Androlaelaps rotundus IN PARAGUAY 425 Androlaelaps rotundus FONSECA (ACARI: LAELAPIDAE) ASSOCIATED WITH AKODONTINE RODENTS IN PARAGUAY: A MORPHOMETRIC EXAMINATION OF A PLEIOXENOUS ECTOPARASITE GETTINGER, D.1 and OWEN, R. D.2 1Department of Biology, University of Central Arkansas, Conway, AR 72035 2Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131 Correspondence to: Donald Gettinger, Department of Biology, University of Central Arkansas, Conway, AR 72035, e-mail: [email protected] Received May 15, 1998 – Accepted November 20, 1998 – Distributed August 31, 2000 (With 4 figures) ABSTRACT A multivariate analysis of morphometric data suggests that the nominally pleioxenous ectoparasite, Androlaelaps rotundus, includes at least three distinct host-associated populations in Paraguay. Where multiple akodontine hosts occur sympatrically, each host species is accompanied by a morphologically distinct mite population. These host-mite associations were consistent across all localities, implying that A. rotundus is a complex of unrecognized species. Key words: ectoparasites, laelapidae, Androlaelaps, Eubrachylaelaps, akodontini, Akodon, Bolomys, Paraguay. RESUMO Androlaelaps rotundus Fonseca (Acari: Laelapidae) associada com roedores akodontinos no Paraguay: um exame morfométrico do ectoparasito pleoxeno Uma análise multivariada de dados morfométricos sugere que o ectoparasito pleixeno Androlaelaps rotundus, composto por distintas populações hospedeiro-associadas, no Paraguai. Quando múltiplos hospedeiros akodontinos ocorrem simpatricamente, cada espécie de mamífero é acompanhada por uma população morfologicamente distinta de ácaro. Estas associações hospedeiro-ácaro repetiram-se nos estudos realizados em diferentes localidades, mostrando que A. rotundus é um complexo de espécies críticas indistinguíveis. Palavras-chave: ectoparasitos, laelapidae, Androlaelaps, Eubrachylaelaps, akodontini, Akodon, Bolomys, Paraguai. INTRODUCTION reported in all ectoparasite surveys where akodontine rodents are present (Botelho & Williams, 1980; Castro The laelapid mite subgenus Eubrachylaelaps et al., 1987; Fonseca, 1958; Furman, 1972; Lareschi, Ewing occurs throughout the New World, 1996; Linardi et al., 1987; Linardi et al., 1991; Mares associated with peromyscine rodents in North et al., 1989; Mauri, 1964; Mauri & Capri, 1970; America and with akodontine rodents in Sout Whitaker & Dietz, 1987; Whitaker & Abrell, 1987), America. The subgenus is morphologically diverse and displays a pleioxenous association with a in Nort America, with seven species recognized number of different, but phylogenetically related, presently. In Sout America only one nominal species, akodontine hosts. Androlaelaps (Eubrachylaelaps) rotundus Fonseca, In Paraguay, akodontine rodents compose a is known. This widely distributed mite has been prominent component of the small mammal fauna. Rev. Brasil. Biol., 60(3): 425-434 426 GETTINGER, D. and OWEN, R. D. Many localities have more than one akodontine species, but most of the mites were taken from two species, and populations of A. rotundus may occur akodontines, identified as Zygodontomys pixuna on different host species at the same locality. We and Akodon arviculoides. Fonseca (1957) used a comparative approach to examine the concluded that A. rotundus is a highly variable hypothesis that populations of A. rotundus infesting mite species, capable of infesting multiple host different host species in the same region are mor- species. However, because Z. pixuna and A. phologically distinct. The study has three objectives: arviculoides are now synonyms of Bolomys (1) evaluate the utility of a simple set of characters lasiurus (Wilson & Reeder, 1993), Fonseca`s in describing morphological variation in A. rotundus, taxonomic decision to refer these specimens to a (2) examine the mite populations infesting different single species appears to have been justified akodontine hosts within and among localities, and biologically. Nevertheless, this conclusion may (3) evaluate the monotypy of A. rotundus. have influenced other taxonomists when they encountered mites on other akodontines. TAXONOMIC HISTORY AND HOST The diversity of the primary host group, the ASSOCIATIONS Akodontini, increases in both temperate and Andean habitats, and A. rotundus has been reported from Androlaelaps (Eubrachylaelaps) rotundus is a large number of different akodontine hosts in the associated strongly with South American rodents southern cone countries of Chile, Bolivia, Argentina, of the tribe Akodontini. Although many studies have Uruguay, and Paraguay. In a small collection of emphasized the broad host range of these mites, ectoparasites from Paraguay, Whitaker and Abrell including numerous records from non-akodontines, (1987) reported