Integrative taxonomy uncovers a new genus and species

A Review by Alice Laciny

Edited by Florian Steiner and Salvatore Brunetti

In their recently published paper, Chung et al. present a novel genus of myrmicine ants, namely Unicumyrmex gen.n., and its type species Unicumyrmex fushanensis sp.n. using a well-described and illustrated integrative taxonomic approach.

The story begins with a situation most myrmecologists will be familiar with – an assortment of specimens collected decades prior, stored under suboptimal conditions and tentatively assigned to a morphologically similar taxon while awaiting further study. In this case, the tiny, eyeless myrmicines were collected in 1997 in northern Taiwan – in the name-giving type locality of the Fushan Botanical Garden – and termed “Anillomyrma sp. 1” despite differing from other known species of this genus by having 11 antennal segments instead of 10. As such, they captured the interest of the present authors. However, molecular analysis based on PCR proved difficult due to the specimens’ age and storage, leading the authors to use several combined methods to ensure the correct description and phylogenetic placement of these animals.

The article thus integrates morphological descriptions, morphometric data, photographic and SEM imaging, as well as whole genome sequencing and barcoding. The morphological analyses place particular focus on including both worker and male characters.

Especially male ants are rare in collections, as they are short-lived and often difficult to assign to the correct species if not collected directly within their colony of origin. Therefore, studies like this one represent a valuable resource for future comparative studies. The authors have included descriptions, images, and illustrations of male genitalia and forewing venation of the new species in comparison with closely related genera. Also, keys to the Solenopsidini genera around the world are provided for workers and males separately and illustrated with easy-to-follow figures of diagnostic morphological characters.

Interestingly, the phylogenetic reconstruction based on 10 nuclear gene segments places U. fushanensis in a monophyletic group with Epelysidris brocha, Erromyrma latin­odis, and Tyrannomyrmex legatus. Even though the workers of these genera show only limited morphological similarities, the characters of their respective males support their proposed close relationship. In contrast, genera such as Anillomyrma, Bondroitia, and Dolopomyrmex – whose small, pale, eyeless workers bear a strong morphological resemblance to those of the new species – did not appear as close relatives in the phylogenetic tree. Again, the corresponding male morphology underlines these uncovered differences.

The present study is a commendable example of integrative taxonomy. The authors’ clever combination of different methods shows how phylogenetic riddles can be solved, even when faced with common difficulties such as limited resources or issues of sample quality.

Their conclusions are a welcome reminder to look past outward morphological similarities and consider ecological conditions as powerful drivers of similar phenotypes in distantly related taxa, which could potentially mask the true diversity of a group. Even within the Myrmicinae, the largest and most diverse subfamily of ants, numerous taxa may well contain many more cryptic species. Especially small, often overlooked groups, such as the Solenopsidini, likely represent a wealth of biodiversity that will only be discovered by creative and integrative taxonomic approaches such as the one presented herein.

As such, results like these beautifully illustrate how many surprises ants still have in store for us.