upper beak divided and widely spaced; lower beak undivided and medially thin.

Body

Body droplet-shaped in dorsal view, widest just anterior to eye level, with a moderate constriction at the head-trunk transition. Body dorsoventrally depressed and streamlined. Spiracle sinistral, attached to the body wall, and very low in vertical position.

Eyes & Nostrils

Nostrils oval, small, and much closer to the eyes than to the snout. Eyes dorsolateral. Iris mostly black with scattered bronze pigment; iris margin with a bronze ring around the pupil.

Tail

Tail approximately two-thirds of total length, strong and muscular; muscular portion nearly equals body height in lateral view. Tail fins low; upper fin rises only in the second third of the tail (>40% of tail length). Upper and lower fin margins converge gradually posteriorly. Tail tip narrowly rounded and pointed.

Similar Species

Confusion is limited to other sucker-mouthed Ansonia species (oral sucker present, gastric sucker absent; cf. Meristogenys and Huia). Ansonia spinulifer tadpoles are small, markedly smaller than those of A. hanitschi. They differ from A. hanitschi, A. guibei, and A. platysoma in oral disc characters, and from A. leptopus and A. longidigita in coloration. Ansonia minuta appears most similar, but its tadpoles grow larger, have a more spear-shaped tail fin with a more posterior fin origin, and exhibit more extensive areas of golden iridocytes; these distinguishing characters are currently considered preliminary.

Literature

Males call from low vegetation or logs near streams, at or away from the stream bank. Males do not aggregate in calling groups but maintain single posts.
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.

Malkmus, R., Manthey, U., Vogel, G., Hoffmann, P., Kosuch, J. (2002) Amphibians & Reptiles of Mount Kinabalu (North Borneo). Koeltz Scientific Books, Königstein. 424 pp.