Lizzia gracilis ( Mayer, 1900 )

Wang, Chunguang, Xu, Zhenzu, Huang, Jiaqi, Guo, Donghui, Lin, Mao & Xia, Zhen, 2016, Taxonomic notes on Hydroidomedusae (Cnidaria) from South China Sea III: Family Rathkeidae and Zancleopsidae, Zoological Systematics 41 (4), pp. 392-403 : 395-397

Lizzia gracilis ( Mayer, 1900) ( Figs 9–11 )

Cytaeis gracilis Mayer, 1900: 39–40 , pl. 36, figs 122–124.

Podocoryne gracilis Mayer, 1910: 141–142 , pl. 16, figs 1–3.

Lizzia gracilis Kramp, 1928: 46–47 ; 1951: 105, 231, 272; 1961: 88; 1968: 31, 154; Li & Chen, 1991: 2, 15, fig. 19; Bouillon et al., 2006: 134; Xu et al., 2014: 229, fig. 84.

Material examined. Nansha Island, July–August, 1988, about abundance 0–0.4 ind./m 3, initially identified as Lizzia gracilis .

Diagnosis. Eight stiff marginal tentacles with large basal bulbs; mouth without prominent lips and surrounded by eight unbranched, oral tentacles, four perradial and four interradial in positation; manubrium small, on a slightly developed peduncle; medusa buds on manubrium; no ocelli.

Description. Medusa with domelike or pyriform with slight apical projection; manubrium small, mounted upon a short, wide and solid gastric peduncle; manubrium and mouth part together only about half as long as the depth of the bell cavity; mouth simple, round opening without prominent lips and surrounded by eight unbranched oral tentacles, each of which terminates in a knob of nematocysts, four of these oral tentacles inserting in the perradial and four interradial position of mouth margin; eight stiff marginal tentacles with large basal bulbs, these tentacles upward curled from the bell-margin, four perradial situated marginal tentacles longer than four interradial ones, the basal bulbs of all of the tentacles large, swollen and hollow, with their endoderm deeply pigmented; with four simple, straight radial canals and a ring canal; medusa buds develop upon the interradial sides of manubrium; velum broad.

Dimensions. Bell size about 3 mm in diameter ( Mayer, 1910; Kramp, 1961).

Biology. It occurs only in the southern of South China Sea from July to August (Li & Chen, 1991). This medusa was quite common on the surface at Tortugas, Florida, in June ( Mayer, 1910).

Distribution. Globally occurs in tropical to subtropical seas, mostly neritic ( Mayer, 1910; Kramp, 1959). In the west Atlantic, it occurs in the Tortugas, Florida on the east coast of North America ( Mayer, 1910; Vanhöffen, 1913). In the Indo-west Pacific tropical region, it is present in the Malayan Archipelago, Philippines, Fiji Islands, Sunda Strait of Indonesia ( Kramp, 1928, 1959, 1965, 1968). It is also present in the Nansha Islands on the southern of South China Sea (Li & Chen, 1991; Xu et al., 2014).

Remarks. This species and Lizzia octostyla ( Haeckel, 1879) are the only form of Lizzia that have eight unbranched oral tentacles, but is distinguished from the latter by its eight oral tentacles lies in four perradial and four interradial position while eight oral tentacles lies in four perradial pairs in the latter.

Figures

Figures 3–13. Lizzia spp. 3–8. L. blondina (Forbes, 1848). 9–11. L. gracilis (Mayer, 1900), in lateral view (after Mayer, 1910). 12–13. L. octostyla (Haeckel, 1879). 3. Medusa before gonad maturation and with medusa buds, in lateral view (after Xu et al., 2014). 4. Mature medusa with two tentacles each perradial marginal bulb, in lateral view (after Schuchert, 2007). 5. Mature medusa with three tentacles each perradial bulbs, in lateral view (modified from Russell, 1953a). 6–8. Semi-diagrammatic illustration of three stages of development in aboral view (after Russell, 1953b). 9. Newly liberated medusa with four perradial tentacles. 10. Halfgrown medusa with eight tentacles. 11. Asexually produced medusa buds. 12. Lateral view. 13. Oral view (after Schuchert, 2007). Scale bars: 3–4=0.1mm; 9–11 =0.5mm; 12=0.2mm.