Beroe forskalii Milne Edwards 1841

BEROE FORSKALII MILNE EDWARDS, 1841

The body is strongly flattened. The aboral part is sharply conical, whereas the oral part is oval with a rounded, voluminous mouth, expanded on the entire oral part. The length is up to 150 mm (Fig. 9A–C). The length/width ratio is 1.75–2.00. The eight meridional canals lie under eight rows of dense ciliary combs plates. The elongate plates, covering them from the surface, extend up to three-quarters of the body length from the aboral pole towards the mouth. Diverticulae are connected to each other, forming dense anastomoses of fine networks. The colour is pink with a dark tinge along the ciliary comb rows, which is specific for B. forskalii (Mills & Haddock, 2007; Shiganova & Malej, 2009). There is an axial funnel-tube. The aboral pole is fringed with a row of long, branched papillae (Fig. 9D). The macrocilia are arranged in long, tapering stripes running from the lip edge to a considerable distance into the stomodaeal cavity. Each stomodaeal wall bears about 20 macrociliary stripes, which increase in length towards the middle of the stomodaeum (Tamm & Tamm, 1993).

Geographical distribution: We presume the existence of two different species, listed under Beroe forskalii following the presumption of Johansson et al. (2018) and our morphological analyses. While there is no sufficient data on the genetic structure of individuals around the world, we only present generalized data on the species distribution.

Beroe forskalii is widely distributed in the Atlantic: the Mediterranean Sea (Madin, 1991; Tamm & Tamm, 1993), off the Brazilian coast (Oliveira & Migotto, 2014), off the USA east coast (Podar et al., 2001); the Pacific: off the California coast (Wrobel & Mills, 1998; Podar et al., 2001; Stout et al., 2002; Schultz et al., 2020); the eastern Pacific off Mexico and near Guadalupe Island (Ruiz-Escobar et al., 2015); off Peru (Oliveira et al., 2016); off Japan (Kubota, 1997; Fujikura et al., 2012) and off Australia (Gershwin et al., 2014). It was recently discovered in the southern waters of the Atlantic (Oliveira & Migotto, 2014). A single specimen was collected in the São Sebastião Channel, in south-eastern Brazil (23.8°S, 45.4°W). The authors conducted a comparative morphological analysis and concluded that the individual belongs to the same species that lives in the Mediterranean Sea. Definitely belonging to this species, a recent specimen was recorded from the coastal waters of Pakistan (Gul & Jahangir, 2019; Shiganova identification from illustration). An individual of Beroe forskalii was found on the coast of Japan (Lindsay, 2006), but there is insufficient data on the morphology of this specimen, which made it difficult to compare it with the Australian or Mediterranean samples.

All these records demonstrate that B. forskalii is a warm-water species (Chun, 1880; Mianzan, 1999). Individuals identified as B. forskalii, but probably belonging to another species, have been reported from cold Antarctic waters (Flores et al., 2010, 2011; Siegel & Harm, 1996).

Habitat: Warm waters.