Kaminski Lab: Systematic Entomology

I. OBJECTIVES

The main goal of this project is to present a robust phylogeny of the subfamily Blaptinae Leach (Coleoptera: Tenebrionidae) – a global radiation of over 4,000 darkling beetle species classified within ~300 genera (Kamiński et al. 2021a). The project will integrate targeted enrichment (TE) high‐throughput DNA sequencing data, including museomics, with morphological traits. Specifically, the sequence data for 548 targeted loci spanning over 510,000 bp (Kamiński et al. 2024) from representatives across the diversity of Blaptinae will be generated by sequencing 200 historical and 200 recently collected specimens (including 60 outgroup taxa). Morphological traits (>150 features) of the majority of the blaptinoid genera (~200 gen.) will be coded into a matrix. Based on these datasets the following subprojects will be investigated: 

(1) Historical biogeography of Blaptinae: the evolutionary story of desert-adapted lineages; 

(2) Anatomical (a) and molecular (b) adaptations for surviving in hyper-arid and arid environments; 

(3) Total evidence based classification of Blaptinae: molecular, morphological, and online tools for taxonomic identifications; 

(4) Phylogeny and generic revision of the tribe Opatrini (PhD project). 

II. SIGNIFICANCE

By covering approximately 20% of the land area of the continents, deserts constitute one of the largest terrestrial biomes of our planet (Brito & Pleguezuelos 2020). Despite their seemingly inhospitable conditions, they are home to a surprising array of plant and animal life, including highly adapted and specialized species (Mace et al. 2005). Given the current desertification of many ecosystems worldwide, studies of desert fauna are becoming more popular. The results of some investigations have helped us to understand the previous aridification processes (Owen et al. 2017), predict the effects of climate change, and inspire bionic inventions (e.g., Fu et al. 2023).

Darkling beetles are widely known for their ability to thrive in dry, desert environments (e.g., Matthews et al. 2010). Unlike most other insect groups, their biodiversity can increase with aridity (Koch 1962). To adapt to such harsh habitats, these insects use different evolutionary strategies such as fog-basking, modifications to respiratory activity, longevity of imaginal forms, burrowing behaviors, and parental care (Fattorini 2023). Our current understanding of these adaptations remains scarce and is derived from studies of selected species mostly representing one subfamily (Pimeliinae Latreille) (Hamilton & Seely 1976). More robust analyses are limited due to the lack of phylogenetic data for the family and its components.

Blaptinae is a recently re-erected subfamily of darkling beetles (Fig. 1B) (Kamiński et al. 2021a). The monophyly of this lineage has been separately supported by non-overlapping molecular datasets (Sanger data: Kamiński et al. 2021a, NGS: Ragionieri et al. 2023, Kamiński et al. 2024), while its formal distinctiveness has been widely accepted by the scientific community (e.g., Bouchard et al. 2021, GenBank). As such, this subfamily constitutes an especially reliable model for evolutionary studies compared to other darkling beetle subfamilies, which in many cases represent non monophyletic assemblages (e.g. Tenebrioninae). Although representatives of Blaptinae are commonly observed in temperate biomes, several lineages colonized arid and hyper-arid habitats of all continents (e.g., Iwan et al. 2020, Kamiński et al. 2021a) and, in some deserts, have become the dominant beetle group (Matthews et al. 2010). Up to now, representatives of this subfamily have been reported from the majority of large deserts of the world (e.g., Koch 1962, Ragionieri et al. 2023), including Atacama, Gobi, Mojave, Namib, and Sahara. Following eight tribes are recognised within Blaptinae (Kamiński et al. 2024): Amphidorini, Blaptini, Dendarini, Dissonomini, Opatrini, Pedinini, Platynotini and Platyscelidini.

The potential of Blaptinae in studies of desert adaptations remains largely unexcavated. Except for Parastizopus armaticeps (Péringuey) – a common burrowing species of Opatrini in Kalahari Desert, which provides parental care for developing larvae (Rasa 1990) – no other species has been subjected to organized analyses. Furthermore, in terms of the cuticular and muscular adaptations toward thriving in desert habitats, only the larvae of Gonopus tibialis Fabricius received some attention (Raś et al.2022). The low interest in Blaptinae regarding their xerophilous lifestyles seems to be largely driven by the lack of robust phylogenetic data.

To date, the most taxonomically comprehensive phylogenetic hypothesis for Blaptinae was presented by Kamiński et al. (2021a) – who erected the taxon. While the Sanger-based dataset was sufficient to indicate the monophyly of the taxon, it was too scarce to provide a clear view of the relations within it (e.g., Fig. 1A). The most severe inconsistencies concerned the relations between Opatrini and other tribes (Kamiński et al. 2021a). Due to the absence of historical museum specimens, the selection of taxa was largely driven by the availability of ethanol-preserved individuals. As such, many tribes (e.g., Pedinini, Opatrini) were represented by less than 15% of their generic diversity, which inhibited detailed biogeographic and evolutionary investigations. 

