''Pseudis'' is a genus of South American

frog A frog is any member of a diverse and largely Carnivore, carnivorous group of short-bodied, tailless amphibians composing the order (biology), order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-f ...

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 s ...

. 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 i ...

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 elsew ...

to this country.

Description

NHM London Paradoxical frog (Pseudis paradoxa) model

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

Breeding and feeding

Mating and egg-laying in ''Pseudis'' is typical of frogs. What sets them apart is their

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 water ...

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 Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

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. Their common name is harlequin frogs. Many frogs in ''Lysapsus'' have a paradoxical life cycle. They are most massive when they are older tadpoles ...

'', 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 ''

'' 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 In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

synonyms A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

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 (biology), family of frogs that most likely diverged from other hyloidea, hyloids during the C ...

, 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 morphologicalDA 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 molecularDARST, 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 Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

solutions for the non

monophyly 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 grou ...

of ''Pseudis'', either resurrecting the genus ''Podonectes'' or placing ''Lysapsus'' as a

junior synonym The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...

of ''Pseudis''. More recent molecular evidence did not find ''Pseudis''

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

with respect to ''

'', so the synonymy is unnecessary.

References

External links

* {{Taxonbar, from=Q1059221 Hylidae Amphibians of South America Amphibian genera Taxa named by Johann Georg Wagler