Ruby Poison Frog, Rana Venenosa
© 2009 Maik Dobiey (1 of 12)
A. parvula tadpoles are very similar to the geographically sympatric species A. bilinguis in size and coloration. The two can be distinguished by small differences in the length of the second lower tooth row (P-2). In A. parvula, the P-2 row is slightly longer than the P-1 row, whereas the converse is true for A. bilinguis tadpoles. Also, the two species can be distinguished by the relative width of their tail fins. The upper fin in A. parvula is slightly wider than the lower fin, while the upper fin in A. bilinguis tadpoles is slightly narrower than the lower fin. Both A. parvula and A. bilinguis tadpoles can be diagnosed from other sympatric species based on body color and oral disc characteristics, such as papillae dorsal gaps or jaw sheath shape (Poelman et al. 2010).
Description: A. parvula ranges from 17.5 mm to 24.0 mm in snout-vent-length. In males, the SVL ranges from 17.5 mm to 22.5 mm and in females 19 mm to 24 mm. Adult skin is strongly granular on the dorsum and on the dorsal surface of the hindlimbs (Silverstone 1976). Jungfer (1989) described the dorsal skin as densely covered in rounded or flattened, evenly distributed granules (Grant et al. 2006). The skin is smooth on the ventral surface of the hind limbs (Silverstone 1976). Maxillary and premaxillary teeth are present in this species. The first finger is longer than the second (Silverstone 1976), and the third finger of males is often swollen in frogs of this clade (Grant et al. 2006). Finger discs of adults in this clade are narrowly to moderately expanded. There is usually no toe webbing in adults of this clade, with at most basal webbing (Grant et al. 2006).
Coloration: Adult frogs have a ground color of black, with a spotted dark red dorsum. The underside of the body and limbs can be either black with blue marbling or a blue with black marbling. This marbling extends partially onto the side of the body. There is an incomplete light blue stripe extending from the forelimbs along the upper lip, ending next to the outside of the eye or nostril (Silverstone 1976). Distinct dorsolateral stripes are absent (Brown and Twomey 2009). Also usually absent are calf-spots. A yellow axillary spot is located on the upper arm and on the thigh. However this upper arm spot can also be blue and the thigh spot can be absent. Juveniles are blueish black on the dorsum, with less blue on the underside compared to the adults. Small juveniles may lack yellow arm and thigh spots (Silverstone 1976).
Live tadpoles have dark brown bodies, densely covered in darker brown to nearly black spots. The tail is pale brown at the body-tail junction, and fades to pale grayish tan at the tip. The tail musculature is covered in irregular small to medium-sized gray to dark brown specks. Dark brown spots may connect to create blotches, most often on the upper part of the tail musculature. The tail fin is transparent with many irregular dark grey flecks or spots. Tadpole hind legs are light tan, with irregular dark gray-brown flecks. The venter is transparent, and intestines are visible through the skin. The posterior end of the underside is slightly pigmented, with dark brown coloration on its anterior end (Poelman et al. 2010).
Coloration in Preservation: In preserved adults, the ground color is similar to live specimens or dark brown. The upper arm and thigh-spots, if present, are usually white in color. The lateral “stripe” usually disappears. The ventral marbling is not distinct and grey but, the marbling may disappear (Silverstone 1976).
Tadpoles in preservation generally have a light tan body and tail. The body color gradually darkens as it develops. The tail has grayish brown to dark gray flecks, but sometimes has pale brown flecks. The body has many uniform dark brown spots on its dorsal side. There is little adult coloration in preserved tadpoles, such as pale red to orange brown markings on the dorsal side. The ventral side can have a pale blue-black flecked pattern that becomes bright blue and black in adults. The ventral, posterior side of the body has a moderate amount of pigment. The ventral, anterior side is transparent with few pale and dark gray spots. Because of the transparency of its venter, guts can be seen on the ventral side. Developing legs are dark gray, darkest at the tibia (Poelman et al. 2010).
Tadpole Morphology: Tadpole total length ranges from 12.10 to 27.13 mm in stages 25-40. The body shape is depressed. The upper fin is deeper than the lower fin, and starts 0.11 mm posterior to where the body and tail meet. The tail is wide and deep at the body’s base, narrows slightly at the middle point (1.98 mm deep), then continues to decrease towards the slender, rounded tip. Eyes are located on the dorsal surface. The snout is narrow and rounded on the dorsal side, whereas on the ventral side, the snout is broad and rounded. Nostrils are tiny and not easily seen, located anterodorsally. On the ventral surface, the spiracle is sinistral and the vent is dextral (Poelman et al. 2010).
The tadpole mouth is located on the ventral side. Oral discs are present, and are normal and emarginate (Grant et al. 2006). Marginal papillae are small, and of equal size, with 6 papillae located laterally on each side of the mouth and 25 located ventrally. However, there is a good deal of variation in papillae number (ranging from 12 to 78). This variation may be due to observations of tadpoles at different stages of development. Papillae are consistently absent on the upper lip, around the dorsal gap of tooth row A-1. An A-2 gap is also present, roughly one-third the total length of the tooth row. The lower jaw sheath is V-shaped, and the upper jaw sheath is mostly straight, but can be slightly V-shaped. Jaw sheaths are finely serrated (Poelman et al. 2010).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Colombia, Ecuador, Peru
Life History, Abundance, Activity, and Special Behaviors
A. parvula has bright, aposematic coloration and produces toxic compounds. Its skin can produce lipophilic alkaloids, as can other species of the Dendrobatidae family (Darst et al. 2005).
Trends and Threats
Possible reasons for amphibian decline
General habitat alteration and loss
Etymology: The name parvula derives from the Latin word parvulus, meaning young or small.
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Written by Amelia Chong, Alexandra Holycross, and Leslie Hill (achong AT ucdavis.edu, arholycross AT ucdavis.edu, leshill AT ucdavis.edu), UC Davis
First submitted 2010-10-13
Edited by Mingna (Vicky) Zhuang (2012-02-14)
Species Account Citation: AmphibiaWeb 2012 Ameerega parvula: Ruby Poison Frog <http://amphibiaweb.org/species/1668> University of California, Berkeley, CA, USA. Accessed Oct 18, 2017.
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