Annotated checklist of Recent Polyplacophora with notes on their systematics.

Area of Science:

• * Malacology and Biodiversity Science
• * Taxonomy and Systematics
• * Phylogenetic Analysis

Background:

• * Chiton systematics relies on morphological and molecular data, with ongoing revisions needed for family and genus-level relationships.
• * A comprehensive, updated species list is crucial for documenting systematic changes and identifying areas requiring further research.
• * Previous classifications sometimes conflict with molecular phylogenies, necessitating formal clarification.

Purpose of the Study:

• * To present an annotated checklist of 1093 accepted Recent chiton species, detailing their classification and systematic positions.
• * To document ongoing systematic revisions, including new family formations and taxonomic clarifications.
• * To provide updates on taxa where molecular phylogenies challenge morphological treatments.

Main Methods:

• * Compilation of morphological and molecular data for chiton systematics.
• * Development of an annotated checklist serving as a platform for systematic data.
• * Comparative analysis of phylogenetic data to resolve taxonomic conflicts.

Main Results:

• * Corroboration of Choriplax and Cryptochiton within Mopalioidea.
• * Establishment of the new family Nuttallochitonidae within Cryptoplacoidea for Nuttallochiton.
• * Restatement of Plaxiphoridae at the superfamily rank (Plaxiphoroidea) and restoration of Icoplax as a distinct genus.
• * Clarification of Ferreiraellidae as the accepted family name, replacing Abyssochitonidae.

Conclusions:

• * The annotated checklist provides a robust foundation for understanding chiton systematics and guides future research directions.
• * Formal taxonomic revisions, including new family and genus placements, enhance the accuracy of chiton classification.
• * Integrating molecular and morphological data is essential for resolving complex phylogenetic relationships in chitons.