DOI: 10.15468/9g5qpg
title: A revision of the rare Strumigenys mnemosyne (Formicidae; Myrmicinae) group using micro-CT scanning, with the description of three new species, and the virtual repair of a broken paratype

description: This dataset contains the digitized treatments in Plazi based on the original journal article Hamer, Matthew T., Katzke, Julian, Tang, Kit Lam, Weemaels, André Ibáñez, Hita-Garcia, Francisco, Economo, Evan P., Guénard, Benoit (2025): A revision of the rare Strumigenys mnemosyne (Formicidae; Myrmicinae) group using micro-CT scanning, with the description of three new species, and the virtual repair of a broken paratype. PLOS One 20 (9): 1-29, DOI: 10.1371/journal.pone.0331762, URL: https://doi.org/10.1371/journal.pone.0331762AbstractOPEN ACCESSThe ant genus Strumigenys is both species rich, with over 800 species described, and morphologically diverse. The Strumigenys mnemosyne species group, a collection of small and infrequently collected Strumigenys known from across the Asian tropics and subtropics is revised. X-Ray microcomputed tomography alongside traditional microscopy is used describe three new species, S. liui sp. nov., S. marmorata sp. nov., and S. rimdahli sp. nov., increasing the number of species within the group to eight. Further, micro-CT scans of the worker and gyne caste of S. mazu are produced, providing the first morphological description for the later caste. Owing to specimen damage obtained during specimen transportation for one of the type specimens used within this study, the utility of 3D models to reconstruct broken type material is explored. Updated distributions and dichotomous keys are also provided for the group.Citation: Hamer MT, Katzke J, Tang KL, Weemaels AI, Hita-Garcia F, Economo EP, et al. (2025) A revision of the rare Strumigenys mnemosyne (Formicidae; Myrmicinae) group using micro-CT scanning, with the description of three new species, and the virtual repair of a broken paratype. PLoS One 20 (9): e0331762. https://doi.org/ 10.1371/journal.pone.0331762Editor: A.P. Ranjith, Chulalongkorn University, THAILANDReceived: March 14, 2025Accepted: August 15, 2025Published: September 24, 2025Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal. pone.0331762IntroductionThe small, slow moving, and cryptobiotic ant genus Strumigenys is the third most species-rich ant genus with over 800 described species spread across the globe, with peaks of diversity observed within the tropical regions [1, 2]. The genus is predominantly leaf litter dwelling, with few occupying the arboreal and subterranean stratums [3 – 5]). Strumigenys species have evolved an array of mandibular forms and ensnaring mechanisms, such as a latch mediated mandibular spring system used to capture soft-bodied, fast moving arthropod prey such as collembola [6]. The genus is morphologically diverse, not only in mandibular morphology, but also numerous morphological characters across the whole body, including (but not limited to) sculpture, pilosity and magnitude of spongiform tissue, particularly around the metasoma [3]. The genus currently consists of over 100 morphologically diverse species groups, diagnosed by a suite of morphological characters [3, 7]. One such group, the S. mnemosyne species group, comprises members that are relatively small (often less than 2mm in total length) and considered to be locally uncommon and rare across Asia [3] (Fig 1). Many species are known only from singleton holotype specimens, or only a handful of specimens. However, they are morphologically recognisable due to their highly reduced eyes (more often a single ommatidia), presence of a marginated elongate cuticular strip below the preocular carina, and reduced basal mandibular lamella [3].Copyright: © 2025 Hamer et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Data availability statement: All cybertype datasets, comprising CT scans (nii format), 3D models (STL format), shaded still image renders of specimen models (PNG & TIFF formats), and digital colour images can be accessed in Zenodo Digital Repository (https:// zenodo.org/records/14830376). All 3D surface models generated within this study are available on Sketchfab (https://skfb.ly/p9yqI).Funding: BG was awarded; Environment and Conservation Fund from the Government of the Hong Kong Special Administrative Region, under the ‘ Environmental Research, Technology Demonstration and Conference Projects’ funding scheme, Project number ECF 137/2020. URL; https://www.ecf.gov.hk/en. Funder did not play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. MTH and AIW recieved salary from ECF 137/2020. BG was awarded; Research Grant Council from the Government of the Hong Kong Special Administrative Region, GRF17103223. URL https://www.ugc. edu.hk/eng/rgc/funding_opport/grf/. Funder did not play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. MTH recieved salary from GRF17103223.X-Ray microcomputed tomography (micro-CT) is a powerful tool capable of producing 3-dimensional (3D) reconstructions of the whole organism or particular parts. Models of organisms can be comprehensively analysed within 3D virtual space via rotation, dissection (i.e., segmentation) and measurements. Although the application of micro-CT analyses are broad, in recent years researchers have used micro-CT data for taxonomic purposes, particularly for extinct arthropod taxa preserved in amber [8 – 10], but also extant taxonomic groups such as myriapods [11], spiders [12], beetles [13], as well as ants [14 – 19]. A notoriously challenging hurdle for systematists is access to the type material deposited in institutions across the world. Virtual collections of ‘ cybertypes’ can help to alleviate this hurdle, with 3D models of types stored online being considerably more accessible than traditional physical collections [16, 19, 20]. During specimen handling procedures, specimens can be broken purely by accident or by physical abrasion. This is particularly worrisome for high value specimens, such as type material. Micro-CT derived data could alleviate this hurdle by providing datasets of individually scanned body parts that can be ‘repaired’ in 3D virtual space.Competing interests: The authors have declared that no competing interests exist.Here micro-CT scanning image stills, 3D models, and traditional microscopy are used to review the Strumigenys mnenosyne group. Three novel species are described, S. liui sp. nov. from Yunnan, China, S. marmorata sp. nov from Hong Kong, and S. rimdahli sp. nov. from Thailand. A 3D model of a virtually repaired paratype specimen of S. marmorata that had been broken prior to scanning is also made available. For S. mazu, micro-CT scans are made available for both worker and queen. A novel description of the queen, as well as a new provincial record for Fujian Province, China is supplied. An updated and expanded species group definition is produced, incorporating novel morphological characters from S. marmorata. An updated dichotomous key is provided, alongside distributional checklist and map of the whole S. mnenosyne group, as well as high-resolution images of all species, including the first for S. runa [3].