Species Description: Brown JL, Twomey E 2009 Complicated histories: three new species of poison frogs of the genus Ameerega (Anura: Dendrobatidae) from north-central Peru. Zootaxa 2049:1-38.
Ameerega yoshina is a large frog species with a snout vent length ranging 26 - 35 millimeters. It has a snout that is bluntly rounded in the dorsal view and sloping in the lateral view, with nares directed posterolaterally to the tip of the snout. The nares are visible from the front and below but not from above. The canthus rostralis is sloped and slightly rounded and the loreal region is nearly vertical and slightly concave. Ameerega yoshina has a medium sized, oval shaped tongue, and premaxillary and maxillary teeth, but lack vocal slits. The species also has large, protuberant, and prominent eyes with rounded and horizontally elliptical pupils and a maximum diameter measuring approximately 9.3% of the snout vent length. Its upper eyelid is approximately 1.5 times wider than the interorbital distance, which is around 4.9 millimeters, and it has circular tympanum with a supratympanic fold. Finally, its head is narrower than the body and the widest part of the head, which is found between the jaw articulations and tympanum, is approximately 29.3% of the snout vent length.The dorsal skin, forelimbs, and legs are all granular while the ventral skin is smooth (Brown and Twomey 2009).
Ameerga yoshina has relatively small hands with them being only 23.7% the length of the snout vent length. The relative length of the appressed fingers are II ≈ IV < I < III with discs moderately expanded on all of the fingers and the disc on finger III being twice as wide as the distal end of the adjacent phalanx. There is a large, circular, outer metacarpal tubercle on the median base of the palm and one well developed subarticular tubercle on fingers I and II, with two of these tubercles on III and IV. Meanwhile, the smaller inner metacarpal tubercle is absent from the base of finger I (Brown and Twomey 2009).
Ameerga yoshina has short hind limbs with the heel of the appressed limb reaching the axillary region and the tibia measuring 50.7% of the snout vent length. The relative lengths of the appressed toes are I < II < V < III < IV with the discs on toes I, II, III, IV barely expanded and the expanded disc on toe V being 1.2 times wider than the adjacent phalanx. The first toe also extends past the subarticular tubercle located on the base of the second toe. Ameerega yoshina possesses moderately sized inner and outer metatarsal tubercles that are protuberant with rounded surfaces. There is one protuberant subarticular tubercle on toes I and II and two protuberant subarticular tubercles on toes III, IV, and V. Both the hands and feet of A. yoshina lack supernumerary tubercles, lateral fringes, tarsal tubercles, and webbing (Brown and Twomey 2009).
Ameerega yoshina is most notably distinguished from other species of Ameerega by its red dorsum. From this, A. yoshina can be further distinguished from species such as A. bassleri, A. bilinguis, A. cainarachi, A. macero, A. pepperi, and A. parvula, which all have or can have a red dorsum, through advertisement calls and slight physical details. Ameerega parvula and A. bilinguis both lack distinct dorsolateral stripes, which is very much present and conspicuous in A. yoshina. Ameerega cainarachi is slightly smaller in stature, with females ranging up to 31.3 millimeters in snout vent length compared to the 35 millimeter snout vent length that A. yoshina can grow up to. Ameerega cainarachi also has an advertisement call consisting of a regular chain of notes that are not frequency–modulated and are repeated at a rate of 9 notes per second compared to the advertisement call of A. yoshina, which consists of ‘bursts’ of frequency-modulated notes and have 3.7 – 4.1 note repeats per second. Ameerega macero is smaller than A. yoshina (the females grow up to 29.5 millimeters in snout vent length) and has a call consisting of a series of harsh ‘peeps’, repeated regularly at a rate of 10 notes per second. Ameerega bassleri and A. pepperi both have an advertisement call consisting of a series of regularly-spaced whistle-like notes given at a rate of 1.6 – 2.1 notes per second and 0.9 – 1.3 notes per second respectively for several minutes. Ameerega yoshina on the other hand has an advertisement call consisting of bursts of 4 - 31 notes at a rate of 3.7 - 4.1 notes and only lasting less than 8 seconds (Brown and Twomey 2009).
Ameerega yoshina is a pigmented black on the dorsum with a brick red to orange mottling near the snout. It has thin light-yellow dorsolateral stripes, which extend from the eyelids to the groin and blends into the red dorsum in the area posterior to the eyes. These dorsolateral stripes are slightly wider at groin.The flanks of A. yoshina are solid black along the entire length of the body and head and there is a yellow labial stripe, which extends from the nares down to the axillae and the metallic-brown forelimb. The legs are a dark brown color with faint olive green stippling and each have a large yellow spot on the anterodorsal surface of the thigh. The hands, feet, and digits are all the same color as their respective limbs. The ventral skin is a uniform olive-gold, greenish-gold to pale yellow-green, or bluish color on the belly. The limbs and a slightly darker olive-gold to black color on the head and chest. Ameerega yoshina has black irises and does not possess distinct black markings on the venter (Brown and Twomey 2009).
