Chrysaora southcotti, Gershwin, Lisa-Ann & Zeidler, Wolfgang, 2008

Gershwin, Lisa-Ann & Zeidler, Wolfgang, 2008, Some new and previously unrecorded Scyphomedusae (Cnidaria: Scyphozoa) from southern Australian coastal waters, Zootaxa 1744, pp. 1-18 : 7-11

Chrysaora southcotti , sp. nov.

(Plates 3, 4)

Previous Australian records

? Chrysaora pentastoma Péron & Lesueur 1810: 366 , No. 117. – Goy 1995: 368, pl. p. 371.? Chrysaora hysoscella . – Goy 1995: pl. p. 371. – Bonnemains 1988: 205, pl. p. 206. Chrysaora sp. – Cleland & Southcott 1965: 95–96, 124, 148, 164, pl. 2, fig. 10,11 nematocysts, color pl. 3 (top right). –

Southcott 1982: 156, plates 14.4, 14.5. – Southcott & Glover 1987: 131–132. –? Edgar 1997: 146, unnumbered fig.,

SA to Vic. –? Edgar 2000: 146, unnumbered fig., SA to Vic.

Material examined. Holotype: SAM H969, Port Noarlunga, SA, drifting with current at surface in 8–10 m, coll. L. Gershwin & W. Zeidler, 18.i.1999; male, (BD 66.0 mm, longest oral arm 20.3 mm).

Paratypes: SAM H939, numerous specimens, collected with holotype. SAM H940, one specimen, Port Noarlunga, SA, type locality, coll. L. Gershwin & S.A. Shepherd, 23.i.1999, used for bioluminescence studies. SAM H941, numerous specimens, data as for H940. SAM H942 (RVS A680), Emu Bay, Kangaroo Island, SA, coll. R.V. Southcott, 13.iv.1963; one specimen. SAM H943 (RVS A689), Emu Bay, Kangaroo Island, SA, surface to 2 m depth, coll. R.V. Southcott, 12.iv.1963; 8 specimens. SAM H944-948 (RVS A689A-D & A676), data as for H943; five lots of one specimen each. SAM H949 (RVS A722A), Troubridge Shoals, SA, at surface, coll. R.V. Southcott, 6.i.1964; one specimen, used for photography. H950 (RVS A722B), data as for H949 SAM; one specimen, used for sting. SAM H951 (A656), Cape d’Estaing, SA, 7–14 m, coll. S.A. Shepherd, 29.xii.1962; numerous specimens. SAM H952 (RVS A686), Emu Bay, Kangaroo Island, SA, coll. R.V. Southcott, 12.iv.1963; one damaged specimen. SAM H953, Brighton, SA, washed ashore, coll. Vowlos, 9.ii.1984; one specimen. SAM H954, 3 specimens, no data. SAM H955 (RVS A687), Emu Bay, Kangaroo Island, SA, coll. R.V. Southcott, 12.iv.1963; one specimen. SAM H956, Edithburg Jetty, Yorke Peninsula, SA, drifting at surface, coll. L. Gershwin, 18.ii.1999; four specimens.

Lots of two specimens each were removed from SAM H939 (same data as holotype) and registered to the following institutions: AM (G16002); California Academy of Sciences, San Francisco, USA ( CASIZ 119064); MTQ (G55284); NTM (C12752); TMAG (K1730); United States National Museum, Smithsonian Institution, Washington DC, USA ( USNM 100350); WAM (Z2929).

Other material: ethanol material as follows; SAM XH 0103-0104, same data as H956. SAM XH 0105, 3 bells and 1 complete medusa, same data as holotype. SAM XH 0106, gonad and oral arms, same data as holotype. SAM XH 0107 & XH 0109, same data as SAM H940. SAM XH 0108, same data as holotype, coll. 17.i.1999.

Diagnosis. Chrysaora with exumbrellar rhopalial pits moderately deep, broadly rounded or narrowly conical, blind ending. Subumbrellar rhopalial pits wide and open. Exumbrella and oral arms densely covered with conspicuous warts. Gastric septa tilting slightly toward rhopalia in distal quarter, meeting margin or stopping short of it, along the rhopalial side of outermost tentacle in each group. Tentacles 40. Lappets 48, of two forms. Diameter to approximately 66 mm. Coloration: bell whitish with warts pigmented red, tentacles white, oral arms appearing dark red to blackish due to heavy concentration of red nematocyst warts.

