Two New Cave-Dwelling Species of the Short-Tailed Whipscorpion Genus Rowlandius (Arachnida: Schizomida: Hubbardiidae) from Northeastern Brazil, with Comments on Male Dimorphism Adalberto J. Santos1*, Rodrigo Lopes Ferreira2, Bruno A. Buzatto3 1 Departamento de Zoologia, Instituto de Cieˆncias Biolo´gicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil, 2 Departamento de Biologia, Universidade Federal de Lavras, Lavras, Minas Gerais, Brazil, 3 Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Perth, Western Australia, Australia Abstract Two new species of the arachnid order Schizomida, Rowlandius ubajara sp.nov. and Rowlandius potiguar sp.nov., are described based on both male and female specimens collected in caves from northeastern Brazil. Rowlandius ubajara is known only from the Ubajara Cave, in the state of Ceara´; R. potiguar is recorded from 20 caves of the Apodi Limestone Group, in the state of Rio Grande do Norte. A remarkable dimorphism in male pedipalp length is described and analyzed in R. potiguar. The distribution of male pedipalp length is clearly bimodal in the species, but the two male morphs (homeomorphic and heteromorphic) present some overlap in the sizes of this structure. Moreover, males show a steeper allometry in pedipalp length than females, indicating that this trait is under a different selective regime in males and in females. Citation: Santos AJ, Ferreira RL, Buzatto BA (2013) Two New Cave-Dwelling Species of the Short-Tailed Whipscorpion Genus Rowlandius (Arachnida: Schizomida: Hubbardiidae) from Northeastern Brazil, with Comments on Male Dimorphism. PLoS ONE 8(5): e63616. doi:10.1371/journal.pone.0063616 Editor: Donald James Colgan, Australian Museum, Australia Received November 4, 2012; Accepted April 3, 2013; Published May 22, 2013 Copyright: ß 2013 Santos 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: This study was financially supported by grants from Conselho Nacional de Desenvolvimento Cientifico e Tecnologico(CNPQ) (www.cnpq.br; Procs. 300498/2009–8) and Instituto Nacional de Cieˆncia e Tecnologia dos Hymenoptera Parasito´ides da Regia˜o Sudeste Brasileira (http://www.hympar.ufscar.br/) to AJS and CNPq (www.cnpq.br; procs. 477712/2006-1) to RLF. BAB was supported by the University of Western Australia through an International Postgraduate Research Scholarship (http://www.scholarships.uwa.edu.au/search?sc_view = 1&id = 454&page = 1&q = IPRS&s = 1&old_key = 0). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: [email protected] Introduction 54 species of the genus [2,6,7,8,9,10] occur in Caribbean islands, mainly Cuba, Jamaica and Hispaniola (see for instance The arachnid order Schizomida, the short-tailed whipscorpions, [11,12,13,14,15]). The genus is represented in continental South is represented in South America mainly in northern forested areas. America by one species in Venezuela (R. arduus Armas, Villareal & Besides its great diversity and broad distribution in Central Colmenares, 2009), one in the eastern Brazilian Amazonia (R. sul America and the West Indies, in the continental South America it Cokendolpher & Reddell, 2000) and another, recently described can be considered a poorly-known Amazonian group. Until very species from the northeastern Brazilian Atlantic Forest (R. recently, the only species known from southern parts of the linsduarteae Santos, Dias, Brescovit & Santos, 2008) [8]. In this subcontinent was Stenochrus portoricensis Chamberlin, 1922 [1,2], a study, two new species are described based on specimens collected widespread and synanthropic species. However, the scarcity of in cave habitats in northeastern Brazil. Most caves from which schizomid species outside the Amazonian forest can be attributed, specimens were retrieved are imbedded in the caatinga, a at least in part, to collecting bias. This happens because schizomids northeastern Brazilian, semi-arid biome [16], an unexpected occur mostly in poorly sampled habitats, like the soil leaf litter, habitat for a group mostly considered as a humid forest dweller. termite and ant nests, and caves [2,3]. Subterranean habitats in Several species of Rowlandius and other genera of schizomids are particular can harbor large schizomid populations [3], and are a known by the remarkable variation in the length of male pedipalp. promising source of undescribed species. Depending on the species, the length of the male pedipalp can Among South American countries, Brazil is known for its vary from approximately the same size as those of the female to up abundance of caves, which are