Ranitomeya sirensis

Aichinger, 1991

Ranitomeya sirensis nominal

Originally described from the Cordillera El Sira in central Peru. Aichinger wrote that the type series was taken at elevations between 750 and 1560 m. The Cordillera El Sira is a large and extremely isolated mountain range, rising to elevations of over 2400 m. Most populations of this species are known from lowland habitats, although it has been recorded as high as ~1500 m elevation near Tingo Maria. Following the redefinition of this species (see Brown & Twomey et al. 2011), it is distributed from southern to central Peru throughout Madre de Dios and the Ucayali drainages. Also occurs in adjacent Brazil and Bolivia.

Natural History
For decades this was one of the most poorly known species of poison frogs. Aichinger suggested that this species was highly arboreal because of its remarkable agility and its long hands with well-developed finger discs. He also speculated that this species employed similar reproductive strategies as other species of Ranitomeya, as females were found to lay clutches of one or two eggs. Our observations are consistent with this idea, as we witnessed a putative courting pair in a phytotelm. This species is most common in areas where phytotelmata are abundant, especially bamboo and Xanthosoma.

Conservation Status
Following the results from Brown & Twomey et al. (2011), the definition of R. sirensis has been greatly expanded and now this species appears to have an extensive distribution from central Peru to Bolivia. It occurs widely throughout the Ucayali, Huallaga, and Madre de Dios drainages of Peru. Following this redefinition of the species, we recommend it being listed as Least Concern (LC)

Brown & Twomey et al. (2011) provided bioacoustic, genetic, and behavioral evidence that R. lamasi, R. sirensis, and R. biolat were all members of a single, widespread and highly polymorphic species. Due to rules of precedence, R. sirensis is the valid name, and lamasi and biolat are now considered junior synonyms of sirensis.

Type Locality Map View Larger

Ranitomeya sirensis nominal
Nominal Morph

The nominal morph of Ranitomeya sirensis was long considered to be the ‘holy grail’ of poison frogs. This frog appeared to be exceedingly rare, occupied a mysterious and isolated massif, and was enigmatic to the point that no one has the faintest idea of its evolutionary relationships. The Cordillera El Sira was bustling with scientific activity in the late 60s and early 70s, with biologists such as John Terborgh and Catherine Toft participating in regular expeditions into these mountains. In fact, Duellman and Toft (1979) published a large paper enititled “Anurans from Serrania de Sira, Amazonian Peru: Taxonomy and biogeography” based on the amphibian collections made during this period. Surprisingly, this paper made no mention of Ranitomeya (= Dendrobates) sirensis.

It wasn’t until 1976 that this species was first collected, found in elfin forest at 1560 m elevation by Dr. Werner Hanagarth. Ten years later, Manfred Aichigner, working on the amphibians of central Peru, conducted an extensive survey of the Sira. Aichinger and his team spent an entire year in the Sira, yet were only able to find five individuals, two of which escaped after capture. Since that time, several field parties entered the Sira in an attempt to find R. sirensis, but were long unsuccessful.

An expedition in 2005 led by Mark Pepper set out to retrace Aichinger’s footsteps. The team reached the infamous Pato Rojo, an abandoned helicopter landing pad made by a Canadian gold mining company and later used by Aichinger. Upon reaching Pato Rojo, Pepper’s team found nothing but thriving bee hive, and were forced to camp a few hundred meters below on the edge of a precipitous gorge on the western face of the Sira. After 4 days camping and hiking throughout the cloud forest of the Sira, the team left with nothing more than bruised egos and no frogs. In 2007, Pepper decided to return, leading a second expedition into the Sira along with Manuel Sanchez, Jason Brown, and Evan Twomey. After suffering several fall-related injuries and barely escaping a flash-flood, the team was lucky enough to find two adult R. sirensis hunkered down in a plant axil.

'Tingo Maria' Morph

These frogs have been referred to as ‘standard lamasi’ in the hobby. However, this was never the nominal form of lamasi, which came from southern Panguana. These are now included in the definition of R. sirensis. The highland frogs have broad yellow stripes, blue legs, and can be found breeding in bamboo stands. This morph is disturbingly rare and does not seem to be nearly as common as reported in the 1980s and 90s. Smugglers have been hitting this populations hard for several years and appear to have made a significant negative impact on wild populations. Other morphs, such as the lowland ‘Panguana’ morphs, have been similarly targeted by smugglers. During an expedition to the Cordillera El Sira, we were stunned to learn from locals that not 1 month prior to our arrival, the area had been visited by a group of Europeans buying hundreds of frogs from the locals at about 5 soles ($1.50) per frog. Those that did not die on their way to Europe have been recently cropping up at frog shows, diminishing greatly the potential for forest conservation projects in these areas.

Panguana Morph

This is an extremely variable population found along Rio Pachitea. In single localities, one can find frogs that are yellow, green, orange, or red. These frogs are extremely common in disturbed habitats, especially along small roads. These roads provide perfect habitat for Xanthosoma plants, their preferred breeding habitat.

Western Panguana Morph

This morph was found in 2007 on a trip to the east-Andean versant in the Panguana region. These frogs appear to be similar to the normal Panguana morph, except that they tend to be brighter green, have whiter legs, and have a bright-yellow ventral patch.

Lower Ucayali Morph

This morph is found far to the north of Pucallpa, and is characterized by a darker green dorsum and large, white spots above the groin and armpits. It is common in secondary growth, and can be found breeding in Xanthosoma and Heliconia.

"Biolat" Morph

This morph was previously referred to as Ranitomeya biolat. This frog is found mainly in the lowlands of southern Peru. Originally described (as R. biolat) from the Pakitza guard post within Manu National Park, this morph is now known in the Andean slopes of the park up to approximately 850 m. This morph is closely associated with bamboo groves, which provide their breeding sites.