A review of histiostomatid mites associated with scolytine bark beetles (Coleoptera: Curculionidae), with a description of Histiostoma shiramba sp. n. (Acari: Histiostomatidae) from galleries of the Sakhalin-fir bark beetle Polygraphus proximus

Abstract Associations of scolytine bark beetles (Coleoptera: Curculionidae: Scolytinae) and histiostomatid mites (Acari: Histiostomatidae) are reviewed. Histiostomatids are associated with a total of 62 described species of bark beetles in 31 countries of the world, except for South America and Antarctica (262 non-redundant records). Non-accidental records include 21 mite species in the genus Histiostoma and 5 species in the Bonomoial Probonomoia generic complex. The biological role of histiostomatids associated with bark beetles is largely unknown and needs further investigation. Available observations suggest that histiostomatids living in bark beetle galleries may feed on different fungi, including those pathogenic to the tree host and/or may serve as food supplement for developing bark beetle larvae (e.g., the fungal genus Ophiostoma). However, based on their mouthpart morphology, instead of feeding on fungi directly, histiostomatids may reduce fungal population sizes by releasing fungicides produced by their opisthonotal glands. Both feeding and phoretic stages of the mites commonly vector considerable numbers of fungal spores or conidia, including those of phloem-infesting, blue stain fungi (e.g., Ophiostoma, Ceratocystis, and Alternaria). Here we describe all developmental stages of a new species of the genus Histiostoma, belonging to the piceae-species group that includes many mite species associated with bark beetles. The new species, Histiostoma shiramba sp. n., was found in the galleries of the Sakhalin-fir bark beetle, Polygraphus proximus, an invasive pest that is quickly spreading outside of its native range in the Eastern Palaearctic, causing large-scale destruction of fir forests. We emend the following names (nom. emend.) to agree in gender with the generic name Histiostoma (gender neuter): Histiostoma capillatum, H. conjunctum, H. hungaricum, H. indetonsum, H. irinum, H. longisetum, H. margaritatum, H. medium, H. ovale, H. pannonicum, H. serratum, H. sordidum, H. spinosum, H. sylvestre, H. varium, H. virginianum. The name Histiostoma scheucheri is emended to Histiostoma scheucherae.