Two new species of the genus Premicrodispus (Acari: Microdispidae) associated with beetles (Coleoptera: Lucanidae: Tenebrionidae), with a key to Palaearctic species of the genus

Two new species of mites of the genus Premicrodispus Cross, 1965 (Acari: Microdispidae) are described and illustrated from northern Iran: Premicrodispus paramaevi Hosseininaveh and Hajiqanbar sp. nov. recovered from Lucanus ibericus (Col.: Lucanidae) and Premicrodispus spinosus Hosseininaveh and Hajiqanbar sp. nov. from Corticeus unicolor (Col.: Tenebrionidae). It is the first phoretic record of the microdispid mites on beetles of the family Tenebrionidae. A key to Palaearctic species of the genus Premicrodispus is provided. http://zoobank.org/urn:lsid:zoobank.org:pub:49368637-B8D0-4697-9184-28B33B89962A


Introduction
Mites of the cohort Heterostigmatina (Acari: Prostigmata) usually have phoretic, parasitoid or parasitic associations with various orders of insects. Within the Heterostigmatina, phoretic relationships have been evolved mostly in the superfamily Pygmephoroidea (Kaliszewski et al. 1995;Khaustov 2008). Based on Khaustov (2008), this superfamily includes four families, one of them the family Microdispidae. The microdispid mites are inhabitants of soil, forest litter and the nests of insects, and many of them use insects for phoretic dispersal (Khaustov 2009). Fungivory appears to be the primitive feeding behaviour of this family (Kaliszewski et al. 1995). The family consists of 17 genera and more than 109 species (Zhang et al. 2011). One of the speciose microdispid genera is the genus Premicrodispus.  reviewed the history of the genus. This genus currently includes three subgenera, Premicrodispus sensu stricto with about 27 species (according to Khaustov and Maslov 2013) and two monotypic subgenera Premicrodispulus Premicrodispoides Khaustov andMaslov, 2013. Hitherto, the subgenus Premicrodispus (Premicrodispus) included 20 described species in the Palaearctic region (Khaustov , 2009Khaustov and Chydyrov 2010). Mites of this family have been found on beetles of the families Carabidae, Scarabaeidae and Lucanidae (Hajiqanbar et al. 2012) but this study reports, for the first time, these mites on beetles of the family Tenebrionidae.
Male and larva unknown.

Differential diagnosis
The new species is distinguished from congeners by having two pairs of cheliceral setae, rounded cupuli and reduced pump 3 of pharyngeal system. On the other hand, due to presence of setae 4a, absence of setae ps 2 and subequal setae ps 1 and ps 3 , the new species is similar to Premicrodispus parasilvestris (Rack, 1974) but differs from it by setae d distinctly longer than distance between their bases (setae d distinctly shorter than distance between their bases in P. parasilvestris). The new species is similar to Premicrodispus dzumaevi (Sevastianov and Chydyrov, 1991) because of setae d distinctly longer than distance between their bases but differs from it by subequal setae ps 1 and ps 3 (setae ps 1 distinctly longer than ps 3 in P. dzumaevi). The new species is also similar to Premicrodispus lambi (Krczal, 1964) but differs from it by setae sc 2 shorter than distance between their bases (setae sc 2 longer than distance between their bases in P. lambi), by setae d longer than distance between their bases (setae d shorter than distance between their bases in P. lambi), by setae f subequal to distance between their bases (setae f as half as distance between their bases in P. lambi), by setae h 1 longer than distance between their bases (setae h 1 shorter than distance between their bases in P. lambi) and by shorter setae in coxal fields I-IV (longer setae in coxal fields I-IV in P. lambi).

Etymology
The name of the new species 'Paramaevi' is derived from combination of two species names parasilvestris and dzumaevi, two species that are most similar to the new species. Gnathosoma ( Figure 8A,B). Gnathosomal capsule about twice as long as its width, dorsally with one pair of cheliceral setae ch 3 (3-3); ventrally with one pair of subcapitular seta su 5 (4-5); palps short, terminated to small tibial claw, and compressed to gnathosomal capsule, with two pairs of setae, dFe 3 (3-4) and dGe 4 (3-4), cheliceral stylets indiscernible; pharyngeal system ( Figure 8C) with three pumps, pump 1 reduced, pump 2 the largest and striated, pump 3 small and rounded.
Leg II ( Figure 9B). Tarsus with solenidion ω 3 (2-3) finger shaped, pl″ modified and spine-like, the rest of setae of the segment subequal; tibia with a small finger-shaped solenidion φ 2 (1-2), setae l′ modified and spine-like, setae d longer than v′ and v″; genu with setae, l″ and v′ subequal and longer than l′; femur with setae d longer than l′ and v″; trochanter with seta v′.
Leg III ( Figure 10A). Tarsus with modified and spine-like setae pl″ and tc′, setae tc″ longest setae on the leg, setae pv″ and pv′ subequal and shorter than u′; tibia with a small solenidion φ 2 (1-2) and setae d modified and spine-like, seta v″ and v′ subequal and longer than l′; genu with setae l′ and v′ subequal; femur divided into basifemur and telofemur, setae d and l′ inserted on telofemur, setae d longer than l′; trochanter with seta v′.
Leg IV ( Figure 10B). Tarsus with subequal setae pl″, pv′ and pv″, setae u′ and tc″ subequal, seta tc′ longest on the segment; tibia with small solenidion φ 1 (1-1), seta d and v′ subequal and longer than l′ and v″; genu with seta v′ as long as femoral seta v′; femur divided into basifemur and telofemur, setae d and v′ inserted on telofemur, seta d longer than v′; trochanter with seta v′. Male and larva unknown.

Differential diagnosis
The new species is readily distinguished from other species of the genus by some spine-like setae on tarsi and tibiae II and III.