Digital microscopic imaging of important taxonomic characters of Philippine Hydraena (Hydraenopsis) species

Biodiversity surveys have revealed several new aquatic beetle species of minute size (0.9 mm to 1.8 mm body length). Following modern standards of morphological taxonomy, internal and external microstructures such as aedeagus, ovipositor, spermatheca, gonocoxite as well as the distribution pattern and shape of certain hair structures were used to illustrate the distinguishing characters of new species. As even the smallest diaphragm opening of light microscopes fails to retrieve images of sufficient depth of the field, light microscope images under ZEISS Primo Vert inverted microscope, equipped with ZEISS LD Plan-ACHROMAT 20X objective lens, and an OLYMPUS SZ 61 stereomicroscope, were taken at various focus layers using digital adapter LW Scientific MiniVid DCM310 and were then “stacked” using CombineZM software. Different ways of obtaining high quality images were tested and are compared here in