Redefinition of the genus Scarabacariphis Masan and new morphological data for S. geotrupes comb. nov. (Ishikawa) (Acari: Mesostigmata: Eviphididae)

Herein, Alliphis geotrupes Ishikawa, 1979 is transferred to the genus Scarabacariphis Masan, 1994 because of its free peritrematal shield (i.e. separated from the dorsal shield). The genus Scarabacariphis is redefined, and a key to the species of Scarabacariphis is provided, as well as additional morphological information for Scarabacariphis geotrupes comb. nov.


INTRODUCTION
Predatory mesostigmatic mites of the family Eviphididae include about 130 described species under 20 genera that occur in soil, litter, and decomposing organic materials like vertebrate dung, carrion and nest of birds and mammals (Berlese 1910;Evans and Till 1979;Halliday 2008Halliday , 2010Karg 1963Karg , 1976Karg , 1993Kazemi and Rajaei 2013;Kazemi et al. 2008;Mašán 1994;Mašán andHalliday 2009, 2010;Ryke and Meyer 1957). Before publishing this paper, the genus Scarabacariphis Mašán, 1994 was a monotypic genus known only from Slovakia and Armenia (Arutunian, 1992;Mašán, 1994;Mašán and Halliday, 2010). Ishikawa (1979) described Alliphis geotrupes based on specimens associated with Geotrupes laevistriatus (Matschulsky) collected in Japan. Based on the original description and illustrations of the species, its peritrematal shields are less developed and free from the dorsal shield anteriorly. These character states define the genus Scarabacariphis. The purposes of this paper are to transfer Alliphis geotrupes to Scarabacariphis, present new morphological information for the species, redefine Scarabacariphis and prepare a key to the current members of the genus.

MATERIALS AND METHODS
The mite specimens used for this study were slides of one female paratype specimen of Alliphis geotrupes ex Geotrupes laevistriatus collected in Japan (Ishikawa 1979), and also three paratypes of Scarabacariphis ankavani (Arutunian, 1992) ex Onthophagus fracticornis (Preyssler) collected in Slovakia.
Morphological observations, measurements and illustrations were made using a compound microscope equipped with differential interference contrast and phase contrast optical systems, and a drawing tube. Measurements were made in micrometres (µm). Some measurements have been given in range when left and right side characters of the body differed in size. Dorsal and sternal shield lengths and widths 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 and at the level of setae st2. The length of the epigynal shield was taken from the anterior margin of the hyaline extension to the posterior margin of the shield along the midline; the shield width was taken at the level of setae st5. Anal shield length and width were measured along the midline from the anterior to posterior margin, including the cribrum, and at the broadest point, respectively. Leg lengths were taken from the base of the coxa to the apex of the tarsus, without 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 the 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.
Notes on the genus -Ishikawa (1979) described an eviphidid species with most typical characters of the genus Alliphis, A. geotrupes, but he illustrated its peritrematal shields free from the dorsal shield. I confirmed this observation in the paratype specimen. The only genera of Eviphididae that bear free peritrematal shields from the dorsal shield are Rafaphis Skorupski & Błaszak, 1997 and Scarabacariphis, so the placement of A. geotrupes is not ac-ceptable. Comparing these genera with free peritrematal shields, Raphafis is unrelated to A. geotrupes because of its unique character states for the Eviphididae, such as the dorsal shield extending ventrally and capturing three pairs of opisthogastric setae, reduced and sub-oval sternal shield, atypical leg chaetotaxy and also epistome. Although Scarabacariphis shares several characters with A. geotrupes, there are some morphological differences between the type species of this monotypic genus and A. geotrupes, including the absence of larval setae J2 in the latter species (present in S. ankavani), setae st5 off the epigynal shield (on the shield in S. ankavani), and exopodal platelets between coxae I-III present and small (absent in S. ankavani). Currently, the only eviphidid genus without setae J2 is Podoniphis Joharchi et al., 2014, but they can be easily separated by the rudimentary peritrematal shields fused to the dorsal shield in Podoniphis, most dorsal shield setae in Podoniphis relatively elongated, except J5 minute and strongly reduced (setae J5 in Scarabacariphis and Alliphis not reduced, other setae not elongated) and also presence of a robust spine-like ventral setae in femur II of the female (absent in females of Scarabacariphis and Alliphis). The insertion of setae st5 off the epigynal shield can be seen in Scarabaspis Womersley, 1956 and some species of Thinoseius Halbert, 1920, and also with intraspecific variation in Podoniphis persicus Joharchi et al., 2014 (on or off the shield but near its border). Moreover, although all of these mites have peritrematal shields fused to the dorsal shield, the members of Scarabaspis bear two sickle-like sensory setae on palptarsus (in contrast one in Scarabacariphis and Alliphis) and also flattened oval-shaped disc setae on coxae I-II (simple setae in Scarabacariphis and Alliphis); Thinoseius has some meaningful different characters that mostly seem to be autapomorphic attributes within Eviphididae, including presence of five setae on the palpgenu (six setae in other eviphidids), female dorsal shield with 11-17 pairs of setae showing considerable sexual dimorphism and also female sternal shield absent, reduced or fragmented into sclerotized platelets. So, based on these observations I propose to transfer Alliphis geotrupes to Scarabacariphis (see more in discussion).

DISCUSSION
The genus Scarabacariphis was erected by Mašán (1994) and diagnosed from the related genera Alliphis Halbert, 1923 and Pelethiphis Berlese, 1911 by the length of dorsal shield setae ("very short and approximately of equal length" in Alliphis and "very long and setae Z5 are usually more than 10-times shorter than the other marginal setae" in Pelethiphis) and size of the peritrematal shields and the shape of iv2 ("rounded in Scarabacariphis, slot-like in Alliphis"). Mašán and Halliday (2010) focused on the reduced peritrematal shields in Scarabacariphis in comparison to the genus Alliphis, but in the same work and in the key for the genera of European Eviphididae they also mentioned several other character states: the subventral position of setae j1 and z1 in Scarabacariphis and dorsal position of these setae in Alliphis; the subequal or moderately varying length of posterior dorsal shield setae in Alliphis compared with the conspicuously longer postero-marginal dorsal shield setae in Scarabacariphis; and the presence of exopodal platelets between coxae I-III in Alliphis and absence of them in Scarabacariphis. I have examined several species of Alliphis collected from Europe (A. kargi Arutunian, 1991, A. halleri (G. and R. Canestrini, 1881), A. phoreticus Mašán, 1994) and Iran (A. halleri, A. scarabaeorum Ogandzhanyan, 1969, and also undescribed species), and found the position of setae j1 and z1 in mounted specimens differs and is related to mounting of the specimens. Also, the length of the postero-marginal setae in A. scarabaeorum are up to five times longer than the shorter J series setae. So, it seems the free peritrematal shield in Scarabacariphis can be the only and main morphological differential diagnostic character between the genera Alliphis and Scarabacariphis.