Pentamerismus collinus Meyer & Van Dis 1993

The generic affiliation of Pentamerismus collinus The species Pentamerismus collinus Meyer & Van Dis, 1993 formally belongs to the subgenus Oligomerimus, since setae f 2 are absent. However, we exclude this species from the diagnostic key, because its placement in the genus Pentamerismus seems to be questionable. In contrast to all other species of the genus, it has only two pairs of pseudanal setae (ps), and setae f 2 occupy sublateral position. Meyer & Van Dis (1993) highlighted that P. collinus shares the presence of two pairs of pseudanal setae with the genus Phytoptipalpus; however, as these authors attached greater taxonomic significance to the number of dorsosublateral setae, they considered setae f 2 to be in a lateral position and referred this species to Pentamerismus. It is crucial to understand which morphological character are persistent enough to be used for clear generic diagnoses of tenuipalpids. Both of the aforementioned characters (position of dorsal opisthosomal setae and number of pseudanal setae) have been used in combination to differentiate various tenuipalpid genera. The taxonomic significance of the number of pseudanal setae could not be denied at the generic level in the family Tenuipalpidae, in particular, in the genera Tenuipalpus, Extenuipalpus, Ultratenuipalpus, etc. (Mesa et al. 2009; Beard et al. 2016). We suggest that the presence of two pairs of ps setae should be confirmed by a careful re-examination of the type specimens of P. collinus, and if this were the case, then it would be reasonable to place this species in the genus Phytoptipalpus.