Received: 10 June 2019 | Revised: 23 August 2019 | Accepted: 4 September 2019 DOI: 10.1111/zsc.12392 ORIGINAL ARTICLE Distribution pattern and radiation of the European subterranean genus Verhoeffiella (Collembola, Entomobryidae) Marko Lukić1,2,3 | Teo Delić2 | Martina Pavlek1,3,4 | Louis Deharveng5 | Maja Zagmajster2 1Croatian Biospeleological Society, Zagreb, Croatia Abstract 2SubBioLab, Department of One of the most striking features of obligate subterranean species is their narrow Biology, Biotechnical Faculty, University of distribution ranges. These prevail not only at specific, but often also at generic level. Ljubljana, Ljubljana, Slovenia However, some subterranean genera have continental scale and disjunct distribu- 3Ruđer Bošković Institute, Zagreb, Croatia tion, which challenges their monophyly and questions the scenarios of their origin 4Department of Evolutionary Biology, Ecology and Environmental Sciences & and colonization. In our study, we investigated the subterranean collembolan genus Biodiversity Research Institute, Universitat Verhoeffiella, currently known from five remote karst regions of Europe. Four nu- de Barcelona, Barcelona, Spain clear and one mitochondrial genes were assembled to reveal the evolutionary his- 5 Institut de Systématique, Evolution, tory of the genus. We tested the monophyly of the genus, explored its relationship Biodiversité, ISYEB ‐ UMR 7205 ‐ CNRS, MNHN, UPMC, EPHE, Museum with putative surface relatives, and its temporal patterns of molecular diversification. national d’Histoire naturelle, Sorbonne The phylogeny revealed a complex relationship of Verhoeffiella with surface species Universités, Paris, France Heteromurus nitidus and partially disentangled the biogeographical question of its Correspondence disjunct distribution. Further on, several lineages of Verhoeffiella were recognized Marko Lukić, Croatian Biospeleological in the Dinarides, showing highly underestimated diversity and, compared with the Society, Demetrova 1, 10000 Zagreb, Croatia. number of described species, a sevenfold increase in the number of MOTUs. The Email: [email protected] radiation is relatively recent, with the events triggering the diversification linked to the Messinian salinity crisis and Pleistocene climatic shifts. The combination of this Funding information Innovative scheme of co‐funding doctoral extensive subterranean radiation and close evolutionary links with epigean relatives studies for promotion of cooperation with makes Verhoeffiella an exceptional case within the subterranean fauna of temperate the economy and solving contemporary areas, which significantly contributes to our understanding of subterranean coloniza- social challenges ‐ generation 2012 (funded by the Ministry of Education, Science and tion and diversification patterns. Sport of Slovenia and European Union by European Social Fund); European KEYWORDS Union’s Human Resources Development colonization, hidden diversity, molecular phylogeny, Pleistocene, troglobionts, Western Balkans Operational Program (funded by the Ministry of Science, Education and Sport of Croatia by the European Social Fund), Grant/Award Number: HR.3.2.01–0015; Slovenian Research Agency, Grant/Award Number: P1‐0184 and Z1‐9164; Linnean Society of London and the Systematics Association, Systematics Research Fund 2016/2017; National Park Krka (Croatia) Marko Lukić and Teo Delić contributed equally to this work. Louis Deharveng and Maja Zagmajster share senior authorship. Zoologica Scripta. 2019;00:1–15. wileyonlinelibrary.com/journal/zsc © 2019 Royal Swedish Academy of Sciences | 1 2 | LUKIĆ ET AL. 1 | INTRODUCTION disjunct distribution patterns challenge the validity of extant monophylies, while the scenarios of origin and coloniza- Understanding processes of colonization, speciation tion call for further testing within molecular phylogenetic and dispersal in subterranean habitats is one of the main frameworks. challenges in evolutionary studies of subterranean spe- With more than 500 troglobiotic species worldwide, cies around the globe (Culver & Pipan, 2019; Moldovan, Collembola are among the most common inhabitants of Kováč, & Halse, 2018). One of the most striking features the subterranean realm (Deharveng & Bedos, 2018; Lukić, of obligate subterranean species (also termed troglobionts) 2019). They have been traditionally used as evolutionary is their narrow distribution ranges (Niemiller & Zigler, models for the study of morphological adaptations to sub- 2013; Trontelj et al., 2009; Zagmajster et al., 2014). In ex- terranean habitats (Christiansen, 1961, 1965, 2012), but their treme cases, the proportion of species known from single potential for testing evolutionary hypotheses using molecular or only a few localities can represent more