Dermatobranchus albineus, Gosliner & Fahey, 2011

Gosliner, Terrence M. & Fahey, Shireen J., 2011, Previously undocumented diversity and abundance of cryptic species: a phylogenetic analysis of Indo-Pacific Arminidae Rafinesque, 1814 (Mollusca: Nudibranchia) with descriptions of 20 new species of Dermatobranchus, Zoological Journal of the Linnean Society 161 (2), pp. 245-356 : 284-288

publication ID	https://doi.org/ 10.1111/j.1096-3642.2010.00649.x
persistent identifier	https://treatment.plazi.org/id/761B2D60-4851-E27A-0AF0-F8C1FB3A3804
treatment provided by	Valdenar
scientific name	Dermatobranchus albineus
status	sp. nov.

Treatment

DERMATOBRANCHUS ALBINEUS View in CoL SP. NOV.

( FIGS 30A, B View Figure 30 , 31 View Figure 31 , 32 View Figure 32 )

Dermatobranchus sp. 1 Gosliner, 1987:110 , figure 211. Type material: Holotype: CASIZ 074050 , 16 mm preserved, Hottentot Huisie, Atlantic coast, Cape Peninsula, Cape Province, South Africa (33°59.2407′S, 18°20.812244′E) 7 m depth, collected 5.xii.1980 by T. Gosliner. Paratypes. CASIZ 073997 , two specimens, 11, 14 mm preserved, dissected, Llandudno Bay, Atlantic coast Cape Peninsula GoogleMaps , Western Cape Province, South Africa, 7 m depth, collected 9.x.1982 by T. Gosliner. CASIZ 074008 , five specimens, Philip’s Reef GoogleMaps , Algoa Bay GoogleMaps , Port Elizabeth GoogleMaps , Eastern Cape Province, South Africa, 11 m depth, collected 15.v.1984 by T. Gosliner. CASIZ 086855 , two specimens, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 7 m depth, date unknown, collected by T. Gosliner. CASIZ 086864 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 7 m depth, collected i.1981 by T. Gosliner. CASIZ 086855 , one specimen, Bakoven GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 7 m depth, collected 17.ix.1982 by T. Gosliner. CASIZ 176963 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner GoogleMaps et al. CASIZ 176267 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 13.4 m depth, collected 5.i.2008 by Gosliner GoogleMaps et al. CASIZ 176268 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 13.4 m depth, collected 5.i.2008 by Gosliner GoogleMaps et al. CASIZ 176269 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 17.5 m depth, collected 5.i.2008 by Gosliner GoogleMaps et al. CASIZ 176962 , 1 specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner GoogleMaps et al. CASIZ 176963 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner GoogleMaps et al. CASIZ 176964 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner GoogleMaps et al. CASIZ 176965 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner GoogleMaps et al. CASIZ 176966 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner GoogleMaps et al. CASIZ 176967 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner GoogleMaps et al. CASIZ 176968 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner GoogleMaps et al. CASIZ 176969 , one specimen, Hottentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Cape Peninsula GoogleMaps , Cape Province, South GoogleMaps tentot Huisie GoogleMaps , Atlantic GoogleMaps coast, Western Cape Province, South Africa, no depth or date recorded, collected by T. Gosliner GoogleMaps .

Geographical distribution: This species has only been reported from the Atlantic and Indian Ocean coasts of South Africa from Oudekraal to Algoa Bay (Gosliner, 1987; present study).

Natural history: This species is found in rocky habitats in relatively shallow water in cold temperate waters of the Cape of Good Hope region where it feeds ( Fig. 30B View Figure 30 ) on the soft coral Eleutherobia variabile (Thomson, 1910) (Gosliner, 1987) .

Etymology: The specific name albineus is a noun in apposition from a Latin word for ‘white’ to describe the whitish coloration of this Dermatobranchus .

Africa, 17.5 m depth, collected 14.i.2008 by Gosliner et al. CASIZ 176970 , one specimen, Hottentot Huisie , Atlantic coast, Cape Peninsula , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner et al. CASIZ 176971 , one specimen, Hottentot Huisie , Atlantic coast, Cape Peninsula , Cape Province, South Africa, 17.5 m depth, collected 14.i.2008 by Gosliner et al. SAM A35753, two specimens, one dissected, 12 and 15 mm preserved, Hottentot Huisie , Atlantic coast, Western Cape Province, South Africa, no depth recorded, collected 14.xii.1981 by T. Gosliner. SAM A35757, ten specimens, one dissected, 4–15 mm preserved, Hottentot Huisie , Atlantic coast, Western Cape Province, South Africa, no depth or date recorded collected by T. Gosliner. SAM A35751, two specimens, 5 and 7 mm preserved, Hottentot Huisie , Atlantic coast, Western Cape Province, South Africa, no depth recorded, collected 9.ix.1982 by T. Gosliner. SAM A35754, three specimens, 12, 13, and 15 mm preserved, Hottentot Huisie , Atlantic coast, Western Cape Province, South Africa, no depth recorded, collected ii.1981 by T. Gosliner. SAM A35728, seven specimens, 6–15 mm preserved, Llandudno and Hot- External morphology: The body shape of the living animal ( Fig. 30A, B View Figure 30 ) is elongate but broad, flattened, and narrows at the posterior end. The wide foot projects beyond the distinct mantle margin. There are approximately 16 longitudinal dorsal ridges with three shorter ridges between them on each side of the median towards the posterior. The distinct anvilshaped oral veil extends well forward and laterally. Behind the oral veil are the closely spaced rhinophores. The rhinophores have a series of longitudinal lamellae on the rounded club. There are no lamellae on the stalk. Marginal sacs are readily visible on the mantle edge. There are no hyponotal or branchial lamellae. Approximately one-third along on the right side of the body is the genital opening. The anus is situated approximately half of the way along the body side .

