AMPHIBIAWEB
Hyla bocourti
Bocourt’s treefrog
Subgenus: Dryophytes
family: Hylidae
subfamily: Hylinae
Taxonomic Notes: Duellman et al. (Zootaxa 2016) treated two major clades as genera; AmphibiaWeb treats these two clades as subgenera(Hyla in the Old World; Dryophytes in the New World and East Asia), thus stabilizing traditional taxonomy.
Conservation Status (definitions)
IUCN (Red List) Status Critically Endangered (CR)
CITES No CITES Listing
Other International Status None
National Status None
Regional Status None

 

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Description
Hyla bocourti is a species native to the Guatemalan highlands of Alta and Baja Verapaz. The average snout-vent length for males is 30.2 mm with a range of 26.3 - 34.6 mm. Females are slightly larger, averaging 33.7 mm with a range of 29.2 - 37.7 mm (Campbell and Lawson 1992). The width of the body is greater than the head width with an average head length that is 24 – 35% of the snout-vent length and head width that is 30 - 38% of the snout-vent length (Fowler 1916). From a dorsal perspective, the snout tapers to a point. From the side, the snout is truncate until the nares at which point it becomes sloped. The snout is long and the distinct protuberantly bulging nostrils are situated approximately two-thirds of the distance between the eyes and snout tip. The canthus rostralis is angular. The loreal region is slightly concave. The diameter of the tympanum is about half the diameter of the eye. The ratio of tympanum diameter to eye diameter does not differ between sexes, averaging 0.56 (0.39 - 0.79) for males and 0.58 (0.41 - 0.75) for females. The tympanic ring ranges from being obscured to moderately well-developed. A supratympanic fold is present starting at the posterior end of the eye, extending over and covering the upper edge of the tympanic annulus, and melding into the body above the arm insertion (Campbell and Lawson 1992).

The arms and legs are long and slender. All the digits have discs with the toe discs being larger than the finger discs. Both toes and fingers are slender and webbed, although the fingers are only slightly webbed. The upper arm has an axillary membrane that extends to one-fourth to one-third of the arm length. The lower arm has a weak transverse fold at the wrist. The hands contain large round subarticular tubercles and a small round palmar tubercle. The proximal segments of the fingers have indistinct, small supernumerary tubercles. The hand webbing formula is I 2 - 3 III 3 - 2.5 IV. The hand has an enlarged prepollex. In males, black nuptial spines can be found on the prepollex, along the ventral side of fingers II – IV, and on the medial sides of fingers II - III. The length of the tibia is approximately 50% of the snout-vent length, and foot length is 46% of the snout-vent length. When adpressed, the limbs overlap by approximately one-fourth of the shank. The tibotarsal articulation reaches the eye when the leg is extended. There is no transverse dermal fold present on the heel but a distinct tarsal fold can be found extending over the whole tarsus. Metatarsal tubercles are present, with the inner tubercle being small oval and slightly elevated and the outer small and sub-conical if present. The subarticular tubercles of the foot are small and round and the supernumerary tubercles are indistinct, low, and, like the fingers, only found on the proximal segments of the toes. The foot webbing formula is I 1 - 2 II 1 - 2 III 1.5 - 2 IV 2 - 1.5 V (Campbell and Lawson 1992).

The cloaca is located at mid-level with the thighs and directed posteroventrally. It has an obvious short cloacal sheath. In males, the dorsum, including the hind limbs, is tuberculate with keratinous spines. Spines are also found on the side of the head, loreal region (including the upper eyelids), tympanic region (including the tympanum), elbows, cloacal area, and lateral surface of the feet. Females have smooth skin on the dorsal surfaces. The ventral skin surface in both sexes is mostly granular in nature, including the throat, abdomen, and ventral surface of the thighs. In males, the vocal is located on the lower portion of the throat and has two lobes (Campbell and Lawson 1992).

Hyla bocourti is morphologically similar to both H. walkeri and H. euphorbiaceae but can be easily distinguished by several distinct traits. The shape of the snout in dorsal view is acuminate in H. bocourti but rounded in the other species. The upper lip of both H. walkeri and H. euphorbiaceae is bordered by a small white strip, while the subgular sac is bilobate in H. bocourti and median in the other species. The dorsum coloration also differs between the species, with H. bocourti having a yellowish-green dorsum and the other species having a verdant green coloration. The dorsal surface in adult males of both H. walkeri and H. euphorbiaceae is smooth, while H. bocourti adult males have a tuberculate dorsal surface. Additionally, the nuptial excrescences of adult males are black in H. bocourti, and white to tan in the other two species. Both H. bocourti and H euphorbiaceae have yellow spots on their hind legs; however, the spots are much larger in H. bocourti – the hind legs of H. walkeri are uniformly tan. Lastly, the toe webbing is more significant in H. bocourti being three-fourths webbed, rather than one-half webbed as in the other species (Campbell and Lawson 1992).

