First eupnoid harvestmen (Arachnida: Opiliones: Eupnoi) from mid-Cretaceous Kachin amber, with notes on sexual dimorphism in Halitherses grimaldii (Arachnida: Opiliones: Dyspnoi)

Abstract

The first eupnoid harvestmen (Opiliones: Eupnoi) are described from the mid-Cretaceous (ca. 99 Ma) Burmese amber (Kachin State, northern Myanmar). All four living suborders of Opiliones are now known from this amber source. Tyrannobunus aculeus gen. et sp. nov. preserves a unique combination of characters including spiny legs, large eyes in an anterior position and a relatively undifferentiated penis. These characters may be plesiomorphic for Eupnoi and are consistent with the hypothesis that the new species belongs to a relatively basal lineage within the suborder. Two more, probably immature, eupnoids are described and figured. They probably belong to the eupnoid family Phalangiidae, but are not formally named at this stage. Additionally, a new Burmese amber specimen is assigned here to Halitherses grimaldii (?) Giribet & Dunlop, 2005 (Dyspnoi: Halithersidae). It reveals for the first time a (male?) cheliceral apophysis and thus offers the first evidence for secondary sexual dimorphism in this extinct family.