What we know and don't know about Earth's missing biodiversity.

Area of Science:

• Biodiversity Science
• Taxonomy
• Conservation Biology

Background:

• Global non-microbial species diversity estimates vary significantly, from 2 million to over 50 million.
• Uncertainties are particularly high for insects, fungi, nematodes, and deep-sea organisms.

Purpose of the Study:

• To summarize current estimates of species diversity across major taxa.
• To review methods used for species estimation and explore future discovery prospects.
• To highlight challenges and opportunities in cataloging Earth's biodiversity.

Main Methods:

• Compilation and synthesis of existing data on species diversity estimates.
• Analysis of methodologies employed in taxonomic and biodiversity assessments.
• Identification of key challenges, including synonymy and morphological identification limitations.

Main Results:

• Significant gaps exist in our knowledge of global species richness.
• Undiscovered species are often small, cryptic, geographically restricted, or inhabit inaccessible environments.
• Novel techniques like DNA barcoding and crowd-sourcing show promise for enhancing discovery rates.

Conclusions:

• Accelerated species discovery is crucial due to ongoing habitat destruction in biodiversity hotspots.
• Current extinction rate estimates may be underestimated because they are based on known species.
• Integrating new technologies is vital for a comprehensive understanding of global biodiversity and conservation needs.