FNZ 70 - Periegopidae (Arachnida: Araneae) - Introduction
Vink, CJ; Dupérré, N; Malumbres-Olarte, J 2013. Periegopidae (Arachnida: Araneae). Fauna of New Zealand 70, 41 pages.
(
ISSN 0111-5383 (print),
ISSN 1179-7193 (online)
;
no.
70.
ISBN 978-0-478-34740-1 (print),
ISBN 978-0-478-34741-8 (online)
).
Published 7 Mar 2013
ZooBank: http://zoobank.org/References/E8D9D21A-46FD-4E6B-9E79-DBE67BAE57D1
Introduction
Periegopidae Simon, 1893 is a family of six-eyed spiders comprising only three species, all in the genus Periegops Simon, 1893. Two species are endemic to New Zealand and the other is endemic to Queensland, Australia (Forster 1995). Periegopids can be distinguished from other families found in New Zealand by a combination of characters. The six eyes are arranged in three, widely spaced diads. The chelicerae have a lamina on the ventral surface and the maxillae are slender and are more than twice as long as wide and directed across the labium. The anterior two pairs of legs have asymmetrical superior claws; the proclaw of legs I and II has a double row of teeth whereas the retroclaw has a single row (Forster 1995: fig. 11–13). There is also a field of spicules on the median surface of the posterior median spinnerets (Labarque & Ramírez 2012; fig. 21F, 22E) and the venom outlet is anterior on the fang (Labarque & Ramírez 2012; fig. 18A); both of these characters require high microscope magnification to see them.
Periegops suterii (Urquhart, 1892) was first described from a female and two immature males collected by the early New Zealand zoologist, Henry Suter, at Dyer’s Pass on the Port Hills near Christchurch (Urquhart 1892; Forster 1995). Urquhart placed his new species in a Northern Hemisphere genus and family; Segestria Latreille, 1804, and Dysderidae C.L. Koch, 1837, respectively. Shortly after, Simon (1893) erected the genus Periegops for his new species P. hirsutus, which he described from a female specimen sent to him at the Muséum national d’Histoire naturelle, Paris, from New Zealand. Although Simon (1893) did not specify the location where the specimen was collected from, it was likely that it was from Banks Peninsula (Forster 1995). The generic description was of a female and Simon (1893: 267) noted that the male was unknown; however, the description of P. hirsutus was listed as male although no male characteristics appear to be described (Simon 1893: 268). Bryant (1935a: 54) and Forster (1995: 92) noted that the listing as a male appears to be in error. Dalmas (1917: 338) also noted the specimen was female and this was the specimen seen by Chamberlain (1946). It is unlikely that Simon realised he had described the same species as Urquhart and P. hirsutus was later made a synonym of P. suterii by Chamberlain (1946). Simon (1893) was first to recognise that the genus Periegops was distinct from other genera and placed it in its own subfamily, Periegopinae Simon, 1893. Forster (1995) elevated the subfamily to family status when he described Periegops australia Forster, 1995 and redescribed P. suterii. Forster (1995: 96) also noted that he had examined a single female specimen collected at East Cape, but there were “no clear characters by which the species could be satisfactorily defined”; a male would need to be collected and the palpal bulb examined to determine if it was a separate species. Forster & Forster (1999) mentioned an additional specimen from the Aldermen Islands, which they believed to be a female, and Vink (2006) reported that he had sequence data from a fragment of the mitochondrial gene cytochrome c oxidase subunit 1 (COI) [specimen Pk1] that suggested that the North Island specimens were a distinct species.
