''Pseudis'' is a genus of South American
frog
A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" ''Triadobatrachus'' is ...
s (swimming frogs) in the family
Hylidae
Hylidae is a wide-ranging family of frogs commonly referred to as "tree frogs and their allies". However, the hylids include a diversity of frog species, many of which do not live in trees, but are terrestrial or semiaquatic.
Taxonomy and ...
.
[ They are often common and frequently heard, but easily overlooked because of their camouflage and lifestyle, living in lakes, ponds, marshes and similar waters with extensive aquatic vegetation, often sitting at the surface among plants or on floating plants, but rapidly diving if disturbed. Whereas the adults are medium-sized frogs, their ]tadpole
A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found ...
s are large; in some species the world's longest.[Franklyn, D. (2015). . The Online Guide to the Animals of Trinidad and Tobago. Retrieved 7 January 2020]
Distribution
''Pseudis'' species are distributed throughout tropical and subtropical South America, almost entirely east of the Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
(''P. paradoxa'' is the only species with populations west of the Andes, in Colombia). They are found from Trinidad
Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...
to northern Argentina, being absent only in Ecuador and Chile, highland regions, and the southernmost part of South America. All species occur in Brazil, and ''P. bolbodactyla'', ''P. cardosoi'', ''P. fusca'' and ''P. tocantins'' are endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
to this country.
Description
These frogs have several adaptations to aquatic life, such as protuberant eyes, robust hind limbs, and fully webbed feet. Nevertheless, they belong to the "true" tree frogs, family Hylidae
Hylidae is a wide-ranging family of frogs commonly referred to as "tree frogs and their allies". However, the hylids include a diversity of frog species, many of which do not live in trees, but are terrestrial or semiaquatic.
Taxonomy and ...
.[
]
Breeding and feeding
Mating and egg-laying in ''Pseudis'' is typical of frogs. What sets them apart is their tadpole
A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found ...
s that start out as fairly normal, but continue growing until reaching gigantic sizes, sometimes as much as in length in ''P. paradoxa'' and ''P. platensis''. They are the longest known tadpoles and also large compared to the adult frogs, which are in snout–to–vent
Vent or vents may refer to:
Science and technology Biology
*Vent, the cloaca region of an animal
* Vent DNA polymerase, a thermostable DNA polymerase
Geology
*Hydrothermal vent, a fissure in a planet's surface from which geothermally heated wate ...
length.[ Less data is available for the tadpoles of most others members of the genus, but they too reach large sizes, although perhaps somewhat less than ''P. paradoxa'' and ''P. platensis''.] Their adult frogs also average somewhat smaller with snout–to–vent lengths of . However, there are two outliers in the genus: The closely related ''P. cardosoi'' and ''P. minuta'' (equalling the proposed genus ''Podonectes'', see '' Phylogenetic relationships'') have more normal tadpoles that are not known to surpass lengths of . This is still large compared to the adults of these two species, meaning that they too "shrink" during metamorphosis from tadpole to frog.[ In most if not all the species, there are noticeable local variations in the final size of the tadpoles, with those in large temporary waters with plenty of food and few aquatic predators growing larger than those in smaller waters with less food or waters with more aquatic predators.][ In at least the species with very large tadpoles, their final stages have unusually well-developed organs, including nearly ripe reproductive organs. This means that recently metamorphosed frogs rapidly reach maturity and essentially stop growing, whereas most other frogs take more time and growing after metamorphosis before they become mature.]
''Pseudis'' is closely related to a second genus, ''Lysapsus
''Lysapsus'' is a genus of frogs in the family Hylidae found in South America east of the Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland alo ...
'', that lacks giant tadpoles and in which adults are smaller, up to .[
''Pseudis'' tadpoles feed mostly on a wide range of algae, but also take small invertebrates.] The adult frogs feed mostly on land-based insects and spiders, but also other land-based or aquatic invertebrates, small frogs and—in some species—plant material.
Species
There are seven species in this genus (given that ''Lysapsus
''Lysapsus'' is a genus of frogs in the family Hylidae found in South America east of the Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland alo ...
'' is accepted as a separate genus). Until the late 1990s and early 2000s, most authorities only recognized ''P. minuta'' and ''P. paradoxa'', but ''P. cardosoi'' was described in 2010 (having formerly been included as a population of ''P. minuta''), while the remaining were considered subspecies, synonyms or populations of ''P. paradoxa''.[ The validity of ''P. platensis'' as a species separate from ''P. paradoxa'' is questionable.][
]
Phylogenetic relationships
The phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
position of frogs currently included in the genus ''Pseudis'' in relation to other anurans was for a long time a matter of debate. They have been placed in Ranidae, Leptodactylidae
The southern frogs form the Leptodactylidae, a name that comes from Greek meaning a bird or other animal having slender toes. They are a diverse family of frogs that most likely diverged from other hyloids during the Cretaceous. The family has u ...
, Hylidae
Hylidae is a wide-ranging family of frogs commonly referred to as "tree frogs and their allies". However, the hylids include a diversity of frog species, many of which do not live in trees, but are terrestrial or semiaquatic.
Taxonomy and ...
, and as their own family Pseudidae This results from their highly derived body plan for a hylid frog due to their mostly aquatic habits. Recent morphological[DA SILVA, H. R. 1998. Phylogenetic relationships of the family Hylidae with emphasis on the relationships within the subfamily Hylinae (Amphibia: Anura). Department of Systematics and Ecology. University of Kansas.] and molecular[DARST, C. R., and D. C. CANNATELLA. 2004. Novel relationships among hyloid frogs inferred from 12S and 16S mitochondrial DNA sequences. Molecular Phylogenetics and Evolution. 31:462-475.] phylogenetic reconstructions have unambiguously placed them within the subfamily Hylinae with ''Scarthyla
''Scarthyla'' is a genus of tree frogs, the family Hylidae
Hylidae is a wide-ranging family of frogs commonly referred to as "tree frogs and their allies". However, the hylids include a diversity of frog species, many of which do not live ...
'' as a sister group.
Phylogenetic relationships among species of the group were recently proposed using molecular evidences.[GARDA, A. A., and D. C. CANNATELLA. 2007. Phylogeny and biogeography of paradoxical frogs (Anura, Hylidae, Pseudae) inferred from 12S and 16S mitochondrial DNA. Molecular Phylogenetics and Evolution. Molecular Phylogenetics and Evolution. 44:104-114.][AGUIAR-JR., O., M. BACCI JR, A. P. LIMA, D. C. ROSSA-FERES, C. F. B. HADDAD, and S. M. RECCO-PIMENTEL. 2007. Phylogenetic relationships of ''Pseudis'' and ''Lysapsus'' (Anura, Hylidae, Hylinae) inferred from mitochondrial and nuclear gene sequences. Cladistics. 23:455-463.] Both publications found identical trees, but proposed different taxonomic solutions for the nonmonophyly
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
of ''Pseudis'', either resurrecting the genus ''Podonectes'' or placing ''Lysapsus'' as a junior synonym of ''Pseudis''. More recent molecular evidence did not find ''Pseudis'' paraphyletic with respect to ''Lysapsus
''Lysapsus'' is a genus of frogs in the family Hylidae found in South America east of the Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland alo ...
'', so the synonymy is unnecessary.[
]
References
External links
*
{{Taxonbar, from=Q1059221
Hylidae
Amphibians of South America
Amphibian genera
Taxa named by Johann Georg Wagler