Opilioacarus With, 1902

Vázquez, Maria Magdalena, Herrera, Ivalú Macarena Ávila, Just, Pavel, Lerma, Azucena Claudia Reyes, Chatzaki, Maria, Heller, Tim Lukas & Král, Jiří, 2021, A new opilioacarid species (Parasitiformes: Opilioacarida) from Crete (Greece) with notes on its karyotype, Acarologia 61 (3), pp. 548-563 : 552

Opilioacarus With, 1902

Type species Opilioacarus segmentatus With, 1902 : by original designation

The genus currently includes four extant species, namely O. segmentatus With, 1902

(Mediterranean region of Algeria), O. italicus ( With, 1904) (Sicily) , O. brignolii Araújo and

Di Palma, 2018 (southern part of the Italian peninsula and Sardinia), and O. baeticus Moraza,

Prieto and Balanzategui, 2021 ( Spain). O. italicus is a nomen dubium ( Araújo et al. 2018b).

Types of this species are missing, the original description is insufficient, and the recollecting efforts at the type locality were unsuccessful ( Araújo et al. 2018b). The main differences between the species of Opilioacarus described by With are in the size of their legs. Information on chaetotaxy, a standard feature nowadays, was provided only for species described recently

( Araújo et al. 2018b, Moraza et al. 2021) and partially for O. segmentatus ( Grandjean 1936) .

Recently, two fossil species have been placed putatively into the genus Opilioacarus , namely the Eocene O. aenigmus Dunlop et al., 2010 from Baltic amber ( Dunlop et al. 2010) and the Upper Cretaceous O. groehni Dunlop and Bernardi, 2014 from Burmese amber ( Dunlop and Bernardi 2014). These findings indicate a considerable antiquity of the clade containing

Opilioacarus .

Diagnosis: 4–6 foliate d setae (d1) and one slightly pectinate d seta (d2) on palp. With´s organ membranous, discoid, hyaline. Two pairs of dorsolateral eyes, preanal region with 4–5

dorsal setae and 2 lateroventral setae. Dorsal segments between prodorsal shield and preanal region without setae. Leg I exhibits crown-like eupathidium (ζ1) close to main sensilla group.