Periegopidae is part of a group of spiders called the Haplogynae Simon, 1893, which are araneomorph spiders that lack separate fertilisation ducts, do not have a sclerotised epigyne and the male pedipalp is relatively simple. Haplogynae are a monophyletic group (Platnicket al. 1991; Ramírez 2000) that includes 17 families. Perigopids have a number of characteristics that are shared with the haplogyne families Diguetidae F. O. Pickard-Cambridge, 1899, Drymusidae Simon, 1893, Plectreuridae Simon, 1893, Scytodidae Blackwall, 1864, and Sicariidae Keyserling, 1880. These include a lamina on the ventral surface of the chelicerae, slender maxillary lobes directed across the labium, and a limited posterior respiratory system with fused apodemes (Forster 1995). Forster (1995) grouped this set of families, along with Periegopidae, into the superfamily Sicarioidea, but did not provide a formal definition of the superfamily. The name Sicarioidea was first used by Berland (1932) and Forster (1995) appears to be the only other arachnologist that has used it.
A more commonly used superfamily name that includes this set of taxa is Scytodoidea (Bristowe 1938; Caporiacco 1938; Brignoli 1978; Lehtinen 1986); however, Scytodoidea has been used to refer to a larger set of haplogyne families that has also included Caponiidae Simon, 1890, Leptonetidae Simon, 1890, Ochyroceratidae Fage, 1912, Pholcidae C. L. Koch, 1850, and Tetrablemmidae O. Pickard-Cambridge, 1873. A morphological phylogenetic analysis by Platnick et al. (1991) supports a clade informally named "scytodoids" (Coddington & Levi 1991) that includes Diguetidae, Drymusidae, Leptonetidae, Ochyroceratidae, Pholcidae, Plectreuridae, Scytodidae, Sicariidae, Telemidae Fage, 1913, and Tetrablemmidae. The monophyly of this clade is supported by the reduction of the posterior spiracles to one and the tetrahedral posterior median spinnerets (Platnick et al. 1991), although these characters have been reversed in some species in the clade (Platnick et al. 1991).
Ramírez (2000) examined the morphology of haplogyne respiratory systems and added characters to the data matrix of Platnick et al. (1991) to produce a phylogeny of the Haplogynae. Periegopidae was not included in the analyses but Ramírez (2000) stated that Periegopidae was sister to the Scytodidae. Periegopidae was also included in the scytodoid clade by Coddington (2005); its inclusion was presumably based on Forster (1995) and Ramírez (2000). Labarque & Ramírez (2007a, b) considered that among the scytodoids, Periegopidae was closest to Drymusidae and Scytodidae as they share two characters; asymmetrical superior claws on the anterior two pairs of legs and a field of spicules on the median surface of the posterior median spinnerets. More recently, Labarque & Ramírez (2012) expanded the morphological dataset of Platnick et al. (1991) and Ramírez (2000) to include Periegopidae along with a restricted Scytodoidea, which included Drymusidae, Scytodidae, and Sicariidae. Periegops, Drymusa, and Scytodidae formed a clade, which all shared the synapomorphies of asymmetrical superior claws and a field of spicules on the median surface of the posterior median spinnerets. Labarque & Ramírez (2012) concluded that Periegopidae was sister to Drymusidae, but they did not find any autapomorphies for Periegops and suggested that the two families might be synonymised.
Very little is known of the biology of periegopids. They are only found in forest with a deep leaf litter layer and well-drained soil. Specimens have been collected from under logs and rocks, in leaf litter, in pitfall traps, in rotted logs and root cavities, and in a mygalomorph burrow (Forster 1995; Vink 2006). Forster (1995) suggested that periegopids were rare as their habitat has been severely reduced due to human deforestation and only 21 Periegops specimens had been collected in New Zealand and Australia between 1891 and 1995. In surveys between October 2002 and May 2003, Vink (2006) found a further 24 specimens of P. suterii at ten different locations on the Banks Peninsula. Sirvid et al. (2012) classified P. suterii as having a relict distribution.
Periegops do not appear to build a web for prey capture, but do build silken retreats. It seems probable that periegopids are cursorial, night-time hunters as they have only been found on the forest floor, have been collected in pitfall traps and lack webs. On two occasions a single female has been found together with two or three males under logs and rocks (Forster 1995; Vink 2006), which implies that the female might possess some method of attracting males.