Fossil habrotrochid rotifers in Dominican amber

Flask-shaped microfossils are reported from bracts of a moss in Eocene-Oligocene amber from the northern Dominican Republic. These microfossils are identical with the thecae of certain living moss-dwelling rotifers in the genusHabrotrocha (Bdelloidea), which have previously been reported as fossils only from Holocene peat. What may be an egg and a rotifer body fossil are associated with these thecae and further support the identification of these fossils withHabrotrocha; the fossils are almost identical to extantH. angusticollis. The parthenogenetic bdelloid rotifers have a longer evolutionary history than was previously thought; habrotrochid rotifers seem to have persisted for 35 million years with very little change in morphology or ecological role.     

Bdelloid rotifers in Dominican amber: Evidence for parthenogenetic continuity

Recently discovered representatives of the Class Bdelloidea from Tertiary amber from the Dominican Republic represent the oldest known fossils of the Phylum Rotifera. Assuming that the fossil bdelloids had a similar mode of reproduction as present day members of the Class (apomictic thelytoky), then contrary to current thought, some lines of parthenogenetic organisms are not doomed to an early extinction and have evolved built-in mechanisms for genetic diversity.     

Epizoic rotifers (Rotifera: Monogononta,Bdelloidea) from the gill chambers of Potamon fluviatile (Herbst, 1785)

We describe some rare epizoic rotifers found on Potamon fluviatile (Herbst, 1785) from Italy. Three species are discussed: Lecane branchicola (Piovanelli, 1903) (Monogononta, Lecanidae; new synonym: L. piovanellii Barto?, 1957 Barto?, E. 1957. Die Rädertiere der Kiemenhöhle der Süsswasserkrabbe (Potamon potamon). Vestnik Ceskoslovenské Zoologiscké Spolecnosti, 21: 376–380.  [Google Scholar]), Anomopus telphusae Piovanelli, 1903 and Embata parasitica (Giglioli, 1863) (Bdelloidea: Philodinidae). Lecane branchicola, previously considered a nomen nudum after Barto? (1957 Barto?, E. 1957. Die Rädertiere der Kiemenhöhle der Süsswasserkrabbe (Potamon potamon). Vestnik Ceskoslovenské Zoologiscké Spolecnosti, 21: 376–380.  [Google Scholar]), is redescribed, and its identity is stabilized by the designation of a neotype. Both L. branchicola and A. telphusae are particularly rare, and have been found on a few occasions only. Lecane branchicola appears to be restricted to a specific body part of their host, namely the branchial chamber. On the contrary, E. parasitica has been recorded as epizoic from several hosts and regions. SEM photographs of the trophi of the three species are presented.