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 jerboa
Tadpoles of Meristogenys jerboa inhabit clear hillside streams of western Sarawak. Their abdominal sucker allows them to adhere to rocks in flowing water. These tadpoles are grazers feeding on organic overgrowth on rock surfaces, including algae, small animals, and bacteria. Although they often feed at night directly in the current on overflown rocks, M. jerboa appears to prefer moderate flow velocities rather than very strong or turbulent sections. Tadpoles sometimes form feeding aggregations of up to 30 individuals on the same rock face. Rock surfaces may also be shared with Ansonia minuta tadpoles, which feed alongside M. jerboa in western Sarawak.
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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:40 mm
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Development:larva, tadpole
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Adult:Meristogenys
Coloration
General coloration of the dorsal and lateral surfaces of body and tail is light brown to ocher, with dense dark dotting or marbling. Dotting becomes more blotchy and higher in contrast on the tail. Additional clusters of iridocytes on body and tail contribute to the overall pattern. Abdomen covered by a sheath of white-silvery iridocytes concealing the gut. Oral disc and abdominal sucker unpigmented; gills and heart not visible. Tail fins may bear larger dark dots. In advanced larval stages, melanocytes along blood vessels accentuate the myosepta and may form a 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 distinct bulge above the oral disc.
Oral Disc
Oral disc ventral and wide, followed posteriorly by a large abdominal sucker. Abdominal sucker thick-rimmed. In ventral view, the distance from snout to posterior rim of the abdominal sucker corresponds to approximately 70–75% of body length. Faintly brown friction areas present inside the rim. Marginal papillation of the oral disc present along the lower lip and lateral parts of the upper lip. Marginal papillae short, rounded, and indistinct. A dense, irregular row of submarginal papillae present on the lateral upper lip. LTRF 6(4–6)/6(1) to 6(4–6)/7(1). Beaks strongly keratinized, deep black. Upper and lower beaks widely divided, both bearing several coarse serrae.
Body
Depressed and streamlined in lateral view, with a long, sloping snout profile anteriorly. In dorsal view, body contour oval to rectangular, snout set off by a notch. Trunk bulges posteriorly on both sides of the tail base. Body widest at the gill region. In lateral view, trunk depth equals head depth; ventral surface flat, belly not bulging. Spiracle sinistral, spiracular tube opening posteriorly and located 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); posterior ventral abdominal glands absent. Skin glands may be difficult to discern. Lateral line organs indistinct. In advanced larvae, dorsal head and trunk bear dense, pointed skin protuberances.
Eyes & Nostrils
Eyes dorsolateral. Nostrils oval, 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. Sclera stippled with silvery iridocytes.
Tail
Tail long, comprising 63–66% of total length. Muscular part strong and high, almost as high as the body in lateral view. Dorsal fin originates well posterior to the trunk-tail junction, at 10–20% of tail length, arches gradually to the highest point, then slopes down in a straight line to a pointed tip. Lower fin originates at approximately one third of tail length and is much lower than the upper fin. Maximum tail height located slightly anterior to mid-tail. Skin glands present on the lower fin only.
Similar Species
Tadpoles of Meristogenys jerboa can occur in sympatry with M. penrissenensis. They are distinguished from M. penrissenensis by possessing six upper lip keratodont rows (three divided), whereas M. penrissenensis has seven upper rows (four divided). Tadpoles of Ansonia species may occur in the same habitats but are easily distinguished by the absence of an abdominal sucker.
Literature
Males perch on low vegetation, roots or rocks along the steep river bank, or on boulders. The male call is an unpulsed, sharp, highpitched whistle, with several minutes of pause between calls.
Shimada, T., Matsui, M., Nishikawa, K., Eto, K. (2015). A new species of Meristogenys (Anura: Ranidae) from Sarawak, Borneo. Zoological Science, 32: 474–484.