Comparative analysis of the external morphology in tritonymphs of parasitic mites of the tribes Elephantulobiini and Protomyobiini (Acariformes: Myobiidae)

The comparative analysis of the external morphology of tritonymphs in parasitic mites belonging to the tribes Elephantulobiini and Protomyobiini (Acariformes: Myobiidae) was carried out based on representatives of the genera Elephantulobia Fain, 1972 (Elephantulobiini); Limnogalobia Fain & Lukoschus, 1976 (Protomyobiini: Afromyobiina); Blarinobia Jameson, 1955, Eutalpacarus Jameson, 1949, Gymnomyobia Fain & Lukoschus, 1976, Placomyobia Jameson, 1970 (Protomyobiini: Amorphacarina), and Nectogalobia Fain & Lukoschus, 1976 (Protomyobiini: Protomyobiina). A key to genera of the tribes Elephantulobiini and Protomyobiini based on tritonymphs is given.

The detailed phylogeny of the family has never been constructed, although the preliminary phylogenetic hypotheses were proposed by Dusbabek (1969) and Bochkov (1997a) based mainly on the morphology of adult mites. The juvenile and adult stages of myobiids strongly differ from each other by their external morphology, and juveniles are poorly studied in this relation. The comparative investigation of external morphology of juvenile myobiids (mainly tritonymphs) is a base for the future step in a comprehensive phylogenetic analysis of the family, and following this goal, representatives of most genera in the tribe Protomyobiini were recently examined (Bochkov and Mirolubov, 2015). The present work is the continuation necessary to fill gaps in our knowledge about tritonymphal mor- Characters phology in mites of this tribe. Tritonymphs of six genera of this tribe and also two of three species known in the tribe Elephantulobiini whose external morphology was not specially investigated are examined here. A key to genera of the tribes Elephantulobiini and Protomyobiini based on tritonymphs is provided for the first time.

MATERIALS AND METHODS
In a total, seven species belonging to six genera of the Protomyobiini and two species of the genus Elephantulobia (Elephantulobiini) were examined (material housing in the Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium). The list of examined species is given in Appendix 1.
Mounted specimens were studied using a Leica compound microscope with phase contrast optics. Drawings were made with a camera lucida.
The idiosomal and leg setation follow Grandjean (1939Grandjean ( , 1944 as interpreted by Bochkov et al. (2008). The designations proposed by Bochkov and Mirolubov (2015) for leg I setae of myobiid immature stages are used. Host taxonomy follows Wilson and Reeder (2005 Figure 2A, B) -The general structure of gnathosoma in myobiid tritonymphs of the tribe Protomyobiini was described in details by Bochkov and Mirolubov (2015). As in the most immatures of myobiids, their palps are absent, the subcapitulum bears one pair of dorsal setae ao1 and one pair of ventral setae n.
Character 1. Among seven genera examined in this paper, setae n are absent in Limnogalobia vs. present in all other genera. Idiosoma (Table 2; Figure 1) -The tritonymphal stage can be absent in some protomyobiins (Lukoschus, 1969;Bochkov and OConnor, 2006). In species of all genera investigated herein, this stage is present.