Morphometrics of the resting eggs of the fairy shrimp Branchinella in Australia (Anostraca: Thamnocephalidae)

Abstract

Branchinella resting eggs are characterised by having surface ridges arranged more or less in polygons and by almost all species having few, if any, spines. The eggs of 33 out of a known possible 40 species (including 4 out of 6 undescribed species) were studied by SEM. A few species are distinctive by being adorned with lighter coloured surface membranes often strengthened by ribs or sparse spines and one (B.longirostris) is regularly spinose. Those species known to be morphological variable also have variable egg morphologies. This makes it difficult to characterise specific egg morphology, but even so in some species eggs are distinct : B. arborea, B. australiensis, B. budjiti, B. compacta, B. complexidigitata, B. hattahensis, B. kadjikadji, B. longirostris, B. lyrifera, B. occidentalis, B. pinderi and B. vosperi. Most of the remainder are easily confused with at least one or more species. Branchinella egg morphology seems of little value in taxonomical studies and of restricted use in distinguishing eggs in dried sediments.