Doriprismatica kyanomarginata, Yonow, 2018

Yonow, Nathalie, 2018, Red Sea Opisthobranchia 5: new species and new records of chromodorids from the Red Sea (Heterobranchia, Nudibranchia, Chromodorididae), ZooKeys 770, pp. 9-42 : 11-13

Doriprismatica kyanomarginata sp. n. Figure 1 , Plate 4

Glossodoris Colourful sea slugs - Dipper and Woodward 1989: 58.

Glossodoris cincta - Yonow 2008: 60, 188 (lower left large and upper small photographs only, Egypt) (non Casella cincta Bergh, 1888).

Type material.

HOLOTYPE SMF 349566: Egypt, Sept/Oct 1995, one specimen 21 × 13 mm preserved (still retains dorsal mottling, marginal bands clearly broad ochre, light blue line, black margin on both sides), leg. Á Valdés & E Mollo (HU-M7), radula already dissected, used for SEM.

Other material.

The Creek , Jeddah, Saudi Arabia, 1980s, photographs of one individual, J Kuchinke ( Yonow 2008: 189, uppermost small photograph on right); one individual, photograph G Brown (Plate 4 ); Egypt, 1990s, photograph of one individual, J Hinterkircher; Egypt, 28 Sept 1995, intertidal, photograph of one individual, Á Valdés & E Mollo (HU-015) .

Diagnosis.

While the body shape and colour are similar to those of Glossodoris cincta , the marginal banding is diagnostic: the diffuse yellow innermost band has a sharp outer line bordering the distinct sky blue band, which is followed by a pitch-black margin visible on both sides of the mantle edge.

Description.

This species is distinctive with its fleshy body thrown into four primary and multiple secondary folds. The approximately 20 gills are simply pinnate but whorled around the anal papilla. The rhinophores issue from low raised sheaths, which may bear tiny white spots around the margin, and carry in the region of 21 lamellae.

The body is cream with beige irregularities; this may be somewhat darker centrally in some individuals (Plate 4 ). The banding on the margin is distinctive: the creamy beige dorsum abruptly becomes more yellow, producing a band that is diffuse on the inside but abruptly demarcated on the outside. It is followed by a light blue line and the mantle margin is marked by a thick black line. This colour pattern is also present on the hyponotum. The gills have a beige-brown line up both sides, which meets over the top of each gill. The pinnules are opaque white. The rhinophores have a mottled beige stalk and the lamellate club is rather rounded. There is a white line up both sides and along the edges of the lamellae.

The coloured banding remains on the preserved specimens (Figure 1A ). Ventrally, it is creamy beige, with the top of the foot a little darker but not as dark as the hyponotum. There are no coloured bands on the margin of the foot. The anterior margin of the foot is thickened, and the radula was already dissected upon reception.

The radular formula is>73 × approx. 50.0.50. There is no median thickening or rhachidian tooth present, but a small space in the middle (Figure 1B ). The first marginal tooth on each side bears four or five denticles on each side of the cusp. The cusp becomes much longer at approximately tooth 4 or 5, and the four or five denticles also become a little larger. The outermost teeth in the row are undifferentiated but somewhat reduced in cusp and root sizes; the denticles are also reduced in both size and number (Figure 1C ).

The jaw rodlets are curved and bicuspid at the tips, 20-25 µm long (Figure 1D ).

Remarks.

Originally considered a colour form of Glossodoris cincta by Rudman (1986a) and Yonow (2008), this species is rarely recorded in the Red Sea compared to the common reddish G. cincta with the ochre-black-white mantle margin: in fact, there are only four photographic records of this new species from Jeddah and Egypt since the 1970s (see Material above) compared to the many others of G. cincta . There are also no records of D. kyanomarginata sp. n. from the Red Sea on SeaSlugForum (http://www.seaslugforum.net/showall/gloscinc) nor the internet. There is, however, one photograph of a pair of this new species in a book on the Persian Gulf ( Dipper and Woodward 1989) but there are no further records from the Gulf.

The Indian Ocean form of Glossodoris cincta is similar to this species, but has a darker body with a similar fading towards the margin and only two coloured marginal bands, a bright yellow submarginal line and a black marginal line: there is no blue. Additionally, the radular and jaw elements differ substantially. There are many more denticles on the teeth of the western Indian Ocean specimen, approximately 8-13 compared to the 4-5 present on the teeth of this new species. The formula of a 55 mm living specimens is 134 × 64.1.64 with a distinct median thickening ( Rudman 1986a: 149). The jaws of Glossodoris cincta also differ, with most being unicuspid; in G. kyanomarginata sp. n. the rodlets are bifid without exception, similar to those of the G. atromarginata group of species as defined in Rudman (1986a) but currently attributed to Doriprismatica ( MolluscaBase 2018).

The body shapes differ from both Doriprismatica atromarginata (Cuvier, 1804) and D. plumbea (Pagenstecher, 1877) as illustrated by Rudman (1986a) and Yonow (1989) (both as Glossodoris ) in being much more convoluted with secondary undulations. This is relevant, as the marginal banding of D. plumbea is similar in colour, and can often be blue. However, the body colour is much more yellow and darker in D. plumbea : Gohar and Abul-Ela (1959) described D. plumbea (as Casella atromarginata ) in detail and subsequently Gohar and Soliman (1967) described the Indian Ocean form of Glossodoris cincta (as Casella obsoleta ) and its development from the Egyptian Red Sea, comparing the two species’ very different modes of development. Clearly, there are morphological, radular, and developmental differences between the two genera.

Distribution.

Possibly endemic to the Red Sea. Only one unconfirmed published record from the Persian Gulf.

Derivatio nominis.

The specific epithet is built by combining the Greek κυανός and Latin marginata, referring to the cerulean blue submargin.

Figures

Figure 1. Doriprismatica kyanomarginata sp. n. A ventral view of whole specimen showing colours of the preserved specimen, including the anterior section of the mantle margin B midline area from the anterior portion of the radula C lateral teeth from the posterior section of the radula D jaw rodlets.

Plate 4. Doriprismatica kyanomarginata sp. n., photograph G Brown (non-type).