Eutima McCrady, 1859

Guo, Donghui, Xu, Zhenzu, Huang, Jiaqi, Wang, Chunguang & Lin, Mao, 2019, Two new hydrozoan species from the Taiwan Strait, China (Cnidaria: Hydrozoa: Leptothecata), Zoological Systematics 44 (3), pp. 185-190 : 187-188

Genus Eutima McCrady, 1859

Type species: Eutima mira McCrady, 1859 .

Diagnosis. The genus is diagnosed by following: medusa with a distinct gastric peduncle; with lateral cirri and marginal warts; mouth with simple lips; 4 simple radial canals; gonads on radial canals, either beneath subumbrella or gastric peduncle or on both; with 8 (exceptionally 12) statocysts.

Remarks. Members of the genus are easily distinguished from all other genera by their medusa with 8 statocysts; with lateral cirri on marginal warts and marginal tentacles. The genus comprises 20 valid species (including the new species) ( Mayer, 1910; Kramp, 1961; Bouillon, 1984; Bouillon et al., 2006; Guo et al., 2008; Xu et al., 2014), of which only 13 species are known in China seas.

Key to the species of the genus Eutima .

1. With 8 gonads, 4 on subumbrella and 4 on peduncle ........................................................................................................................... 2

With 4 gonads, either on subumbrella or peduncle .............................................................................................................................. 9

2. Tentacle without lateral cirri ................................................................................................................................................................ 3

Tentacle with lateral cirri...................................................................................................................................................................... 4

3. With 32 marginal warts with lateral cirri; subumbrellar gonads linear-like, peduncular gonads in middle part of peduncle ................. .................................................................................................................................................................... E hartlaubi Kramp, 1958

With 80–120 marginal warts with lateral cirri; subumbrellar gonads sinuous-like, peduncular gonads near proximal end of peduncle ....................................................................................................................................... E taiwanensis Xu, Huang & Guo , sp. nov. *

4. With 4 tentacles....................................................................................................................................................................................5

With 8–16 tentacles..............................................................................................................................................................................6

5. Peduncle with a dome-like base, prismatic below; with 60–80 marginal warts ...................................... E. orientalis (Browne, 1905)

Peduncle slender; with 100 marginal warts................................................................................................... E. mira McCrady, 1859 *

6. Tentacular bulbs and marginal warts with adaxial papillae ................................................................ E. gegenbauri (Haeckel, 1864) *

Tentacular bulbs and marginal warts without adaxial papillae ............................................................................................................. 7

7. With 16 tentacles and 3 marginal warts between successive tentacles ................................................... E. variabilis McCrady, 1859 *

With 8 tentacles....................................................................................................................................................................................8

8. Tentacular bulbs without abaxial spurs, marginal warts without black spot........................... E. levuka (A. Agassiz & Mayer, 1899) *

Tentacular bulbs with abaxial spurs, marginal warts with black spot on extreme tip ............................................................................. ............................................................................................. E. diademata (Kramp, 1959) [= E. krampi Guo, Xu & Huang, 2008] *

9. Gonads on peduncle only ................................................................................................................................................................... 10

Gonads on subumbrella portion of radial canals ................................................................................................................................14

10. With 32 tentacles or 8 tentacles.......................................................................................................................................................... 11

With 4 tentacles or 2–4 tentacles........................................................................................................................................................13

11. With 32 tentacles and 96 marginal warts with lateral cirri .................................................................. E. coerulea (L. Agassiz, 1862) *

With 8 tentacles..................................................................................................................................................................................12

12. Umbrella higher than wide; tentacle with 2 pairs of lateral cirri, 16 marginal warts with lateral cirri .... E. gentiana (Haeckel, 1879) *

Umbrella broader than high; tentacle without lateral cirri, 64–80 marginal warts with a pair of lateral cirri......................................... ............................................................................................................................................................... E. longigonia Bouillon, 1984

13. 4 tentacles with abaxial hook-like process ................................................................................................... E. curva (Browne, 1905) *

2–4 tentacles with abaxial hook-like process ........................................................................... E. gracilis (Forbes & Goodsir, 1853) *

14. Tentacles without lateral cirri............................................................................................................................................................. 15

Tentacles with lateral cirri.................................................................................................................................................................. 16

15. With 4 tentacles, with 28 marginal warts .................................................................................. E. sapinhoa Narchi & Hebling, 1975

With 8 tentacles, perradial tentacles longer than interradial; gonads with lateral swelling, not reaching to peduncle ........................... ........................................................................................................................................................... E. neucaledonia Uchida, 1964 *

16. With 16 tentacles with swollen bulbs, with lateral cirri, gonads in middle portion of radial canals....... E. modesta (Hartlaub, 1909) *

With 8 tentacles..................................................................................................................................................................................17

17. Up to 32 marginal warts..................................................................................................................................................................... 18

With 50–80 marginal warts ................................................................................................................................................................ 19

18. Peduncle short, never exceeding beyond bell opening ................................................................................ E. japonica Uchida, 1925 * Peduncle long, exceeding beyond bell opening.......................................................................................... E. suzannae Allwein, 1967

19. Bell flatter than hemisphere; peduncle long about 2/3 length exceeding beyond bell opening; gonads sinuous-like............................. .................................................................................................................................................................... E. mucosa Bouillon, 1984

Bell nearly hemisphere; peduncle short about 1/3 length exceeding beyond bell opening; gonads linear-like ...................................... ................................................................................................................................................. E. commensalis Santhakumari, 1970

* Recorded in China seas.