Though published, phylogenomic studies of Blaptinae are extremely taxonomically limited (Ragionieri et al. 2023, Kamiński et al. 2024). Nevertheless, they illustrate the methodological advantage of TE sequencing over the Sanger strategy. Under the support of the OPUS-19 grant (see Kamiński 2020), the PI developed and implemented a Blaptinae-tailored TE workflow to address the systematics of the tribe Platynotini. Acquired data revealed the great applicability of this method for simultaneously processing freshly collected and museum specimens (e.g., Kamiński et al. 2024). Even in cases of targeted sequencing failure, historic specimens were efficiently added to the phylogeny using mitochondrial sequences obtained as a bycatch from the TE approach.

Morphological data on most higher-level taxa among darkling beetles originates from a few classical taxonomic studies (e.g., Watt 1974, Doyen & Tschinkel 1982). Although in the beginning this knowledge enabled the introduction of the modern classification of Tenebrionidae, it has become insufficient to accommodate more recent molecular phylogenetic data (Kergoat et al. 2014). This is reflected in poor definitions of many tribes and subfamilies, and contributes to the extension of the phylogeny-classification gap (Franz 2005). This seems unfortunate, as the reinterpretation of old morphological concepts offers game-changing outcomes to our understanding of the evolution of different Blaptinae lineages (e.g., Lumen et al. 2019). The main goal of this project is to test previous phylogenetic hypotheses of Blaptinae by using a newly generated dataset of molecular (TE) and morphological traits. Acquired information will be used to investigate the specific goals specified below.

Ad. 1. Until present, no papers have been published on the geological time context nor biogeographic scenarios of desert colonization by major Tenebrionidae groups. The closest available study focuses on habitat preferences of different pimelinoid lineages and is based on a Sanger dataset (Kergoat et al. 2014). In particular, the authors hypothesised that the scarce presence of this subfamily in Australia could be tied to the old origin of xerophilic preferences within the group (Kergoat et al. 2014). Due to weak resolution of the phylogeny, the study did not provide any insights into the evolution of Blaptinae. Other contributions on the phenomenon of desert colonization in Tenebrionidae are rather narrative (e.g., Koch 1962). According to two independent calibrations performed by Kamiński et al. (2021b), Blaptinae originated about 75 Ma, which predates the origin of the World's oldest current desert – the Namib (e.g., Huntley 2023). Given this and the global omnipresence of Blaptinae, this subfamily seems to constitute an especially interesting object for a historical biogeographic study concerning desert colonization. When analyzing the worldwide distribution of Blaptinae the following patterns emerge: (i) the lack of endemic lineages of the Australian zone, Atacama, and Sahara deserts (Koch 1962, Ragionieri et al. 2023); (ii) the presence of highly diversified and endemic morphologies in the Namib and Kalahari deserts (Koch 1962); (iii) amphitropical and amphi-Atlantic distributional patterns of some of tribes (Kamiński et al. 2021b). The project team will conduct a global, time-calibrated ancestral area reconstruction using a comprehensive distributional dataset to test the following biogeographic hypotheses: H1. Desert-dwelling lineages of Blaptinae evolved independently from less-xeric ancestors across different continents. H2. The divergence of Old and New World desert-dwelling lineages reflects vicariance due to Gondwanan-Laurasian breakup rather than recent long-distance dispersal. H3. The high endemism observed in Namib and Kalahari Blaptinae reflects the ancestral ecological association of this subfamily with southern African arid biomes.

Ad. 2. When considering invertebrates, it has to be stated that Tenebrionidae are the best-represented beetle family in the majority of deserts around the World (Crawford 1981). Despite this our understanding of xeric adaptations in this group is shallow, and mostly derived from subjective interpretations rather than detailed study. 

(a) The evolution of body shape is a key component of functional adaptation to arid environments (e.g., Mousseau 1997, McQueen et al. 2022). In desert-adapted darkling beetles, particularly Blaptinae, external morphology appears tightly linked to ecological pressures such as extreme heat, substrate type, and the demands of thermoregulation or burrowing. Repeated observations suggest a strong relationship between ecological niche and body form (e.g., Koch 1962, Draney 1993, Fattorini 2009). Elytral shape, and thus total body roundness, is likely related to thermoregulation. Koch (1962) states that 98% of tenebrionids in the Namib Desert are flightless, with the few winged species confined to mesic microhabitats such as riverbeds. This pattern holds true for many desert-adapted Blaptinae. Several authors have proposed that flightlessness is a secondary consequence of the formation of the subelytral cavity—a hermetically sealed air space beneath the elytra (Fig. 1C)—which may function as a thermal insulator (e.g., Hadley 1972, Draney 1993). As such, enlargement of this structure may influence the overall body shape of sand-dwelling species (Koch 1962, Fattorini 2009). Conversely, body flattening in fossorial species likely reflects anatomical adaptations for digging (Koch 1962, Raś et al. 2022). Despite the ecological relevance of these patterns, differences in shape among desert-adapted Blaptinae, nor Tenebriondiae, has never been rigorously quantified in a statistical framework. As a result, the evolution of body shape in this group remains poorly understood.

