Dragons guard secrets: integrative systematics of Pteraeolidia semperi species complex (Gastropoda, Nudibranchia) from Vietnam.

Authors

Maria N Meshik, Tatiana I Antokhina, Yury V Deart, Olga V Chichvarkhina, Irina A Ekimova

Published in

ZooKeys. Volume 1293. Pages 347-376. Epub Oct 02, 2026.

Abstract

The nudibranch genus Pteraeolidia has traditionally been treated as taxonomically simple, but recent molecular studies suggest that it includes hidden species diversity across the Indo-Pacific. In this study, the Pteraeolidia semperi species complex was investigated from the coastal waters of Vietnam using an integrative approach. Thirty-five specimens from five localities were analysed using mitochondrial (COI, 16S rRNA) and nuclear (H3) markers, together with external and internal morphological data and haplotype network analysis. Our results revealed two deeply divergent clades (Clades A and B) occurring sympatrically in Vietnam. These clades correspond to several molecular operational taxonomic units and show strong geographic structure across the Indo-West Pacific. One of these units (MOTU20), which falls within Clade B, corresponds to Pteraeolidia ianthina (Angas, 1864), a valid species restricted to its type locality, Sydney Harbour, New South Wales; it is treated here as separate from the P. semperi complex. Nuclear data support the separation of the two clades as independent evolutionary lineages, whereas relationships among mitochondrial lineages within each clade remain unresolved. The two clades also differ in external morphology, especially in body colouration, pigmentation pattern, and ceratal arrangement, while internal anatomy is largely similar. Mitochondrial divergence in Pteraeolidia is exceptionally high, including within clades, and exceeds values usually reported between species. This unusual pattern may reflect accelerated mitochondrial evolution, possibly linked to the photosymbiotic lifestyle of these nudibranchs. Our data show that Vietnamese populations of Pteraeolidia include at least two species within a broader and highly diverse species complex. These findings confirm that Pteraeolidia semperi represents a complex of cryptic or semi-cryptic taxa and highlight the need for genomic data to resolve species limits more precisely.

PMID:
42859732
Bibliographic data and abstract were imported from PubMed on 11 Oct 2026.

Read full publication at:
Please sign in to see all details.

Stats

1-terrible, 9-excellent. How would you rate this publication? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.