Genus Onchodellus Berlese, 1904

Pachylaelaps (Onchodellus) Berlese, 1904: 452 .

Type species Pachylaelaps (Onchodellus) reticulatus Berlese, 1904, by monotypy.

Berlese’s (1904) attempt to divide the genus Pachylaelaps into subgenera Pachylaelaps s. str. and Onchodellus was not generally accepted. Koroleva (1977b) and Karg (1993) synonymised Onchodellus with Pachylaelaps . Later, the separate taxonomic status of Onchodellus was accepted by Evans & Till (1979) and Moraza & Johnston (1990), because the original Pachylaelaps exhibits two main morphological patterns previously noted by Koroleva (1977b) and Evans & Till (1979) in their identification keys: (1) species with a slender hypostome and elongated corniculi, a sperm access system associated with coxae IV, sexual dimorphism of the palp tibia (male with palp tibial outgrowths), two spur-like distal setae on female tarsus II, and 13 setae on genu I; and (2) species with a wider and shorter hypostome and normal horn-like corniculi, a sperm access system associated with coxae III, sexual dimorphism of palp tibia not developed, one spur-like distal setae on female tarsus II, and 12 setae on genu I.

The genus Onchodellus is now based especially on the following character states: (1) spermathecal tubes of sperm access system strongly elongated, fine, and associated with coxae III, (2) clunal setae J5 needle-like and similar in size to the other dorsal shield setae, (3) gland opening gdZ1 mostly not modified and circular (if slit-like, then antiaxial to alignment Z1–Z2), (4) female tarsus II with one spur-like distal seta, and genu I with 12 pairs of setae. It is by far the largest genus of Pachylaelapidae, with up to 80 species distributed mainly in Europe, Asia and Africa.