Sebadoris nubilosa, (Pease, 1871)

Valdés, Ángel, 2002, A phylogenetic analysis and systematic revision of the cryptobranch dorids (Mollusca, Nudibranchia, Anthobranchia), Zoological Journal of the Linnean Society 136 (4), pp. 535-636 : 608-611

SEBADORIS NUBILOSA ( PEASE, 1871)

( FIGS 34C , 42 , 43 )

Doris nubilosa Pease, 1871b: 13–14 , pl. 6.

Thordisa crosslandi Eliot, 1904: 368–369 , pl. 32, fig. 3, pl. 33, figs 4–8.

Diaulula gigantea Bergh, 1905: 119–120 , pl. 15, figs 11–16.

Type material

The type material of Doris nubilosa , collected from Huaheine Island, Society Islands, French Polynesia, is untraceable. The holotype of Thordisa crosslandi , collected from Chuaka, Zanzibar, could not be located at BMNH and is probably lost. The holotype of Diaulula gigantea could not be located at ZMUC and is also presumed lost.

Additional material

Reef flat South of Avera , Rututu Island, Austral Islands, French Polynesia, 28 January 1983, one specimen, 64 mm preserved length, leg. G. Paulay ( CASIZ 071727 )

External morphology

The background colour of the living animals is brownish grey ( Fig. 34C ). The dorsum is covered with large, dark grey, oval patches, which are larger in the centre of the dorsum. There are also numerous small opaque white spots. The rhinophores and gill are brownish grey with white apices. The dorsum is covered with soft, think and pointed papillae. Some of the papillae are larger than the rest, and have a elongate prolongation on the tip. Larger papillae are surrounded by several small ones ( Fig. 42E ). The rhinophoral and branchial sheaths have small papillae, similar to those on the rest of the dorsum. There are five tripinnate branchial leaves. The anal papilla is situated in the centre of the branchial circle of leaves. The rhinophores are elongate, having 25 lamellae in a 64-mm preserved length specimen.

Ventrally the anterior border of the foot is grooved and notched ( Fig. 43F ). The oral tentacles are conical. The colour of the underside of the mantle is yellowish cream, with a submarginal, dark brown band, surrounding the entire mantle margin and several dark brown, rounded spots irregularly arranged. There are also numerous opaque white spots. The foot sole is yellow with dark brown spots.

Anatomy

The posterior end of the glandular portion of the oral tube has six strong retractor muscles ( Fig. 43C ), which attach to the body wall. The oval, muscular buccal bulb has two large additional muscles attached; two long salivary glands connect with it at each side of the oesophageal junction. The buccal bulb is as long as the glandular portion of the oral tube. The labial cuticle is armed with a number of small rodlets. The radular formula is 54 ¥ 124.0. 124 in a 64-mm long specimen. Rachidian teeth are absent. The lateral teeth are hamate and lack denticles ( Fig. 42A ). The teeth from the middle portion of the half-row are larger than those closer to the medial portion of the radula ( Fig. 42B ). The outermost teeth are smaller and also lack denticles ( Fig. 42C ). The oesophagus is short and connects directly to the stomach.

The ampulla is long and convoluted ( Fig. 43B ). It branches into a short oviduct and the prostate. The oviduct enters the female gland mass near to its centre. The prostate is elongate. It has two different portions that are clearly distinguishable in colour and texture. The prostate connects with a long duct that narrows and expands again into the large ejaculatory portion of the deferent duct. The penis is unarmed but internally covered with soft lamellae ( Fig. 42D ). The muscular deferent duct opens into a common atrium with the vagina. The vagina is wide and short. At its proximal end it joins the bursa copulatrix. From the bursa copulatrix leads another duct connecting to the uterine duct and the seminal receptacle ( Fig. 43C ). The bursa copulatrix is oval in shape, about three times as large as the elongate seminal receptacle.

