Clytia simplex ( Browne, 1902 )

Mendoza-Becerril, María A., Estrada-González, Mariae C., Mazariegos-Villarreal, Alejandra, Restrepo-Avendaño, Luisa, Villar-Beltrán, Rogelio D., Agüero, José & Cunha, Amanda F., 2020, Taxonomy and diversity of Hydrozoa (Cnidaria, Medusozoa) of La Paz Bay, Gulf of California, Zootaxa 4808 (1), pp. 1-37 : 24

Clytia simplex ( Browne, 1902)

Figs. 8 I–J, 9A–B

Phialidium simplex Browne 1902: 282 .— Segura-Puertas 1984: 33, pl. 8, fig. 1.

Type locality. Falkland Islands: Stanley Harbour ( Browne 1902) .

Material examined. Medusa—PB7_1a, sampling site 1 (1), mature, female, 27°C.

Description. Umbrella slightly flat, hemispherical (2.3 mm wide), with narrow velum. Manubrium short, with quadrangular base (0.2 mm wide), without peduncle; mouth with four crenulated lips. Circular canal and four narrow radial canals. Gonads 0.3 mm long, sac-like, located on the proximal portion of the radial canals, widening towards the circular canal and becoming free of the radial canal. With 12 hollow marginal tentacles, each with a tentacle bulb. Perradial tentacle bulbs larger than rudimentary bulbs. Twelve ectodermal closed statocysts, each with one statolith, alternating with tentacle bulbs.

Nematocysts (length x diam.). Microbasic b-mastigophore type A (8.4–9.2 x 2.1–3.3 µm).

More detailed description in Browne & Kramp (1939, as Phialidium simplex ) and Galea (2007).

Taxonomic status. Accepted. AphiaID 284388.

Remarks. The genus Phialidium Leuckart, 1856 traditionally comprises species known from the medusa stage (e.g., Kramp 1961), that are frequently attributed to hydroids of the genus Clytia Lamouroux, 1812 , with which Phialidium was later synonymized ( Cornelius 1982, 1995). Although a single specimen represents this record, it presents at least two distinctive characters usually attributed to C. simplex ( Browne, 1902) : the crenulated lips of the manubrium ( Browne 1902; Browne & Kramp 1939; Kramp 1961) and the shape of the gonads, which became partially free from the radial canals ( Galea 2007). Adult medusae of this species were described initially with 60 to 85 tentacles and a diameter of 22 mm ( Browne 1902; Kramp 1961). However, Browne & Kramp (1939) described specimens in earlier stages of development that are much smaller (0.6–2 mm wide) and present fewer tentacles (4–16), corresponding to the dimensions of our specimen.

Distribution. This species is widely distributed, with records from the Pacific and Atlantic coasts of South America ( Oliveira et al. 2016), southeastern Atlantic ( Pagès et al. 1992), and Indian Oceans ( Kramp 1953, 1957). In Mexican Pacific, it was reported along the coast of Colima ( Segura-Puertas 1984).

Figures

FIGURE 8. A–H Clytia linearis (Thornely, 1900): A–E, medusa; B, manubrium; C, female and male gonads; D, statocyst; E, nematocysts microbasic b-mastigophore type A; F–H, polyp; G–H, hydrothecae and gonothecae. I–J Clytia simplex (Browne, 1902): I, medusa with gonads; J, manubrium. Scale equals A, G, I—500 µm; B, C, J—200 µm; D—100 µm, E—20 µm; F—1 mm; H—340 µm.