Published in Zoologica Scripta: link here.

The paper named “Insight into the phylogeny of the intertidal beetle genus Aegialites (Coleoptera, Salpingidae)“, by Marianne N. Haugen, Vladimir I. Gusarov, Derek S. Sikes & Torsten H. Struck is now published in Zoologica Scripta.

This paper, which is an important part of Marianne’s PhD project about the Aegialites beetles, is the first important step in any traditional research on a particular taxa, namely the investigation of species counts and species relationships. In this paper, our main goal was to infer the phylogenetic relationships of the Aegialites beetles, as well as to discuss and make a statement regarding the number of species present in the genus.

To do so, we sequenced, two genetic markers (COI and ITS2) of specimens spanning nearly the entire distribution range of the genus. Additionally, we included some 18S sequences and complete mitochondrial genomes, which all were used to create phylogenies, both with Maximum Likelihood and Bayesian Inference. Some additional measurements of genetic diversity was calculated: FST-values and P-distances, as well as haplotype networks. Furthermore, to investigate and make a statement regarding the species count present in the datasets, three different species delimitation analyses was conducted, namely ASAP, ABGD and bPTP.

Our results indicate the presence of three, well-supported, geographic clades; one including specimens from northern North America, the second including specimens from Russia and Japan and the third including specimens from California. These large clades were supported in all datasets, including both single markers (COI, ITS2 and 18S) but also in the concatenated datasets (COI+ITS2 and mitochondrial genomes). Also, an additional single, monophyletic clade of specimens from the Farallon Islands also stood out in all analyses.

Based on the phylogenetic results, together with additional genetic analyses, we support the finding of seven distinct Aegialites species in our datasets. This finding contrasts with earlier assumptions by Zerche’s (2004) whom, based on morphological investigations suggested a species count of 30 for the entire genus. Accordingly, our dataset could potentially include the presence of 17 distinct Aegialites species (if including type localities and localities very close to) as described by Zerche (2004), hence our species number are far more conservative.

In this study, we support the finding of four species with seemingly local distributions:  A. farallonensis from the Farallon Islands, one new species from Trinidad, Humboldt County, CA another new species from southern Russia, and a species termed ‘Group A’ from Hojito et al. (2010) in Japan. Additionally, we support the finding of three more widespread species: A. californicus in southern California, A. debilis in northern North America, and A. stejnegeri across the remaining areas and islands of Russia (Sakhalin, Kamchatka, and the Kuril Islands).

With three new species present in our datasets, only three species remain as historically described species additional to A. farallonensis as described by Zerche (2004).

This study provides the first molecular evaluation of species diversity in Aegialites and demonstrates that
morphology-based taxonomy can differ substantially from molecular-based results. This work is a big step in the right direction, but the genus would still benefit from a comprehensive integrative taxonomic treatment to produce formal species descriptions and clear delimitations.

Haugen, M. N., V. I. Gusarov, D. S. Sikes, and T. H. Struck. 2025. “ Insight Into the Phylogeny of the Intertidal Beetle Genus Aegialites (Coleoptera, Salpingidae).” Zoologica Scripta 1–23. https://doi.org/10.1111/zsc.70035.