Gaeolaelaps carabidophilus n. sp., a new mite species (Acari: Mesostigmata: Laelapidae) from carabid beetles (Coleoptera: Carabidae) from the Southern Ukraine

Gaeolaelaps carabidophilus n. sp., a new laelapine mite (Acari: Mesostigmata: Laelapidae) is described and illustrated based on females collected from Stenolophus mixtus (Herbst, 1784) (Coleoptera: Carabidae) on the north-western Black Sea coast (Ukraine, Odessa province). The new species differs from all congeners by the following combination of characters: dorsal soft cuticle hypertrichous, very short peritremes (reaching only to mid-coxa III), dorsal shield with only 39 pairs of setae, sternal shield with 3 pairs of lyrifissures.


INTRODUCTION
Gaeolaelaps is a large cosmopolitic genus of the laelapid mites, which currently includes approximately 100 described species (Walter and Moser, 2010). Halliday and Lindquist (2007) provided nomenclatural remarks on the use of the generic name Gaeolaelaps Evans and Till, 1966. The detailed review of the genus Gaeolaelaps Evans and Till, 1966 was provided by Beaulieu (2009).
During a study on mites associated with beetles in Ukraine, an undescribed species of Gaeolaelaps mite was found on carabid beetles Stenolophus mixtus (Herbst) living on the north-western Black Sea Coast (Ukraine, Odessa province). The purpose of this paper is to describe this new species of Gaeolaelaps.

MATERIALS AND METHODS
Host beetles were collected by using an ultraviolet lamp. Mites collected from beetles were mounted on slides in Hoyer's medium. Morphology of mites was studied with aid of a stereomicroscope Mikmed-1 Lomo with binocular head AU-12, ocular micrometer AM9-2 and camera lucida RA-7U 4,2. The morphological nomenclature follows Evans and Till (1979). Measurements are given in micrometers (µm) for the holotype and all paratypes (in parentheses, from minimum to maximum). Gaeolaelaps carabidophilus Trach n. sp. (Figures 1 and 2) Diagnosis -Body strongly swollen. Dorsal shield elongate oval, slightly narrowed posteriorly, with 39 pairs of setae, unpaired setae absent. Dorsal soft cuticle hypertrichous. Sternal shield with three pairs of lyrifissures. Epigynal shield narrow, with 7 (5 -8) cells in the posterior area delimited by two lines forming an inverted-V and elongated longitudinal cells in the anterior part. Peritremes very short (reaching only to mid-coxa III). Fixed digit of chelicerae with 4 (4 -6) teeth, movable digit with 2 large teeth.
Etymology -The new species is named "carabidophilus" referring to its association with carabid beetles.
Remarks -The new species belongs to the genus Gaeolaelaps (following the concept of genus as defined by Beaulieu (2009)), because it is characterized by dorsal shield with 39 pairs of simple setae, sternal shield longer than its width, presternal area weakly sclerotized, epigynal shield tongueshaped, ventral hypertrichy absent, tectum with anterior rounded and denticulate margin, six rows of deutosternal denticles, well-developed chelatedentate chelicerae and normal laelapid leg setation.
The new species differs from species of other laelapine mite genera associated with beetles (Coleolaelaps Berlese, 1914 and Hypoaspis Canestrini, 1884) by the absence of long setae on the dorsal shield and on some leg segments, number of dorsal setae and other characters (Joharchi and Halliday, 2011). Differential diagnosis. Gaeolaelaps carabidophilus Trach n. sp. differs from all congeners by the following combination of characters: • dorsal soft cuticle hypertrichous; • very short peritremes (reaching only to midcoxa III); • dorsal shield with only 39 pairs of setae; • sternal shield with 3 pairs of lyrifissures.
By the hypertrichous dorsal soft cuticle, Gaeolaelaps carabidophilus Trach n. sp. is similar to G. millipedus Rosario, 1981 andG. angustiscutatus (Willmann, 1951). It differs from the first species by shorter dorsal shield, longer dorsal setae, lack of unpaired setae on the dorsal shield, sternal shield with 3 pairs of lyrifissures, short peritremes (in G. millipedus, longer dorsal shield, shorter dorsal setae, dorsal shield with some unpaired median setae, sternal shield only with 2 pairs of lyrifissures, peritremes of normal length). G. carabidophilus Trach n. sp. differs from G. angustiscutatus by the shape of dorsal shield, longer dorsal setae, length of peritremes (very short in G. carabidophilus Trach n. sp. and of normal length in G. angustiscutatus), shape of the tectum and digits of the chelicerae (4 (4 -6) teeth on fixed digit, 2 teeth on movable digit in G. carabidophilus Trach n. sp., and about 10 on both digits in G. angustiscutatus).
Two more species of the genus Gaeolaelaps also have shortened peritremes -G. nolli (Karg, 1962) and G. similisetae (Karg, 1965). G. nolli also has chelicerae similar in shape to G. carabidophilus Trach n. sp. These species clearly differ from G. carabidophilus Trach n. sp. By the shape of dorsal shield (suboval in G. nolli and G. similisetae, elongate oval and slightly narrowed posteriorly in G. carabidophilus Trach n. sp.), shorter dorsal setae (for example, in G. nolli and G. similisetae dorsal setae j2 -4 not reaching to base of next row setae, in G. carabidophilus Trach n. sp. j2 -4 always reaching to base of next row setae), shorter peritremes (in G. nolli and G. similisetae, peritremes ending near the middle of coxae II, in G. carabidophilus Trach n. sp., peritremes ending near the middle of coxae III).
By the shape of dorsal shield, G. carabidophilus Trach n. sp. is also similar to a group of species which have dorsal shield tapering posteriorly (G. angustiscutatus, G. angusta (Karg, 1962), G. fishtowni Koehler andRuf, 1993, G. queenslandica Womersley, 1956). Females of G. angusta, G. fishtowni and G. queenslandica have peritremes of normal length, a large spur-like seta on femur II (only slightly thickened in G. carabidophilus Trach n. sp.) and lack dorsal hypertrichy. A comparison with G. angustiscutatus has been given above.
The morphology of the new species confirms the opinion of Beaulieu (2009) that many of arthropodassociated mites species have rare or unique characteristics of Gaeolaelaps.