Rhopilema nomadica, Galil, 1990

Morandini, André C. & Gul, Shahnawaz, 2016, Rediscovery of Sanderia malayensis and remarks on Rhopilema nomadica record in Pakistan (Cnidaria: Scyphozoa), Papéis Avulsos de Zoologia 56 (15), pp. 171-175 : 173-174

Remarks on Rhopilema nomadica

record in Pakistan

Currently the genus Rhopilema Haeckel, 1880 ( Scyphozoa: Discomedusae: Rhizostomeae : Rhizostomatidae ) is composed of five valid species which differ mainly in their exumbrella morphology (smooth/ rough) and the kind of appendages on mouth arms ( Gul & Morandini, 2015). From these five species, only two have rough exumbrellar surface: (1) Rhopilema hispidum , with two kinds of warts: a) minute, blunt, colourless, and b) tiny, conical, pointed, reddish-brown warts (pronounced on marginal area); (2) Rhopilema nomadica , with only minute, blunt warts (“blunt tuberculation”, Galil et al., 1990:103) ( Omori & Kitamura, 2004; Kitamura & Omori, 2010; Gul & Morandini, 2015). Recently, Tahera & Kazmi (2015, Figs. 1 -3) surprisingly reported R. nomadica from Keti Bundar, Pakistan with rough exumbrellar surface bearing minute, blunt tuberculation and warts. However, the Rhopilema jellyfish in their figures is clearly showing presence of minute reddishbrown warts on marginal area of umbrella, which are however, characteristic only of R. hispidum . Moreover, the authors mentioned the presence of vermicular filaments terminal to the mouth arms in their specimens though, not visible in the figures.

According to the literature, although Rhopilema nomadica was described from the Red Sea ( Galil et al., 1990) no further records provide solid evidence of its presence in the Indian Ocean so far. In fact, the species is expanding its distribution into the Mediterranean Sea (Yahia et al., 2013). In contrast, Rhopilema hispidum is widespread in Indo-Pacific waters ( Gul & Morandini, 2015).

We consider that the jellyfish reported by Tahera & Kazmi (2015) as R. nomadica is possibly misiden- tified R. hispidum previously reported from Pakistan ( Gul & Morandini, 2015).

Although the life cycle of three Rhopilema species were formally described (Calder, 1973; Ding & Chen, 1981; Lotan et al., 1992), none of these studies focused on the recognition of developmental changes in characters used for the systematics of the genus. That is the next step for a better understanding of morphology of the species in this genus, to clear if we are dealing with species that present a huge variation in general colour pattern and also in the shape of appendages.

Figures

FIGURE 1: Freshly collected specimen of Sanderia malayensis Goette, 1886 from Pakistani coast, off-Karachi. Bell diameter 11 cm: (A) Exumbrellar view showing transparent umbrella with numerous nematocyst warts, (B) Subumbrellar view showing gastric pouches in closeup, note the heart-shape contour of gastric pouches.