Verconia sudanica (Rudman, 1985)

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 : 27-29

Verconia sudanica (Rudman, 1985) Plate 10

Noumea sudanica Rudman, 1985: 254, figs 1e, 7b, 8 (Red Sea); Yonow 2008: 61, 200 (Red Sea).

Material.

South of Hurghada , Egypt, 22 Jan 2009, 2- 4 m depth on rocks during night dive, four specimens 15-20 mm alive approx. (6.5, 7, 7, 8 mm preserved); leg. and photographs S Kahlbrock; photographs of numerous individuals, the Creek, Jeddah, Saudi Arabia, 1970-1994, W Pridgen, D & S Sharabati; photographs only, vicinity of Hurghada, Egypt, 13 Aug 2012, S Kahlbrock; photographs of the type specimen, Suakin, Sudan, 25 April 1980, leg. and photographs C Todd (Australian Museum C. 131570) .

Description.

Since Rudman’s (1985) and Yonow’s (2008) records, Verconia sudanica has been recorded somewhat more frequently in the Red Sea (http://www.seaslugforum.net/showall/noumsuda, https://www.inaturalist.org/taxa/126112-Noumea-sudanica). It is described here from specimens collected in the northern Red Sea. The excellent series of photographs depict five individuals, of which three are grouped together (four specimens were collected). In the photograph of the group, the rhinophores and nine plumose but simply pinnate gills are all pure white. The edges of the rhinophore lamellae (numbering 9-11) and main axes of the gills (facing outwards) are opaque white. In photographs of a single animal, the apical one third of the rhinophore is very faintly orange, with opaque white edges to the 9-11 lamellae. All five animals have a white dorsum with pits and a narrow yellow margin, which is faintly darker orange at the edge (Plate 10 ). In two individuals, the pits are slightly yellow and in a third one, there are small conical papillae dotted on the surface. The foot is also white, and the tip is bordered with a yellow line; one photograph from the side shows that the margins of the foot are white.

The preserved specimens are identical, opaque cream with a thickened but slightly lighter coloured margin containing single round mantle glands that are semi-translucent. The gill pocket is large and slightly raised and in two specimens, the unipinnate gills barely protrude. The foot extends beyond the mantle slightly in all but one specimen. The foot is angular anteriorly, and the large oral tentacles are clearly visible.

Remarks.

There are no similar species in the Red Sea; only the western Pacific Verconia simplex (Pease, 1871) is equally small, white to pale pink, with a bright orange margin; however, there are no specimen records further to the two photographs in Yonow (2008) so these records remain unconfirmed. Verconia simplex has bright orange tips to both the rhinophores and the gills.

Some comments are necessary on the generic placement of this species. Gosliner and Johnson (2012: 6) found that Noumea was not monophyletic but its species were distributed in two clades (and within other genera): " Noumea consists of two separate clades (both pp = 1.00) that are poorly supported as a combined clade in the analysis when variable positions are included (pp = 0.61). Although this support is not sufficient, all of the species in both of these clades are currently named Noumea and will retain this name in order to maintain stability."

With this, they synonymised Verconia , a monotypic genus containing V. verconis (Basedow & Hedley, 1905). However, they failed to recognise that Noumea was preoccupied. WoRMS has a small note to that effect and Verconia (as a synonym) should be the correct generic designation (http://www.marinespecies.org/aphia.php?p=notes&id=279974) despite its type species being morphologically different: " Noumea Risbec, 1928 ( Mollusca: Gastropoda) is a junior homonym of Noumea Fauvel, 1874 ( Arthropoda: Coleoptera ), a name in current use. Verconia Pruvot-Fol, 1931 was recognized as a synonym of Noumea Risbec by Johnson and Gosliner (2012) and is here used for species of the chromodoridid group previously known as Noumea ."

Examination of Rudman’s (1984) review of the chromodorid genera and his descriptions of species of Noumea ( Rudman 1986a, b) show that these two genera are in fact similar, but because the external morphology of Verconia verconis is so distinctive, it has historically been considered in its own genus. The radular formulae and teeth shapes are very similar, as are some morphological characters (although these are also similar to other chromodorid genera). The reproductive systems vary a little within the group described as Noumea by Rudman (1984, 1986a, b although some species belonging to a second clade have been re-assigned to Diversidoris ) and in some cases are more similar to that of V. verconis (see also Rudman 1986b: 402). As it is very unlikely that the specimens of V. verconis used in the molecular analysis by Johnson and Gosliner (2012) were misidentified, the synonymy must be accepted, but it is unfortunate that these authors did not examine the literature and, as a result, the species they assigned to Noumea must now be reassigned to Verconia .

Distribution.

Endemic to the Red Sea.

Figures

Plate 10. Verconia sudanica Rudman, 1985, photograph S Kahlbrock.