F the macroseta is fairly distinctive PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/20182574 from these of araneids, despite the fact that it is in the same position on the tarsus. A row of sustentaculumlike macrosetae occurs on metatarsus arsus 4 of Mongolarachne, which is similar to the comb of similarly shaped macrosetae in Deinopidae (Griswold et al. 2005, Fig. 141B; Coddington et al. 2012, Fig. 5f), although these macrosetae are weakly organized in Menneus (Griswold et al. 2005). In contrast, the macrosetae in the uloborid comb are short and sculptured (Opell 1979, plate 1A, C). In Nicodamidae, Megadictyna has sustentaculum-like macrosetae uniformly distributed, while in Nicodamus similar macrosetae are not arranged in a comb (Griswold et al. 2005). Some other araneoids have macrosetae on the fourth tarsus, but these are not sustentaculum-like (Griswold et al. 2005). Among the taxa bearing sustentaculum-like macrosetae, there seems to be a variation from these arranged in a loose row (Mongolarachne, Nicodamus), through these in a distinct comb (Megadictyna, Deinopis), to the single sustentaculum (araneids, nephilids), which is likely derived with respect to the others (Griswold et al. 2005; Kuntner et al. 2008). The reduction of the row or comb could be related to the loss of the cribellum and calamistrum. Tarsus 4 macrosetae: 0 row, 1 comb, 2 sustentaculum, 3 one or more, 4 absent; tarsus 4 macrosetae shape: 0 sustentaculum-like, 1 sculptured, 2 simple, 3 RP6530 custom synthesis absent. The calamistrum varies in number of rows of bristles, length, position on the metatarsus, and whether is it situated on a pinched ridge or a shallow depression. The calamistrum is situated in an excavation of the metatarsus in Uloboridae (Opell 2001, Fig. 2; Griswold et al. 2005, Figs. 142E and 145A) and adjacent to an excavation in Hickmania (Gertsch 1958, Fig. 44); it is on a ridge in Deinopidae (Peters 1992, Fig. 8d) and Megadictyna, and adjacent to a ridge in Thaida (Griswold et al. 2005, Fig. 144A) (also pers. obs. for all). Calamistrum bristles: 0 uniseriate, 1 biseriate, 2 triseriate, 3 absent; calamistrum position: 0 proximal 1 proximal 2 medial, 3 absent; calamistrum substructure: 0 none, 1 excavation, 2 ridge, 3 absent. The associated cribellum is poorly preserved, but the spinneret region is visible in the counterpart (Fig. 2e, Electronic supplementary material Fig. 2c). A wide, oval field of fine setae in front of the anterior lateral spinnerets (which are both rotated to the right) resembles a similar patchof fine setae in some other cribellates (e.g., Griswold et al. 2005, Fig. 103; Davies 1993, Figs. 2 and 3) and may represent a vestigial cribellar region. The tarsi of males of Filistatidae are slightly sinuous (Electronic supplementary material Fig. 3j), and these of hypochilid males are curved (Electronic supplementary material Fig. 3a,d; Doran et al. 2001, Fig. 1d). Male tarsi: 0 straight, 1 curved or sinuous. The elongate tibia of the male pedipalp of Mongolarachne is unusual in spiders but is similar to those of the primitive araneomorph family Hypochilidae (Forster et al. 1987; Lehtinen 1967, Figs. 146), some Tetragnathidae ( varezPadilla and Hormiga 2011), and the filistatids Filistata and Kukulcania, for example. However, in Ectatosticta, the tarsus is also greatly elongated and bears distinctive spines, whereas the pedipalp tarsus in Mongolarachne is very short, and the tibia of Ectatosticta does not bear the distinctive bristles seen in Mongolarachne (Fig. 2f). Elongation of the male pedipalp of the filistatid Kuku.