PLATE 3. Chrysaora southcotti , sp. nov., holotype, in life. A, exumbrellar view, showing colour pattern. B, lateral view.

PLATE 4. Chrysaora southcotti , sp. nov., holotype. A, subumbrellar view, in preserved state. (Scale = 5 mm). B, subumbrellar margin. C, rhopalium. (Scale = 1.0 mm). D, close-up of portion of tentacle showing nematocyst pattern. E, abraded tip of tentacle showing the coiled central core of a retracted tentacle (Scale = 1.0 mm).

Description. Bell flat to subhemispherical, to about 66 mm BD; exumbrella with many round to amorphous nematocyst warts concentrated near center of bell, warts oval to elongate in streaky pattern of 16 main rays corresponding to rhopalia and central tentacles, alternating with 16 lesser-defined rays; subumbrella densely covered with prominent nematocyst warts on central gastro-gonadal region and manubrium, lacking warts entirely over radial stomach pouch region (Plate 4A).

Marginal lappets 48, six between adjacent rhopalia; of two forms: those flanking each rhopalium and central tentacle of each octant tongue-shaped and rounded, those between shorter, narrow, pointed (Plate 4B). Some specimens with narrower lappets and rhopaliar lappets fused.

Rhopalia eight, four perradial, four interradial, contained within niches in bell between lappets but proximal to margin; finger-shaped, projecting outward from end of ridge. Exumbrellar sensory pores deep, rounded, not reaching through to rhopalium. Subumbrellar sensory pores with crescentic proximal boundary, open distally (Plate 4C).

Tentacles variable, typically 40, five per group between adjacent rhopalia; issuing from margin between lappets; laterally flattened proximally, becoming round in cross section distally; with nematocysts in scattered warts, lacking longitudinal muscle bands (Plate 4D, E); with basal adaxial keel; in life 2– 3 x BD while undisturbed, contracted to half BD when disturbed.

Oral arms four, perradial, curved counter-clockwise; folded longitudinally in half, with outer surface densely studded with knobby nematocyst warts (Plate 4A); with tightly crenulated margin; length 1–1.5x BD in life, less than half BD preserved. Manubrium tubular, short, covered with oval-elongate nematocyst warts in pattern radiating orally.

Gonads four, interradial, crescentic to M-shaped, in pleated folds contained within subumbrellar cavities. Radial stomach pouches 16, of equal size proximally, tentacular pouches expanding in peripheral quarter to encompass all five tentacles; continuing into marginal lappets as pointed projections, with simple or jagged edges. Radial gastric septa 16, bent toward rhopalia in distal quarter, running along outer edge of first and fifth tentacles in each octant; reaching or not reaching margin; proximal terminus simple to teardrop-shaped, somewhat diverticulated.

Color in life: bell cloudy whitish to colorless above and below, exumbrellar nematocyst warts marked with dark red pigments; oral arms darkly reddish, typically appearing black; gonads whitish; rhopalium violet, with numerous sparkly concretions.

Nematocysts. Tentacular nematocysts clustered into small warts scattered on all sides of tentacles. Tentacular cnidome comprising large spherical isorhizas (13.73–17.18µm diameter, n=23), and euryteles of two size classes, larger (8.78–10.33µm long x 6.13–7.69µm wide, n=9), and smaller (5.80–7.16µm long x 3.77– 4.44µm wide, n=9).

The oral arms densely dotted with nematocyst warts containing medium-sized spherical isorhizas (6.52– 8.57µm diameter, n=21) and small subspherical isorhizas (4.33–5.65µm diameter, n=33).

Etymology. Named to honor the late Ronald V. Southcott for his pioneering efforts in the study of Australian jellyfishes, and whose diligent collection, preservation, and note-taking have provided a wealth of comparative material for study.

Associations. Often accompanied by young trevally, Usacaranx georgianus (Valenciennes, 1843) (RVS A730, H352=A2305, H353=A2306), or juvenile leatherjackets, Eubalichthys mosaicus Ramsay and Ogilby, 1886 (H354=A2307) ( Southcott 1987). One specimen was found with an unidentified isopod on the exumbrella (RVS notes A2308). The holotype (SAM H969) is infested with numerous unidentified minute eggshaped larvae (?) throughout the lappets.

