AMPHIBIAWEB
Hyperolius nasicus
family: Hyperoliidae
 
Species Description: Schiotz A 2006. Reflections on the Hyperolius nasutus group (Anura, Hyperoliidae). Alytes 24: 61-71.

Country distribution from AmphibiaWeb's database: Congo, the Democratic Republic of the, Mozambique

View distribution map using BerkeleyMapper.


Conservation Status (definitions)
IUCN (Red List) Status Data Deficient (DD)
See IUCN account.
CITES
Other International Status None
National Status None
Regional Status None

   

From the Encyclopedia of Life account:

Etymology

The specific epithet “nasicus” comes from the Latin word “nasus” meaning nose and refers to the highly pointed snout of this species.


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/

Taxonomic Notes

Hyperolius nasicus is in the H. nasutus group, a species complex in which characterization and nomenclature are difficult and still controversial. This difficulty is due in part to the extensive morphological similarity of the group’s members (Channing et al., 2002). H. nasicus has traditionally been considered synonymous with H. nasutus, but Schiøtz (2006b) suggests it may be closer to H. benguellensis.


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/

Summary

Hyperolius nasicus is a small, slender frog with a markedly pointed snout. It is a very poorly known member of the H. nasutus group, a group of tree frogs whose taxonomic classification remains controversial. Frogs in this group generally have translucent green skin with a white dorsolateral line. Members of this group also typically lay their eggs directly in water, develop indirectly via a tadpole larval stage.


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/

Distribution

Hyperolius nasicus is known only from its type locality, Kasiki, at 2,300 m asl in the Marungu Highlands in southeastern Democratic Republic of Congo. This locality was inadvertently stated to be in northeastern Democratic Republic of Congo by Schiøtz (2006a; Schiøtz 2008).


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/

Morphology

The head is as wide as it is long. The length of the body is 3 1/4 to 3 1/2 times the length of the head. The snout is pointed and sometimes slightly raised at the tip, and it strongly surpasses the lower jaw. It is truncated in profile as in H. oxyrhynchus, greater than or equal to the diameter of the eye, and comprises 1 2/5 to 1 1/2 times the distance of the anterior ocular angles. The canthus rostralis is well pronounced and somewhat rectilinear. The frenal region is vertical and almost planar. The distance between the eye and the nostril is equal to 1 1/3 to 1 1/2 times the distance from the nostril to the tip of the snout, and less than or equal to the internasal space. The internasal space, in turn, is included 1 1/3 to 1 2/5 times in the interorbital space, which is slightly greater than or equal to twice the width of the upper eyelid (Laurent, 1943). The anterior webbing is 1/3 to 1/2. Adhesive discs and sub-articular tubercles are normal. The fourth digit is longer than the second, and the third digit is slightly greater than or equal to the length of the snout. The posterior webbing is 2/3, leaving one phalange free on the fourth toe, 3/4 on the first toe, and 1/2 on the other toes. The fifth toe is longer than the third. The external metatarsals are fused. There is a small medial metatarsal tubercle but no lateral metatarsal tubercle. The tibio-tarsal joint exceeds the anterior side of the eye. The thigh is shorter than the tibia, which is longer than the foot, about 3 to 3 3/4 times as long as it is wide, and about half the length of the body. The heels overlap when the hind limbs are bent perpendicular to the axis of the body. The skin is slightly shagreen on the dorsum and granular on the venter (Laurent, 1943).

The pigmentation is made up of melanophores and guanophores dispersed on the dorsum and on the parts of the limbs that are visible in the frog’s resting position. The melanophores form somewhat longitudinal lines and a subcanthal concentration. The guanophores are particularly numerous along the canthus and on the upper eyelid, and they comprise a white dorsolateral ray. This ray is vague on adults but quite distinct on juveniles, which also have concentrations of melanophores along these rays and in the middle of the back (Laurent, 1943). In life, members of the genus Hyperolius have translucent green skin that fades to white or light yellow after preservation (Schiøtz 2006b). When preserved, the green color fades to white or light yellow, but the dorsolateral lines of H. nasicus juveniles remain visible, unlike those of most other members of the H. nasutus group which become indistinguishable from the faded ground color.


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/

Size

The average adult snout-vent length is approximately 23 mm, and adult males and females are approximately the same size. The holotype, an adult male, has a snout-vent length (SVL) of 23.4 mm, and the largest female, a paratype, has an SVL of 22.5 mm (Laurent, 1943; Schiøtz, 2006b).


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/

Diagnostic Description

As the taxonomic status of Hyperolius nasicus is uncertain and the genus Hyperolius is marked by substantial morphological similarity, distinguishing H. nasicus from its closest relatives is difficult. However, according to Laurent (1943), this species can be differentiated from other members of the H. nasutus group by its wider head (about as wide as it is long) and more massive build, as well as the more extensive webbing on its hands (1/3 to 1/2). Coloration may also be heplful in distingushing H. nasicus from other members of the H. nasutus group. In four juvenile paratypes of H. nasicus, the white dorsolateral lines remained after preservation, unlike in most members of the group, in which the preservation process causes these lines to vanish once the skin’s green ground color fades (Schiøtz, 2006a, 2006b). Interestingly, H. nasicus shares the persistence of these lines with the morphologically similar H. benguellensis, leading Schiøtz (2006b) to suggest that they be compared to investigate potential synonymy.


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/

Habitat and Ecology

Very little is known about the habitat or ecology of Hyperolius nasicus, as the species is known only from its type locality, Kasiki, at an altitude of 2,300 m asl in the Marungu Highlands in southeastern Democratic Republic of Congo. In general, frogs in the genus Hyperolius live primarily on shrubs and trees (Laurent, 1943; Schiøtz 2006b; Schiøtz 2008).


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/

Reproduction

Reproduction has not been documented for Hyperolius nasicus in particular, but frogs in the genus Hyperolius generally lay their eggs in water and develop indirectly (Schiøtz, 2006b).


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/

IUCN Red List Category and Justification of Conservation Status

The IUCN Red List (2008) categorizes this species as Data Deficient in view of continuing doubts as to its taxonomic validity, extent of occurrence, status and ecological requirements (Schiøtz, 2008).


Author: Dietterich, Lee
License: http://creativecommons.org/licenses/by-nc/3.0/