Dictynidae, , Forster, 1970

Paquin, Pierre, Vink, Cor J., Dupérré, Nadine, Sirvid, Phil J. & Court, David J., 2008, Nomina dubia and faunistic issues with New Zealand spiders (Araneae), Insecta Mundi 2008 (46), pp. 1-6 : 2-3

Dictynidae

Linyphia decolora Urquhart 1894: 208 , no illustrations (now Dictyna urquhartii Roewer 1951: 454 ). Nomen dubium.

Linyphia decolora Urquhart 1894 was described from a single specimen from the Powell collection, no data or locality given. Upon examination of the type, Bryant (1933) transferred it to Dictyna and proposed that Dictyna nigella Dalmas 1917 was a junior synonym, a placement followed by Chamberlain (1946: 92) and Marples (1959: 358), but the latter noted that this synonymy was unlikely. Forster (1970: 130) rejected the synonymy under D. decolor without any justification and listed D. nigella as a junior synonym of D. cornigera Dalmas 1917 (now Arangina cornigera ).

Dictyna decolor was preoccupied by Westring (1861) and Roewer (1951) provided a replacement name for it: Dictyna urquhartii , under which it is still known today. Marples (1959) gave a detailed description and a rough illustration of the female epigynum (as Dictyna decolor ), but there was no indication that he examined the type. Marples (1959) noted that his description of D. decolor corresponded to D. nigella Dalmas 1917 , and that the descriptions of Dalmas (1917) and Urquhart (1894) were contradictory and thus doubted the synonymy of Bryant (1933), but still used D. decolor as the name of the species he described.

There are two possible explanations:

(Scenario 1) Marples (1959) examined Urquhart’s type and, therefore, his description is of D. urquhartii Roewer 1951 . Marples (1959) noted that in many characters, the species resembled other members of the Ixeuticus species group III that he described in the same paper [ Ixeuticus angustiae Marples (now Dunstanoides angustiae ), Ixeuticus nuntius Marples (now Dunstanoides nuntia ) and Ixeuticus vallus Marples (now Oparara vallus )], all currently placed in the Amphinectidae ( Forster and Wilton 1973) . In a revision of the New Zealand Dictynidae, Forster (1970) stated that all known New Zealand species are placed in three endemic genera, and did not make any reference to Dictyna or Dictyna urquhartii . Based on Marples’ statements, it is possible that Forster considered the species to belong to another family, probably the Amphinectidae , and did not mention it in his revision of dictynids. However, in a revision of New Zealand Amphinectidae, Forster and Wilton (1973) did not mention D. urquhartii either. Provided that the statements of Marples (1959) are correct, and that Forster and Wilton (1973) overlooked Dictyna urquhartii , this species would likely be a senior synonym of another species in the Amphinectidae .

(Scenario 2) Marples (1959) did not examine the type, and provided a description of a female specimen that he believed was conspecific. This seems likely as he stated that the female he examined was from Lake McKerrow , but did not mentioned the specimen belonged to the Powell collection, as Urquhart did. In this case, the description he gives cannot be used to clarify the identity of D. urquhartii .

We were able to locate the type specimen (under Linyphia decolora ) at CMNZ (see Nicholls et al. 2000), but the specimen is in very poor condition and the female genitalia are missing. Apparently, after Ray Forster left in 1956 (see Patrick et al. 2000), the collection at CMNZ went through a phase without proper curation and many specimens deteriorated (P.M. Johns pers. comm.). The type label did not include any locality data, which supports scenario 2 that Marples (1959) provided a description of a specimen he believed to be conspecific, otherwise he could not have provided a locality. In an attempt to investigate whether scenario 1 was possible, we tried to match Marples’ illustration (1959, fig. 9) of the female genitalia with Amphinectidae illustrations of Forster and Wilton (1973), but we were not successful; a few species may be a match, but we could not be certain enough to reliably recognize the species.

Therefore, we have reached the following conclusions: (1) while the type specimen of Linyphia decolora has been found and examined, it was unrecognizable due to its poor condition, even to the family level; (2) Marples’ (1959) description is not of D. urquhartii ; (3) the species described by Marples (1959) could be an amphinectid redescribed under another name; (4) the most recent work on New Zealand Dictynidae and Amphinectidae ( Forster 1970; Forster and Wilton 1973) both ignored D. urquhartii and it is doubtful that the species will ever be recognized or that it is known under another name [in which case, Marples’ (1959) D. urquhartii is a simple misidentification]; (5) Dictyna urquhartii is best considered a nomen dubium; (6) thus, there are no Dictyna in New Zealand.