The fossil mite family Archaeorchestidae (Acari, Oribatida) II: redescription of Plategeocranus sulcatus and family-group relationships

Abstract

The oribatid mite family Archaeorchestidae was proposed based on a single specimen of Archaeorchestes minguezae Arillo & Subías, 2000, from Lower Cretaceous amber (Spain). In a previous paper we redescribed Strieremaeus illibatus Sellnick, 1918, from Eocene Baltic and Rovno amber, and considered Strieremaeus a senior synonym of Archaeorchestes. Herein, we transfer a second genus, Plategeocranus, to Archaeorchestidae. This is based on a redescription of the type species, P. sulcatus (Karsch, 1884), using non-type specimens (44 adults and 2 immatures from Baltic and Rovno ambers). Among these are eight Baltic amber specimens identified by Max Sellnick and currently housed in two museums in Kaliningrad: from the Museum of the World Ocean we designate specimen #39 as neotype and specimens 22, 30, 33, 35 and 37 as paraneotypes; from the Kaliningrad Museum of Amber we designate specimens 197-22 and 197-54 as paraneotypes. The contention of Arillo and Subías that Archaeorchestidae is a member of Zetorchestoidea (Eremaeoidea auct.), and is the extinct sister-family of Zetorchestidae, is supported with additional characters that relate to leg setation and the morphology of immatures. The possible inclusion of another Cretaceous fossil mite, Rasnitsynella punctulata Krivolutsky, in Archaeorchestidae or Zetorchestoidea was rejected, leaving it in Plateremaeidae pending the direct investigation of specimens. New diagnoses are presented for Plategeocranus, Archaeorchestidae, and Zetorchestoidea.