FNZ 64 - Pisauridae (Arachnida: Araneae) - Introduction
Vink, CJ; Dupérré, N 2010. Pisauridae (Arachnida: Araneae). Fauna of New Zealand 64, 60 pages.
(
ISSN 0111-5383 (print),
ISSN 1179-7193 (online)
;
no.
64.
ISBN 978-0-478-34722-7 (print),
ISBN 978-0-478-34723-4 (online)
).
Published 13 Jul 2010
ZooBank: http://zoobank.org/References/05FA0262-846F-4216-96B4-D5ED10D3A7D9
Introduction
Spiders of the family Pisauridae Simon, 1890 (nurseryweb spiders) are found worldwide and with 339 described species in 53 genera (Platnick 2009). Pisauridae appears to be a monophyletic family (Griswold 1993, Santos 2007), which is supported by two synapomorphies; an apical pseudosegment on the tarsi (Jocqué & Dippenaar-Schoeman 2007, Santos 2007) and a distal tegular projection on the male pedipalp (Sierwald 1990, Santos 2007). However, these characters have also been observed in other, closely related families (Sierwald 1990, Jocqué & Dippenaar-Schoeman 2007). It is possible to distinguish Pisauridae from other families by a combination of characters.
The eyes are in two rows; the anterior row consists of four small eyes, the posterior eyes are larger and the posterior eye row is strongly recurved. The posterior eyes have a layer of light-reflecting cells called the grate-shaped tapetum (Homann 1971), which is a synapomorphy for the superfamily Lycosoidea (Griswold 1993). Within the Lycosoidea, both Lycosidae Sundevall, 1833 and Trechaleidae Simon, 1898 have eye arrangements that are similar to pisaurids. However, trechaleids are found only in the Americas, have flexible tarsi and flattened eggsacs carried attached to the spinnerets. Lycosidae have larger posterior eyes in a more strongly recurved row, no retrolateral tibial apophysis on the male pedipalp, the eggsac is carried on the spinnerets of females, and the early instar spiderlings are carried on specialised setae on the dorsal surface of the female abdomen (see Vink 2002). New Zealand adult pisaurids are also much larger than adult lycosids.
Females of many pisaurid species carry their spherical eggsac in the chelicerae and by a thread from the spinnerets (Carico 2005). Shortly before the spiderlings are due to hatch females of some species build an elaborate web structure, called a nurseryweb, around the eggsac. The spiderlings hatch within the nurseryweb and spend at least the first instar inside. The construction of a nurseryweb has been suggested as a synapomorphy for the Pisauridae; however, nurserywebs have been observed in only a few pisaurid species and are also known in other spider families (Sierwald 1997). All New Zealand pisaurid species build a nurseryweb. The early instars of some pisaurid species disperse by ballooning on long buoyant strands of silk (Bell et al. 2005). As a result, some species may not be restricted by geographic boundaries. If they have particular habitat requirements, they can be restricted to local areas of suitable habitat despite being widely distributed (Carico 1973). Pisaurids are found in a wide range of habitats and some genera (e.g., Dolomedes Latreille, 1804, Megadolomedes Davies & Raven, 1980, Thalassius Simon, 1885) are most common near water (Davies & Raven 1980, Sierwald 1989b, Carico 2005), which they are able to move across (Davies & Raven 1980, Sierwald 1989b, Stratton et al. 2004) and dive under (Carico 1973, Davies & Raven 1980, Sierwald 1989b).
