Phyllidia schupporum Fahrner & Schroedl , 2000

Yonow, Nathalie, 2020, Red Sea Opisthobranchia 6: Phyllidiidae and their paradorid mimic: new species and new records (Heterobranchia, Nudibranchia, Doridina), ZooKeys 1006, pp. 1-34 : 1

Phyllidia schupporum Fahrner & Schroedl, 2000 Plates 9-14 ; Figures 7 , 8

Phyllidia schupporum Fahrner & Schrödl, 2000b: 5-60, figs 1-4 (Dahab, Gulf of Eilat); Debelius and Kuiter 2007: 267; Yonow 2008: 217, three figs incl. ventral anterior of holotype; Gosliner et al. 2008: 289.

Phyllidia (Fryeria) rueppelii : - Nithyanandan 2012: 4, fig. 6 (Kuwait). non P. (F.) rueppelii (Bergh, 1869).

Material.

Egypt - Hurghada, Sha’ab Dorfa, 7 Sept 2010, one specimen 32 × 21 mm pres., alcohol, 14 m depth, leg. and photographs S. Kahlbrock.

Photographic records.

Egypt - Caves, Ras Umm Sid, Sha’arm el Sheikh, 19 Nov 2007, one individual, photograph H. Blatterer; El Quseir, 2007, one individual, photograph H. Blatterer; Dahab, 2008, two individuals together, photographs H. Blatterer; Sha’ab Mahmoud/Beacon Rock, Dahab, 5 May 2010, 8 June 2010, 15 Apr 2012, photographs S. Kahlbrock; Hurghada, 14 May 2012, photograph of one individual, S. Kahlbrock; "SS Thistlegorm," Sha’arm el Sheikh, 9 Oct 2012, 17 m depth, photograph S. Kahlbrock; House Reef of Rima Life Resort, Makadi Bay, 9 August 2014, 8 m depth, one individual ~ 30 mm, photograph Hsini Lin; Dahab, 19 July 2015, one individual, photograph H. Blatterer. Israel - Eilat. 16 Apr 2008, photographs of one individual, B. and S. Koretz (also published in Gosliner et al. 2008: 289); 4 September 2015, photographs of one individual, R. Amar.

Description.

The single large (32 mm) preserved specimen is mostly black, which forms deep scallops around the mantle sides with three elongations on the left and four irregular ones on the right, almost reaching the mantle margin, and a small one on the posterior margin (Plate 9 ). These semi-circular areas formed by the black scalloped pattern are white but contain some black patches and bright yellow tips on both the large and small tubercles. The white areas are almost translucent and full of white granules; even the tiniest tubercles have granulated white pigmentation. The large tubercles in each area are white, topped with yellow, and the bases of the pigmented tubercles are more opaque white as well as more granular than the others, which makes them appear ocellated (Fig. 7B ). These white semi-circles are pustulate, as are the yellow parts of the largest tubercles in these areas and elsewhere on the dorsum. There is no coloured edge remaining on the margin in this specimen, but all photographs of living animals show orange spots and/or lines on the mantle margin (Plates 9-14 ) and three display almost complete yellow margins (Plates 12-14 ).

The central black area in life bears a few barely discernible pustules, visible only at great magnification. The four large central tubercles are pustulose and irregular. There is one large tubercle just behind the rhinophores followed by two more. These three tubercles are the largest and rugose, with the basal pustules faintly tipped in yellow pigment which deepens towards tips. The white anal papilla is located just behind the third dorsal tubercle and located in a white area; the anal opening is surrounded by tiny black spots. There is one smaller white and yellow pustulose tubercle behind the anal papilla (far right on Plates 9 , 11 , 13 ). The deep yellow rhinophores are almost parallel sided with a short tip (Plates 9 , 11 , 14 ). They are each set in a tapering white patch with a yellow rhino-tubercle just behind and slightly displaced laterally. The rhinophores have 16-20 lamellae (counted from photographs).

The preserved specimen is black and white (Fig. 7A ). Both the black and white areas are pimpled with small pustules, which are more obvious on the white areas. The tubercles are very unusual for species of Phyllidia and in preservative resemble the tubercles of Dendrodoris tuberculosa (Quoy & Gaimard, 1832). They are composed of ridges and incomplete rings of smaller pustules, some even tipped with yellow pigment, and very clearly visible in a large living animal (Plates 9 , 14 ). The rhinophores are retracted and the anus is a puckered hole placed after the third tubercle and clearly visible.

Ventrally, the spicules of the hyponotum are arranged in a distinctly hatched pattern, and the black pigment shows through from the dorsal side, darkest around the margin (Fig. 7C-E ). The gill leaflets are grey. The uniformly grey foot sole is oval with no black midline and notched anteriorly (Fig. 7D, E ) in the preserved specimen but not in the living specimen (Fig. 7C ). The anterior margin is rounded, the ‘lips’ are prominent, and the retracted oral tentacles are conical structures with an obvious deep groove on each side, similar to those depicted in the photograph of the living holotype (Fig. 7C , courtesy of M Schrödl).

A dorsal incision to remove the very thick notum revealed a digestive system (Fig. 8 ) similar of that of other species of the genus excluding the Dendrodoris multituberculata Boettger, 1918 complex [e.g., P. varicosa , P. alyta (Yonow, 1996: figs 7-9), P. coelestis Bergh, 1905 ( Yonow 2011: figs 14, 15), P. koehleri Perrone, 2000 ( Yonow 2012: fig 19)] and matches the drawing by Fahrner and Schrödl (2000b: fig. 2). The pharyngeal bulb is creamy yellow and bears an upside-down U-shaped concavity on the dorso-posterior side; this is where the retractor muscles attachments and the small pharynx originate. The creamy-white blood gland lies in or over this concavity. The bursa copulatrix (left sphere) is a solid yellowish colour.

