Lycosoidea is a

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, ...

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

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 cl ...

spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

s. The traditional

circumscription Circumscription may refer to: *Circumscribed circle *Circumscription (logic) *Circumscription (taxonomy) * Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthrop ...

was based on a feature of the eyes. The tapetum is a reflective layer at the back of the eye, thought to increase sensitivity in low light levels. Lycosoids were then defined by having a "grate-shaped" tapetum. Research from the late 1990s onwards suggests that this feature has evolved more than once, possibly as many as five times, so that the original Lycosoidea is

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 ...

. Studies published in 2014 and 2015 suggest that a smaller group of families does form a clade. The reflective attributes of the tapeta vary significantly betwixt lycosoid spiders.

Phylogeny

The

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

of the Lycosoidea and related groups has been studied using both morphological and molecular data. Comparing these studies is complicated by the redrawing of family boundaries. Thus potential lycosoid genera placed in the family

Miturgidae Miturgidae is a family (biology), family of Araneomorphae, araneomorph spiders that includes nearly 170 species in 29 genus, genera worldwide. First described by Eugène Simon in 1886, it has been substantially revised, and includes the previous f ...

in 1993, such as '' Uliodon'', have since been placed in the Zoropsidae. The family Ctenidae, placed in the Lycosoidea in many analyses, has been reduced by moving some genera into the new family

Viridasiidae This page lists all described species of the spider family Viridasiidae accepted by the World Spider Catalog The World Spider Catalog (WSC) is an online searchable database concerned with spider taxonomy. It aims to list all accepted families, g ...

. The "classical"

of the Lycosoidea was based on the possession of a grate-shaped tapetum in some or all of the indirect eyes. In 1993, Griswold concluded that the Lycosoidea so defined was monophyletic, although some of the lycosoid families (as then circumscribed) were not. (See the table below for the families included in this and later studies.) Stiphidiidae was later excluded from the Lycosoidea. Later studies have recovered a version of Lycosoidea as a

monophyletic 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 gro ...

group, although with varying compositions and placements within clades. Ramírez, as part of a study primarily directed at dionychans, suggested that a reduced Lycosoidea, consisting of only five families, was monophyletic. Ctenidae and Zoropsidae were excluded from the lycosoid clade. (Trechaleidae was not included in the study.) An alternative hypothesis explored by Ramírez also placed Thomisidae in the Lycosoidea. Polotow et al. (2015) concluded that a seven-family Lycosoidea was monophyletic. Of the "classical" lycosoid families, they put back Ctenidae left out by Ramírez (although saying that the family is not monophyletic), but additionally excluded Senoculidae. They supported Ramírez' alternative of placing Thomisidae in Lycosoidea. Lycosoid families are located within the large

RTA clade The RTA clade is a clade of araneomorph spiders, united by the possession of a retrolateral tibial apophysis – a backward-facing projection on the tibia of the male pedipalp. The clade contains over 21,000 species, almost half the current total ...

of araneomorph spiders. Within this clade, Polotow et al. place them within a "grate-shaped tapetum clade", with the family Zoropsidae as their sister:

References

Bibliography

* * {{Taxonbar, from=Q54901 Araneomorphae Arachnid superfamilies