World Database of Nematodes

Halalaimus is one of the most widespread and frequently encountered nematode genera, especially in marine and deep-sea environments, but species-level identification has long been complicated by incomplete descriptions, scattered records and confused nomenclature.
In a new ZooKeys paper, Bezerra, Smol, Alves and Pape present a major taxonomic review of the genus. The study consolidates information for 102 valid species, reassesses problematic records, corrects nomenclatural inconsistencies, and describes two new abyssal species from the nodule-bearing Clarion-Clipperton Zone: Halalaimus marcosi sp. nov. and Halalaimus pierri sp. nov.
A particularly useful feature of this work is its biogeographic component. The authors compiled geographical, habitat, morphometric and morphological information from original descriptions, redescriptions and published ecological studies. Based on these data, they produced global distribution maps for Halalaimus species, including an interactive online map that allows users to explore known records of the genus worldwide. The maps were built using GEBCO bathymetric data, with contract-area outlines based on the International Seabed Authority’s interactive map.
The paper also provides an online morphometric traits table, updated identification keys for Halalaimus, and a new key for deep-sea species. Together, these resources make the study especially valuable for nematode taxonomists, deep-sea ecologists and researchers working on biodiversity in polymetallic nodule regions.

Reference: Bezerra TN, Smol N, Alves RMS, Pape E (2026) Review of Halalaimus (Nematoda, Enoplida, Oxystominidae) and description of two new species from the abyssal nodule-bearing Clarion-Clipperton Zone. ZooKeys 1284: 1–48. DOI: 10.3897/zookeys.1284.187212
Full-text https://doi.org/10.3897/zookeys.1284.187212
Interactive distribution map: https://alvesrms.web.app/NematodeMap