An insight into the tribe Hexathrombiini (Actinotrichida: Trombidioidea, Microtrombidiidae, Eutrombidiinae) with new data on host-parasite interaction

Abstract

The status of the genera in the small microtrombidiid mite tribe Hexathrombiini is reevaluated. Type specimens representing all genera were studied and diagnostic characters for Hexathrombiini are reviewed, summarized, and new data and a key to the genera in the tribe are provided: Alhamitrombium, Beronium, Hexathrombium and Hoplothrombium. Hexathrombium is the most speciose genus in the tribe and species recorded from South America are compared, as well as those with a divided pygidial plate. A provisional key to species assigned to Hexathrombium is provided. Finally, Hexathrombium abirami was captured in Peru parasitizing a bright metallic tiger beetle (Tetracha fulgida). A total of 361 larvae were removed parasitizing a single carabid host; this is the highest load of parasites reported in terrestrial Parasitengona mites associated with arthropods. This capture represents a new record of Hexathrombiini mites for Peru. A redescription of He. abirami using all specimens available to date is included.

A subterranean new genus and species of Eutrombidiinae (Trombidiformes: Microtrombidiidae) from Turkey

“…The number of Eutrombidiinae larvae attached per host varies between genera. The highest number of parasites per single host ever recorded to date is 361 for Hexathrombium abirami (Makol et al . 2021).…”

“…Southcott (1986) erected this genus based on eyeless larva ectoparasitic on troglobitic Carabidae and drew attention to the similarity of the ectoparasite itself to a troglobitic organism (Southcott 1986). The records of eyeless Beronium from subterranean habitats continued (Haitlinger 1994;Mayoral & Barranco 2005;Mayoral 2013), and finally, Mąkol et al (2021) stated the reduction of eyes into ocular sclerites as a character informative on identifying Beronium.…”

“…Most Eutrombidiinae species are known based on few specimens and single localities. Among the eleven genera of Eutrombidiinae known by larvae, Aranneothrombium, Alhamitrombium , Hoplothrombium , Kepongia , Milliotrombidium , Phnompetrombium , Spinnitrombium , and Verdunella are monotypic (Mąkol et al . 2021), whereas the most species-rich genus is Eutrombidium with forty-six species (Mąkol & Wohltmann 2012, 2013; Haitlinger 2015; Noei & Šundić 2020).…”