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The subfamily Sepiolinae (Mollusca: Cephalopoda: Sepiolidae), currently containing the genera Sepiola Leach, 1817, Euprymna Steenstrup, 1887, Inioteuthis Verrill, 1881, Rondeletiola Naef, 1921 and Sepietta Naef, 1912, is characterized by the hectocotylization of the left dorsal arm, i.e., its transformation into a copulatory organ thanks to modifications of sucker/pedicel elements. The hectocotylus morphology varies to a great extent across genera and species. In particular, one to several pedicels in its proximal third lose their sucker and become highly and diversely modified in shape to constitute a copulatory apparatus. An evolutionary gradient was observed in the copulatory apparatus morphology, from the simple modification into a papilla of just one pedicel from the third element of the ventral sucker row (some nominal species of Euprymna) to a quite complex structure involving several variously modified pedicels from both the ventral and dorsal sucker rows (Inioteuthis). In some species, elements in the distal portion of the hectocotylus may also be highly modified, such as the columnar suckers in Euprymna. The hectocotylian diversity allows to distinguish nine groups of species that do not match the current generic subdivision of Sepiolinae. Additional morphological characters (number of sucker rows on arms, female bursa copulatrix, occurrence and shape of visceral light organs, etc.) corroborate the subdivision of Sepiolinae into nine subtaxa, i.e., genera. Accordingly, a cladogram is drawn to describe the possible phylogenetic relationships among the nine clades. To comply with these results, all current genera are redefined and four new genera are described, namely Adinaefiola gen. nov., Boletzkyola gen. nov., Eumandya gen. nov. and Lusepiola gen. nov.
A new sepioline species, Sepiola boletzkyi sp. nov. (Cephalopoda: Sepiolidae), is described based on two specimens from the Aegean Sea (eastern Mediterranean). The type specimens are lodged in the Ege University Faculty of Fisheries Museum of Izmir (Turkey). The new species belongs to the Sepiola atlantica group sensu Naef, hence it is compared with the species in this group, namely Sepiola affinis, Sepiola atlantica, Sepiola bursadhaesa, Sepiola intermedia, Sepiola robusta, Sepiola rondeletii, Sepiola steenstrupiana and Sepiola tridens. The male of S. boletzkyi sp. nov. differs from all the others in having the combination of homomorphous ventral arm tips, eight enlarged suckers, subdivided into two groups, in the dorsal row of the distal part of the hectocotylus and a dorsal lobe complementing the copulatory apparatus. In females of S. boletzkyi sp. nov. the bursa copulatrix is large and, unlike all other species in the genus, has a large fungiform process towards the mantle wall. The discovery of S. boletzkyi sp. nov. increases to 12 the number of NE Atlantic- Mediterranean species of Sepiola.