''Pseudis'' is a genus of South American

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

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 or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...

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 Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

(''P. paradoxa'' is the only species with populations west of the Andes, in Colombia). They are found from

Trinidad Trinidad is the larger, more populous island of the Republic of Trinidad and Tobago, the country. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is the southernmost island in ...

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 only 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 foun ...

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

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 A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA. In o ...

'') 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 transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

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'', 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'' 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 Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

synonyms A synonym is a word, morpheme, or phrase that means precisely 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 a ...

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 () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

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 ...

, 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. They are found in the upper Amazon Basin The Amazon basin is the part of South America drained by the Amazon River and its tributary, tributaries. The Amazon drainage basin covers ...

'' 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 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...

solutions for the non

monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...

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

junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

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

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

with respect to '' Lysapsus'', so the synonymy is unnecessary. Intrinsic phylogeny tree of genus ''Pseudis'':

References

External links

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