Reproduction. Unknown. Planulae could not be obtained either through attempts to trigger spawning in the laboratory or through artificially placing male and female gonad fragments together.

Bioluminescence. Could not be elicited with mechanical stimulation of freshly-caught specimens that were tested approximately hourly throughout the night. Thus, it is assumed that this species is not capable of bioluminescence.

Sting ability. This species is capable of inflicting a painful sting, as discussed by Cleland and Southcott (1965) and Southcott (1975, 1979).

Distribution. Currently known only from Gulf St. Vincent, South Australia, from Kangaroo Island to Edithburg and Port Noarlunga, where it is extremely abundant in the summer months. Within days of finding it at Port Noarlunga and Edithburg, we were unable to find it in the Spencer Gulf or along the west coast of South Australia. Edgar (1997, 2000) illustrated a medusa resembling C. southcotti from Portsea, Victoria, but the specimen was not retained and its identity cannot be confirmed. It could just as easily have been the following species.

Remarks. This species closely resembles Chrysaora pentastoma Péron and Lesueur, 1810 , especially in the exumbrellar colour pattern of the medusa and as figured in an illustration which apparently remained unpublished until recently ( Bonnemains 1988; Goy 1995). Unfortunately the type material of C. pentastoma is lost, or was never designated, so that a direct comparison is impossible. However, we cannot conclude that our specimens are conspecific with C. pentastoma because two different forms occurring in southern Australian waters reasonably approximate the figure and description of C. pentastoma . Although Péron and Lesueur described their species from South Australia, their description is inadequate to differentiate the present South Australian form from an undescribed New South Wales form (see next). Also, while one might argue that the South Australian material is “probably the same,” the similarity between the illustration and the present material is not perfect. The written description is likewise inadequate, stating: “Ombrelle hémisphérique, rouxcapucin; trente-six a quarante échancrures profondes et autant de tentacules très-longs au rebord; cinq bras ramifiés; cinq bouches; cinq estomacs; 6–7 centimètres; de la terre Napoléon.” This basically describes only a symmetrical deviant, with few other distinguishing characters.

In comparison with the written description, the umbrella of C. southcotti is hemispherical only during the power stroke of a pulsation; during relaxation it is flat. The body is not red; it is milky with a striking radiate red pattern on the exumbrella, and the oral arms are dark reddish, most often described anecdotally as black. The tentacles vary from 5–6 per octant in a tetramerous specimen, not 3–4 as for the pentamerous species indicated. While size and location are the same, one would not typically use those characters alone as the basis for species determination. It seems unlikely that most competent workers would consider the two as identical based on the written description; in fact, Goy (1995) assigned the taxon depicted in the illustrations to C. hysoscella .

However, C. southcotti bears very little resemblance to C. hysoscella (24 tentacles, whitish body with 16 dark brown V-shaped streaks and brown lappets), providing further evidence that the medusa of Péron and Lesueur is essentially unrecognizable. In addition, it does not appear that Péron and Lesueur recognized the species itself as new in the present sense, but rather they recognized only symmetrical deviants; they failed to note the presence of 4-parted specimens, which most certainly must have been the majority of medusae observed ( Gershwin, 1999). Given the inadequacy of the original description and lack of type material, the most stable course of action seems to be to regard C. pentastoma as unrecognizable (i.e., as a nomen dubium). Thus, we have described C. southcotti as a new species based on numerous specimens, tissues available for genetics, and a thorough description.

In some ways, this species seems intermediate between the genera Pelagia and Chrysaora . For example, the depth and shape of the exumbrellar rhopalial pits is deeper than those in Pelagia noctiluca (barely a perceptible dent in the exumbrella) but not open through to the rhopalium as in northern hemisphere species of Chrysaora . However, it is interesting to note that two other species of Australian Chrysaora (see below) share the same character state. Also, the warty oral arms are reminiscent of P. noctiluca , yet the starburst pattern of exumbrellar nematocyst patches is similar to that in some species of Chrysaora . The tentacle number and arrangement are most similar to those species of Chrysaora earlier assigned to Dactylometra . No trace of the tentacle ridges known in Pelagia could be found in this species, a character on which Russell (1964) placed considerable importance. While a new genus for this species may be warranted, we think the most conservative approach for now is to classify it with the “ Dactylometra ” group of Chrysaora (sensu Gershwin & Collins 2002).