Description of a new species of the genus Laelaspis Berlese (Acari, Mesostigmata, Laelapidae) from Iran

Abstract A new species of the genus Laelaspis Berlese, Laelaspis elongatus sp. n. is described based on adult female and male specimens collected in association with Pheidole pallidula (Nylander) (Hym., Formicidae) in Ahwaz, Khuzestan Province, southwestern Iran, and also Acinopus (Acinopus) picipes (Olivier) (Col., Carabidae) in Bam, Kerman Province, southeastern Iran.

The original description of Laelaspis was very poor. Although Hunter (1961) reviewed the genus and some authors tried to clarify its boundaries since Hunter's (1961) work (Evans and Till 1966, 1979, Bregetova 1977, Joharchi et al. 2011, the genus diagnosis was not clear. Recently, Kazemi (2015) reviewed the concept of Laelaspis, presented its generic diagnosis and detailed diagnosis, and considered the genus to include 40 described species of usually myrmecophilous mites, although some species occur in different habitats such as free-living in soil, litter and moss, or associated with beetles, and mammals or their nests (Berlese 1903, 1904, 1920, Evans and Till 1966, Lapina 1976, Hunter 1961, 1962, 1964, Hunter and Davis 1962, Hunter and Glover 1968, Joharchi et al. 2012a. Until now 13 species of Laelaspis have been reported from Iran, including seven new species found mostly in association with ants, but also rarely in soil and litter (Faraji et al. 2008, Joharchi et al. 2012a, b, Babaeian et al. 2013, Kazemi and Rajaei 2013, Ramroodi et al. 2014, Kazemi 2015. Herein, we follow Kazemi's (2015) diagnosis of the genus and describe a new species of Laelaspis from Iran.

Material and methods
Mite specimens of the new species were removed from under elytra of a beetle host, Acinopus (Acinopus) picipes (Olivier, 1795) (Col., Carabidae) in Bam County, Kerman Province, southeastern Iran, and also associated with an ant host, Pheidole pallidula (Nylander) (Hymenoptera, Formicidae) in Ahwaz County, Khuzestan Province, southwestern Iran. Mite specimens were cleared in Nesbitt's fluid and then mounted in Hoyer's medium on microscope slides before examination.
Morphological observations, measurements and illustrations were made using compound microscopes (Olympus BX51) equipped with differential interference contrast and phase contrast optical systems, and a drawing tube. Figures were prepared using Microsoft Office Powerpoint 2003 based on scanned line drawings. Measurements were made in micrometers (μm). Dorsal shield length and width were respectively taken from the anterior to posterior shield margins along the midline, and from the lateral margins at the broadest level between setae j6-J1. The length of sternal shield was measured from the anterior to posterior margins of the shield along the midline, and its width at the lateral margins at the levels of setae st2 and st3. The length of genitiventral shield was taken from the anterior margin of the hyaline extension to the posterior margin of the shield along the midline and also from the level of setae st5 to the posterior tip of the shield; shield widths were taken at the level of st5 and also at the broadest points. The anal shield length and width were measured along its midline from the anterior to posterior margins, including the cribrum, and at the broadest point, respectively. The leg lengths were taken dorsomedially from the base of the coxa to the apex of the tarsus, excluding the ambulacrum (stalk, claws and pulvillus). The length of the second cheliceral segment was measured from the base to the apex of the fixed digit, and its width at the broadest point. The length of the fixed cheliceral digit was taken from the dorsal poroid to the apex, and that of the movable digit from the base to apex. The notation for idiosomal setae follows that of Lindquist and Evans (1965) adapted by Till (1965, 1966) and Lindquist (1994), and that for leg and palp setae follows Evans (1963aEvans ( , 1963b. The notation for idiosomal pore-like structures as gland pores and poroids follows mostly Athias-Henriot (1971, 1975, adapted by Kazemi et al. (2014). Kazemi (2015) indicated in the diagnosis of the genus Laelaspis that the genitiventral shield bears at least two pairs of setae on its lateral margins, always including st5 and JV1. Herein, based on Evans and Till (1965) and also Lindquist (1994), we consider that st5 and ZV1, not JV1, are the two 'core' setae always inserted on the genitiventral shield of Laelaspis species, and that the arrangement of opisthogastric setae in members of the genus is similar to that of the new species illustrated herein.

