Description
Bolitoglossa aurae is a gold-colored species of plethodontid salamander known from a single adult female specimen found in Costa Rica. This holotype has a snout-vent length of 40.5 mm and a total length of 96.1 mm. The head is wider than the neck and shoulders and widest just posterior to where the jaws articulate. The snout is long, protruding, and anterodorsally raised. In the dorsal view, the snout is truncate, in the profile the snout is rounded, and in the ventral view the snout prominently protrudes over the lower lip. On the tip of the snout are rounded cirri that are poorly developed but still discernible. The tiny, protruding, laterally directed nostrils are located very close to the end of the snout. The internarial region is somewhat convex. The canthus rostralis is rounded and distinct. The intercanthal region is somewhat convex and the loreal region is somewhat concave. The anterolaterally directed eyes are relatively large, have a distinct suborbital groove, and protrudes past the outline of the head in both the dorsal and ventral views. The top of the head is smooth and flat, without any interorbital dermal structure. The gular fold is well defined and begins at the lateral region of the neck and curves somewhat posteriorly before straightening and then curving somewhat anteriorly at the mid-ventrum. In life, the skin around the gular fold is transparent enough to see the heart just posterior to the fold. No mental gland is visible. A nuchal groove is evident at the level of the lower edge of the eye just posterior to the jaw articulation and running slightly posterior from the side of the head down onto the ventrum along the mandibular bones before curving anteriorly (Kubicki and Arias 2016).

Bolitoglossa aurae has short arms, relatively hypertrophied forearms, and moderate-sized hands. Overall, the palm is smooth with an obvious dermal crease converging from the margins of each of the interdigit webbings to the center of the hand. Finger I is completely covered by webbing. Fingers II, III, and IV are robust with square-shaped, truncate tips and ventral terminal pads. The relative finger lengths are I < II < IV < III. From the dorsal view, the margins of the fingers are well defined by interdigit grooves on the webbing. The moderate to extensive webbing has a webbing formula of I 0- – 1 1/2 II 1 1/2 – 2- III 2- – 1+ IV and concave margins (Kubicki and Arias 2016).

The hindlimbs are short and have an equal diameter throughout their length. The foot is moderate-sized, has moderately to extensively webbed, and is smooth on the ventral surface with dermal creases like the hands. Like the hands, the webbing of the feet has concave margins. From the dorsal view, the toes are well-defined by interdigit grooves in the webbing. Also, similarly to the hands, toe I does not protrude beyond the webbing. Toes II – V are robust with square-like, truncate tips, and have well-defined, ventral, terminal pads. A weak terminal pad is also present on toe I. The relative toe lengths are I < II < V < IV < III with toe III only being slightly longer than the others. The webbing formula for the toes is I 0- – 1 1/2 II 1 – 2- III 2 – 1 1/2 IV 1 1/ 2 – 1+ V (Kubicki and Arias 2016).

Bolitoglossa aurae has a subcylindrical, slender, smooth body that is wider than high, and 13 weak costal grooves with 4.5 costal grooves between adpressed limbs. The costal grooves are more distinct on the ventrum and lateral regions. There is a discrete mid-dorsal depression down the length of the body beginning at the base of the head and ending around the anterior third of the tail. The tail is long, is cylindrical, is prehensile, has a slight constriction at the base just posterior to the cloaca, and ends in a point. The tail has 27 caudal grooves along the anterior 3/4th of the tail. There are no groves on the posterior fourth of the tail (Kubicki and Arias 2016).

Bolitoglossa aurae forms a clade with B. aureogularis, B. jugivagans, and B. robinsoni, which are all endemic to northwestern Panama and southeastern Costa Rica. The species can be differentiated based on genetics and morphology, especially with regards to coloration and limb length. More specifically, B. aureogularis is dorsally tan or reddish-brown and has dark brown streaks; ventrally, this species has a medial dark stripe. Additionally, B. aureogularis has 6.5 costal grooves between adpressed limbs, more premaxillary teeth, and longer digits. Bolitoglossa jugivagans has darker pigmentation in a greater concentration than B. aurae on its dorsal side and appendages, is overall reddish-brown in color, and has rounded digit tips. Bolitoglossa robinsoni has relatively darker pigmentation on the dorsal portions of its body and appendages, is larger, has fewer maxillary and vomerine teeth, and two costal grooves between adpressed limbs (Kubicki and Arias 2016).

