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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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Leptobrachella mjobergi

The species occurs in lowland and hillside primary and secondary forests and appears to tolerate lightly disturbed forests. Tadpoles are always associated with streams, typically occupying shallow riffles in gravel beds. The diet of L. mjobergi tadpoles is not fully understood, but Inger (1985) suggested they feed on dead leaves, a hypothesis supported by gut contents and powerful jaw morphology. Several anatomical features have been linked to adaptation to interstitial habitats (Haas et al. 2006).
  • Family:
    Megophryidae
  • Genus:
    Leptobrachella
  • Ecomorph:
    exotrophic, fossorial, gravel-interstice specialist, lotic
  • Waterbody Type:
    flowing
  • Water Column:
    fossorial
  • Feeding Type:
    feeding, generalist, leaf litter
  • Size:
    42 mm
  • Development:
    larva, tadpole
  • Adult:
    Leptobrachella
    mjobergi

Coloration

Advanced larval stages are uniformly dark brown dorsally and unpigmented, semitranslucent ventrally (including the oral disc). Early stages are lighter, appearing pinkish gray. Skin has a hatched texture, reminiscent of fabric, and shows bluish iridescence in life. Iridophores are absent. Gut coils are visible through the ventral skin; heart and gills appear red, at least in early stages. Body coloration continues seamlessly onto the muscular part of the tail. Tail fins are dark pigmented at the base, lightening towards the edges. Myosepta faintly visible.

Snout

Broadly rounded, blunt, and moderately long in dorsal view. In lateral view, head conical with a blunt snout profile. Nostril positioned on a small lateral bulge.

Oral Disc

Positioned anteroventrally, approximately half the body width or more. Funnel-shaped and protruding from the body. Medial emarginations present in both upper and lower lips, with infolded oral funnel. Both lips bear short, numerous marginal papillae in a continuous row. Deep in the funnel, irregular rows of submarginal papillae occur on upper and lower lips. Keratodonts absent (LTRF 0/0). Beaks thick, strongly keratinized, black, with sharp serrations, deeply recessed in the oral funnel behind transverse ridges.

Body

Midsized, elongate, eel-like. In lateral view, head slightly depressed; trunk subcylindrical, almost circular in cross-section. In dorsal view, body slender, slightly wider than base of tail. Trunk-tail transition smooth; trunk long, head much shorter than trunk. Body widest at the trunk. Spiracle sinistral, opening posterodorsally. Spiracular orifice above the longitudinal body axis, free from the body wall (free tube). Lateral line organs visible as series of light dots on the head, along flanks, and along the tail.

Eyes & Nostrils

Eyes dorsolateral, nonprotruding in early stages; tiny in early stage tadpoles and increasing in size with development. Orbits unpigmented, white. Iris black in late larval stages, with thin silvery circle around the pupil. Nostril closer to snout than to eye, oriented anterolaterally, with dorsal triangular projection.

Tail

Long, 66–68% of total length. Muscular part strong, as high as body in lateral view. Upper fin starts well posterior to trunk-tail junction (approximately one third of tail), rises in a shallow arch, and slopes downward toward tip. Lower fin starts at trunk-tail junction, low and almost straight. Fins converge in distal tail into a triangular, narrowly rounded tip (tail tip often damaged). Upper fin slightly higher than lower fin. Maximum tail height approximately at mid-tail. Skin glands absent.

Similar Species

All Leptobrachella tadpoles occupy gravel interstices, usually in riffles. They are distinguished from other Bornean tadpoles by their slender, eel-like bodies and funnel-shaped, protruding oral discs. Ontogenetic and intraspecific variation is mostly unknown. DNA barcoding is recommended to match larvae with adults for reliable identification.

Literature

Males are found calling along stream banks. Males may call from the ground or rocks or perch slightly elevated, often 5–30 cm high on vegetation, usually facing the stream. The call is a series of very highpitched chirps. Males can form choruses. Despite the small size of the frogs, the calls are loud and assemblages of synchronously calling males can produce an impressive sound pressure level.
Inger, R.F. (1983) Larvae of Southeast Asian species of Leptobrachium and Leptobrachella (Anura: Pelobatidae), pp. 13–32. In Rhodin, A., and K. Miyata (eds.). Advances in Herpetology and Evolutionary Biology. Museum of Comparative Zoology, Cambridge, Mass.

Inger, R.F. (1985) Tadpoles of the forested regions of Borneo. Fieldiana Zoology new series 26: 1–89.

Haas, A., Hertwig, S., Das, I. (2006) Extreme tadpoles: The morphology of the fossorial megophryid larva, Leptobrachella mjobergi. Zoology 109: 26–42.