Campbell and Lawson (1992) re-described the coloration of the species, but were not explicit if it was in life or preservative. The dorsal surface coloration is highly variable, extending from tan to green. The dorsum of males tends to present with a tannish coloration, while females typically present with a more greenish dorsum. Additionally, the dorsum typically presents with patches of brown. A distinct brown bar is present along each side, extending from the tip of the snout to the flanks – dissecting both the eye and the tympanum, and is bordered dorsally by a pale line. The iris is yellow in both sexes. The thighs are dark brown with yellow spots in a reticulated pattern, with all limbs having 3 - 4 dark bars. The ventral surface is creamy white in color, contrasting with the mottled yellow coloration of the groin. Males have black spines on their dorsum, loreal and tympanic regions, elbows, cloacal area, and lateral sides of their feet (Campbell and Lawson 1992).

There are several sexually dimorphic characters. Males have tubercular dorsal skin while females have smooth dorsums. Additionally, the dorsum coloration is reported to vary between sexes. Males tend to present with a tan colored dorsum, while females tend to present with a green dorsum (Campbell and Lawson 1992).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Guatemala

 

View distribution map using BerkeleyMapper.
The species is found in the highlands of Guatemala at moderate elevations (Stuart 1963), specifically from Alta and Baja Verapaz; however, due to a variety of factors the species has been reported from other regions – likely being mistaken for the morphologically similar species H. walkeri (Stuart 1948; Campbell and Lawson 1992). The preferred habitat is the meadow and marshlands of the cloud forests (Mendelson et al. 2004), with higher abundances found during the rainy season (Campbell and Lawson 1992). Additionally, one gravid specimen was found within a bromeliad.

Life History, Abundance, Activity, and Special Behaviors
Few records of Hyla bocourti exist, thus, little is known about their natural history. Campbell and Lawson (1992) notes that the majority of their specimens were terrestrial, found in treeless flooded meadow complexes. Stuart (1948) reports that several specimens have been found beneath banana leaves. A single specimen with developing eggs was collected by Stuart (1948) in association with a bromeliad, of which tadpoles from Hyla bromeliaca were occupying.

Tadpoles of H. bocourti remain undescribed (Campbell and Lawson 1992). However, closely related species, H. wrightorum and H. arenicolor, oviposit eggs in small water bodies, and undergo indirect development, whereby the free-swimming tadpoles metamorphose after hatching (Zweifel 1961).

No descriptions of the calls have been made; however, males from closely related species have been reported to have a diverse repertoire of calls that are performed year-round, and call more frequently during the mating season (Zweifel 1961).

Trends and Threats
Hyla bocourti is listed as “Critically Endangered” on the IUCN Red List because of drastic population declines (Acevedo and Young 2017). Recent surveys of the known range of H. bocourti have discovered few to no individuals, and it is estimated that the population has decreased by over 80% within the last three generations, with a rapid disappearance between 1983 through 1984. Causes of this drastic decline include agriculture-related habitat destruction (Mendelson et al. 2004), as well as possible chytridiomycosis exposure (Mendelson et al. 2014).

The range of H. bocourti includes areas of Guatemala that are used for the agriculture of commercially available ornamental plants — this industry is thought to be a major contributor to the species’ rapid decline. Deforestation and slash-and-burn agricultural methods are used to expand plantation fields, and in the process, the habitat of these frogs is destroyed. Flowers and ferns exported for decorative use are also heavily treated with pesticides that have severely contaminated waterways potentially used by H. bocourti with chemical run-off. Water contamination poses serious and possibly lethal consequences to H. bocourti, as the species relies heavily on water bodies for survival (Mendelson et al. 2004).

Chytridiomycosis, a fungal disease caused by Batrachochytrium dendrobatidis (Bd), may also be a contributor to the decline in abundance of H. bocourti as multiple sympatric amphibian species have been reported to be infected (Mendelson et al. 2014). Additionally, tadpoles from sympatric anuran species have been observed to have malformations of the mouth and tail, and discoloration of the body, suggesting contact with the pathogen (Mendelson et al. 2004).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Habitat fragmentation
Disease

Comments
The species authority is: Mocquard, F. (1899). “Contribution à la faune herpétologique de la Basse-Californie.” Nouvelles archives du Muséum d'histoire naturelle. Muséum d'histoire naturelle.

Hyla bocourti has a complex taxanomic history. Mocquard first proposed he species name, Hyliola boucourti, in 1899 for a population of Hyla regilla near Coban, Guatemala. However, in 1939, Taylor synonymized the species with H. euphorbiacea based on literature alone, not examining any specimens. In 1948, Stuart revived H. bocourti but noted that the information provided by previous biologists was confusing and calling for an independent description. While Duellman returned H. bocourti to synonymy with H. euphorbiacea in 1970, he, along with Campbell, conceded that H. bocourti could be a distinct species in 1985. The species was finally re-described by Campbell and Lawson in 1992 (Campbell and Lawson 1992).