Remarks.

The external details of this specimen described in this work clearly fit those given for the holotype by Fahrner and Schrödl (2000b) despite the preponderance of black and the lack of orange- or yellow-tipped oral tentacles: as no orange/yellow pigment remains on the dorsum of the preserved specimen it is not surprising that the oral tentacles have lost their pigmentation. The species is distinctive, recognised in Yonow (2008) from photographs (see also references listed in the synonymy). Whilst this specimen is much darker than both the holotype and the available photographs, it does bear the diagnostic characters of three large, tall, spiculose, and pustulose orange/yellow-tipped tubercles along the dorsal midline, the presences of a smaller one posterior to the anus, two longitudinal black lines with at least one transverse band, an anterior black Y-shaped mark originating between the rhinophores and extending to the anterior margin, three or four white semi-circular areas on the margin on each side, orange/yellow rhinophores, and no black line on the sole of the foot.

The individuals photographed (Plates 10 , 11 , 13 ) are most similar to the holotype, but the black markings are thinner. In four individuals, there are three complete transverse lines (Plates 10 , 11 , 13 , 14 ) which match the incomplete bands of the holotype.

Internally, the digestive system is as described and illustrated in Fahrner and Schrödl (2000b: figs 2, 3) but it no longer retains any bright orange-red colour that they described in the freshly collected animal.

One additional character for P. schupporum observed from this material should be added to its diagnosis: there is an orange or yellow border present on the mantle margin which is usually very patchy: it can be almost absent or almost entire with only small breaks. It is in fact present as one patch on the coloured illustration of the holotype ( Fahrner and Schrödl 2000b: fig. 1) just ‘above’ the tip of the right rhinophore. Of the records presented here, all images examined at high magnification also show at least small marginal patches of orange or yellow. Therefore, all records of Phyllidia (Fryeria) rueppelii (Bergh, 1869) from the Red Sea, Persian Gulf, and Gulf of Oman must now be re-examined considering this new observation. The illustrated individual from Kuwait ( Nithyanandan 2012: 5, fig. 6) clearly belongs to P. schupporum and not to P. (F.) rueppelii due to the three high spiculose and tuberculate central tubercles and the dorsal black pattern, indicating that P. schupporum may not be endemic to the Red Sea. Individuals depicted in several photographs examined from the United Arab Emirates can be attributed to P. schupporum (Carole Harris, Sydney, Australia, pers. comm.). There are transverse bands present in some of her images and there are extensions to the sides forming white semi-circular areas as in P. (F.) rueppelii . Apart from P. (F.) rueppelii , there are no other species in the Red Sea which have an orange or yellow margin; however, the black pattern is different in the two species. Phyllidia (F.) rueppelii has three rows of central tubercles with a more linear black pattern, and it has a ventral anus.

The individuals and holotype with less black are similar to the Indo-West Pacific Phyllidia exquisita Brunckhorst, 1993, also noted by Fahrner and Schrödl (2000b) but the Red Sea P. schupporum differs externally, having only two (instead of three or four) curved black longitudinal lines extending from the fronto-lateral mantle margins to the posterio-lateral margins.

Phyllidia schupporum is very similar with its light and dark variations to the images of a species identified as P. exquisita from Hawaii, which is probably a new species ( Pittman and Fiene 1999). It is remotely possible that the Red Sea species and the Hawaiian ones are the same, as they resemble each other externally including the very dark variants. However, given their very disjunct localities and that both regions have high levels of endemism, the same identity is unlikely but further collections will eventually resolve this issue.

Phyllidia schupporum is a rare species in the Red Sea, with only two known specimens and several photographed individuals in the last forty years. It was not present in the more recent collections in the southern half of the Red Sea (e.g., Sanganeb 1991 by T. Paulus; Farasan banks 2017 by KAUST) but was recorded as early as the 1980s (single photograph by Pam Kemp in Yonow (2008) from the Jeddah area, central Red Sea). There are photographs on the internet from the northern Red Sea which have been variously identified as F. rueppelii , P. cf. exquisita , and P. schupporum .

Figures

Figure 7. Phyllidia schupporum A dorsal view of preserved specimen (same orientation as living animal in Plate 9 with head to the left) B detail of lateral tubercles and margin (lower) of specimen (enlarged from photograph of the living specimen C ventral view of holotype (M. Schroedl) D, E oral tentacles, ' lips' and anterior foot margin of specimen.

Figure 8. Phyllidia schupporum, drawing of the digestive anatomy, also showing the genitalia (in heavier ink).

Plates 9 - 14. Phyllidia schupporum, specimen and individuals illustrating variations 9 dorsal view of living specimen, Sha'ab Dorfa, 7 Sept 2010 (photograph S. Kahlbrock) 10 Sha'arm el Sheikh, 15 Apr 2012 (photograph S. Kahlbrock) 11 Makadi Bay, 9 Aug 2014 (photograph Hsini Lin) 12 Sha'arm el Sheikh, Oct 2012 (photograph S. Kahlbrock) 13 Sha'ab Mahmoud / Beacon Rock, 9 Oct 2012 (photograph S. Kahlbrock) 14 Eilat, Israel, 4 Sept 2015 (photograph R. Amar).