Description
Bolitoglossa caldwellae is a small, tube-like salamander with a standard length in males of 32.3 - 39.2 mm, while females have a greater range of 30.2 - 43.2 mm. Its body is cylindrical, and displays 13 costal grooves. The head is longer than it is wide by 0.9 - 1.2 times, although the head is distinctly wider than the neck. The snout is short, ranging from 1.7 - 2.2 mm in males and 1.3 - 2.2 mm in females, and broad. In the dorsal view, the snout appears truncated; in the lateral view, the snout appears slightly rounded to truncated. The canthus rostralis was barely noticeable, and both sexes display a slight snout projection over the chin. At the snout’s extremity, the middle portion is concave. The nostrils are located at the tip of the snout and are small in size. There are also obvious nasolabial protuberances in both sexes. The eyes are large and protrude laterally from the head. Oval-shaped mental glands were only found in males and measured 2.1 – 3.3 mm wide. The limbs are slender but short; when the fore- and hind limbs are adpressed towards each other, there are 2.5 – 5.5 (mean 4.0) costal grooves between them. The hands and feet are moderately broad, completely webbed but with the distal phalanges of all digits free. Fingers in order of decreasing length are: 3–2–4–1. In males, finger length ranges from 2.0 - 2.3 mm, while in females finger length ranges from 1.7 - 2.7 mm. The ranges for foot width were similar between both sexes, with males ranging 2.2 - 3.3 mm and females 2.2 - 3.4 mm. Toes in order of decreasing length are: 3-2-4-5-1. In males, toe length ranges from 1.9 - 2.9 mm, while in females toe length ranges from 1.6 mm - 3.0 mm. The short tail is rounded and gradually tapers to a point. In males, tail length ranges from 16.0 - 28.6 mm and 20.4 - 34.8 mm in females (Brcko et al. 2013).

DIAGNOSIS:

Bolitoglossa caldwelldae can be distinguished from other, non-Brazilian, neotropical salamanders by a combination of its extensive webbing, 13 costal grooves, and the lack of a sublingual fold. From other Amazonian Bolitoglossa species, B. caldwellae is distinguished by its light brown ventral coloring with cream-colored specs and wide head. From Brazilian Boliotoglossa, B. caldwellae has a smaller standard length than B. altamazonica, B. tapajonica, and B. madeira. Standard lengths of B. altamazonica average 39.0 mm for males and 47.0 mm for females. Standard lengths of the B. tapajonica average 41.4 mm in males and 41.5 mm in females. Only female specimens of B. madeira were examined, with standard lengths averaging 54.4 mm. On the contrary, standard lengths of the B. caldwellae average 35.2 mm for males and 34.8mm for females. Bolitoglossa caldwellae also differs in having a snout length that is 30 - 40% the size of the head width. In contrast B. altamazonica has a snout length that is 30% - 50% of the head width and both mature sexes of B. paraensis have snout lengths that are greater than or equal to 40% of head length. Lastly, Bolitoglossa paraensis has a larger tail length to standard length ratio, from 75 - 103% in males and 71 - 99% in females while B. caldwellae have a ratio of 60 - 90% in males, and 61 - 89% in females (Brcko et al. 2013).

COLORATION:

In life, B. caldwellae displays a speckled mix of red and brown on its dorsal surface. The ventral surface can appear any color from dark brown to a light reddish-brown. The color of B. caldwellae’s eyes can depend on the individual. Some have reddish brown irises, while others have silver irises. Each eye has a black pupil and a black ring around each iris. Above the nasal protuberances, reddish-brown spots are present on the snout. Some B. caldwellae have a brown or reddish-brown triangle between their eyes and extending down the mid-dorsal line (Brcko et al. 2013).

When preserved in alcohol, the dorsal surface appears light brown with the occasional spot of dark brown. The reddish-brown specks that were present above the nasolabial protuberances in life, now appear as cream-colored specks. On the top of the head, a lighter mark becomes visible originating between the eyes and extending down the mid-dorsal line. The dorsolateral band is dark brown. The ventral surface now appears light brown with some cream-colored flecks. In males, the mental gland becomes more visible and is a pale cream (Brcko et al. 2013).

VARIATION:

Common variations among B. caldwellae include coloration and iris color. Individuals can appear brighter or darker. The ventral skin of B. caldwellae is a motley assortment of red and brown, while dorsal skin is slightly paler than ventral. The iris of the B. caldwellae can range from brown to dark red to silver (Brcko et al. 2013).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Brazil

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (262 records).

At the time of the species description, B. caldwelldae was only found in undisturbed forests of western Acre, Brazil. Acre is one of the westernmost states in Brazil, and borders Peru and Bolivia. Specimens collected in this study were found between 215 and 240 miles above sea level in a forest ecosystem surrounding the upper Juruá River Basin (Brcko et al. 2013).

Life History, Abundance, Activity, and Special Behaviors
Specimens were collected near streams at 0.15 - 1.0 m above the ground, and found on various vegetation. Researchers conducted their search for specimens at night when salamanders are most active. Although no specimens were collected from the ground, some were observed in leaf litter (Brcko et al. 2013).

Trends and Threats
Although this species is not currently considered at risk, human development and associated deforestation in Acre harm the quality of their available habitat (IUCN 2023)

Comments
Researchers conducted a stepwise discriminant function analysis on the morphology of Brazilian specimens of Bolitoglossa that resulted in the description of three new species: B. caldwellae, B. madeira , and B. tapajonica. In this analysis, they used 13 characteristics: standard length, head length, snout to gular fold, head width, snout length, orbital diameter, interorbital distance, axilla to snout, snout width at the narrowest point, snout projection beyond mandible, axilla to groin, length of third toe, and eyelid width. The first discriminant factor accounted for 81% of the variation, and the first and second discrimination factors together accounted for 100% of species variation. The length of the third toe was the first characteristic selected, and correctly identified 64% of specimens. After adding the rest of the characteristics, species were confidently identified 90% of the time, with an 88% jackknife (Brcko et al. 2013).

References
Brcko, I. C., Hoogmoed, M. S., and Neckel-Oliveira, S. (2013). Taxonomy and distribution of the salamander genus Bolitoglossa Duméril, Bibron & Duméril, 1854 (Amphibia, Caudata, Plethodontidae) in Brazilian Amazonia. Zootaxa, 3686(4), 401-431. [link]

IUCN SSC Amphibian Specialist Group & Instituto Boitatá de Etnobiologia e Conservação da Fauna. (2023). Bolitoglossa caldwellae. The IUCN Red List of Threatened Species 2023: e.T81659538A86254624. https://dx.doi.org/10.2305/IUCN.UK.2023-1.RLTS.T81659538A86254624.en. Accessed on 21 October 2024.

Species Account Citation: AmphibiaWeb 2024 Bolitoglossa caldwellae: Caldwell’s Mushroomtongue Salamander (English) <https://amphibiaweb.org/species/8030> 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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