Intra-island patterns of cryptic diversity within an oceanic island: Insights from the differentiation of Schizidium Verhoeff, 1901 (Oniscidea, Armadillidiidae) within Cyprus, with descriptions of two new species

Andreas C Dimitriou; Ivanklin Soares Campos-Filho; Anastasia Georgiou; Stefano Taiti; Spyros Sfenthourakis

doi:10.1016/j.ympev.2023.107884

Intra-island patterns of cryptic diversity within an oceanic island: Insights from the differentiation of Schizidium Verhoeff, 1901 (Oniscidea, Armadillidiidae) within Cyprus, with descriptions of two new species

Mol Phylogenet Evol. 2023 Oct:187:107884. doi: 10.1016/j.ympev.2023.107884. Epub 2023 Jul 18.

Authors

Andreas C Dimitriou¹, Ivanklin Soares Campos-Filho², Anastasia Georgiou², Stefano Taiti³, Spyros Sfenthourakis²

Affiliations

¹ Department of Biological Sciences, University of Cyprus, Panepistimiou Ave. 1, 2109 Aglantzia, Nicosia, Cyprus. Electronic address: adimit04@ucy.ac.cy.
² Department of Biological Sciences, University of Cyprus, Panepistimiou Ave. 1, 2109 Aglantzia, Nicosia, Cyprus.
³ Istituto di Ricerca sugli Ecosistemi Terrestri, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Florence), Italy; Museo di Storia Naturale dell'Università di Firenze, Sezione di Zoologia "La Specola", Via Romana 17, 50125 Florence, Italy.

PMID: 37467903
DOI: 10.1016/j.ympev.2023.107884

Abstract

Cyprus is a Mediterranean island of volcanic origin isolated for at least 5.3 Myr from surrounding continental areas. The present study focuses on the diversification of the isopod genus Schizidium within the island, including also specimens from surrounding continental areas. The genus Schizidium sensu lato is probably non monophyletic, comprising 26 species distributed from Greece to Iran. Up to date the only representative of the genus reported from Cyprus was Schizidium fissum. Aiming to investigate the patterns of genetic diversity within the focal island, to evaluate the morphology-based taxonomy of the species in the genus, and at the same time to explore phylogenetic relationships with mainland populations, we applied genome-wide ddRADseq as well as Sanger sequencing targeting three mitochondrial (16S, COI and 12S) and the nuclear NaK loci. Results of phylogenetic analyses support the existence of two distinct epigean Schizidium clades with well-defined geographic boundaries that conform to the known paleogeography of Cyprus, plus one endogean clade with restricted distribution within the island. Genetic data and morphology corroborate the assignment of this latter endogean clade to a new species, Schizidium myrrae n. sp. The two epigean clades are also considered as distinct species, one corresponding to the known S. fissum at the eastern part of the island (Pentadaktylos massif) and the other to the newly described S. christosi n. sp. distributed along the western part of the island (Troodos massif). Even though detailed examination of many specimens could not retrieve any morphological differences among representatives of these two clades, clado-chronological analysis indicates a long isolation between them, estimated at ∼ 9 Mya, as well as the sharing of a common ancestor with S. tiberianum from Israel at ∼ 15 Mya. Hence, we can consider these epigean Schizidium species as one more case of cryptic diversity on Cyprus, exhibiting similar patterns with the recently described case in the genus Armadillo.

Keywords: Cryptic species; Integrative taxonomy; Intra-island diversity; Paleogeography; Terrestrial isopods.