Exploring the Potential of Serpulid External Tube Morphology for Rapid Grouping Assessment in Ecological Research: A Case Study From Southern New Zealand

In ecological field studies where species‐level identification is challenging, practical approaches based on external morphological traits may provide a useful basis for rapid assessments. Here, New Zealand serpulid worms were initially grouped based on their external calcareous tube morphology and subsequently sequenced using the 18S rRNA gene to explore whether tube features may be used to distinguish ecologically relevant morphogroups in local Spirorbinae and Serpulinae assemblages. Preliminary phylogenetic analyses consistently grouped individuals assigned to the same morphogroups into distinct molecular lineages, indicating a close association between tube‐based grouping under field conditions and genetic differentiation. While recent studies have improved the description of tube features for some Spirorbinae taxa, much of the group remains insufficiently characterised, particularly at regional scales. Our results highlight the potential of tube‐based morphogroups as a practical framework for organising serpulid assemblages in ecological studies and emphasise the need for future work combining detailed morphology, voucher material and expanded molecular reference libraries to further validate and refine this approach, including its application in palaeoecological reconstructions.