Abstract
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.
Highlights
The subfamily Sepiolinae Leach, 1817 is one of three subtaxa into which the family Sepiolidae Leach, 1817 (Cephalopoda: Sepiolida) is currently subdivided; the other two are Heteroteuthinae Appellöf, 1898 and Rossiinae Appellöf, 1898 (Reid & Jereb 2005)
Its affinities with Sepiola, as understood here, are mainly limited to the same type of light organs, kidney-shaped, and the same type of bursa copulatrix, character state shared by all NE Atlantic-Mediterranean Sepiolinae (Rondeletiola, Sepietta and Sepiola)
It differs from Sepiola in that the modified sucker pedicels in the dorsal row of the copulatory apparatus are separate from the ventral ones
Summary
The subfamily Sepiolinae Leach, 1817 is one of three subtaxa into which the family Sepiolidae Leach, 1817 (Cephalopoda: Sepiolida) is currently subdivided; the other two are Heteroteuthinae Appellöf, 1898 and Rossiinae Appellöf, 1898 (Reid & Jereb 2005). The diagnostic characters used to separate genera and species in this subfamily include the presence and shape of the mantle cavity light organs, the number of longitudinal sucker rows on the arms and tentacle clubs, the pattern of enlarged suckers on the arms, the morphology of the male hectocotylus and the shape of the female bursa copulatrix Their geographical distribution, as revised by Reid & Jereb (2005), indicates some disjunction among the nominal genera, with Euprymna and Inioteuthis occurring in the Indo-Pacific region, Rondeletiola and Sepietta inhabiting the eastern Atlantic Ocean and the Mediterranean Sea, whereas Sepiola is found in both the east Atlantic-Mediterranean region and the Indo-Pacific.
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