The Eresoidea or eresoids are a group of

araneomorph The Araneomorphae (also called the Labidognatha) are an infraorder of spiders. They are distinguishable by chelicerae (fangs) that point diagonally forward and cross in a pinching action, in contrast to the Mygalomorphae (tarantulas and their ...

spiders that have been treated as a superfamily. As usually

circumscribed In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius. Not every polyg ...

, the group contains three

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...

Eresidae Velvet spiders (family Eresidae) are a small group (about 130 species in 9 genera) of spiders almost entirely limited to the Old World, with exception of a few species known from Brazil. In Europe some are commonly called the ladybird spiders ...

Hersiliidae Hersiliidae is a tropical and subtropical family of spiders first described by Tamerlan Thorell in 1869, which are commonly known as tree trunk spiders. They have two prominent spinnerets that are almost as long as their abdomen, earning them ano ...

and

Oecobiidae Oecobiidae, also called disc web spiders, is a family of araneomorph spiders, including about 100 described species. They are small to moderate sized spiders (about long combined head and body length, depending on the species. Larger ones tend to ...

. Studies and reviews based on morphology suggested the

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 the group; more recent gene-based studies have found the Eresidae and Oecobiidae to fall into different

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

s, placing doubt on the acceptability of the taxon. Some researchers have grouped Hersiliidae and Oecobiidae into the separate superfamily Oecobioidea, a conclusion supported in a 2017 study, which does not support Eresoidea.

Phylogeny

Some largely morphology-based phylogenetic studies that included the three families assigned to the Eresoidea supported their

, with the internal structure of the clade being as shown below. Eresoidea was placed as basal in the

Entelegynae The Entelegynae or entelegynes are a subgroup of araneomorph spiders, the largest of the two main groups into which the araneomorphs were traditionally divided. Females have a genital plate ( epigynum) and a "flow through" fertilization system; m ...

, with its precise position relative to the

Palpimanoidea The Palpimanoidea or palpimanoids, also known as assassin spiders, are a group of araneomorph spiders, originally treated as a superfamily. As with many such groups, its circumscription has varied. , the following five families were included: * A ...

, also basal, varying. In 2015, Jonathan A. Coddington summarized this as a trichotomy: Another summary phylogeny groups Eresoidea and Palpimanoidea into a single clade, sister to the "canoe tapetum clade" holding the remaining entelegynes. Other studies, particularly those using genetic data, have presented different views. A 2010 study of the phylogeny of entelegyne spiders separated Eresidae from Oecobiidae and Hersiliidae, placing the latter two in a superfamily Oecobioidea. In 2014, a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

was presented in which Eresoidea is similarly

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 ...

(shading marks Eresoidea families): A 2014 study based on a larger portion of the spider

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

than any previous study also separates the Eresidae and the Oecobiidae (Hersiliidae was not included) (eresoid families are again shaded): A 2017 study also did not support Eresoidea, agreeing with earlier studies in placing Eresidae away from Hersiliidae and Oecobiidae, which were grouped as Oecobioidae.

References

{{Taxonbar, from=Q54487 Araneomorphae Historically recognized spider taxa