Anapidae, Simon, 1895

Lopardo, Lara, Michalik, Peter & Hormiga, Gustavo, 2022, Take a deep breath … The evolution of the respiratory system of symphytognathoid spiders (Araneae, Araneoidea), Organisms Diversity & Evolution (New York, N. Y.) 22 (1), pp. 231-263 : 245

Anapidae

Anapidae is the largest symphytognathoid family, comprising 233 described species in 58 genera and including the subfamily Micropholcommatinae (World Spider Catalog, WSC, 2020). The respiratory system of Anapidae has been studied and partially or completely reported for quite a number of species belonging to 49 out of the 58 current genera ( Hickman, 1939a, 1944, 1945, 1979; Fage, 1937; Forster, 1958, 1959; Gertsch, 1960; Levi, 1957, 1967; Platnick & Shadab, 1979; Forster & Platnick, 1981, 1984; Platnick & Forster, 1986, 1989; Kropf, 1995; Ramírez et al., 2004; Rix, 2005; Lopardo & Hormiga, 2008, 2015; Rix & Harvey, 2010). Our findings and the published data suggest at least 14 different respiratory arrangements (Fig. 5, Table 1 and supplementary material), varying from anterior reduced book lungs and posterior simple or absent tracheae, to anterior tracheae and complex, simple, or even absent posterior tracheal system. The anterior tracheae/book lungs can be connected by a transverse duct or not connected, the tracheae extending into the prosoma or limited to the abdomen, and/or with spiracles connected to the epigastric groove or advanced and located near the pedicel. The respiratory system remains unknown for Borneanapis , Conculus , Crozetulus , Dippenaaria , Enielkenie , Forsteriola , Gaiziapis , Metanapis , and Sinanapis . Although it is out of our scope to perform a detailed review on the evolution of anapid respiratory system (a comprehensive phylogeny of the Anapidae that will allow for a more accurate account of their evolution is currently a work in progress by S. Kulkarni and G. Hormiga), we nevertheless preliminarily discuss the implications of the optimization of the respiratory system in the current phylogenetic hypotheses (see discussion below).