Comprehensive DescriptionRead full entry
Diagnosis: Ranitomeya sirensis is a very small Peruvian dendrobatid, reaching about 15-17 mm SVL (three adult males 14.7-15.4 mm, 1 adult female 16.8 mm SVL). It can be distinguished from all other dendrobatids by its uniform red dorsum and turquoise-green limbs. The venter is turquoise-green with a rectangular red patch on the belly, and the chin is red. Skin texture is slightly granular on the dorsum, while the venter is moderately granular, and limbs are smooth. The first finger is much shorter than second; all fingers have conspicuously enlarged finger discs at least twice finger width. The tympanum is visibly concealed posterodorsally. Neither teeth nor an omosternum are present.
Description: Male SVL measures 14.7-15.4 mm, and the single female specimen measured 16.8 mm in SVL. The head is narrower than the body. The snout is subtruncate when viewed dorsally, and sloping in lateral view. The canthus rostralis is rounded, while the loreal region is flat. The tympanum is vertically elliptical, but is hidden posterodorsally. Hands are relatively large, with all fingers except the first possessing considerably expanded discs (at least 2x finger width). The third finger is the longest, followed by the fourth, second, and first. A circular metacarpal tubercle lies at the base of the palm, and a smaller inner metacarpal tubercle is present at the base of the first finger. On the first, second and fourth fingers, there is one subarticular tubercle; in contrast, there are two on the third finger. All subarticular tubercles are inconspicuous with the exception of the distal subarticular tubercle on the third finger, which is distinctly raised. Hindlimbs are moderate in length, with the heel of the adpressed limb reaching the tympanum. The fourth toe is the longest, followed by the fifth, third, second and first. All toes except the first have expanded discs. The medium-sized inner and small outer metatarsal tubercle have rounded surfaces and are protuberant. Hands and feet lack webbing, supernumerary tubercles, and lateral fringe. The dorsal skin is slightly granular, while the venter is moderately granular and the limbs are smooth (Aichinger 1991).
The head and dorsum are red and lack spots or stripes. The arms and legs are turquoise. However the coloration is lighter on the anterodorsal side of the proximal half of the upper arm and on the proximal part of the thigh extending to the body. The venter is turquoise-green with a five by three mm red patch on the belly. The area below the rectangular patch and on the ventral surface of the legs are turquoise. The surface of the palms and soles are black. Iris is black (Aichinger 1991).
Similar species: Other small poison-dart frogs having a bright red dorsal coloration may be confused with this species. Ranitomeya sirensis differs from Oophaga speciosa,Andinobates opisthomelas, and Minyobates steyermarki by having turquoise-green limbs, from Oophaga granulifera in having only slightly granular skin, and from Oophaga pumilio by having a rectangular red patch on the turquoise-green venter (Aichinger 1991).
The species is named after the type locality, Serranía de Sira (Aichinger 1991). In 2011, the genus Dendrobates was subdivided into seven genera, including the new genus Ranitomeya by Brown et al (2011).