Description
Dendrobates nubeculosus is a rare small- to medium-sized poison dart frog that was described from one specimen. That specimen has a snout-vent length of 24.5 mm, a head length of 8.2 mm, and a head width of 8 mm. Dendrobates nubeculosus has a round head and its nostrils open horizontally. Its lacks premaxillary and maxillary teeth. This frog has a circular tympanum that is roughly ½ the diameter of its eye. Dendrobates nubeculosus has a weakly granular dorsum and smooth venter and limbs. While the skin on its limbs is mostly smooth, the top surfaces of its thighs have a grainy texture. Dendrobates nubeculosus is characterized by the first finger being shorter than the second and a lack of webbing between the toes. It has a large, round tubercle on both its hands. It lacks a tarsal tubercle. The soles of its feet are smooth. The length of the holotype’s foot was 14.8 mm (Jungfur and Bohme 2004).

DIAGNOSIS:

Size and coloration differentiate D. nubeculosus from all other species of its genus in northern South America. Four species of Dendrobates from other regions—D. mysteriosus, D. arboreus, D. histrionicus, and D. sylvaticus—have dorsal patterns of light spots that resemble D. nubeculosus. Dendrobates mysteriosus from northern Peru bears well-defined light spots that are evenly distributed, but are ill-defined ventrally. Dendrobates arboreus from western Panama is smaller than D. nubeculosus. Additionally, unlike D. nubeculosus, D. arboreus has light spots that are always discrete and never merge (Myers 1982). Some populations of the polymorphic D. histrionicus and D. sylvaticus from the Pacific versant of Columbia and northwestern Ecuador resemble D. nubeculosus in color (Jungfer and Bohme 2004). Dendrobates maculatus from around western Panama is spotted dorsally and laterally. Unlike D. nubeculosus, its finger I is slightly longer than finger II (Myers 1982).

COLORATION:

In life, the holotype was primarily black or dark brown with blue splotches on the dorsum. It had lateral blue and black patterns, with a solid black ventral surface. The dorsum and venter were dark with ill-defined light spots. In alcohol, the dorsal surfaces of the head and body are covered with numerous irregular, ill-defined light grey spots. The dorsal surfaces of the humeri have a few slightly darkened spots. When the specimen dries after being removed from the preservative, several reddish-brown areas appear on the posterior part of the abdomen, dorsally and laterally on the thighs, and in the interorbital area. This information might indicate lighter reddish-brown coloration in the living frog (Jungfur and Bohme 2004).

VARIATION:

Drawing conclusions from other members of the Dendrobates genus, it is surmised that D. nubeculosus females are larger than their male counterparts (Jungfur and Bohme 2004).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Guyana

View distribution map in BerkeleyMapper.

This species is only known from one individual, which was found in northern central Guyana near Rockstone in a town on the Essequibo River, 7 meters above sea level. The vegetation in the areas is lowland, flooded riparian tall evergreen forest (Jungfur and Bohme 2004).

Life History, Abundance, Activity, and Special Behaviors
As of 2023, the social behavior, reproductive habits, call, and toxicity of D. nubeculosus are unknown (Jungfur and Bohme 2004).

Larva
No larvae/tadpoles have been found for this species, but the species is assumed to have a larval phase due to its taxonomy.

Trends and Threats
Because only one specimen of this species is known, the threats toward D. nubeculosus are unknown (IUCN 2018).

Comments

PHYLOGENETIC RELATIONSHIPS:

References
IUCN SSC Amphibian Specialist Group. 2018. Dendrobates nubeculosus. The IUCN Red List of Threatened Species 2018: e.T61769A120314617. https://dx.doi.org/10.2305/IUCN.UK.2018-1.RLTS.T61769A120314617.en. Accessed on 06 November 2023.

Jungfer, K.-H. and W. Böhme (2004). A new poison-dart frog (Dendrobates) from northern central Guyana (Amphibia: Anura: Dendrobatidae). Salamandra, 40, 99–104. [link]

Myers, C.W. (1982). Spotted poison frogs: Descriptions of three new Dendrobates from western Amazonia, and resurrection of a lost species from "Chiriqui". Amer. Mus. Novit., New York, 2721, 1-23. [link]

Species Account Citation: AmphibiaWeb 2024 Dendrobates nubeculosus: Rockstone Poison Dart Frog <https://amphibiaweb.org/species/6578> University of California, Berkeley, CA, USA. Accessed Nov 24, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Nov 2024.

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