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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Meristogenys dyscritus
Tadpoles of Meristogenys dyscritus have been reported from Gunung Kinabalu Park and Crocker Range Park, where they inhabit clear, cascading streams. Their abdominal sucker allows them to adhere firmly to rocks in strong currents. Like all other Meristogenys tadpoles, these larvae are grazers feeding on organic overgrowth on rock surfaces, including algae, small animals, and bacteria. Habitat and microhabitat are often shared with tadpoles of Ansonia species.
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Family:Ranidae
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Genus:Meristogenys
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Ecomorph:exotrophic, gastromyzophorous, lotic, rheophilous, suctorial
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Waterbody Type:flowing
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Water Column:rock surface
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Feeding Type:feeding, hard surface grazer, omnivorous, rasping
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Size:48 mm
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Development:larva, tadpole
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Adult:Meristogenys
Coloration
Body and tail generally grayish to brown, with the trunk darker dorsally and laterally than the head. Diffuse dark areas present at the nostrils and between the eyes. Abdomen covered by a sheath of white-silvery iridocytes concealing the gut. Oral disc and abdominal sucker unpigmented; gills and heart not visible. Pigmentation of the trunk extends seamlessly onto the muscular part of the tail, though lighter in appearance. Tail fins stippled with melanocytes, except for a light zone at the bases of the dorsal and ventral fins. In advanced stages, melanocytes along blood vessels accentuate the myosepta and may form a somewhat reticulate pattern on the tail fins.
Snout
Expanded and broadly rounded in dorsal view. In lateral view, snout long, sloping in a smooth convex curve, with a slight bulge above the oral disc.
Oral Disc
Oral disc ventral in position and wide, followed posteriorly by a large abdominal sucker. Abdominal sucker thick-rimmed and covering parts of the trunk ventrally. A faintly brown, U-shaped friction area discernible inside the rim. Posterior rim of the abdominal sucker located at approximately 80% of body length in ventral view. Marginal papillation of the oral disc present on the lower lip and lateral parts of the upper lip. Marginal papillae short, rounded, and indistinct. Several submarginal papillae present on the lateral parts of the upper lip. LTRF 6(4–6)/6(1) to 6(4–6)/8(1). Beaks strongly keratinized, deep black. Upper beak widely divided; lower beak divided. Beaks bear coarse serrae.
Body
Depressed and streamlined in lateral view, anteriorly with a long, sloping snout profile. In dorsal view, body contour elongate oval to rectangular, snout slightly set off. Trunk bulges posteriorly on both sides of the tail base. Body widest at the level of the gill region. In lateral view, trunk depth equals head depth; ventral surface flat, belly not bulging. Spiracle sinistral; spiracular tube opening posteriorly and well below the longitudinal body axis in lateral view. Spiracular orifice at the end of a free, relatively long spiracular tube. Small groups of skin glands present at the cheek, anterior to the spiracle, behind the eyes, and at the posterior bulges of the trunk (see also tail). Lateral line organs indistinct. Dense, pointed skin protuberances present on the snout in at least advanced larval stages.
Eyes & Nostrils
Eyes dorsolateral. Nostrils closer to eyes than to snout and oriented anterolaterally. Iris black, with a thin ring of golden iridocytes around the pupil; peripheral iris dusted with golden iridocytes. Scleral iridocyte stippling silvery.
Tail
Muscular part of the tail strong and high, slightly lower than body height. Dorsal fin originates posterior to the trunk-tail junction at approximately 10% of tail length, rises gradually in a straight line to its maximum height, then changes abruptly to a downward slope, forming a pointed tip. Lower fin originates at approximately one third of tail length and is lower than the upper fin. Maximum tail height located approximately at mid-tail. Skin glands present on the lower fin only.
Similar Species
Huia and Meristogenys are the only Bornean taxa with gastromyzophorous tadpoles. Tadpoles of Meristogenys dyscritus differ from those of M. amoropalamus by possessing six upper lip keratodont rows (seven in M. amoropalamus). Skin glands on the upper tail fin are absent in M. dyscritus, and the dorsal tail fin originates more posteriorly than in M. amoropalamus. Keratodont formula, skin glands, jaws, and skin protuberances must be examined carefully when identifying Meristogenys tadpoles. Tadpoles of Huia cavitympanum are easily distinguished by their undivided jaws and spotted color pattern. Tadpoles of Ansonia species lack an abdominal sucker.
Reproduction
Males perch on low vegetation along the river bank. The male call is an unpulsed, sharp, whistle, with several minutes of pause between calls. The dominating frequencies are high, between 6.000–10.000 Hz. 700–1.500 eggs have been counted in gravid females.
Literature
Males perch on low vegetation along the river bank. The male call is an unpulsed, sharp, whistle, with several minutes of pause between calls. The dominating frequencies are high, between 6.000–10.000 Hz. 700–1.500 eggs have been counted in gravid females.