Radiolaria front the Telychian (Llandovery, Early Silurian) of Dalarna, Sweden

A Haplotaeniatum-dominated radiolarian fauna has been discovered in Llandov erian (Early Silurian) strata of the Scandinavian platform, Dalarna, Sweden . As one of six occurrences of this fauna world-wide, it supports the premi se that many elements in the Haplotaeniatum Assemblage have a wide geograph ic distribution and will be of significance in building an Early Silurian r adiolarian biostratigraphic scheme with global application. In addition to Haplotaeniatum, this fauna contains palaeoscenidiid and secuicollactine tax a that are known only from one other locality, the Cape Phillips Formation, Canadian Arctic. These taxa may prove to be fairly cosmopolitan and biostr atigraphically useful as more data from other localities are collected. Two new genera, Labyrinthosphaera and Gyrosphaera, and three new species, Laby rinthosphaera macdonaldi, Gyrosphaera siljanensis, and Gyrosphaera raneatel a, are described herein. Labyrinthosphaera has a multi-layered labyrinthine meshwork and with six or more tri-bladed spines. Gyrosphaera has a labyrin thine meshwork and displays spiraliform layering, similar to that described in Haplotaeniatum, indicating a close phylogenetic link between these two Llandoverian taxa. Further data from additional localities is needed to det ermine the potential diachroneity of a global Haplotaeniatum acme zone, and to identify additional taxa whose first and last occurrences may be used a s biostratigraphic datums for the Llandoverian.