To address this gap, an investigation of shape evolution in selected xerophilous lineages of Blaptinae will be conducted using 3D geometric morphometrics. Unlike traditional linear morphometrics or descriptive morphology, this enables the quantification of subtle but evolutionary relevant shape variation (Fig. 1C). This approach has proven extremely effective in vertebrate studies (Klingenberg 2016; Gündemir & Szara 2025), but remains underutilized in insects (Szara et al. in press). Specific hypothesis to be tested: H4. Desert-dwelling lineages of Blaptinae have independently evolved similar body shapes as adaptations to arid environments, despite divergent phylogenetic histories.

(b) Despite the increasing popularity of heat shock proteins (Hsp) for studies of xerophilous taxa, only a handful of investigations have been done for darkling beetles (e.g., Xu et al. 2010). In general, many of the studies dealing with Hsps investigate expression patterns under laboratory conditions (e.g., Malewski et al. 2015). In contrast, the analysis proposed here will focus on homolog evolution instead. No such published studies for darkling beetles are available; however, Swichtenberg (2021) proved the feasibility of this method for Pimeliinae. The probes for the Hsp40 homologs are already included in the TE probeset, which will be used to reconstruct the phylogeny of Blaptinae (Kaminski et al. 2024). This methodological convergence enables a close and economically efficient investigation of the evolution of this family of Hsps without additional sequencing costs. This pioneer analysis will lay a foundation for further follow-up studies of other Hsp families and detailed analysis of gene expression patterns. Specific hypothesis to be tested: H5. The evolution of Hsp40 homologs in Blaptinae reflects lineage-specific adaptations to arid environments and shows convergent sequence evolution across independently desert-adapted clades.

Ad. 3. The lack of a robust, phylogeny-informed classification for Blaptinae is a major obstacle for both systematists and applied researchers. Specialists working on regional faunas (e.g., Soldati et al. 2017, Bai & Ren 2019, Johnston et al. 2022), as well as institutions monitoring invasive species (e.g., USDA), have emphasized the need for reliable taxonomic tools – several Blaptinae lineages represent the most frequently intercepted darkling beetles in global trade (pers. comm.). Moreover, the absence of a stable classification hampers the broader use of this group in disciplines such as aDNA recovery, climate change modeling, and behavioral ecology (Smith et al. 2021, Lumen & Kamiński 2023, Szara in press). To address these shortcomings, the project’s team will implement generated phylogenetic data to test the monophyly of all 22 recognized subtribes within Blaptinae (Kamiński et al. 2021a, 2024). Where necessary, revisions of tribal and subtribal boundaries will be provided, guided by both molecular evidence and morphological synapomorphies. This will culminate in a new classification system, accompanied by richly illustrated identification resources (e.g., keys, annotated images, online access). These tools will be openly accessible and designed to serve both research and applied communities. Specific hypothesis to be tested: H6. The current subtribal classification of Blaptinae does not reflect monophyletic groupings and requires redefinition based on combined molecular and morphological evidence.

Ad. 4 (PhD project). With over 2,000 described species, Opatrini is the most diverse and widely distributed tribe within Blaptinae—and Tenebrionidae as a whole. Members of this tribe are found on every continent except Antarctica, and are uniquely the only Blaptinae present in remote or extreme regions such as the Galapagos Islands, Atacama Desert, and Australia (Iwan & Kamiński 2016). Furthermore, many species exhibit remarkable ecological adaptations—for example, the ultraxeric Parastizopus armaticeps, which is well known for providing parental care to its developing larvae. Despite its prominence, the current subtribal classification of Opatrini remains unstable and untested. It is largely based on morphological traits of female terminalia (Kamiński et al. 2022), which in many cases are plesiomorphic and insufficient for confident taxonomic placement. The only available phylogenetic study (Lumen et al. 2019) includes just 21 of 117 genera, is poorly supported, and highlights serious ambiguities—especially within Ammobiina and Opatrina, which together comprise more than half of the tribe’s generic diversity (Iwan & Kamiński 2016, Kamiński et al. 2023). 

To resolve these issues, the hired PhD student will conduct a comprehensive phylogenetic analysis of ~120 operational taxonomic units (OTUs) sampled across the full generic spectrum of Opatrini. The project will combine TE approach, museomic data, and morphological character sets, resulting in a well-supported classification that will serve as a stable foundation for ecological, evolutionary, and biogeographical studies of this globally significant lineage. The project will directly address the following hypothesis: H7. The current generic classification of Opatrini does not reflect phylogenetic relationships.