''Peripatopsis aereus'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

velvet worm Onychophora (from , , "claws"; and , , "to carry"), commonly known as velvet worms (for their velvety texture and somewhat wormlike appearance) or more ambiguously as peripatus (after the first described genus, '' Peripatus''), is a phylum of e ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Peripatopsidae Peripatopsidae or the Southern Velvet Worms are one of two extant families of velvet worm. This family includes more than 140 described species distributed among 41 genera, but some authorities deem only 131 of these species to be valid. The Fre ...

. This species is known only from the

Riviersonderend Mountains The Riviersonderend Mountains are a mountain range in the Cape Fold Belt of the Western Cape province of South Africa. They run east to west from Riviersonderend to Villiersdorp, separating the Breede River Valley from the Overberg region. Th ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. This velvet worm was discovered living in

sympatry In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...

with another species in the same

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

, '' P. lawrencei''. These two sympatric species can be distinguished based on the number of legs: The species ''P. aereus'' has 18 pairs of legs, whereas the species ''P. lawrencei'' has only 17 leg pairs.

Discovery

In 2009, a

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 ...

analysis of the genus ''

Peripatopsis ''Peripatopsis'' is a genus of velvet worms in the Peripatopsidae family. These velvet worms are found in the KwaZulu-Natal, Western Cape, and Eastern Cape provinces of South Africa. This genus was proposed by the British zoologist Reginald I. ...

'' using molecular data first identified this velvet worm as a distinct lineage in a

phylogenetic tree 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 ...

based on a single specimen. This species was first described in 2024 by the

zoologists This is a list of notable zoologists who have published names of new taxa under the International Code of Zoological Nomenclature. A * Abe – Tokiharu Abe (1911–1996) * Abeille de Perrin, Ab. – Elzéar Abeille de Perrin (1843–1910) * ...

Julian A. Nieto Lawrence and Savel R. Daniels. They based the original description of this species on two specimens, a

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

and a

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype (biology), isotype ...

, both collected in 2022 in Oubos, near the site where the first specimen was found in the Riviersonderend Mountains in

Western Cape The Western Cape ( ; , ) is a provinces of South Africa, province of South Africa, situated on the south-western coast of the country. It is the List of South African provinces by area, fourth largest of the nine provinces with an area of , an ...

province in South Africa. These specimens were found inside or under decaying logs or leaf litter in a patch of

Afromontane The Afromontane regions are subregions of the Afrotropical realm, one of the Earth's eight biogeographic realms, covering the plant and animal species found in the mountains of Africa and the southern Arabian Peninsula. The Afromontane regions o ...

forest. The

type specimens In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes t ...

are deposited in the

South African Museum The Iziko South African Museum, formerly the South African Museum (Afrikaans: Suid-Afrikaanse Museum), is a South African national museum located in Cape Town. The museum was founded in 1825, the first in the country. It has been on its present ...

Cape Town Cape Town is the legislature, legislative capital city, capital of South Africa. It is the country's oldest city and the seat of the Parliament of South Africa. Cape Town is the country's List of municipalities in South Africa, second-largest ...

Description

The size of the specimens ranges from 34 mm in length (in the paratype) to 38 mm in length (in the holotype). All three specimens feature 18 pairs of legs, with the last pair reduced in size. Each leg features two claws, including the last pair of legs. The dorsal surface is dark brown, and the ventral surface is golden brown. Each surface features a consistent color, with no lines or variations in color visible. The species name is the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word for bronze, alluding to the bronze-like ventral surface of this velvet worm. The

integument In biology, an integument is the tissue surrounding an organism's body or an organ within, such as skin, a husk, Exoskeleton, shell, germ or Peel (fruit), rind. Etymology The term is derived from ''integumentum'', which is Latin for "a coverin ...

of this species features primary dermal papillae that are densely packed, with deep ridges between papillae structures. The dermal papillae are conical, with fifteen scale ranks on the dorsal primary papillae and nine scale ranks on the ventral primary papillae. This velvet worm exhibits traits shared with other species of ''Peripatopsis'', such as the reduced size of the last leg pair. The species ''P. aereus'' shares more traits with the sympatric species ''P. lawrencei''. For example, both species feature two claws on each foot, including the feet on the last leg pair. Several other traits, however, distinguish ''P. aereus'' from ''P. lawrencei''. For example, the species ''P. lawrencei'' always has 17 pairs of legs, whereas ''P. aereus'' has 18 leg pairs. Furthermore, the species ''P. lawrencei'' features only seven scale ranks on the dorsal papillae and only four on the ventral papillae, markedly fewer than observed in ''P. aereus'', which features fifteen on the dorsal papillae and nine on the ventral papillae. Moreover, the ventral surface of ''P. lawrencei'' is usually cream white but is sometimes pale orange or yellow. Thus, the consistent golden brown of the ventral surface of ''P. aereus'' also distinguishes this species from ''P. lawrencei''.

Phylogeny

The molecular evidence places ''P. aereus'' on a branch in a phylogenetic tree with a

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

that includes the three species '' P. capensis'', '' P. sedgwicki'', and '' P. moseleyi'', each in a separate

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

corresponding to an associated

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

within this sister group. The sympatric species ''P. lawrencei'', for example, appears in the clade corresponding to the ''P. capensis'' species complex. The molecular data suggest a relatively ancient origin of ''P. aereus'', with this lineage diverging from its sister group an estimated 13.68 million years ago, in the

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

epoch.

References

{{Taxonbar, from=Q130624817 Endemic fauna of South Africa Onychophorans of temperate Africa Onychophoran species Animals described in 2024