Taxonomy
Genus Laelaspis Berlese, 1903 Type species. Laelaps astronomicus Koch, 1839 Diagnosis. The genus diagnosis of Kazemi (2015) was followed. Diagnosis (adult male and female). Dorsal shield relatively elongate, ratio of length/ width of shield≈1.7, with 39 pairs of setae, including Px2-3, and three unpaired setae Jx, setae mostly subequal in length and relatively short, usually not reaching to following seta base, j1 and z1 shortest, subequal and lanceolate, situated subventrally, J5 and Z5 short, ratio of J5/Z5 length≈1.5. Sternal shield of female with lineate-reticulate ornamentation on anterior and lateral surface, ratio of shield length/width (at st3 level) ≈ 0.9; subequal sternal setae shorter than distance to following seta base. Genitiventral shield of female longer than wide, ratio of length/width (at broadest level) ≈ 1.9, shield bearing two pairs of smooth setae, st5 and ZV1. Anal shield almost as long as wide (slightly wider than long in specimen removed from beetle host); circumanal setae smooth, postanal seta slightly shorter than para-anals. Opisthosomal membrane in female with 17 pairs of setae, 13 pairs in male. Peritrematal shields well developed, hind edge of shield not reaching to posterior edge of subtriangular parapodals. Peritremes long, reaching to anterior level of coxae I. Epistome with smooth and subtriangular anterior margin. Subcapitular setae h3>h1>cs>h2. Movable and fixed cheliceral digits in female bidentate; fixed and movable digits of male chelicera each with an acuminate weakly sclerotised apical projections, fixed digit with a prominent tooth (apical hook), movable digit thickened, unidentate, spermadactyle finger-like, slightly shorter than movable digit, parallel with an acuminate protrusion inserted below it. Leg chaetotaxy normal for genus, including nine setae on genua IV and 10 setae on tibiae IV, setae mostly simple and slender or slightly thickened, except following setae: pv1 on femur I, pv on genu I, pv and pd2 on tibia I thickened; pd2 on femur I short and spine-like. Seta pv1 in femura II of male thicker than those in female.
Remarks. The new species, L. elongatus sp. n., can be easily distinguished from other members of the genus by combination of three unique characters: (1) postanal seta slender and slightly shorter than para-anal setae (thicker and longer than paraanals in other described species, except L. kamalii Joharchi et al. 2012  (2) length/width ratio of the genitiventral shield in the new species almost 1.9 (the ratio less than 1.6 in other described species); (3) male chelicera with pointed and fine projections on the fixed and movable cheliceral digits, as those in figure 8 (without these projections in other described species).

Discussion
The genitiventral shield in Laelaspis species is often longer than wide, and the length/ width ratio at the broadest level of the shield is usually between 1-1.5 (in L. aviator Berlese, 1920 andL. volgini Shereef andAfifi, 1980 wider than long), but in L. elongatus sp. n. this ratio is almost 1.9. On the other hand, in some keys (Joharchi et al. 2012a, Ramroodi et al. 2014) L. secedens Berlese, 1920 has been separated from related species by its elongated genitiventral shield. We studied the photographs taken from slide 201/22 (the holotype of L. secedens) in the Berlese's collection in Florence, Italy, and also the measurements of the species: the body size length 432, width 288; the genitiventral shield length 211 and its width 141 in the broadest point (pers. comm. of R. Nanelli with senior author), giving a ratio of the length/width of the genitiventral shield in L. secedens≈1.5, a usual ratio within the genus. On the other hand, L. elongatus sp. n. can be easily distinguished from L. secedens by some more features like postanal seta in L. elongatus sp. n. fine and shorter than para-anals, but serrate, considerably thicker and longer than para-anals in the latter species, length ratio of Z5/J5 in the new species ≈ 0.75, but Z5/J5 ≈ 2 in L. secedens, JV5 almost as half-length of JV1 in L. elongatus sp. n., but JV5 almost as long as JV1 in L. secedens.
So far only two species of the genus have been reported in association with beetles, L. aviator and L. secedens. In this research, two female and one male specimens were found in association with an ant, P. pallidula, in Ahwaz County (southwestern Iran), but one specimen of the new species was also found under the elytra of a carabid beetle in Bam County (southeastern Iran). This is the third report of a Laelaspis species from a beetle.