Vouchering 3D Morphology of Challenging Organisms using High-Definition Multifocal Images and their Practical Applications

Abstract

American Entomologist • Volume 54, Number 4 Accurate representation and effortless distribution of taxonomic information, particularly morphology, can be challenging, especially when organisms are microscopic and transparent with 3D external and internal diagnostic features. Examples include highly diverse groups of microscopic invertebrates such as nematodes, rotifers, tardigrades, and gastrotrichs. Identifying these organisms requires initial observations using high-resolution light microscopy to visualize structures from multiple focal planes, which is easily accomplished using the fine focal controls. Accurate depiction in 2D space is difficult, however, especially as the number of focal planes and diagnostic features increase. Hand-drawn illustrations are prone to misrepresentation and omission of micro-morphological structures because they are dependent on an author’s drawing abilities. These problems have diminished, somewhat, with technological advances in photography, which allow for more accurate depictions. However, photographs are still incomplete representations, recording only a single focal plane, omitting structures above and below the targeted focal plane. To solve these problems, De Ley and Bert (2002) proposed a new approach to document nematode morphology, called Video Capture and Editing (VCE). This procedure makes it possible to record a short video containing a multifocal series of images that scans through the organism’s body, much like an MRI (Fig. 1). Two non-automated VCE systems were assembled with commercial analog camcorders and video editing software and tested. Resulting images had limited resolution when compared with the microscope optics and 35-mm film photographs, but allowed for easy multifocal recording directly to hard disk (De Ley and Bert 2002). Multifocal images also can be manipulated by annotating structures through multiple focal planes and/or removing redundancy in duration, frames, resolution, or background, allowing large (10–50 MB) unedited multifocal images to be reduced in size about 10% without compromising quality. Images are viewed using multimedia player software, such as QuickTime, which allows viewers to scroll through the different focal planes via the video slider, simulating the fine focal controls Vouchering 3D Morphology of Challenging Organisms using High-Definition Multifocal Images and their Practical Applications