Fossil Mayfly Collections of the Museum Für Naturkunde, Humboldt University, Berlin. II. Redescription ofBaltameletus oligocaenicusDemoulin, 1968 with Notes on Ameletidae McCafferty, 1991 (Insecta: Ephemeroptera) from the Eocene Baltic Amber

Abstract

The holotype of Baltameletus oligocaenicus Demoulin, 1968 preserved in Eocene Baltic amber and housed in the W. Simon amber collection at the Museum für Naturkunde, Humboldt University, Berlin is redescribed and illustrated. Baltameletus Demoulin, 1968 can be attributed to the family Ameletidae McCafferty, 1991 by a combination of following characteristics: (1) lateroparapsidal suture of mesothorax relatively elongate; (2) epimeron of mesothorax with membranous area between anepimeron and katepimeron; (3) mesonotal suture stretched backward medially and anterior paracoxal suture complete; (4) furcasternal protuberances contiguous; (5) hind wings well developed with RS, MA and MP triads; (6) tarsi 5-segmented with first tarsal segment fused with tibia; (7) forceps with two distal segments; (8) all tarsal claws dissimilar. This fossil genus clearly differs from all other representatives of the family Ameletidae by the following combination of characteristics: (1) unpaired projection of the vertex; (2) dorsally contiguous compound eyes (3); 2–3 mainly simple veins stretching from CuA to basitornal margin of forewing. Additionally, some data on the fossil representatives of Ameletidae are given.