Symphytognathidae Hickman 1931
Creators: name: Miller, Jeremy
name: Griswold, Charles
name: Yin, Chang
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Symphytognathidae

description: Family Symphytognathidae Hickman, 1931 Symphytopgnathids are typically characterized by cheliceral fusion, a sternum broadly truncated posteriorly, reduction of the female palp and eye number, and the absence of book lungs (Forster and Platnick 1977, Wunderlich 2004). However, some sym- phytognathid genera have the chelicerae fused only at the base (e.g., <i>Patu</i>, <i>Curmagua</i> Forster and Platnick 1977) and the distinction between basally fused chelicerae and unfused chelicerae can be subtle. The remaining characters are present in other symphytognathoid families so enumerating synapomorphies for the family is problematic. At least the symphytognathid species described here also share with anapids an insertion of the pedicel on the posterior slope of carapace (as typically associated with Anapidae; e.g. Jocqué and Dippenaar-Schoeman 2006) rather than the pleural region between carapace and sternum. Epiandrous gland spigots, present in theridiosomatids, mysmenids, and synaphrids, are absent from anapids and symphytognathids. <i>Crassignatha</i> is the only symphytognathid in which the male has an abdominal scutum, a trait more typical of Anapidae. The presence of a single tooth-like keel on the chelicerae and the lack of a fang furrow has been used in part to diagnose Synaphridae (Lopardo et al. 2007, Miller 2007). Some <i>Patu</i> (Fig. 69 E-F) and <i>Crassignatha</i> (Fig. 78A) species exhibit these same characteristics. Another character of possible interest for circumscribing Symphytognathidae concerns the situation of the aggregate gland spigots on a common base (Figs 71D, 85D, 92D; Griswold et al. 1998: figs 35D, 36D). The presence of a colulus is homoplasious within some symphytognathid genera (Forster and Platnick 1977). A colulus is absent at least from <i>P. jidanweishi</i> and <i>Crassignatha</i> (investigated in <i>C. quanqu</i> sp. n. and <i>C. longtou</i> sp. n.). Some other <i>Patu</i> species do have a small colulus (e.g. Griswold et al. 1998: figs 23A, 37A). The symphytognathid species described here are placed in the genera <i>Patu</i> and <i>Crassignatha</i> Wunderlich, 1995. <i>Patu</i> is a particularly problematic genus. Comparative anatomy of the genitalia across the genus has been rudimentary, a problem exacerbated by the scarcity of material in collections and the minute size of these animals. In practice, <i>Patu</i> are symphytognathids with minimal fusion of the chelicerae and 1-3 teeth (Forster 1959, Forster and Platnick 1977, Saaristo 1996). However, at least two of the <i>Patu</i> species described here have a distinctive cluster of 2-4 strong setae on the distoventral part of the male tibia II. Similar structures have been described for <i>Patu samoensis</i> Marples, 1951 and are found in <i>Crassignatha</i>. <i>Crassignatha</i> was cataloged in the Mysmenidae, apparently based on the presence of cymbial lobes and mating claspers. However, the distal cymbial tooth found in <i>Crassignatha</i> does not interact with the embolus as a functional conductor, as is typically the case in mysmenids. Also, the mating claspers in <i>Crassignatha</i> are on the distoventral part of tibia II; mating claspers in Mysmenidae are always found on the prolateral face of metatarsus and/or tibia I. <b>Diagnosis.</b> Symphytognathidae distinguished from other spider families in the Gaoligongshan except Anapidae by the following combination of characters: the lack of a female pedipalp (Fig. 70C) and male epiandrous gland spigots (Fig. 78E), and by the insertion of the pedicel through an opening in the posterior declavity of the carapace (Fig. 65B, 74B); distinguished from Anapidae by the fusion of the chelicerae at least at the base (Figs 69F, 78A) and by having the aggregate gland spigots arise from a common base (Figs 71D, F, 92D). Like Anapidae and unlike most other spiders, Symphytognathidae typically have the tarsi longer than the metatarsi (Figs 74E, 83E), but the tarsi are rarely as much as 1.5 times the length of the metatarsi.
description: Published as part of <i>Miller, Jeremy, Griswold, Charles &amp; Yin, Chang, 2009, The symphytognathoid spiders of the Gaoligongshan, Yunnan, China (Araneae: Araneoidea): Systematics and diversity of micro-orbweavers, pp. 9-195 in ZooKeys 11 (11)</i> on pages 61-62, DOI: 10.3897/zookeys.11.160, http://zenodo.org/record/576459
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