A new species of Neoscirula (Acari: Cunaxidae: Coleoscirinae) from the Ozark Highlands (USA), with a note on biogeography

A BSTRACT — A new species of the family Cunaxidae, Neoscirula reticulata Skvarla n. sp. , is described from two locations in the Ozark Highlands of North America. The importance of biodiversity research in this understudied region is dis-cussed, as well as the biogeographic connection between the Interior Highlands and highlands of Mexico in relation to this species. Also, in concordance with recent advances in taxonomic procedures, both N. reticulata and all other described species of Neoscirula have been registered with Zoobank. A comprehensive list of these species, incorporating citations of their original description and Zoobank LSID numbers, is provided to aid future researchers. Images were created using digital illustration techniques designed to speed-up the description process and were subsequently deposited into Morphbank. Finally, an updated key to the adults of world species is included.


INTRODUCTION
Cunaxidae are predatory mites found in soil/litter, vegetation, vertebrate nests, agricultural settings, and stored products (Den Heyer 1977;Ferla and Moraes 1998;Grout and Ueckermann 1999;Gupta and Chattopadhyay 1978;Hughes 1976). These mites are well known for their raptorial, spineequipped palpi (except in the subfamily Bonziinae) that are used to grasp prey (Krantz and Walter 2009). Unlike Cunaxinae, which ambush passing prey with their long spiny palpi, Coleoscirinae (including Neoscirula) and Cunaxoidinae are active predators with shorter, less adorned palpi that search out less active prey, including nematodes (Den Heyer 1981;Krantz and Walter 2009;Walter, Hunt, and Elliot 1988;Walter and Kaplan 1991).
Twenty-five Neoscirula Den Heyer, 1977 are known worldwide. Only one species has been described from North America north of Mexico, N. kenworthyi Smiley, 1992, which is known only from the type locality in Maryland, USA.
This study marks the first Neoscirula recorded from the Ozark Highlands. The Ozark Highlands are a proposed area of hyperdiversity, comprising some of the oldest continuously exposed land worldwide. As a result, the Ozark Highlands have potentially served as refugia for species displaced by glaciation or flooding events throughout biological history (The Nature Conservancy, Ozarks Ecoregional Assessment Team 2003). Although many species found in the Ozarks are typical of midwestern North America, many are more characteristic of other continuously exposed refugia such as the southern Appalachian Mountains and Sierra Madre in Mexico. Furthermore, the Interior Highlands (including the Ozarks) is a proposed area of high endemism, with over 200 known endemics (Allen 1990;Redfearn 1986). Nevertheless, in comparison to other regions of suspected hyperdiversity, the region remains grossly understudied with unsettlingly few active researchers investigating basic questions about biogeography and species composition, especially with regard to arthropods (but see Moulton and Stewart 1996 [caddisflies], and Poulton and Stewart 1991 [stoneflies]).
The present work represents another steppingstone toward resolving this issue, and brings mites, a group well known for being both diverse and underrepresented, into the forefront of Interior Highland biogeographic and biodiversity research.

MATERIALS AND METHODS
Leaf litter samples were collected at two sites in the Ozark Highlands: Steel Creek in the Buffalo National River (Arkansas) and Hercules Glades Wilderness in the Ava-Cassville-Willow Springs ranger district of Mark Twain National Forest (Missouri). Both sites are Eastern mixed deciduous forest dominated by oak (Quercus) and hickory (Carya), although eastern red cedar (Juniperus virginiana L.) was also abundant at the Buffalo National River site. All samples were processed for three to seven days using modified Berlese-Tullgren funnels.
All specimens are mounted in Hoyer's medium. The holotype and three paratypes are deposited in the Acarology Collection at the University of Arkansas (ACUA). One paratype is deposited in the United States National Museum (USNM) and an-other paratype is deposited in the Ohio State University Acarology Collection (OSAL).
In accordance with recent efforts to make taxonomic information more attainable, both Neoscirula reticulata and all other known Neoscirula have been registered with ZooBank (http://www.zoobank.org/). A list of LSID numbers and descriptions is given with corresponding species in Table 1.
All line drawings were created digitally from montaged compound micrographs using the vector-based Adobe Illustrator CS5 and a Wacom Cintiq 21UX with touch sensitive, draw-onscreen capability. This process, described by Fisher and Dowling (2010), is designed to greatly speed the drawing process by eliminating paper steps. Line drawings have been submitted to MorphBank (http://www.morphbank.net).
All measurements are from type specimens and given in micrometers (µm). Body length is measured from the posterior limit of the idiosoma to the anterior edge of the propodosomal shield. Leg length is measured from the proximal edge of the trochanter to the distal end of the claw. Lengths are reported as the range recorded followed parenthetically by the median.