scattered in several geological to three times as long (e.g. [11,15]). Authors describing species of formations [4]. Despite the richness of cave habitats, the Brazilian these genera usually discriminate males in two categories, namely subterranean fauna is mostly unknown [5], though it is currently homeomorphic males and heteromorphic males, for specimens attracting the interest of many biologists. with short and long pedipalps, respectively [11]. This classification The genus Rowlandius Reddell and Cokendolpher, 1995, the is based on the assumption that two discrete male morphs can be focus of this study, is a good example of how little is known about recognized based on the pedipalp size, relative to total body size. the schizomids and the cave fauna of Brazil. The majority of the Male dimorphism has been described for several groups of PLOS ONE | www.plosone.org 1 May 2013 | Volume 8 | Issue 5 | e63616 New Species and Male Dimorphism in Schizomida arthropods, like insects [17], crustaceans [18] and, among This parameterization was performed in SAS version 9.2 (SAS arachnids, spiders [19], mites [20], pseudoscorpions [21] and Institute 2004) with code kindly provided by J.M. Rowland and harvestmen [22,23]. This phenomenon has been attributed to C.R. Qualls. Finally, the likelihood of belonging to each male intrasexual selection pressures favoring a conditional strategy with morph was computed from the mixture models for each male different tactics for small and large males [24]. However, the based on their pedipalp length. detection of male dimorphism can be statistically challenging, Simple linear models were fitted to the allometric relationship especially when the differences between the morphs are subtle between pedipalp length and prosoma length for females and for [25]. For schizomids, no criteria have been proposed to each male morph separately, through standard major axis discriminate between homeomorphic and heteromorphic males, regression using package ‘lmodel2’ [34] in R version 2.14.2 [35]. and this distinction is generally based on small sample sizes, For this last step of the analysis, males were classified as usually no more than five or six specimens. In this study, we take homeomorphic or heteromorphic when their likelihood of advantage of a large sample of specimens to evaluate whether or belonging to one particular male morph (computed from the not it is possible to recognize discrete male morphs in one of the mixture models) was higher than 95%. Males with less than 95% newly described species. chances of belonging to either male morph were left out when adjusting the allometric relationships between pedipalp length and Materials and Methods prosoma length for homeomorphic and heteromorphic males. Specimens and Laboratory Procedures Nomenclatural Acts The specimens examined for this study were collected in several The electronic edition of this article conforms to the require- caves in two states in northeastern Brazil (Fig. 1) and were ments of the amended International Code of Zoological Nomen- deposited in the arachnid collections of Colec¸a˜o de Invertebrados clature [36], and hence the new names contained herein are Subterraˆneos de Lavras, Universidade Federal de Lavras, Lavras available under that Code from the electronic edition of this (ISLA, curator R.L. Ferreira); Colec¸o˜es Taxonoˆmicas da UFMG, article. This published work and the nomenclatural acts it contains Belo Horizonte (UFMG, A.J. Santos); Departamento de Zoologia, have been registered in ZooBank, the online registration system for Universidade de Brası´lia, Brası´lia (DZUB, P.C. Motta) and the ICZN. The ZooBank LSIDs (Life Science Identifiers) can be Instituto Butantan, Sa˜o Paulo (IBSP, D.M. Barros-Battesti). Field resolved and the associated information viewed through any collecting permits were issued to R.L. Ferreira by SISBIO/ CECAV (license n. 14783-1). Cave geographic coordinates were standard web browser by appending the LSID to the prefix obtained through CECAV’s database (available at http://www4. "http://zoobank.org/". The LSID for this publication is: (urn:l- icmbio.gov.br/cecav/index.php?id_menu = 228). Specimens were sid:zoobank.org:pub:4882594A-5176-4668-A8B3- illustrated in a Leica MZ12.5 stereomicroscope with a camera 20DFFDD4DA73). The electronic edition of this work was lucida and measured in an Olympus SZ40. Female genitalia were published in a journal with an ISSN, and has been archived and excised, temporarily mounted in slides with clove oil and is available from the following digital