The first record of the genus Myrmozercon Berlese (Acari: Mesostigmata: Laelapidae) in the Neotropical region and a description of a new species

A new species of the mite genus Myrmozercon Berlese, 1902, Myrmozercon patagonicus n. sp., is described and illustrated based on adult females collected on ants, Camponotus sp., in Southern Chile (Patagonia). The new species differs from all congeners by the following combination of characters: dorsal shield hypotrichous; dorsal cuticle not hypertrichous; setae st1–st5 present; anal shield with circum-anal setae only; peritremes short; ventral soft cuticle hypertrichous; fixed and movable cheliceral digits edentate; epistome smooth; leg setation not hypotrichous. This new species represents the first Myrmozercon from the Neotropical region. A key to non-Palaearctic species of Myrmozercon is provided.


Introduction
The family Laelapidae comprises a multitude of morphologically and behaviourally diverse mites that are free living or associated with arthropods (including ants), mammals, or birds (Lindquist et al., 2009). Worldwide, this family comprises about 90 genera and 1300 species (Beaulieu et al., 2011).
During the study of arthropod-associated mites in the Chilean part of Patagonia, a new species of the genus Myrmozercon was revealed. The aim of this article is to describe this new species and to provide a key to non-Palaearctic species of Myrmozercon.

Materials and methods
Ants were sampled by suction and transferred into vials containing 96% ethanol. Mites from alcohol sediments were extracted and mounted in Hoyer's medium. Morphology of mites was studied with the aid of a compound microscope, a Mikmed-1 Lomo equipped with a binocular head AU-12, ocular micrometer AM9-2 and digital camera DCM900. The morphological nomenclature generally follows Evans and Till (1965). All pore-like structures, glandular openings (solenostomes) and poroids (lyrifissures) are named as pores. Dorsal setae were labelled according to the system of Lindquist and Evans (1965), although we stress that our designations are preliminary. Palpal and leg chaetotaxy follows Evans (1963aEvans ( , b, 1969. Measurements are given in micrometres (μm) for the holotype and paratypes (in parentheses, minimum to maximum). Lengths of shields were measured from the anterior to posterior shield margins along the midline. The length of the second cheliceral segment was measured from the base to the apex of the fixed digit. Length of legs was taken from the base of the coxa to the apex of the tarsus, excluding the ambulacrum.

Etymology -The name of a new species refers to its distribution in Patagonia.
Differential diagnosis -According to the presence of palpcoxal setae and setae st4, anal shield without anterolateral extensions, absence of hypotrichous leg setation and long legs, Myrmozercon patagonicus n. sp. belongs to the group of species referred to as "Myrmozercon sensu lato" by Joharchi et al. (2015).
By the hypotrichous dorsal shield, hypertrichous ventral soft cuticle and by its large size, M. patagonicus n. sp. is similar to M. antennophoroides (Berlese, 1904) Myrmozercon patagonicus n. sp. also differs from all congeners by the number setae on leg segments. The presence of 14 setae on femur I is also known in M. burwelli Shaw and Seeman, 2009, M. hunteri and M. rotundiscutum; the presence of 14 or 15 setae on genu I is unknown in other species. The presence of 10 setae on femur II is known in M. beardae, M. iainkayi Walter, 2003, M. iranicus Babaeian andNemati, 2014, andM. rotundiscutum. Seven setae on femur III occur in M. cyrusi Ghafarian and Joharchi, 2013, and M. hunteri (Hunter and Hunter, 1963) 5. Opisthonotal part of dorsal shield with 5 or 6 setae longer than others. Body length 561  (Berlese, 1916) (Hull, 1923) 9. Dorsal shield with no more than 30 pairs of setae. Coxae I-III with 2 setae; coxa IV with 1 -2 setae . . 13. Dorsal shield with 24-25 pairs of setae. Dorsal soft cuticle not hypertrichous, with about 5 pairs of setae. Ventral soft cuticle not hypertrichous, with about 9-11 pairs of setae. Femur II with 11 setae; genu II with 12 setae; tibia II with 10 setae; femur III with 6 setae; tibia III with 9 setae; femur IV with 6 setae; genu IV with 11 setae; tibia IV with 10 setae  Rosario and Hunter, 1988