Image use in field guides and identification keys: review and recommendations

Area of Science:

• Biodiversity and Taxonomy
• Scientific Illustration
• Digital Humanities

Background:

• Illustrations have been crucial in identification keys and guides since the 18th century.
• The application and quality of images in these resources have varied significantly over time.
• This review addresses image utilization in both traditional paper and modern electronic formats.

Purpose of the Study:

• To review the current use of images in paper and electronic identification guides.
• To establish a set of best practices for incorporating images into illustrated keys and guides.
• To improve the effectiveness of visual aids in species identification and taxonomic understanding.

Main Methods:

• A comprehensive review of image usage in various identification guides, including species descriptions and technical keys.
• Focus on how images are employed, rather than the operational aspects of the guides themselves.
• Consideration of both paper-based and electronic resources, with a brief note on mobile applications.

Main Results:

• Most illustrated keys and guides inadequately represent taxonomic variation due to insufficient or non-standardized images.
• The use of multiple, standardized images enhances taxon identification and character comprehension.
• Many electronic guides lack essential features like image enlargement, hindering detailed examination.

Conclusions:

• Optimal keys and guides feature standardized, easily viewable images arranged for easy comparison across species.
• Multiple images per character state are essential for users to assess variation.
• Professional illustrations with clear labeling and uncluttered backgrounds, along with scalable electronic images, are recommended.