Pisaurids, like all spiders, are predators and their main prey is arthropods. Species that are common near water feed mainly on aquatic insects (Williams 1979). Using stable isotopes of carbon and nitrogen, Collier et al. (2002) determined that Dolomedes found alongside streams in the North Island of New Zealand obtained over half of their body carbon from aquatic production. Some pisaurid species will catch and feed on small fish (Carico 1973, Williams 1979, Zimmermann & Spence 1989, Carico 2005). Webs are used for prey capture in some pisaurid genera, such as Eurychoera Thorell, 1897, Inola Davies, 1982 and Polyboea Thorell, 1895 (Davies 1982, Zhang et al. 2004), but New Zealand pisaurids do not build a web for prey capture and are sit-and-wait predators (Williams 1979, Forster & Forster 1999). Some pisaurid species are nocturnal hunters and the eye physiology of Dolomedes is consistent with night-time activity (Blest & Day 1978). Sexual cannibalism has been studied in some Dolomedes species (Arnqvist 1992, Arnqvist & Henriksson 1997, Johnson 2001, Kreiter & Wise 2001, Johnson 2005, Johnson & Sih 2005). Males of the Palaearctic Pisaura mirabilis (Clerck, 1757), which is the type species of the family, offer females insect prey as nuptial gifts and feign death to avoid sexual cannibalism (Bilde et al. 2006, 2007, Hansen et al. 2008). Much of what is known about moulting in spiders is based on studies of P. mirabilis (Bonaric 1976, Bonaric & De Reggi 1977) and it is also one of the few spiders in which diapause has been examined (Dondale & Legendre 1970, 1971).
Dolomedes is the most speciose genus in the Pisauridae with 100 species (Platnick 2009). Lehtinen (1967) proposed the family Dolomedidae for Dolomedes and several other pisaurid genera, but the family has never been clearly defined and is not currently recognised (Jocqué & Dippenaar-Schoeman 2007, Platnick 2009). All of the eleven New Zealand pisaurid species that have been described so far are in Dolomedes. The first pisaurid to be described from New Zealand was Dolomedes mirificus Walckenaer, 1837; however, this species is considered nomen dubium (see below).
NOMEN DUBIUM
Dolomedes mirificus Walckenaer, 1837. Walckenaer (1837) described this species from an unspecified number of unsexed specimens collected from Australia and New Zealand. His description was not detailed enough for adequate identification (Walckenaer 1837) and the type was not located in the Muséum national d’Histoire naturelle, Paris (C. Rollard, pers. comm.). Unsuccessful attempts have been made to locate other type specimens of other New Zealand spiders described by Walckenaer (Court & Forster 1988) and his collection is believed to be lost (H.W. Levi, unpublished). Walckenaer (1837) did not specify where in Australia and New Zealand the specimens were collected from. The material he described was collected in early 1827 during the voyage of the French corvette Astrolabe (Forster 1967), which landed at localities in the north of the South Island (Astrolabe Bay, French Pass, D’Urville Island) and the North Island (Tolaga Bay, Whangarei, Waitemata Harbour, Bay of Islands) (Oliver 1951, Andrews 1986). Dolomedes minor, D. aquaticus, and D. dondalei can be found at or near all of these localities and all three species could have been found at some localities (e.g., Astrolabe Bay). The Astrolabe also landed at Port Jackson, Australia (Oliver 1951) but New Zealand and Australia do not appear to share any Dolomedes species (R.J. Raven, pers. comm.). Walckenaer’s (1837) description is not sufficient for adequate identification and we here consider D. mirificus as nomen dubium.
SPECIES NOT CONSIDERED PART OF NEW ZEALAND FAUNA
Dolomedes facetus L. Koch, 1876. Recorded from Australia (New South Wales and Queensland), Samoa, New Guinea, and New Zealand (Koch 1876, Chrysanthus 1967). In his description of D. facetus, Koch (1876) stated there were examples of this species in “Mr Bradley’s Sammlung [Collection]” from New Zealand. Chrysanthus (1967) examined Koch’s existing types and illustrated specimens from New Guinea. Chrysanthus’ (1967) illustrations are good and there are similarities to New Zealand species of Dolomedes. However, D. facetus is clearly different from any Dolomedes species found in New Zealand; therefore we believe either Koch (1876) incorrectly identified the specimens he mentioned from the Bradley Collection, which is considered almost completely lost (Framenau 2005), or there were specimens of D. facetus in the Bradley Collection that were incorrectly labelled as originating from New Zealand. Dolomedes facetus is here considered not part of the New Zealand fauna.