SYNAPHRIDAE, Wunderlich, 1986

LOPARDO, LARA, HORMIGA, GUSTAVO & MELIC, ANTONIO, 2007, Spinneret Spigot Morphology in Synaphrid Spiders (Araneae, Synaphridae), with Comments on the Systematics of the Family and Description of a New Species of Synaphris Simon 1894 from Spain, American Museum Novitates 3556 (1), pp. 1-28 : 11

SPINNERET MORPHOLOGY AND WEBS IN SYNAPHRIDAE

Males and females of C. longiseta and S. saphrynis present one major ampullate spigot on their ALS that is separated from the piriform field by a weak furrow, and it is accompanied by a nubbin and a tartipore. In C. longiseta , the PI field presents few piriform spigots, the posterior one with enlarged and more distinctive base. Piriform spigots with different size bases seem to also occur in other spiders (Martín J. Ramírez, personal commun.).

The presence of only one spigot on the PMS of S. saphrynis and two morphologically similar PMS spigots in C. longiseta (not including the cylindrical spigot in females) suggest that these spigots are either minor ampullate silk gland or aciniform silk gland spigots, although these spigots do not necessarily serve the same silk glands in each species. A single spigot is also present in the two recently described Synaphris species and the new synaphrid genus from Madagascar, which has been assigned to a minor ampullate gland (Miller, in press), in which case it would be homologized to that of S. saphrynis as well. Unfortunately, external morphology alone is not sufficient to discriminate between these two spigot types. In the case of C. longiseta , the two PMS spigots most likely correspond to aciniform gland spigots, as the presence of two minor ampullate spigots in araneoid adults is rare. Also, the anterior chemosensory seta in the PMS of C. longiseta has been previously considered a median-anterior minor ampullate silk gland spigot ( Schütt, 2003), although its morphology is similar to the chemosensory seta on the female palp tip (see Lopardo and Hormiga, in press, fig. 12 ).

The PLS in both S. saphrynis and C. longiseta have two types of spigots in addition to the cylindrical spigot found only in females. If one of these two is an aciniform spigot, at least one spigot from the araneoid triad would have been retained. Consequently, the PLS retained the combination of either one aciniform plus one triad spigot (flagelliform or aggregate), or one aggregate plus flagelliform (a ‘‘triplet’’ of two spigots) and no aciniform. As is the case of the singular PMS spigot in Synaphris , external morphology alone is not sufficient to discriminate between these two spigot types.

The weak demarcation of the major ampullate field from the piriform field on the ALS of Synaphris saphrynis and Cepheia longiseta (coded as absent in Cepheia by Schütt, 2003; see also Miller, in press) contradicts the evidence supporting Synaphridae as a member of Araneoidea. Should the monophyly of Synaphridae and its current placement within Araneoidea hold, then Synaphridae would become the only araneoid family with a weakly demarcated major ampullate field (as proposed by Schütt, 2003), a condition that is common outside Araneoidea ( Griswold et al., 2005). Based on the morphology of PLS spigots, we could describe synaphrid spiders as having retained at least one of the three triad spigots on their PLS in both sexes.

The web of only one species of synaphrids has been reported. Synaphris lehtineni builds a small, thin sheet web underneath stones in hollow depressions where they live ( Marusik et al., 2005: 129). The web building behavior of S. lehtineni and the rest of synaphrid species is still unknown. The presence of only one AG and one FL spigot on the PLS has also been reported for the linyphiid Linyphia hortensis ( Schütt, 1995) , which spins a small sheet web composed in part by sticky silk (at least for juveniles, Benjamin and Zschokke, 2004), although the details of the sticky thread structure have not been studied. Given that one of the alternative interpretations of the PLS spigot composition in synaphrids is the retention of a triplet consisting of one AG and one FL spigot, then it is possible that these spiders also spin webs that include some kind of sticky silk.

Figures

Figs. 11–18. Synaphris saphrynis, n.sp. Male paratype, right leg I. 11. Prolateral view; 12. Tarsus and metatarsus, retrolateral view; 13. Femur, ventral view; 14. Same, detail at femoral spot area; 15. Tibia and patella, dorsal view; 16. Tarsus and metatarsus, dorsal view; 17. Detail of tarsus-metatarsus joint, dorsal view; 18. Same, prolateral view.