Redescription of Paracaropsis Travisi (Baker, 1949) (Trombidiformes: Cheyletidae), with Range Expansion, Additional Host Records
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Acarologia 54(3): 335–345 (2014) DOI: 10.1051/acarologia/20142135 REDESCRIPTION OF PARACAROPSIS TRAVISI (BAKER, 1949) (TROMBIDIFORMES: CHEYLETIDAE), WITH RANGE EXPANSION, ADDITIONAL HOST RECORDS, AND REEVALUATION OF CHEYLETID CHAETOTAXY BASED ON THE SEJUGAL FURROW Michael SKVARLA*, J. Ray FISHER and Ashley P.G. DOWLING (Received 15 April 2014; accepted 14 June 2014; published online 30 September 2014) Department of Entomology, 319 Agriculture Building, University of Arkansas, Fayetteville, Arkansas 72701, USA. ( * Corresponding author) [email protected], jrfi[email protected], [email protected] ABSTRACT — A lectotype and paralectotype are designated for Paracaropsis travisi, which is redescribed and illustrated. Specimens are reported from additional Laphria hosts in Michigan and leaf litter in Arkansas. After comparision of Nearc- tic and Palearctic specimens, the synonymization of Paracaropsis travisi (Baker, 1949) and Paracaropsis strofi (Samšiˇnák, 1956) is upheld. We also review the Grandjean System and reevaluate idosomal setal nomenclature in Cheyletidae based on the sejugal furrow. KEYWORDS — Acari; Acariformes; Prostigmata; Cheyletoidea INTRODUCTION (1970) reillustrated Paracaropsis travisi and syn- onymized P. strofi with it without giving explicit Cheyletidae are small (generally 400-700 µm) yel- reasons. low, orange, or brown mites (Volgin 1969). More Previous authors illustrated the dorsum and than 370 species are known from 74 genera. Many gnathosoma of Paracaropsis travisi only. Improved are free-living predators in leaf litter and soil, tree illustrations of the dorsum and gnathosoma, as well bark, stored food products, and bird, mammal and as detailed illustrations of the legs and the first illus- insect nests, though some are vertebrate and inver- tration of the venter are provided. Named setae are tebrate parasites or associates (Walter et al. 2009). labeled across all illustrations. In addition, P. travisi Species found on vegetation or in stored grain can is reported for the first time from multiple species be important predators of crop pests and graminiv- of Laphria (Diptera: Asilidae) in Michigan as well as orous mites (Hughes„1976; de Moraes et al., 1989). leaf litter in Arkansas. Volgin (1969) erected Paracaropsis for two species, Acaropsis travisi Baker, 1949 and Acarop- MATERIALS AND METHODS sis strofi Samšiˇnák,1956, which were collected in Georgia (U.S.A.) and Dˇeˇcín(Czech Republic) from Nearctic, including the lectotype and paralectotype a spiny lizard (Sceloporus) and bee-like robber flies of Paracaropsis travisi (Baker, 1949), and Palearctic (Laphria flava), respectively. Summers and Price specimens were examined. The holotype of P. strofi http://www1.montpellier.inra.fr/CBGP/acarologia/ 335 ISSN 0044-586-X (print). ISSN 2107-7207 (electronic) Skvarla M. et al. (Samšiˇnák,1956) could not be located as "[s]ome of 2010), with infracapitulum being historically fa- Samsinak’s slides survive, but many were presum- vored by cheyletoid workers (e.g., Swift, 1996; Di ably kept in his private collection. Nobody can trace Palma et al., 2009; Filimonova, 2010). Although them now" (Klimov, pers. comm. December 2012). both terms have been applied to a variety of taxa, Only Nearctic specimens were measured and re- subcapitulum is not only more common, it is the ported as future genetic work may resurrect P. strofi preferred term in several major mite references as a valid species. (e.g., Kethley, 1990; Walter et al., 2009). Therefore, All measurements are listed in micrometers: lec- in support of the recent trend to unite terminol- totype given, followed by range of Nearctic mate- ogy across mite taxa, we implement subcapitulum rial in parentheses. Range measurments are com- herein despite the historical use of infracapitulum posed of the one paralectotype, as well as 19 spec- with Chyletidae. imens from Arkansas and Michigan. Palaearctic Hypostome has sometimes been used synony- specimens were excluded from the measurements mously with subcapitulum, however it more accu- due to the possibility of P. strofi being resurrected in rately refers to the area of the subcapitulum anterior the future. Large stippling indicates unsclerotized to the oral opening and not to the entire structure arthrodial membrane. (Evans, 1992; Krantz, 2009). Specimens were mounted in Hoyer’s medium Within Cheyletidae, two pairs of relatively long and viewed using both phase and differential in- anterior gnathosomal setae have historically been terference contrast microscopy. Illustrations were referred to as adoral setae (ao1-2) (e.g., Goff, 1982; made from the lectotype with confirmation of struc- Bochkov and Klimov, 2005; Xia et al., 