Cassiopea ndrosia Agassiz & Mayer, 1899

Keable, Stephen J. & Ahyong, Shane T., 2016, First Records of the Invasive “ Upside-down Jellyfish ”, Cassiopea (Cnidaria: Scyphozoa: Rhizostomeae: Cassiopeidae), from Coastal Lakes of New South Wales, Australia, Records of the Australian Museum 68 (1), pp. 23-30 : 25-26

Cassiopea ndrosia Agassiz & Mayer, 1899

Figs 2 A–D, 3A–B

Cassiopea ndrosia Agassiz & Mayer, 1899: 175 , pl. 14, figs 45, 46; Stiasny, 1934: 913–921; Kramp, 1965: 265; Southcott, 1982: 159, pls. 15.3, 15.4; Gershwin et al., 2010: 91.

Material examined. AM G.18074, 1 specimen, from bottom of canal through “Jetties By The Lake Lifestyle Village” at Windang Road , Lake Illawarra, New South Wales, Australia ,

34°31'36"S 150°51'53"E, 0–1 m, M. Cameron, 8 May 2013; AM G.18075, 1 specimen (80 mm), locality data as for G.18074; AM G.13568, 3 specimens (90–120 mm), Hayman Island, Whitsunday Passage , Queensland , 20°03'S 148°53'E, tidal flat, coll. F. A. McNeill, January 1933.

Remarks. The Lake Illawarra specimens, collected in 2013, conform well to C. ndrosia according to diagnostic characters indicated by Mayer (1910), Southcott (1982), Gershwin et al. (2010: tab. 9) and comparative specimens from Queensland (AM P.13568; originally reported by Stiasny, 1934). The “pinnate” branching of the oral arms (i.e., with lateral arms opposing each other on the primary arm) is the most significant distinction from C. maremetens in which the lateral arms “alternate” in position along the primary arm (see Fig. 2C for C. ndrosia from Lake Illawarra versus Fig. 2K for C. maremetens ). Additionally, the oral arms are subequally branched just distal of the midpoint of the total arm length in the material from Lake Illawarra, a condition found in C. maremetens only on the distal extremity of the oral arms due to the arrangement of alternate branching of the proximal lateral arms. The vesicles are elongate and leafshaped, of varying size, and numerous, especially toward the centre. Numbers of these vesicles are relatively small and no longer than the width of the oral arms, however, initially giving the impression that relatively fewer vesicles are present until examined under magnification. The Lake Illawarra and Queensland (Hayman Island) specimens agree closely and correspond to the current concept of C. ndrosia (see Mayer, 1910; Gershwin et al., 2010). Cassiopea ndrosia , first described from Fiji, is currently attributed a wide distribution in the central and western Pacific, from French Polynesia to Australia and Japan ( Kramp, 1965); records, however, require confirmation ( Holland et al., 2004; Gershwin et al., 2010). In Australia, C. ndrosia has been reported from Queensland (Torres Strait, the Gold Coast, Hayman Island; Stiasny, 1934; Kramp, 1965) and South Australia (Angas Inlet; Southcott, 1982).

Gershwin et al. (2010) noted the very close similarity between C. ndrosia and C. maremetens , with the chief differences recognized in the branching of the oral arms (pinnate versus alternate), and shape and number of lappets per paramere (1–2 indistinctly lobed versus 4 square, deeply incised); we question the latter distinction below under the account of C. cf. maremetens .

The collector of the Lake Illawarra specimens noted this jellyfish started appearing and multiplying two weeks prior to the samples being obtained. Over 100 individuals were observed at this time at the same location—a small, shallow, artificial canal (8–10 m wide, approximately 100 m long, less than 1 m deep) within a residential village on the Lake Illawarra foreshore ( Fig. 4A ). Water temperatures measured daily within the canal for over a week while the jellyfish were present ranged from 17 to 22°C but within two months of collection, and the onset of cooler winter weather (water temperature not measured), the population disappeared (M. Cameron, pers. comm.). A check of the area in May 2014 and discussion with local residents living next to the canal indicates the jellyfish have not reappeared at this location. Other sites along the shoreline within Lake Illawarra were also inspected in May 2014 without encountering any Cassiopea .

Figures

Figure 2. (A–D) Cassiopea ndrosia, bd 80 mm, Lake Illawarra, AM G.18075. (E–H) Cassiopea cf. maremetens, bd 80 mm, Wallis Lake, AM G.18155.(I–L) Cassiopea maremetens, bd 110 mm, Moreton Bay, paratype, QM G.6645.A, E, I, aboral surface;B, F, J, oral surface; C, G, K, aboral view of oral arm; D, H, L, oral view of oral arm.

Figure 4. (A) Collection site for Cassiopea ndrosia from Lake Illawarra, canal through “Jetties By The Lake Lifestyle Village” looking toward lake.(B) Collection site for Cassiopea cf. maremetens from Pipers Creek, Wallis Lake, looking toward lake.(C) collection site for Cassiopea cf. maremetens from inlet on south east side of Mather Island, Wallis Lake, looking toward lake.(D) field measurement of bell diameter of c.210 mm for Cassiopea cf. maremetens from Pipers Creek, Wallis Lake. (E–F) Aggregation of Cassiopea cf. maremetens at inlet on southeast side of Mather Island, Wallis Lake from above and below water surface, respectively.