A. rotundus from Akodon nigrita prevalences and intensities of infestation support (Lichtenstein, 1929) and Akodon varius Thomas, the primacy of a biological relationship with akodon- 1902. In Argentina, Mauri & Capri (1970) noted the tine rodents. Problems inherent in the design of sur- specificity of association between A. rotundus and veys, sampling biases, and the instability of both hosts of the genus Akodon, including Akodon mammal and arthropod systematics, often make it azarae (J. Fischer, 1829), A. kempi (Thomas, 1917), difficult to gain a clear understanding of naturally A. obscurus Waterhouse, 1837 (= Bolomys occurring associations. For example, in Venezuela, obscurus), A. varius, and Akodon boliviensis Furman (1972) reported A. rotundus from seven tucumanensis (= A. spegazzinii Thomas). Lareschi species of sigmodontine rodents, two murine ro- (1996) reported a strong association betweem A. dents, a caviomorph rodent, a marsupial, several spe- rotundus and Akodon azarae in the province of cies of bats, and a bird. However, of a total of 772 Buenos Aires, Argentina. In Brazil, A. rotundus was mites, 719 (93%) were recorded from 70 individuals reported from Akodon cursor (Winge, 1887), from of the akodontine, Akodon urichi J. A. Allen & the Federal District (Mares et al., 1989) and the State Chapman, 1897. The importance of the association of Santa Catarina (Linardi et al., 1991). In addition, between Androlaelaps rotundus and Akodonurichi Bolomys lasiurus is a common akodontine in many is revealed clearly by a prevalence of 60 percent, and parts of central Brazil, and A. rotundus has been mean intensity of 10.27 mites per infested host in- reported from this host in the Brazilian State of Minas dividual. Gerais (Botelho & Williams, 1980; Linardi et al., 1987; Androlaelaps rotundus was first described Whitaker & Dietz, 1987), and the Federal District, near from an “unidentified wild mouse” in the State of Brasília (Mares et al., 1989). São Paulo, Brazil (Fonseca, 1935). Although the type host was not known, a series of topotypes MATERIAL AND METHODS (specimens from the same locality) of A. rotundus were collected from the akodontine Bolomys In an ongoing survey of small mammals in lasiurus (Lund, 1841) (Furman, 1955; Jameson, 1951). Paraguay, rodents and small marsupials are Later, when Fonseca (1958) examined a collection captured in live traps, and etherized and brushed of mites from small mammals surveyed by the for ectoparasites before they are prepared as National Plague Service in northeastern Brazil, he standard museum specimens. Ectoparasite sampling reported A. rotundus from a long list of host techniques are described in Gettinger (1992). All Rev. Brasil. Biol., 60(3): 425-434 Androlaelaps rotundus IN PARAGUAY 427 mite specimens used in this study were mounted analyses were conducted on these subsets individually in Hoyer’s medium, ringed in glyptal, separately, to detect patterns of host-related or and measured with a stage-calibrated ocular geographic variation within these groups of mites. micrometer. These analyses followed the same protocol des- The adult female mite was used in all cribed previously. morphometric analyses, because it is the most The 82 specimens of Androlaelaps rotundus abundant life stage in populations sampled from that were used in this study were collected from four the host mammal, and it is the stage upon which species of akodontine at 17 localities in nine Para- formal mite species descriptions are based. Thirty- guayan departments (Fig. 1). In the following listing eight continuous characters were chosen, of host specimens, the number preceeded by “TK” representing different parts of the laelapid body: is the field catalog number. One female mite was dorsal shield (two), dorsal chaetotaxy (eight), selected randomly from each host individual. Host gnathosoma (four), sternal shield (six), epigynial voucher specimens will be deposited in the Museo shield area (five), anal shield (five), peritreme (one), Nacional de Historia Natural del Paraguay, and the and legs (seven). See Appendix 1 for a list and Museum of Texas Tech University. descriptions of characters. Some characters were Locality numbers, names and descriptions are chosen because they have been used in the those that are being used uniformly in publications taxonomic literature as discriminators between taxa, pertaining to the “Mammals of Paraguay and their and others were added as descriptors of shape. Ectoparasites” project (Fig. 1). Each TK number is Mite specimens were selected randomly for a unique field catalog number that is associated measurement, but were included only if all 38 with a single primary specimen and with all materials characters could be seen clearly and measured.