Two laniatorid harvestmen (Opiliones: Cladonychiidae) from Eocene Baltic amber

Abstract

Two new specimens of laniatorid harvestmen (Opiliones: Laniatores) from Eocene (ca. 44-49 Ma) Baltic amber are described. One is clearly adult and assignable to Proholoscotolemon nemastomoides (Koch & Berendt, 1854) from the family Cladonychiidae. The second, smaller, specimen is treated as cf. Proholoscotolemon sp., but probably represents a juvenile instar of P. nemastomoides and allows us to infer at least part of the ontogenetic sequence for Baltic amber laniatorids. The juvenile differs from the adult in the relative size of the body, weaker pedipalpal spination and the absence of tarsomeres subdividing the tarsi at the ends of the legs. Of particular note is the presence of unbranched claws at the tips of legs III-IV. This was unexpected given that juveniles of extant cladonychiids usually have four to six branches on these claws; a condition also thought to be plesiomorphic for this, and some related families.