The ground colour of the dorsum and oral veil is pinkish to greyish white. The dorsal ridges and the margin of the foot are opaque white. The rhinophores are creamy pale yellow with opaque white on the vertical lamellae.

Buccal armature: The jaws are large and thickly cuticularized ( Fig. 31A View Figure 31 ), with a thick masticatory margin and seven to eight rows of multifid, triangular, pointed denticles ( Fig. 31B View Figure 31 ). The radula ( Fig. 31C View Figure 31 ) of three specimens have formulae of 37 ¥ 13– 17.1.1.1.13–17 (CASIZ 073997) and 39 ¥ 11.1.1.1. 11 in two additional specimens (SAM A35753). The rachidian teeth ( Fig. 31D, E View Figure 31 ) are broad with a large, pointed central cusp that extends well beyond the 11 flanking denticles on each side. On the outer edge of each rachidian is a broad, blunt ended cusp that is longer than the 11 denticles, but shorter than the central cusp. The first lateral tooth ( Fig. 31F View Figure 31 ) is extremely broad and laterally directed with a hook-shaped first denticle that extends beyond the following 16 long, pointed denticles. The next six to seven lateral teeth ( Fig. 31G View Figure 31 ) are elongate with a primary denticle that is longer than the subsequent three to six denticles. The next eight to ten lateral teeth ( Fig. 31H View Figure 31 ) are elongate hooks with no denticles, and the last two of these are smaller than the others.

Reproductive system: The reproductive organ arrangement is androdiaulic. The hermaphroditic duct is narrow and leads into the ovoid ampulla ( Fig. 32 View Figure 32 ). The ampulla bifurcates within the centre of the female gland mass into the short oviduct and the thick, tubular prostate. The prostate expands into the bulbous, muscular penial sheath. The round bursa copulatrix is somewhat smaller than either the ampulla or the penial sheath. From the bursa, the narrow vaginal duct expands into a bulbous vagina, which exits adjacent to the penial opening.

Remarks: Externally, D. albineus looks most similar to an Armina with white longitudinal ridges and the wide oral veil. However, the coloration is not similar to any described Armina or Dermatobranchus . Armina gilchristi Bergh, 1907 from South Africa has white ridges but the ground colour is grey and black at the anterior end of the dorsum ( Bergh, 1907; Gosliner, 1987: fig. 210). Armina loveni ( Bergh, 1860) has opaque white, wavy longitudinal ridges, but the ground colour of that species is tan or reddish ( Thompson, 1988). These Armina species have branchial and hyponotal lamellae, as is typical for the genus, whereas D. albineus lacks lamellae and does not have a continuous anterior notal ridge separating the rhinophores from the notum.

Both D. albineus and its sympatric congener, D. arminus have opaque white longitudinal ridges and a wide oral veil, but the ground colour of D. arminus is light brown or tan, with dark spots between the ridges, not white as found in D. albineus .

There are several other species with similar radular features such as broad rachidian and inner lateral teeth. These species include D. fortunatus ( Bergh, 1888) , D. substriatus Baba, 1949 , D. funiculus sp. nov., D. piperoides sp. nov., D. kokonas sp. nov., D. earlei sp. nov., and D. rodmani sp. nov. None of these species have as many lateral teeth as D. albineus nor do any of these species have as many as seven rows of denticles on the masticatory surface of the jaw, and none of them have a white body colour with opaque white ridges. The radular teeth of D. albineus ( Fig. 31 View Figure 31 ) are not at all similar to the sympatric D. arminus sp. nov. ( Fig. 33 View Figure 33 ). Although the rachidian of both species is wide with an elongate median cusp, the rachidian tooth of D. arminus more resembles a species of Armina with a blunt median cusp and knob, with fewer denticles than in D. albineus . The inner lateral tooth differs between these two species. That of D. albineus is wider with 16 pointed denticles and that of D. arminus is shorter and has only four to six denticles. The 12 outer lateral teeth of D. albineus are hook-shaped, whereas in D. arminus the 9–12 lateral teeth are pointed and needle-like.

Other Dermatobranchus species have similar reproductive characters such as a large, bulbous, penial sheath and slightly expanded vagina. These species include D. albus ( Fig. 11 View Figure 11 ), D. semilunus sp. nov. ( Fig. 81 View Figure 81 ), and D. funiculus sp. nov. ( Fig. 57 View Figure 57 ). However, none of these species, including D. arminus , have a large bulbous vagina as found in D. albineus . The ampulla of D. albineus ( Fig. 32 View Figure 32 ) is an ovoid mass, whereas in D. arminus ( Fig. 34 View Figure 34 ) the ampulla is elongate and narrow, in D. albus it is tubular, and in D. funiculus the ampulla is pear-shaped.