Lizzia blondina Forbes, 1848

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 : 394-395

Lizzia blondina Forbes, 1848 ( Figs 3–8 )

Lizzia blondina Forbes, 1848: 67–69 , pl. 12, fig. 4; Russell, 1953b: 145, text-figs 69–71, pl. 7, Figs 1–2, pl.34, Figs 5–6 ; Kramp, 1959: 105, fig. 78; Kramp, 1961: 87; Brinckmann-Voss, 1970: pl. 8, fig. 2; Bouillon et al., 2004: 47, fig. 28A–D; Schuchert, 2007: 289, figs 36A–G, 37–38.

Lizzia claparedei Chun, 1896: 36 , Figs 2–4; Braem, 1908: 795, figs 4–5.

Lizzia fulgurans Brinckmann-Voss, 1970 : pl. 8, fig. 1; Kramp, 1959: 105, fig. 80; Kramp, 1961: 88.

Podocoryne fulgurans Mayer, 1910: 139 , pl. 12, figs 5–9, pl. 13, figs 3–5.

Podocoryne minuta Mayer, 1910: 140 , pl. 14, fig. 1; Kramp, 1959: 102, fig. 68; Kramp, 1961: 69; Lin, 1989: 59, fig. 1.

Podocoryna minuta Schchert, 1996: 50 , fig. 28a–b.

Dysmorphosa minuta Mayer, 1900: 41 , pl. 18, fig. 42.

Hydractinia minuta Bouillon et al., 2004: 66 , fig. 39F–G; Bouillon et al., 2006: 150; Xu et al., 2006: 117; Du et al., 2010: 74; Xu et al., 2014: 258–259, fig. 117.

Material examined. Daya Bay, 15 August 1989, about abundance 0–5 ind./m 3, initially identified as Podocoryne minuta ; Changjiang River Estuary, 14 June 2003 and Beibu Gulf, 15 July 2006, about abundance 0–13.6 ind./m 3, identified initially as Hydractinia minuta .

Diagnosis. Four unbranched oral tentacles; eight marginal bulbs, four perradial each with one to three tentacles, four interradial each with only one simple tentacle, rarely two; medusa buds on manubrium, with manubrial peduncle; no ocelli.

Description. Umbrella spherical, sometimes a little higher than wide, usually with a shallow, rounded apical process, jelly moderately thick, especially in apical region; gastric peduncle present, slim, usually shorter than manubrium; four radial canals and a narrow ring canal, radial canals along manubrial peduncle with enlarged gastrodermal cells; eight marginal bubls, without ocelli, four perradial ones each with one to three tentacles, four interradial bulbs with a simple tentacle, rarely two; manubrium short, not reaching beyond umbrella margin in full extension, cone-shaped, either with broad quadrangular base attached to peduncle or perradial corners somewhat extending along peduncle, gastrodermis thickened interradially; medusae budding from stomach wall in interradial position, medusa budding phase overlaps with gonad maturation phase; four unbranched oral tentacles, attached very obliquely and adnate for some distance, lower axils at level of mouth-margin, oral tentacles relatively long but contracted, each with one terminal nematocyst cluster; gonads completely surrounding stomach in a form of ring-shaped cushion.

Dimensions. Earliest stages of vegetatively produced medusa 0.5–0.7 mm high; sexually mature medusa height around 1 mm, maximally 2 mm ( Schuchert, 2007; Xu et al., 2014).

Biology. Lizzia blondina is found in nearshore waters of summer. Owing to the rapid proliferation by asexual budding, this species may be sometimes exceedingly abundant, with a patchy distribution, but it may be often overlooked due to its small size. It occurs in the plankton around the northern South China Sea from April to August, but mostly abundant in July to August ( Lin, 1989; Xu et al., 2006; Guo et al., 2008). In Changjiang River estuary, the medusae appear in June ( Xu et al., 2006). In the Daya Bay, the species can be found at August ( Lin, 1989). In Beibu Gulf, they are present from April to August ( Guo et al., 2008).

Distribution. Under the name Podocoryne minuta , it has also been recorded from Daya Bay, northern South China Sea ( Lin, 1989), Changjiang River estuary, East China Sea ( Xu et al., 2006 as Hydractinia minuta ), and Beibu Gulf, northern South China Sea ( Guo et al., 2008). It is also recorded along the coast of the western Africa ( Thiel, 1938 as Podocoryne minuta ), Florida ( Mayer, 1900 as Dysmorphosa minuta ) and New Zealand ( Schuchert, 1996 as Podocoryna minuta ).

Lizzia blondina occurs from Norway to the Mediterranean as well as the northwestern Atlantic ( Allwein, 1967; Russell, 1970).

Remarks. The synonymy and history of this species is treated by Russell (1953b). Kramp (1961) suspected that the Mediterranean records of Podocoryne minuta by Neppil & Stiasny (1913) were actually L. blondina . After reexaminating Hydractinia minuta material from Mediterranean, Schuchert (2007) found it is indistinguishable from eight-tentacled Lizzia blondina originating from Great Britian, and proposed that H. minuta should be considered as a synonym of L. blondina . This result was also confirmed by their 16S sequence data ( Schuchert, 2007).

Since the medusae may be found mature at different stages of the tentacles development, the identity of the species was at first not certain, and three separate species were described previously. The first stage, medusa with one tentacle on each perradial marginal bulb, was recognizable as Hydractinia minuta ( Figs 3, 6 ); the second stage, medusa with two tentacles on each perradial marginal bulb, was considered as Lizzia claporedei ( Figs 4, 7 ); and the third stage, medusa with three tentacles on each perradial marginal bulb, was named Lizzia blondina ( Figs 5, 8 ).

The materials from China Sea, previously identified by Lin (1989), Xu et al. (2006) and Guo et al. (2008) as Podocoryne / Hydractinia minuta , are also conformed with the eight-tentacle stage of Lizzia blondina . The name Podocoryne / Hydractinia minuta recorded from China Sea should be revised as Lizzia blondina Forbes, 1848 .

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.