In the central nervous system ( Fig. 43D ) the cerebral and pleural ganglia are fused and distinct from the pedal ganglia. The cerebral and pleural ganglia are entirely covered with large ganglionic tubercles. There are five cerebral nerves leading from the left cerebral ganglion and four from the right one, and three pleural nerves leading from each pleural ganglion. There is no separate abdominal ganglion on the right side of the visceral loop. The buccal ganglia are near to the rest of the central nervous system, joined to the cerebral ganglia by two relatively long nerves. Gastro-oesophageal, rhinophoral and optical ganglia are present. The pedal ganglia are clearly separated, having five nerves leading from each one. The pedal and parapedal commissures are enveloped together with the visceral loop.

The circulatory system ( Fig. 43A ) consists of a large heart and two blood glands situated in front of and behind the central nervous system.

Remarks

Pease (1871b) described Doris nubilosa from Huaheine Island, Society Islands, as large, flaccid, the dorsum covered with soft papillae, mottled with different shades of brown and grey, and with two dorsal longitudinal rows of cloud-like brown patches. The excellent colour illustration published by Pease (1871b: pl. 6) makes this species easy to recognize.

Eliot (1904) described Thordisa crosslandi based on several specimens collected from the East coast of Africa. The living animals were described as follows: sandy with blotches of brown irregularly bordered with black; the underside whitish with numerous brownish spots and a brownish border; the dorsal tubercles thick-set pointed papillae, some of which are developed into distinct filaments at their extremities. Eliot (1904) studied the anatomy of several specimens and found the penis to be twisted spirally and provided with two rows of tubercles. He later ( Eliot, 1910) suggested that Thordisa crosslandi could be a synonym of Doris nubilosa Pease, 1871 .

Bergh (1905) described Diaulula gigantea as a brownish grey species with numerous lighter specks and large black patches; the dorsum covered with conical and rounded tubercles about 2 mm long; the underside yellowish with a dark brown band near to the border of the mantle and dark spots. All these features agree with the descriptions of Doris nubilosa and Thordisa crosslandi .

Marcus & Marcus (1960) redescribed Thordisa crosslandi from the Red Sea, and introduced the genus Sebadoris based on it, due to the particular shape of the penis. They considered the tubercles described by Eliot (1904), and also seen by themselves, to be penial spines.

Kay & Young (1969) and Edmunds (1971) regarded Thordisa crosslandi and Diaulula gigantea as synonyms of Doris nubilosa Pease, 1871 . Kay & Young (1969) transferred this species to the genus Archidoris , whereas Edmunds (1971) maintained the usage of the genus name Sebadoris .

Soliman (1980) studied specimens of Sebadoris crosslandi from the Red Sea, and at the same time considered that this species differs from Thordisa crosslandi in texture and colour of the dorsum, radular teeth and reproductive system. According to Soliman (1980) these two nominal species could be different.

The anatomy and external morphology of the specimens studied by Eliot (1904), Bergh (1905), Kay & Young (1969), Edmunds (1971) and Soliman (1980) are identical to those of the material examined here, and there is no question that all of them belong to the same species.

Figures

Figure 34. Living animals. A, Paradoris indecora, Southern Spain, photo by D. Moreno. B, Otinodoris sp. (CASIZ 073238), photo by T. M. Gosliner. C, Sebadoris nubilosa, Seychelles, photo by T. M. Gosliner. D, Conualevia marcusi, La Paz Bay, Baja California Sur.

Figure 42. Sebadoris nubilosa (CASIZ 071727), SEM images of the radula, penis and dorsal papillae. A, inner lateral teeth; scale bar = 50 Mm. B, mid-lateral teeth; scale bar = 75 Mm. C, outer lateral teeth; scale bar = 43 Mm. D, penial lamellae; scale bar = 100 Mm. E, dorsal papillae; scale bar = 500 Mm.

Figure 43. Sebadoris nubilosa (CASIZ 071727). A, general view of the anatomy; scale bar = 1 mm. B, reproductive system; scale bar = 1 mm. C, detail of several reproductive organs; scale bar = 1 mm. D, central nervous system; scale bar = 1 mm. E, lateral view of the buccal bulb; scale bar = 1 mm. F, ventral view of the mouth area; scale bar = 1 mm.