Boletzkyola, Bello, 2020

Bello, Giambattista, 2020, Evolution of the hectocotylus in Sepiolinae (Cephalopoda: Sepiolidae) and description of four new genera, European Journal of Taxonomy 655 (655), pp. 1-53 : 37-38

Boletzkyola gen. nov.

urn:lsid:zoobank.org:act:AA294852-E5A5-40E6-A8F4-288A22290823

Figs 10–11 (the generic name used in the captions is the former one)

Type species

Sepiola knudseni Adam, 1984 , here designated.

Diagnosis

Sepiolinae with fins rounded; their length about half mantle length. Suckers biseriate on all arms. Tentacle club suckers in 8 longitudinal rows. Mantle-head occipital band narrow (not reaching over the ocular globes). A single cordiform photophore on ventral surface of ink sac. Ventral mantle margin slightly sinuate, without any deep funnel indentation. Hectocotylus (male left arm I) tripartite: basal part with one incomplete transverse row of suckers (only the ventral one is present); copulatory apparatus with three ventral modified suckerless pedicels enlarged and lengthened into thick, bluntly pointed horn-like structures; distal part with several suckers missing proximally in ventral row and four enlarged suckers in dorsal row. Female bursa copulatrix pouch-like with wide opening.

Included species

Boletzkyola knudseni (Adam, 1984) gen. et comb. nov.

Etymology

This genus is named in honour of Sigurd von Boletzky (formerly Observatoire Arago / CNRS, Banyulssur-Mer, France; presently retired) for his outstanding contribution to the study of cephalopods, including Sepiolinae , and to the enhancement of Mediterranean teuthology; it is formed by his family name and the diminutive suffix - ola. Gender feminine.

Discussion of affinities

Boletzkyola gen. nov. differs from all other genera and species-groups in Sepiolinae because of its unique cordiform visceral light organ (different from that of Rondeletiola ; see below). It differs from all genera with a copulatory apparatus involving dorsal modified pedicels. As for the other species sharing the character state ‘only ventral modified pedicels in the copulatory apparatus’, i.e., all nominal Euprymna species, the modified ventral pedicels of Boletzkyola gen. nov. display a modification (thick horn-like instead of papilla-like) and, more importantly, its hectocotylus distal part suckers are carried by regular pedicels (i.e., not columnar). The affinity with Rondeletiola , fostered by the presence of similar visceral light organs, is just apparent. In fact, those organs are quite different from each other (see Remarks in the description of Group C hectocotylus). Furthermore, the copulatory apparatus and the bursa copulatrix of this genus differ completely from those of Rondeletiola .

Remarks

The hectocotylus of Boletzkyola gen. nov. is the least modified among Sepiolinae , hence may be primitive. In addition, the morphology of its visceral light organ may reflect incomplete development of the two-kidney-shaped arrangement that is typical of the subfamily. Both traits, as well as the small body size of Boletzkyola knudseni gen. et comb. nov. – seemingly the smallest among Sepiolinae : males mature at 8.5 mm mantle length – suggests that the evolution of this species might have been fostered by heterochronic development.

Figures

Fig. 10. Hectocotylus of Sepiola knudseni Adam, 1984. A. Oral view. B. Dorsal view; the arrows point to the three modified ventral sucker pedicels. Scale bars: 1 mm.

Fig. 11. Visceral light organ of Sepiola knudseni Adam, 1984. Scale bar: 1 mm.