A new species of Reticulolaelaps Costa (Acari: Laelapidae) associated with Tapinoma sp. (Hymenoptera: Formicidae) from Iran, with a review of the world species

A BSTRACT — We describe a new mite species from Iran — Reticulolaelaps costai n. sp. (Acari: Laelapidae). The new species was collected from the nest of Tapinoma sp. (Hymenoptera: Formicidae) in Alborz Province. The additional morphological characters for complementing the description of Reticulolaelaps lativentris Karg is presented. A revised diagnosis for Reticulolaelaps , as well as a key to the world species of the genus, is presented.


INTRODUCTION
The genus Reticulolaelaps Costa, 1968 was first described from forest litter in Israel. This genus currently includes only three described species, Reticulolaelaps faini Costa, 1968, Reticulolaelaps lativentris Karg, 1978, and Reticulolaelaps hallidayi Joharchi, Nemati and Babaeian, 2013; two which were found in association with ants, the other one was found in soil and litter. Reticulolaelaps lativentris was transferred to the Pseudoparasitus Oudemans by Nemati et. al, 2013 which we confirmed here by examining the paratypes of that species. The genus Reticulolaelaps was first reported from Iran, in Isfahan province, associated with the bark of elm trees (Ghafarian et al., 2012). The most recent taxonomic work to the genus was by Nemati et al. (2013), who clarified the diagnosis of this genus. We now remove a species that has been wrongly placed in Reticulolaelaps, and move it into Pseudoparasitus Oudemans. We also describe a new species of Reticulolaelaps found in Iran and review the world records, and provide a key for identification of the species. Using these additional data, we redefine the genus Reticulolaelaps more precisely.

MATERIALS AND METHODS
Laelapidae were collected from ant nests mainly over a period of five years (2008)(2009)(2010)(2011)(2012)(2013)(2014), mainly in Alborz Province, Mites were removed from ants' nests by hand picking or by extraction from ant nest material using Tullgren funnels. Mites were cleared in Nesbitt's solution and slide-mounted in Hoyer's medium. The nomenclature used for the dorsal idiosomal chaetotaxy is that of Lindquist and Evans (1965), the leg chaetotaxy is that of Evans (1963a), the palp chaetotaxy is that of Evans (1963b), and names of other anatomical structures mostly follow Evans and Till (1979). We use the terms "lyrifissures" to refer to slit-shaped sensilli, "gland pores" to refer to structures that we believe are the openings of secretory pores, and "poroids" for circular or oval-shaped cuticular of unknown function. Holotype of the new species is deposited in the Acarological collection, Department of Plant Protection, Yazd Branch, Islamic Azad University (YIAU); paratype is deposited in the Jalal Afshar Zoological Museum, College of Agriculture, University of Tehran, Iran (JAZM). All measurements in the descriptions are given in micrometres (µm). Costa, 1968: 26. Type species: Reticulolaelaps faini Costa, 1968. Diagnosis -The genus is characterised by a well sclerotised hypertrichous holodorsal shield, convex dorsal shield and flat venter, and a large genito-ventral shield, strongly expanded posterior to coxae IV, abutting the anal shield, bearing six pairs of setae, with strong reticulated ornamentation. Pre-sternal absent; female sternal shield deeply concave in posterior margin and lateral corners extended to the posterior level of coxa III, with three pairs of simple sternal setae; endopodal shields between coxae II and III fused with sternal shield. Metasternal setae st4 apparently absent; poroids iv3 present on the posterolateral extensions of sternal shield; exopodal plate behind coxa IV large and triangular, more or less contiguous with but separate from peritrematal shields and genitoventral shield; peritrematal shield extending posteriorly well past coxae IV; anal shield large and nearly twice as wide as long, cribrum relatively broad; opisthogastric membrane with five pairs of smooth setae; surface of epistome faintly reticulated, its anterior margin smooth, curved and well extended; chelicera with small and robust digits with few teeth. Hypostomal groove relatively narrow, with four rows of denticles on the anterior half of the groove, each bearing 2-5 small teeth; hypostome with two large membranous flaps near the insertion of corniculi. Corniculi relatively short, and somewhat membranous. All the sclerotised parts of the body are well ornamented throughout, including the legs. Legs significantly shorter than idiosoma, genu III (2 2/1 2/0 1) and IV (2 2/1 3/1 1) with eight and ten setae respectively. Male with sterno-genitiventral shield with ten pairs of setae, with separate anal shield similar to that of the female.
Etymology -This species is named in honour of Michael Costa, who made many important contributions to the systematics of the family Laelapidae.
Remarks -Reticulolaelaps costai n. sp. differs from R. faini Costa, 1968 andR. hallidayi Joharchi, Nemati andBabaeian, 2013 by having thick and falciform dorsal setae (in R. faini and R. hallidayi the dorsal setae simple and delicate), genitoventral shield wider than in the two other described species in this genus.
Pseudoparasitus lativentris (Karg) new combination (Figure 3) Reticulolaelaps lativentris Karg, 1978: 26. Specimens examined -The two paratype specimens of Karg's  Notes -Here are morphological features of P. lativentris that complement the original description of Karg (1978): The dorsal shield with 39 pairs of setae 21 podonotal, 17 opisthonotal, including three pairs of Zx setae between J and Z setae, and four unpaired median Jx setae; setae increasing in length from anterior to posterior, except Z5, shorter than surrounding setae; most setae long enough to reach well past base of next posterior seta. Dorsal shield wrapping around onto the ventral idiosoma, forming a marginal strip, except for the caudal end of the idiosoma. Genito-ventral shield very wide, bearing four pair of setae (including st5), with truncate posterior margin, and its surface reticulated. Hypostomal groove wide, with six rows of denticles each bearing 6-10 very small teeth, except the first row with four teeth, and a smooth anterior transverse line (Fig. 3B). The palp tarsal claw has two pointed tines of unequal length; palp trochanter setae simple, needle-like. Genu IV with nine setae (2 2/1 3/0 1), anteroventral seta spine-like. Male with sternal, genital, endopodal, ventral and anal shields fused into a holoventral shield, with nine pairs of setae and four pairs of poroids, with strong reticulation throughout. Unpaired post-anal seta shorter than para-anal setae, cribrum small, paranal gland pores not visible (Fig. 3A). Nemati et al. (2013) have recently modified the diagnosis of this genus, included a new species, R. hallidayi, and tentatively placed Reticulolaelaps lativentris Karg (1978) in the genus Pseudoparasitus, which we follow here. Maybe, the genus Reticulolaelaps is superficially similar in morphology to Pseudoparasitus Oudemans in having a large genito-ventral shield of the female which is expanded to posterior to coxae IV, so that its posterior margin abuts the anal shield and the large genito-ventral shield usually captures some pairs of setae on the surface of the shield.