The holotype of B. aurae was kept in captivity for six months and expressed minor tonal shifts in the intensity of the yellow ground color that may be attributed to the substrate she was kept in. At the time of capture, B. aurae had a unique and evident greenish-yellow tone across the entire dorsal surface, which was lost in captivity. More specifically, light iridescent green chromatophores were scattered across the head, body, and tail with a particularly strong concentration on the eyelids. There was a reddish-sepia, Y-shaped middorsal stripe starting at the posterior margins of the eyes, merging above the gular region, and extending posteriorly to beyond the hindlimbs before veering off the midline. Additionally, there were two thin brown lateral stripes extending from the lower-posterior edge of the eyes, along the lateral surface of the holotype and onto the tail. The ventrum of the head and body were a uniform, translucent cream to light orange. The red coloration of the capillaries and the heart showed through the ventrum. There were concentrations of iridophorses scattered under the skin along the mid-ventrum. On both the dorsum and ventrum, minute dark melanophores, in the form of fine dots or reticulations, were visible under magnification. The hands and feet were yellow with orange-brown speckling on the edges of the dorsal surfaces. The tips of the digits varied from yellow to orange. The ground color of the iris was golden with dark reddish-brown and yellow-green spots (Kubicki and Arias 2016). After six months in captivity, B. aurae had a gold-yellow coloration on the dorsum, and the ventrum was a lighter cream to light orange-yellow. The greatest change in coloration was along the margins of the head, on the body, on the tails, and on the limbs where the lateral stripe widened and shifted the flanks and dorsal surfaces of the limbs from light yellow to pale brown, orange-brown, or amber. The yellow-green spots in the irises also changed color over time (Kubicki and Arias 2016).

After three years of storage in 70% ethanol, this specimen lost its bright yellow coloration, becoming more yellowish-beige or beige-pink colored throughout. The dark features of the specimen, including its middorsal stripe and lateral stripes became slightly more rufous. The melanophores turned greyish-brown. The external layer of skin over the eye became a light blue hue with the pigmentation in the dermal tissue rather than a reflective coloration from the eye (Kubicki and Arias 2016).

At the time of the species’ description variation could not be determined because the species is only known from a single specimen.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Costa Rica

View distribution map in BerkeleyMapper.

Bolitoglossa aurae is known from the single specimen found in the Tropical Premontane Rain Forest life zone in in the vicinity of Moravia de Chirripó, Distrito de Chirripó, Provincia de Limón Costa Rica. It was found in cloud forests at an elevation of 1300 m on the northeastern slopes of Cordillera de Talamanca, in moss around an orchid root mass that was growing on a rotting tree (Kubicki and Arias 2016).

Life History, Abundance, Activity, and Special Behaviors
Though B. aurae was only described from one specimen, the holotype was kept alive in a small terrarium for six months before preservation for natural history observations (Kubicki and Arias 2016).

The holotype was found during the day, curled in the root mass of an orchid that was three meters off the ground. It is assumed that the species is naturally found in thick, arboreal moss and other arboreal epiphytes in cloud forests (Kubicki and Arias 2016).

This species is nocturnal; the holotype could be found walking or climbing at night during captivity. During the day she burrowed deeply in provided moss (Kubicki and Arias 2016).

The holotype did well in captivity, had a good appetite of wild Drosphila, and maintained a robust body (Kubicki and Arias 2016).

Comments
The species authority is: Kubicki B, Arias E. (2016). “A beautiful new yellow salamander, genus Bolitoglossa (Caudata: Plethodontidae), from the northeastern slopes of the Cordillera de Talamanca, Costa Rica.” Zootaxa 4184(2):329-346.

Based on Bayesian Inference and Maximum Likelihood analysis of 16S and cyt b mitochondrial genes, B. aurae was found to be part of the B. robinsoni species group, consisting of B. aurae, B. aureogularis, B. jugivagans, and B. robinsoni. Bolitoglossa aurae is the sister taxa to B. jugivagans, and the two form a clade, sister to the clade consisting of B. robinsoni and B. aureogularis (Kubicki and Arias 2016).

Brian Kubicki, the co-author of the species description, named the species “aurae” after his wife, Aura Reyes, who co-discovered the holotype. The name additionally has origins related to the Latin word aureus, which means golden (Kubicki and Arias 2016).

References

Kubicki, B., Arias, E. (2016). ''A beautiful new yellow salamander, genus Bolitoglossa (Caudata: Plethodontidae), from the northeastern slopes of the Cordillera de Talamanca, Costa Rica.'' Zootaxa , 4184(2), 329-346.

Species Account Citation: AmphibiaWeb 2018 Bolitoglossa aurae: Aura's Golden Salamander <https://amphibiaweb.org/species/8527> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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