Neoscirula Den Heyer, 1977
Den Heyer (1977) erected Neoscirula to accommodate three African cunaxids. The genus was subsequently placed into Coleoscirinae (Den Heyer 1981). Smiley (1992) moved Neoscirula to Bonziinae based on seta hg1 being geniculate. Den Heyer and Castro (2008b) moved the genus back to Coleoscirinae, saying that hg1 is only bent and not truly geniculate. The authors agree with Den Heyer and Castro that Neoscirula should be placed in Coleoscirinae.
The palpi of Neoscirula are five-segmented and end in a strong claw, which is complemented with a tooth in some species; they extend to the tip of the hypognathum or slightly beyond. The palp tibiotarsus is short and cone-like. Four pairs of setae are present on the hypognathum (hg1-4); hg1 is longest and in some species bent at 90 degrees. Adoral setae present or absent.
A cheliceral seta is usually present near the digit, though may be absent. The propodosomal shield is weakly sclerotized and ill-defined. It is granulated or papillated; some species possess subcutic-ular reticulations. Coxal plates I and II may be separate or fused medially into a single sternal shield. Coxal plates III and IV contiguous on either side, restricted to area around trochanteral bases. Dorsal cupules im present laterad to e 1 ; ventral cupules ih present near h2, anal plates. All legs are shorter than body. The basifemur and telofemur are fused but retain the suture; each has a dorsolateral simple or spine-like seta. Ambulacral claws are smooth.

Diagnosis
Neoscirula reticulata Skvarla sp. nov. and N. baloghi Mejía-Recamier and Palacios-Vargas, 2007 can be distinguished from all other Neoscirula by a lack of a cheliceral seta and medially fused coxal plates I and II. N. reticulata can be distinguished from N. baloghi by the presence of reticulations on the chelicerae, as well as differences in leg setal complements as follows: genua II, 2 ats-5 sts; genua IV, 1 ats-5 sts.
Venter - (Fig. 2b). Coxal plates I and II well sclerotized, fine subcuticular granulation forming striations. Plates fused medially into a sternal shield with narrowly rounded posterior limit. Sternal shield bearing with 7 pairs of sts, sometimes capturing an extra pair of setae between coxae III. Coxal plates III and IV also well sclerotized and finely granulated. Coxae III with 3 sts, one of which may appear dorsal; coxae IV with 2 sts and 1 pcs. 3 pairs of setae on integument between coxae IV (not including pair sometimes captured by sternal shield). Granulae on integument form striations around coxae. Genital plates weakly sclerotized with 4 pairs of setae and 2 pairs of underlying genital papillae. Anal plates bearing 2 pairs of pseudanal setae (ps 1 and ps 2 ). Cupule ih present laterad to para-anal setae (pa).

Male and immatures
Unknown.

Etymology
This species is named for the distinctive reticulations on the chelicerae.

Material examined (all on slides)
Holotype: female, ex.
To the authors' knowledge, the present study represents the first attempt to implicate a mite, and perhaps any arthropod, as a representative of the Mexican-East North American affinity. The presumed low-dispersal capabilities and hyperdiversity of soil/litter dwelling organisms, as well as their underrepresentation in biogeographic studies, make them perfect candidates to address such questions.