DISCUSSION
Herein, we further refined the diagnosis of Reticulolaelaps. Reticulolaelaps lativentris Karg (1978) does not fit easily into the genus Pseudoparasitus, because the epistome has smooth anterior edge, palp tarsal claw has two pointed tines (three-tined, posterior tine small in almost all Pseudoparasitus) and metasternal setae st4 apparently absent (always present in Pseudoparasitus). These characters are not present in other Pseudoparasitus species. However, we believe that erecting a new monotypic genus for P. lativentris would be precocious, without a better understanding of related laelapid taxa.
We exclude this species of Reticulolaelaps because it lacks the hypostomal flap characteristic of Reticulolaelaps species, the chaetotaxy of genu IV (2 2/1 3/0 1) is normal, its hypostomal groove has six rows of denticles, and the male has a holoventral shield. For these reasons R. lativentris fits better in Pseudoparasitus than in Reticulolaelaps or any other genera.
The ecological role of Reticulolaelaps is unknown. Our specimens were found in the nest of Tapinoma sp. (Hymenoptera: Formicidae), but not on the ants (it is unknown whether Reticuloaelaps species are phoretic on ants). This is consistent with the observations of Nemati et. al. (2013) for R. hallidayi. Reticulolaelaps faini Costa, 1968 has previously been reported from Israel (forest litter), Iran (soil and associated with elm tree bark) and Iraq (Cogan grass around the base of date-palm trees) (Costa, 1968;Ghafarian et al., 2012;Nemati et. al., 2013;Abulhab, 1984). Therefore, species of this genus have been collected on only a few occasions, so it is difficult to draw any firm conclusions about their host specificity. Related to its cheliceral morphology, we may speculate that they are predators that feed on other small invertebrates in their hosts' nests, but do not appear to be harmful to the ants. This has not been established experimentally, and it will be necessary to do feeding experiments to establish the true ecological role of these mites. The following key is based on direct examination of specimens.