thumb|right The Ischnocolinae are a problematic subfamily of tarantulas (family Theraphosidae). In 1892, Eugène Simon based the group, which he noted was only weakly homogeneous, on the presence of divided tarsal scopulae. This feature was later considered to be plesiomorphic (i.e. potentially inherited from an ancestor by multiple descendant groups), and both morphological and molecular phylogenetic studies have shown that, as traditionally circumscribed, the subfamily is not monophyletic. A much more narrowly defined Ischnocolinae sensu stricto was proposed in 2014. One of the authors of tha
thumb|right The Ischnocolinae are a problematic subfamily of tarantulas (family Theraphosidae). In 1892, Eugène Simon based the group, which he noted was only weakly homogeneous, on the presence of divided tarsal scopulae. This feature was later considered to be plesiomorphic (i.e. potentially inherited from an ancestor by multiple descendant groups), and both morphological and molecular phylogenetic studies have shown that, as traditionally circumscribed, the subfamily is not monophyletic. A much more narrowly defined Ischnocolinae sensu stricto was proposed in 2014. One of the authors of that proposal subsequently said that no further taxonomic changes should be considered until there had been a more comprehensive sampling of the subfamily. , the status of the Ischnocolinae remains unresolved.
== Taxonomy == In 1872, Anton Ausserer erected the genus Ischnocolus. Ausserer used the division of the scopulae on the tarsi of the third and fourth legs as a key characteristic. The subfamily Ischnocolinae was first described (as the group Ischnocoleae) by Eugène Simon in 1892. Following Ausserer's characterization of the genus, Simon used the divided tarsal scopulae as the defining characteristic of the group. However, Simon noted that "" (apart from this character .. the Ischnocoleae have hardly any common characteristics and they form a weakly homogeneous set). Doubts were expressed early on as to the validity of the divided tarsal scopulae as a defining characteristic. In 1895, R.I. Pocock said that it could be "nothing but a sign of immaturity". Young spiders have only fine hairs (setae) rather than scopulae. In successive moults, scopulae replace the setae in stages, so divisions at first present may disappear when the scopulae are complete at full maturity. In spite of these concerns, genera were continually added to the subfamily, so that in 1986, for example, Andrew M. Smith said the subfamily included 49 genera, although he regarded it as "ripe for sweeping revision". In his 1985 monograph on the Mygalomorphae, Robert Raven considered the divided tarsal scopulae to be a plesiomorphic character and the Ischnocolinae to be non-monophyletic, treating it as Theraphosidae incertae sedis. His key to the subfamilies of the Theraphosidae split genera that had been placed in the subfamily among three informal groups.
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