Discodoris zibethina, (Bergh, 1878)

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 : 566-569

DISCODORIS ZIBETHINA ( BERGH 1878)

( FIGS 17 , 18 )

Fracassa zibethina Bergh, 1878a: 598–601 , pl. 66, figs 21–26, pl. 67, figs 1, 2.

Type material

HOLOTYPE (by monotypy): Canal at Lapinig, Philippines, March 1865, 54 mm preserved length, leg. C. Semper ( ZMUC GAS-2112 ).

Description

The colour of the living animal is unknown ( Fig. 17 ). The body is very elongate and narrow, with a very reduced mantle margin, which is completely absent in some areas. The gill is situated on the posterior border of the body. The dorsum is covered with a number of small, rounded tubercles ( Fig. 18E ). The rhinophoral and branchial sheaths have tubercles similar to those on the rest of the dorsum. There are six tripinnate branchial leaves. The anal papilla is situated in the centre of the branchial circle of leaves. Ventrally the anterior border of the foot is grooved and notched.

The labial cuticle is armed with a number of small, simple rodlets ( Fig. 18D ). The observed radular formula is n ¥ 83.0.83. Rachidian teeth are absent. The lateral teeth are hamate and lack denticles ( Fig. 18A ). The teeth from the middle portion of the half-row are larger than those closer to the medial portion of the radula ( Fig. 18B ). The outermost teeth are smaller and also lack denticles ( Fig. 18C ).

Remarks

The holotype of Discodoris zibethina is the only known specimen of this species. The specimen was studied and dissected by Bergh (1878a), and only the skin and some internal organs, including the radula, remain. The description of the species was based on preserved material and there is no information on the features of the living animal. With the preserved holotype it is not possible a positive identification of this species. Therefore this name is here regarded as nomen dubium.

The shape of the animal strongly resembles the remains of some species of Discodoris or Sebadoris after the autotomization of the notum ( Gohar & Soliman, 1967; Soliman, 1980; pers. obs.).

Figures

Figure 17. Discodoris zibethina (ZMUC GAS-2112). dorsal view of the preserved holotype.

Figure 18. Discodoris zibethina (ZMUC GAS-2112), SEM images of the radula, jaws and dorsal tubercles. A, inner lateral teeth; scale bar = 100 Mm. B, mid-lateral teeth; scale bar = 150 Mm. C, outer lateral teeth; scale bar = 100 Mm. D, jaw elements; scale bar = 30 Mm. E, dorsal tubercles; scale bar = 430 Mm.