Dextrasepiola, Lu & Okutani, 2022

Lu, Chung Cheng & Okutani, Takashi, 2022, Two new genera and species of sepioline squids (Cephalopoda: Sepiolidae) from Australia, Memoirs of Museum Victoria 81, pp. 1-23 : 2

Dextrasepiola n. gen.

Type Species: Dextrasepiola taenia n. gen., n. sp. by monotypy

Diagnosis: Sepiolinae with fins rounded with large anterior lobes, which do not reach the anterior mantle margin; fin length about 50–80% mantle length. Suckers biseriate on all arms. Tentacular club suckers in 4–8 longitudinal series. Nuchal commissure narrow, not reaching over the ocular globes. A pair of dumbbell-shaped photophores on ventral surface of ink sac. Gladius absent. Ventral mantle margin slightly sinuate, without any deep funnel indentation. Right arm I of male hectocotylised. Hectocotylus tripartite: basal part with five suckers in two series, two suckers in dorsal series and three in ventral series; copulatory apparatus long, fleshy, tape like, formed by fusion of two adjoining very elongate sucker stalks, no additional modified structure on the arm (i.e. hook-like stalks); distal to tape-like copulatory apparatus biserial suckers to arm tip (19 suckers in holotype, 23 suckers in paratype 2). Female bursa copulatrix on right side of mantle cavity, open type (cf. Bello, 2020), roughly ear shaped.

Etymology: Generic name Dextrasepiola is derived from Latin dextra meaning right or on the right side plus sepiola meaning a small cuttlefish. The name denotes the unique feature among the Sepiola and its kin having the right dorsal arm hectocotylised instead of the left dorsal one in mature males and the bursa copulatrix in females on the right side of the mantle cavity.

Remarks: The hectocotylisation in Sepiolinae has been thoroughly discussed and illustrated by Bello (2020), Naef (1912a, b; 1923) and Nesis (1982). All known species have the left dorsal arm hectocotylised and the sucker stalks of some suckers are modified into a horn-like or hook-like copulatory organ. The present genus is unique in having the right dorsal arm hectocotylised and the copulatory organ as one thick tape-like structure. In addition, the hectocotylus has the regular tripartite structure typical of most sepioline genera except for Euprymna and Eumandya (cf. Bello, 2020). The females of all known species of Sepiolinae possess a bursa copulatrix on the left side of the mantle cavity. The present genus is unique in having the bursa copulatrix on the right side of the mantle cavity. This right-handedness of the copulatory organs of both sexes of this genus certainly facilitate copulation in a normal fashion as they are on the same side of the animal.