2011). Di tures on the Arkansas specimen by methods out- Palma et al. (2009), however, identified two pairs of lined by Fisher and Dowling (2010). minute setae at the anterior tip of the gnathosoma as the adoral setae. These minute setae are present The lectotype and paralectotype are deposited in in Paracaropsis travisi and are therefore identified as the National Mite Collection, National Museum of adoral setae. The homologies of the setae previ- Natural History, Smithsonian Institution, Beltsville, ously identified as ao1-2 and the subcapitular setae Maryland. The specimen collected in Arkansas is previously identified as n are unknown. We there- deposited in the Acarology Collection at the Univer- fore refer to them by position: dorsal subcapitular sity of Arkansas. The specimens collected in Michi- setae (ds, =ao2 of previous authors), ventral subca- gan and Russia are deposited in the Museum of Zo- pitular setae 1 (vs1, = ao1 of previous authors), and ology at the University of Michigan. ventral subcapitular setae 2 (vs2, = n of previous au- thors). TERMINOLOGY Idiosoma — Terminology for idiosomal struc- tures (i.e., setae and plates) across Acariformes An effort was made to implement terminology has been heavily debated and remains contentious. that is broadly accepted and used across acariform The dominant system used by most acarologists is mites, despite conventions among cheyletid work- called the Grandjean System, but this system is con- ers as some terms used in cheyletid literature are tested. In general, we follow Grandjean (1939, 1944) innacurate or synonymous with other terms used as implemented by Kethley (1990) for dorsal setae, more broadly across acariforms. We therefore fol- but with significant modifications discussed below. et al. low the suggestions outlined by Fisher (2011) The Grandjean System — Based upon his stud- et al. and expanded by Skvarla (2014), with some ies in comparative arachnology, van der Hammen modifications, which are outlined below. (1963) hypothesized that the acariform body com- Gnathosoma — Infracapitulum and subcapitu- prised 14-17 body segments (6 prosomal and 8-11 lum are synonymous (Evans, 1992; Dunlop, 2000; opsithosomal); he also proposed that the opistho- Jesionowska, 2003; Walter, 2005; Smit and Alberti, soma had overgrown the metapodosoma dorsally. 336 Acarologia 54(3): 335–345 (2014) Building upon van der Hammen’s ideas, Grand- ’proterosoma’ (body anterior to the sejugal furrow), jean (1970) proposed that the propodosoma is also even though the latter is more inclusive than neces- overtaken dorso-anteriorly by an outgrowth of the sary (i.e., ’proterosoma’ includes the gnathosoma). gnathosoma, which he termed ’aspidosoma’. Un- Since then, the sejugal furrow has been recoginized der this hypothesis, the opisthosoma contains ten as a key synapomorphy uniting acariform mites segments and begins immediately posterior to the with camel spiders (Solifugae) into a clade called sejugal furrow with the first segment ’C’. Dorsal se- Poecilophysidea (Dunlop et al., 2012), which is sup- tae are named according to their corresponding seg- ported by large molecular datasets (Dabert et al., ment, so that the setae on segment C are named 2010, Pepato et al., 2010) and characteristics of the c1, c2, c3, etc. Grandjean especially applied his hy- reproductive system (Alberti 1980a, b, 2000; Al- pothesis to Oribatida, although it was later adapted berti and Peretti, 2002; Klann et al. 2009). There- to Caeculidae (Coineau ,1974), and currently it has fore, as noted by Skvarla et al. (2014), terminol- gained popularity across disparate acariform taxa ogy focused on the sejugal furrow (i.e., ’protero- (e.g., Erythraeidae: M ˛akol,2010; Penthalodidae: soma’ and ’hysterosoma’) is no longer hypothesis- Jesionowska, 2010; Tydeidae: Kazmierski, 2008). independent, but is based on well-supported hy- Weigmann (2001) pointed out that there is no ev- potheses about acariform relationships. Therefore, idence for such overgrowths of the gnathosoma we continue with the suggestion of Fisher et al. and opisthosoma, and instead argued for reimple- (2011), with the modified rationale of Skvarla et al. mentation of Grandjean’s previous systems (since (2014), and herein use ’proterosoma’ when referring 1934) that acknowledged the dorsal appearance to the dorsal idiosoma anterior to the sejugal furrow of the podosma and therefore identified the first and ’hysterosoma’ when referring to the dorsal id- two segments posterior to the sejugal furrow as iosoma posterior to the sejugal furrow. metapodosomal. Recent studies by Barnett and ’Prosoma’ (podosoma + gnathosoma) has been Thomas (2012, 2013) investigating the embryology incorrectly used by some cheyletid workers (e.g., of the oribatid Archegozetes longisetosus Aoki, 1965 Volgin 1969) to refer to the body anterior of the further call into question the