Arenita Huber & Carvalho 2019, gen. n.

Arenita Huber & Carvalho gen. n.

Type species. Arenita fazendinha sp. n.

Etymology. The genus name is derived from the Latin arena = sand, and refers to the small size of the type species comparable to a grain of sand; gender feminine.

Diagnosis/Description. See diagnosis and description of single known species below.

Notes. The recent molecular phylogeny of Pholcidae (Eberle et al. 2018) placed this genus/species as sister to an undescribed species from Argentina (“Gen.n. MACN270”), and both among ‘basal’ Modisiminae. However, relationships among ‘basal’ Modisiminae were poorly resolved, so the closest relatives of Arenita (beyond “Gen.n. MACN270”) remain unknown. The new species described below and “Gen.n. MACN270” are unusual among Modisiminae in lacking an apophysis on the male palpal coxa, in having the PME and ALE very close together, in lacking a thoracic furrow; and in having the plesiomorphic set of ALS spigots (i.e. with 7–8 spigots on each ALS, see below; this character was not studied in “Gen.n. MACN270”). The latter character is only shared by the mysterious genus Priscula Simon, 1893 (Huber 2000), whose position within Modisiminae is far from clear (Huber et al. 2018). At the same time, Arenita fazendinha has several highly distinctive characters (see diagnosis below) that are not present in “Gen.n. MACN270”, justifying the creation of a new monotypic genus. The undescribed species “Gen.n. MACN270” will be treated in a separate paper together with further undescribed congeneric species present in Argentinean collections (M.A. Izquierdo, unpubl. data).