Monocanna Xu, Guo & Wang, 2019

Wang, Xuefeng, Lin, Kun, Xu, Zhenzu, Guo, Donghui & Huang, Jiaqi, 2019, Some new Hydroidomedusa (Cnidaria) from the northern South China Sea, Zoological Systematics 44 (3), pp. 191-205 : 201

Genus Monocanna Xu, Guo & Wang , gen. nov.

Type-species: Multioralis ovalis Mayer, 1900 = Gastroblasta ovale ( Mayer, 1900) .

Diagnosis. The genus can be recognized by: medusa nearly spherical-like; with 2–4 manubria, all manubria along a straight radial canal, and along major axis of bell; no centripetal canals; all canals formed centrifugally from manubria; with 2–3 small, ovoid gonads on radial canals; with numerous marginal tentacles and statocysts.

Remarks. Although Gastroblasta ovale has the 2–4 manubria, similar to G. timida Keller, 1883 , the type species of Gastroblasta , its structural features of radial canals and blindly canals are different from the latter, which has 1–4 manubria and 4–17 radial canals with 17 blindly ending centripetal canals ( Fig. 16 ). As a contrast, G. ovale has 2–4 manubria and all manubria along a straight canal, and no centripetal canals ( Figs 6 , 14–15 ). Therefore, G. ovale is removed from the genus Gastroblasta and transferred to the new genus Monocanna Xu, Guo & Wang , gen. nov.

Etymology. The generic name is derived from the Latin Monocanna , meaning mono-canna, referring to the single straight radial canal.

Figures

Figures 12–16. Hydroidomedusa spp., line drawing. 12. Euphysora knides Huang, 1999, lateral view. 13. Euphysora verrucosa Bouillon, 1978, lateral review (after Bouillon, 1978). 14. Monocanna ovale (Mayer, 1900) comb. nov., oral view. 15. Ditto, lateral view (after Mayer, 1910). 16. Gastroblasta timida Keller, 1885, oral view (after Mayer, 1900). Scale bars: 12, 14= =0.5 mm; 13 = 1.0mm.

Figures 1–6. Hydroidomedusa spp. 1. Nubiella terminaliknoba Xu, Huang & Guo, sp. nov., lateral view. 2. Paranubiella shenzhenensis Xu, Guo & Wang, sp. nov., lateral view. 3. Eucodonium crassonemalis Xu, Guo & Lin, sp. nov., lateral view. 4. Proboscidactyla trifurcata Xu, Huang & Guo, sp. nov., lateral view. 5. Euphysora knides Huang, 1999, lateral view. 6. Monocanna ovale (Mayer, 1900) comb. nov., oral view. Scale bars: 1=0.2mm; 2–3, 5–6=0.5mm; 4=1.0mm.