In preservative, the coloration of Ameerega yoshina stays mostly the same with a couple of exceptions. The red dorsum is instead black, the yellow dorsolateral stripes are silver-white, and the gold coloration on venter are a black and grey-green (Brown and Twomey 2009).
In the two known populations of Ameerega yoshina, individuals from near Contamana vary in dorsal coloration from brick-red to orange and vary in venter coloration from greenish-gold to pale yellow-green. Individuals from Callanayacu on the other hand, tend to be more orange as opposed to red on the dorsum, and have blue venters that have diffuse and irregular black markings. Both populations’ limbs vary in color from black to pale olive (Brown and Twomey 2009).
Distribution and Habitat
Ameerega yoshina can be found in two localities, one in the Serranía de Contamana and the other in the Huallaga Canyon in the northern Cordillera Azul, both of which are 130 km apart and separated by the Ucayali floodplain. Ameerega yoshina is expected to be restricted to the undisturbed premontane forests of the Serranía de Contamana and northeastern Cordillera Azul and occurs at elevations from 280 – 600 meters. Because of the separation between these two localities, it is unlikely that there is any gene flow across the Ucayali floodplain. Ameerega yoshina are mostly typically found in undisturbed premontane forests, more particularly particularly in areas that are near streams. Of the few recorded individuals, adults were mostly found under logs or under piles of leaf litter and two were found moving above the leaf litter after a period of heavy rainfall (Brown and Twomey 2009).
Life History, Abundance, Activity, and Special Behaviors
Within its range, A. yoshina was only found in very specific habitats along streams, indicating they have highly specific habitat requirements. Additionally, the species is extremely cryptic and difficult to locate even when males are calling. Adults were found under piles of leaf litter and under logs, but can also be found moving around in the leaf litter after heavy rain (Brown and Twomey 2009).
Males call from the leaf litter and are well-hidden. The “retarded trill” advertisement call for A. yoshina consists of a series of short bursts of 4 - 31 notes at a rate of 3.7 - 4.1 notes a second. These notes are 90 - 156 ms long, are spaced 110 - 150 ms apart, are frequency modulated by about 325 Hz and resemble “short whistles” (Brown and Twomey 2009).
Reproduction tends to take place near small streams and forest pools. However, this finding is based on the collection of one metamorph located at the edge of a stream in Contamana. Additionally, numerous males have been observed calling around shallow forest pools where A. yoshina tadpoles were identified (Brown and Twomey 2009).
Trends and Threats
Based off the IUCN Red List criteria, researchers have suggested A. yoshina be listed as “Near Threatened” because the estimated occurrence is less than 4500 kilometers and the two known populations of the species are fragmented. There has also been a small amount of potential habitat loss in the Cordillera Azul near Rio Huallaga where one of the populations resides (Brown and Twomey 2009).
Possible reasons for amphibian decline
General habitat alteration and loss
Based on Bayesian Inference using data from 1682 base pairs of mitochondrial DNA (12s, 16s, and cytochrome b), A. yoshina is paraphyletic, with the Callanayacu populations being more closely related to A. bassleri populations from Rouque, Chumia, Sauce, Cainarachi Valley, Lowere Haullaga Canyon, Chazuta, Saposa, Alto Shima, Sisa, and Tara-moyo. The clade form by the populations above and the population of A. yoshina from Contamana is sister to a clade formed by A. pepperi and A. bassleri from Alto Shima and Saposoa. Basal to all of these clades is A. ignipedis, which can be found at the same site in Contamana as A. yoshina (Brown and Twomey 2009).
The species name is derived from the Panoan word ‘Yoshin,’ which means ‘devil’ or ‘evil spirit’. This references the cryptic nature of the species and its haunting and penetrating call (Brown and Twomey 2009).
Brown, J. L., and Twomey, E. (2009). ''Complicated histories: three new species of poison frogs of the genus Ameerega (Anura: Dendrobatidae) from north-central.'' Zootaxa, 2049, 1-38.
Written by Elizabeth Brizuela and Michael Chou (mchou359 AT berkeley.edu), University of Florida and UC Berkeley
First submitted 2018-02-28
Edited by Ann T. Chang (2018-02-28)
Species Account Citation: AmphibiaWeb 2018 Ameerega yoshina <http://amphibiaweb.org/species/7277> University of California, Berkeley, CA, USA. Accessed Mar 21, 2018.
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Citation: AmphibiaWeb. 2018. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Mar 2018.
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