Theridiosomatidae

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 : 246

Theridiosomatidae

This family of “large” symphytognathoids (their body length is usually over 1.5 mm) includes to date 133 described species in 19 genera. Curiously, although the first account on the symphytognathoid internal respiratory system was performed for a theridiosomatid more than a century ago ( Lamy, 1902) and given the relatively large amount of taxonomic literature available for this family (more than 80 references), merely nine publications describe in part (e.g., externally) or in more detail their respiratory configuration ( Pickard-Cambridge, 1894; Fage, 1937; Marples, 1955; Coddington, 1986; Song et al., 1999; Jocqué & Dippenaar-Schoeman, 2006; Labarque & Griswold, 2014; Lopardo & Hormiga, 2015; Prete et al., 2018). Furthermore, only four species in three genera are partially accounted for their internal respiratory system, as textual descriptions or illustrations: Theridiosoma gemmosum ( Lamy, 1902: fig. 47; Lopardo & Hormiga, 2015: fig. 123A), Theridiosoma lopdelli ( Marples, 1955) , Cuacuba mariana ( Prete et al., 2018: fig. 8C), and Chthonos quinquemucronata ( Fage, 1937) . The respiratory system of Coddingtonia euryopoides was scored in the morphological matrix of Lopardo and Hormiga (2015) but not illustrated. The typical theridiosomatid respiratory arrangement consists of two book lungs, and a posterior narrow tracheal spiracle adjacent to the spinnerets and opening into two seemingly median entapophyses and two single lateral tracheae restricted to opisthosoma. This arrangement is presumed to be invariant across the family. Our findings on Coddingtonia euryopoides reveal a similar posterior respiratory arrangement, but the presence of reduced book lungs ( Fig. 4c ), suggesting that the family might show some diversity in respiratory arrangements awaiting further investigation. Unfortunately, the respiratory system of the majority of theridiosomatids remains unknown.

Figures

Fig. 4 The respiratory system of symphytognathoid spiders. Dor- sal view. a Tasmanapis strahan (Anapidae), ARS with uncon- nected reduced book lungs and tracheal tubes arising from the leaves. b Patu-SYMP-001-DR (Symphytognathidae), overview of ARS and PRS, which con- sists of numerous tracheae. Note the single median entapophysis. c Coddingtonia euryopoides (Theridiosomatidae), overview of ARS and PRS. d Cepheia longiseta (Synaphridae), ARS with few tracheae and promi- nent transverse duct. Abbre- viations: aTt, anterior tracheal tubes; mE, median entapophy- sis; plT, posterior lateral tra- chea; rBL, reduced book lung; Sp, spermatheca; TD, transverse duct; Tt, tracheal tube