The taxonomic status of the species is still debated, with H. bocourti having been provisionally placed in the genus Dryophytes, and being reclassified as D. bocourti by Duellman et al. (2016; However, please see our Taxonomic Note above). Previously, H. bocourti has been referred to as H. regilla by Baird and Girard (1852).

Hyla bocourti is a species in the treefrog family Hylidae and is a member of the H. eximia group of hylids that also contains the closely related species H. walkeri, H. eximia, H. euphorbiaceae, H. plicata, H. wrightorum, and H. arenicolor (Hua et al. 2009).

Though few records of the species natural history exist, Campbell and Lawson (1992) report that H. bocourti is not a tree-dwelling species, and is predominantly found within meadow complexes.

The genus Hyla is a reference to the companion of Hercules in Greek mythology, Hylas (Laurenti 1768). The specific epithet, “bocourti”, was given in honor of Marie Firmin Bocourt, a 19th-century zoologist.

References

Acevedo, M. Young, B.E. 2017. Dryophytes bocourti. (amended version published in 2004) The IUCN Red List of Threatened Species 2017: e.T55416A112712386. http://dx.doi.org/10.2305/IUCN.UK.2017-1.RLTS.T55416A112712386.en. Downloaded on 28 September 2017.

Baird, S. F., Girard C. (1852). ''Description of new species and reptiles, collected by the U.S. exploring expedition under the command of Capt. Charles Wilkes, U.S.N. part 1.'' Proceedings of the Academy of Natural Sciences of Philadelphia , 6, 174 - 177.

Campbell, J. A., Lawson, D. P. (1992). ''Hyla bocourti (Mocquard, 1899) a valid species of frog (Anura: Hylidae) from Guatemala.'' Proceedings of the Biological Society of Washington, 105(2), 393 - 399.

Duellman, W. E., Marion, A. B., Hedges, S. B. (2016). ''Phylogenetics, classification, and biogeography of the treefrogs (Amphibia: Anura: Arboranae).'' Zootaxa , 4104, 1 - 109.

Fowler, H. W. (1916). ''Cold-blooded vertebrates from Costa Rica and the canal zone.'' Proceedings of the Academy of Natural Sciences of Philadelphia , 68(3), 389 - 414.

Hua, X., Fu, C., Li, J., Montes de Oca, A. N., Wiens, J. J. (2009). ''A revised phylogeny of holarctic treefrogs (genus Hyla) based on nuclear and mitochondrial DNA sequences.'' Herpetologica, 65(3), 246 - 259.

Laurenti, J. N. (1768). ''Specimen medicum, exhibens synopsin reptilium emendatam cum experimentis circa venena et antidota reptilium austriacorum.'' ''.''

Mendelson, J. R. III, Brodie, E. D. Jr, Malone, J. H., Acevedo, M. E., Baker, M. A., Smatresk, N. J., Campbell, J. A. (2004). ''Factors associated with the catastrophic decline of a cloud forest frog fauna in Guatemala.'' Revista de Biologia Tropical , 52(4), 991 - 1000.

Mendelson, J. R. III, Jones, M. E. B., Pessier, A. P., Toledo, G., Kabay, E. H., Campbell, J. A. (2014). ''On the Timing of an Epidemic of Amphibian Chytridiomycosis in the Highlands of Guatemala.'' South American Journal of Herpetology , 9(2), 151 - 153.

Stuart, L. (1948). ''The amphibians and reptiles of Alta Verapaz, Guatemala.'' Miscellaneous Publications Museum of Zoology, University of Michigan, 69, 1 - 109.

Stuart, L. (1963). ''A checklist of the herpetofauna of Guatemala.'' Miscellaneous Publications Museum of Zoology, University of Michigan , 122, 1 - 150.

Zweifel, R.G. (1961). ''Larval development of the tree frogs Hyla arenicolor and Hyla wrightorum.'' American Museum Novitates, 2056, 1 -19.



Written by Malachi Whitford, Barbara Carballo, Angelica Grunloh (mwhitford AT ucdavis.edu, bcarballo AT ucdavis.edu, argrunloh AT ucdavis.edu), University of California Davis
First submitted 2017-09-27
Edited by Ann T. Chang (2017-09-28)

Species Account Citation: AmphibiaWeb 2017 Hyla bocourti: Bocourt’s treefrog <http://amphibiaweb.org/species/740> University of California, Berkeley, CA, USA. Accessed Oct 18, 2017.



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Citation: AmphibiaWeb. 2017. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Oct 2017.

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