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''Leiopelma'' is a genus of New Zealand primitive frogs, belonging to the
suborder
Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
Archaeobatrachia. It is the only genus in the monotypic family Leiopelmatidae. The leiopelmatids' relatively basal form indicates they have an ancient lineage. While some taxonomists have suggested combining the North American frogs of the genus ''Ascaphus'' in the family
Ascaphidae
The tailed frogs are two species of frogs in the genus ''Ascaphus'', the only taxon in the family Ascaphidae . The "tail" in the name is actually an extension of the male cloaca. The tail is one of two distinctive anatomical features adapting the ...
with the New Zealand frogs of the genus ''Leiopelma'' in the family Leiopelmatidae, the current consensus is that these two groups constitute two separate families. The four extant species of Leiopelmatidae are only found in
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island country ...
.
Overview
The New Zealand primitive frogs' defining characteristics are their extra
vertebrae
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...
(for a total of nine) and the remains of the tail
muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of m ...
s (the tail itself is absent in adults, although it is present in the younger frogs, which need the extra skin surface until their lungs are fully developed). The family Ascaphidae (found only in North America), of the same suborder, shares these primitive characteristics, hence the two have often been described as related, or even part of the same family.
Late jump recovery is unique in Leiopelmatidae. When leiopelmatid species jump, they land in a "belly flop" fashion, repositioning their limbs for takeoff for the next jump only after hitting the ground with the ventral surface of their torsos. The appearance of early jump recovery in more advanced taxa is a key innovation in anuran evolution.
They are unusually small frogs, only in length. Most species lay their eggs in moist ground, typically under rocks or vegetation. After hatching, the
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 nest in the male's back, all without the need for standing or flowing water. However, Hochstetter's frog lays its eggs in shallow ponds and has free-living tadpoles, although they do not swim far from the place of hatching, or even feed, before metamorphosing into adult frogs.Lifespans may be long (more than 30 years) for such small organisms.
Introduced fauna are thought to have had a negative impact on these native frogs, with 93% of all reported predation events on native frogs being attributed to introduced fauna, primarily ship rats.
subfossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Leiopelma bishopi'' Easton, Tennyson and Rawlence, 2021
Two species are known from
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent ...
deposits of the
Saint Bathans fauna
The St Bathans fauna is found in the lower Bannockburn Formation of the Manuherikia Group of Central Otago, in the South Island of New Zealand. It comprises a suite of fossilised prehistoric animals from the late Early Miocene (Altonian) period, ...
DNA analysis indicates that Leiopelmatidae share a distant common ancestry with
Ascaphidae
The tailed frogs are two species of frogs in the genus ''Ascaphus'', the only taxon in the family Ascaphidae . The "tail" in the name is actually an extension of the male cloaca. The tail is one of two distinctive anatomical features adapting the ...
to the exclusion of all other frogs, and Leiopelmatidae and Ascaphidae diverged from all other frogs around 200 million years ago. ''L. archeyi'' and ''L. hochstetteri'' are thought to have diverged from each other between 40 and 50 million years ago, based on genomic divergence estimates. Fossils of the genus are known from the early
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent ...