First fossil record of a nymph (Ephemeroptera, Teloganellidae) from the Indian subcontinent

A fossil of a mayfly nymph that shows similarities with the modern genus Teloganella Ulmer, 1939 of the family Teloganellidae is recorded for the first time from the Indian subcontinent. It is systematically described from the Gurha lignite mine of Bikaner, Rajasthan which belongs to the Palana Formation (late Paleocene-early Eocene). As assignment of the fossil to a modern species of Teloganella is difficult due to indistinguishable location of gills in the impression, a new species, Teloganella gurhaensis Agnihotri et al., sp. nov. is instituted to include this fossil naiad resembling the extant Teloganella.

The mayfly nymph Austrophlebioides pusillus Harker defies common osmoregulatory assumptions

Osmoregulation is a key physiological function, critical for homeostasis. The basic physiological mechanisms of osmoregulation are thought to be well established. However, through a series of experiments exposing the freshwater mayfly nymph Austrophlebioides pusillus (Ephemeroptera) to increasing salinities, we present research that challenges the extent of current understanding of the relationship between osmoregulation and mortality. A. pusillus had modelled 96 h LC 10 , LC 50 and LC 99 of 2.4, 4.8 and 10 g l −1 added synthetic marine salt (SMS), respectively. They were strong osmoregulators. At aquarium water osmolality of 256 ± 3.12 mmol kg −1 (±s.e.; equivalent to 10 g l −1 added SMS), the haemolymph osmolality of A. pusillus was a much higher 401 ± 4.18 mmol kg −1 (±s.e.). The osmoregulatory capacity of A. pusillus did not break down, even at the salinity corresponding to their LC 99 , thus their mortality at this concentration is due to factors other than increased internal osmotic pressure. No freshwater invertebrate has been previously reported as suffering mortality from rises in salinity that are well below the iso-osmotic point. Recently, studies have reported reduced abundance/richness of Ephemeroptera with slightly elevated salinity. Given that salinization is an increasing global threat to freshwaters, there is an urgent need for studies into the osmophysiology of the Ephemeroptera to determine if their loss at locations with slightly elevated salinity is a direct result of external salinity or other, possibly physiological, causes.

Description of Caenoephemera shangyuanensis, gen.nov., sp.nov. (Ephemeroptera), from the Yixian Formation

A fossil mayfly nymph Caenoephemera shangyuanensis, gen.nov., sp.nov., discovered in the lower part of the Upper Jurassic – Lower Cretaceous Yixian Formation of Jianshangou, Beipiao district, West Liaoning, China, is described. It has several archaic features typical of Paleozoic mayfly nymphs, such as 5 tarsal segments and hind wing pads not covered by fore wing pads, but also exhibits specialized modern features, such as a short metathorax, abdominal tracheal gills, and cerci. It appears to be intermediate in structure between Paleozoic and extant mayfly nymphs.

A new monotypic fungal genus, Allantomyces, and a new species of Legeriomyces (Trichomycetes, Harpellales) in the hindgut of a Western Australian mayfly nymph (Tasmanocoenis sp.)

Allantomyces caenidarum sp.nov., a trichomycete fungus that lives in the hindgut of Tasmanocoenis sp. (Caenidae) mayfly nymphs in southwestern Western Australian streams, is described. In addition to normal trichospores and zygospores that serve to reinfest other nymphs, A. caenidarum also produces what may be modified trichospores that serve to increase gut infestation endogenously. The same species of mayfly also harbored a new species, Legeriomyces raus, which belongs to a genus previously known only from North America and Europe. Key words: Caenidae, Allantomyces, Australia, Tasmanocoenis, Trichomycetes, Legeriomyces.