Mites Parasitic on Australasian and African Spiders Found in the Pet Trade; a Redescription of Ljunghia pulleinei Womersley Peter Masan 1,2 *, Christopher Simpson 1 , M. Alejandra Perotti 3 , Henk R. Braig 1 1 School of Biological Sciences, Bangor University, Bangor, Wales, United Kingdom, 2 Institute of Zoology, Slovak Academy of Sciences, Bratislava, Slovakia, 3 School of Biological Sciences, University of Reading, Reading, United Kingdom Abstract Parasitic mites associated with spiders are spreading world-wide through the trade in tarantulas and other pet species. Ljunghia pulleinei Womersley, a mesostigmatic laelapid mite originally found in association with the mygalomorph spider Selenocosmia stirlingi Hogg (Theraphosidae) in Australia, is redescribed and illustrated on the basis of specimens from the African theraphosid spider Pterinochilus chordatus (Gersta ¨ cker) kept in captivity in the British Isles (Wales). The mite is known from older original descriptions of Womersley in 1956; the subsequent redescription of Domrow in 1975 seems to be questionable in conspecificity of treated specimens with the type material. Some inconsistencies in both descriptions are recognised here as intraspecific variability of the studied specimens. The genus Arachnyssus Ma, with species A. guangxiensis (type) and A. huwenae, is not considered to be a valid genus, and is included in synonymy with Ljunghia Oudemans. A new key to world species of the genus Ljunghia is provided. Citation: Masan P, Simpson C, Perotti MA, Braig HR (2012) Mites Parasitic on Australasian and African Spiders Found in the Pet Trade; a Redescription of Ljunghia pulleinei Womersley. PLoS ONE 7(6): e39019. doi:10.1371/journal.pone.0039019 Editor: Dirk Steinke, Biodiversity Insitute of Ontario – University of Guelph, Canada Received February 24, 2012; Accepted May 15, 2012; Published June 13, 2012 Copyright: ß 2012 Masan et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: These authors have no support or funding to report. Competing Interests: The authors have declared that no competing interests exist. * E-mail: peter.masan@savba.sk Introduction Close inspection of spiders often reveals mites associated with various body parts. Although these associations are most frequently reported from tropical spider families, mites are not uncommon on temperate spider species. Deutonymphs of Astigmata mites and Heterostigmata mites can be found phoretic on spiders; larvae of the Prostigmata families Erythraedae, Trombiculidae and Trombidiidae (chigger mites) can be parasitic on spiders, while Mesostigmata mites in the family Laelapidae often occur both as immature stages and adults on spiders [1–3]. Mites on spiders go back in time at least 50 Ma. Baltic amber shows phoretic and parasitic Acari together with jumping and cell spiders [4], [5]. In addition, free-living mites (Asigmata and Mesostigmata) can become a problem for captive tarantulas when high numbers start to occlude the moist surfaces of the book lungs [6]. The large number of saprophilous and predatory Mesostig- mata might overshadow the host-specific associations particularly between spider and mites of the mesostigmatic family Laelapidae. However, specific associations are well documented. For example, all life stages of Androlaelaps pilosus Baker (Laelapidae) can be found on the hexathelid spider Macrothele calpeiana (Walckenaer), the only European tarantula [7]. Here we report laelapid mites living on captive Pterinochilus chordatus Gersta ¨ cker, the Kilimanjaro mustard baboon spider. The laelapid genus Ljunghia includes species that have estab- lished close associations with various mygalomorph spiders in Indonesia [8,9], Malaysia [10], Australia [11–13], New Caledonia [14], Africa [15], and China [16]. It is assumed that they have developed obligatory parasitic relationships with their hosts [1]. To date, there is only one comprehensive review of Ljunghia, which includes a description of a new species from a Central American mygalomorph spider kept in captivity in Spain, a key for their identification and an enumeration of their host species [17]. Although there is no published record of an Ljunghia species from the British Isles, reports of mites parasitizing captive spiders is a common occurrence, often owing to contamination [17]. The presence of a seemingly Australian mite species on an African spider on the territory of the UK is interesting and might be either a consequence of the brisk business of tarantulas as pets including the wide-spread exchange of spiders among the breeders or an indication for a wider geographical distribution of Ljunghia. The main aim of this study was a morphological redescription of Ljunghia pulleinei. Detailed observations of the most important morphological features of this mite allowed to discern more details than those reported in the original descriptions [11]. Generally, the original description of Womersley does not include illustrations of diagnostic morphologies as well as important metric data of some idiosomal structures and setae. There is one redescription of this species, that of Domrow [12], based on specimens that differ in some characters, e.g. distinctly shorter idiosomal setae when compared with the type specimens. Inconsistencies in the descriptions of Womersley and Domrow are another good reason for the following redescription. PLoS ONE | www.plosone.org 1 June 2012 | Volume 7 | Issue 6 | e39019