A new species of Cenopalpus Pritchard & Baker (Acari: Tenuipalpidae) from Japan, with ontogeny of chaetotaxy and a key to the world species

A new species of flat mite, Cenopalpus umbellatus sp. nov. (Acari: Trombidiformes: Tenuipalpidae) is described and illustrated based on females, males, deutonymphs, protonymphs and larvae. The morphological ontogeny in idiosomal and leg chaetotaxy is briefly described for all stages. Mite specimens were collected from the leaves of Rhaphiolepis indica var. umbellata Makino (Rosaceae), an evergreen shrub native to Japan. An identification key to the world species of Cenopalpus is also provided.


Etymology
The specific name umbellatus is named after the host plant species. The gender is masculine.

Differential diagnosis
Cenopalpus umbellatus sp. nov. closely resembles C. lanceolatisetae (Attiah, 1956) in various aspects including the chaetotaxy of legs; however, female differs in having rostrum not reaching distal end of femur I (vs. rostrum extending to middle of genu I in C. lanceolatisetae), reticulations behind ventral setae 4a medially connected (vs. smooth or slightly striate medially in C. lanceolatisetae) and variation in lengths of some idiosomal setae (Table 3). Male of C. umbellatus sp. nov. also differs in having reticulations behind ventral setae 4a (vs. reticulations absent in C. lanceolatisetae) and in having no opisthosomal pores (vs. one pair of opisthosomal pores present in C. lanceolatisetae). Also, the deutonymph of the new species has propodosoma smooth medially (vs. propodosoma reticulated medially in C. lanceolatisetae).

Ontogeny
The ontogenetic changes in the idiosomal and leg chaetotaxy of Cenopalpus umbellatus sp. nov. resemble the typical pattern for tenuipalpid mites (Lindquist, 1985). Regarding the setal additions on ventral idiosoma, the ventral (1a, 3a) and anal (ps2, ps1) setae appeared since the larval stage. However, aggenital seta (ag) is added in the protonymph and the ventral seta (4a) is added in the deutonymph. Also, genital setae (g1) appeared in the deutonymph and g2 in the adults. The coxal setae 1c, 2c and 3b are added in the protonymph and the setae 2b and 4b are added in the deutonymph. Setae v' appeared on trochanters I, II and III in the deutonymph while appeared on trochanters IV in the adults. Seta l' on trochanter III is added in the protonymph. Also, seta l' is added to femora I and II in protonymph. Setae l' is present on genua I and II of the larva. Setae d and l" are  Table 3 Measurements of idiosomal setae for Cenopalpus umbellatus sp. nov. and its congener C. lanceolatisetae (Attiah, 1956

DISCUSSION
The present study provides morphological description of a new species of flat mites belonging to the genus Cenopalpus, with a key to the world species. This genus is mainly reported from the Mediterranean and East Asia regions. Only 14 tenuipalpid species were previously known from Japan, with only one Cenopalpus species. Though members of the Tenuipalpidae are currently not posing a serious threat to agriculture in the country, we must be prepared for the consequences of global trafficking of people and goods. Therefore, this study will for sure act as a very useful early intervention tool. Examination of all known species of Cenopalpus was toilsome especially with some species which are poorly described, and we had to rely on what was available.

CONCLUSIONS
Faunistic information about flat mites in Japan is scarce. The new mite species described with the world key to species increases the available information about the taxonomy of tenuipalpid mites in this country. We hope that this study will serve as the departure point for future research on Cenopalpus mites and encourage for more comprehensive surveys in Japan since a large number of undiscovered species is expected.