than half of the approaches has rarely been exploited (Katz, Taylor, & Davis, species pool in a region (Bregović, Fišer, & Zagmajster, 2018). Among the taxa with disjunct distributions, one of the 2019; Niemiller & Zigler, 2013; Trontelj et al., 2009). most interesting examples to study is the exclusively subter- Small ranges are often related to limited dispersal abilities, ranean European genus Verhoeffiella Absolon of the family due to species morphological and physiological adapta- Entomobryidae. tions (Christiansen, 1961, 1965; Polak, Delić, Kostanjšek, The genus Verhoeffiella embodies several features of in- & Trontelj, 2016; Porter, 2007; Thibaud & Vannier, 1986; terest: (a) the genus has a wide disjunct distribution, occur- Vannier & Thibaud, 1984). Range sizes of subterranean ring in five karst regions of Europe; (b) its centre of diversity taxa have so far been explained via the fragmented karstic is in the Dinarides; and (c) it has a putative surface relative, landscapes, complex paleogeographic events and/or his- Heteromurus nitidus (Templeton, 1835). Currently, the genus toric climatic variability (Deharveng & Gers, 1993; Eme encompasses 14 nominal species, ten of which are described et al., 2014; Fresneda, Valenzuela, Bourdeau, & Faille, from caves in the Dinarides (Lukić, Delić, Zagmajster, & 2019; Rizzo, Comas, Fadrique, Fresneda, & Ribera, 2013; Deharveng, 2018). Four other karst regions contain one spe- Trontelj et al., 2009; Zagmajster et al., 2014). Small distri- cies each and are from 150 to 1,000 km apart: Jakupica (North bution ranges of troglobionts prevail at specific level, but Macedonia), south‐eastern Calcareous Alps (Italy), southern are also frequent at the generic level. However, some genera Catalonia and Cordillera Cantabrica (Spain) (Lukić, Porco, exhibit large distribution ranges (Baratti, Filippelli, Nardi, Bedos, & Deharveng, 2015). This intriguing distribution, & Messana, 2010; Faille et al., 2010; Gibert & Deharveng, coupled with diversity of morphological traits, has already 2002; Isaia, Mammola, Mazzuca, Arnedo, & Pantini, 2017; led to recent taxonomic revisions of the existing and descrip- Trontelj et al., 2009; Zakšek, Sket, & Trontelj, 2007), es- tions of new species of the genus (Lukić et al., 2018, 2015). pecially among Collembola (Christiansen, da Gamma, & As stated in previous works, there is a need to resolve the Bellinger, 1983; Lukić, 2019). relationship of Verhoeffiella and Heteromurus s.str. Wankel, The most intriguing cases of widespread and exclusively as both genera share most characters used at the generic level subterranean genera are the ones with disjunct distribu- within Heteromurinae (Cipola, Oliveira, Morais, & Bellini, tions—occurring in geographic regions that can be hundreds 2016; Mari Mutt, 1980b). Remarkable morphological sim- or thousands of kilometres apart. Among European terrestrial ilarity of the genus Verhoeffiella and the epigean species troglobionts, such examples have been reported in different H. nitidus (Bonet, 1931; Lukić et al., 2018, 2015; Mari Mutt, taxonomic groups, from gastropods to insects (Deharveng 1980a) sets the latter as the most likely candidate for a surface & Bedos, 2018; Duchae, 2001; Faille, Casale, Hernando, relative of Verhoeffiella. Aït Mouloud, & Ribera, 2018; Fanciulli, Inguscio, Rossi, & The close relationship of the two taxa may offer an insight Dallai, 2003; Weigand et al., 2013). Some of them, known into the origin of disjunct distribution of Verhoeffiella and from the Iberian Peninsula, the Alps and the Dinarides, even contribute to a better understanding of colonization and diver- share similar distribution patterns (Inäbnit et al., 2019; Lukić, sification dynamics within the subterranean habitats in gen- Houssin, & Deharveng, 2010; Sendra, Lara, Ruiz Aviles, & eral. Therefore, we first tested the monophyly of Verhoeffiella Tinaut, 2004; Taiti et al., 2018). Among the subterranean populations from remote European regions and determined taxa with disjunct distribution, only spiders and terrestrial the position of the genus within the Entomobryidae family. gastropods were studied with molecular approaches (Pavlek We then explored the relationship of Verhoeffiella to its pu- & Ribera, 2017; Ribera, Elverici, Kunt, & Özkütük, 2014; tative surface relative H. nitidus from different geographi- Weigand et al., 2013), while for the others, the taxonomical cal areas. Further, we estimated hidden diversity within the assignments of geographically disjunct populations rely on genus Verhoeffiella with a special emphasis on the Dinarides. morphology alone. Due to striking morphological conver- Finally, we explored the relationship between different popu- gences common among troglobionts (Culver & Pipan, 2019), lations