Doris kerguelenensis

DORIS KERGUELENENSIS (BERGH, 1884)

(FIGS 11, 12)

Archidoris kerguelenensis Bergh, 1884b: 85–89, pl. 1, figs 1–12.

Archidoris australis Bergh, 1884b: 89–91, pl. 1, figs 13–18, pl. 2, fig. 13.

Archidoris rubescens Bergh 1898: 501–503, pl. 29, figs 17–20.

Austrodoris michaelseni Odhner, 1926: 68–71, pl. 2, figs 30-32, text figs 47-50.

Austrodoris crenulata Odhner, 1926: 75–76, pl. 2, figs 38, 39, text fig. 54.

Austrodoris macmurdensis Odhner, 1934: 260–263, pl. 2, figs 21–23, text figs 25-27.

Austrodoris tomentosa Odhner, 1934: 265–267, pl. 2, figs 19, 20, text fig. 32.

Austrodoris nivium Odhner, 1934: 267–269, pl. 2 figs 21–23, text figs 33-35.

Austrodoris mishu Marcus, 1985: 219–222, figs 1–12.

Austrodoris vicentei Marcus, 1985: 214, 217.

Austrodoris georgiensis García et al. 1993: 417–421, figs 1–8.

Type material

For a list of the extant type material of the nominal species included in the genus Austrodoris see Wägele (1990).

Additional material

North-west of Explorer’s Cove, New Harbor, west side of McMurdo Sound, Antarctica, 17 December 1985, two specimens, 54–66 mm preserved length, leg. K. A. Miller (CASIZ 087312).

External morphology

The external morphology of this species has been described in detail by Wägele (1990). My specimens were preserved, so no data on the living animals are available.

The general colour of the living animals is uniformly white (Wägele, 1990). The rhinophores and gill are also white. The whole dorsum is covered with rounded and simple tubercles varying in size and shape (Fig. 11D). The largest tubercles are situated in the central region of the body. The rhinophoral and branchial sheath are surrounded by tubercles similar to the rest of the dorsal tubercles. There are 7–9 tripinnate branchial leaves, forming a circle. The anal papilla is prominent, situated in the centre of the branchial circle of leaves. The rhinophores are elongate, having 32 lamellae in a 66-mm preserved length specimen.

Ventrally there are no oral tentacles, but two blunt prolongations on each side of the mouth opening (Fig. 12F). The anterior border of the foot is grooved but not notched.

Anatomy

The posterior end of the glandular portion of the oral tube has six strong retractor muscles (Fig. 12D) which attach to the body wall. The oval, muscular buccal bulb has two additional muscles attached; two long and wide salivary glands connect with it at each side of the oesophageal junction. The buccal bulb is twice as long as the glandular portion of the oral tube. The labial cuticle is smooth. The radular formula is 24 ¥ 37.0. 37 in a 54-mm long specimen. Rachidian teeth are absent. The lateral teeth are narrow and elongate, having a single cusp and lacking denticles (Fig. 11A). The teeth from the middle portion of the half-row are larger than those closer to the medial portion of the radula (Fig. 11B). The outermost teeth are smaller and also lack denticles (Fig. 11C). The oesophagus is short and connects directly to the stomach (Fig. 12A).

The ampulla is very long and convoluted. It branches into a short oviduct and the prostate (Fig. 12B). The oviduct enters the female gland mass near to its centre. The prostate is tubular, very long and folded (Fig. 12B). It connects with a long duct that narrows and expands again into the large ejaculatory portion of the deferent duct. The muscular deferent duct opens into a short common atrium with the vagina. The vagina is short and wide. Near to its proximal end it joins the bursa copulatrix and the seminal receptacle. The uterine duct also leads from this duct. The bursa copulatrix is irregular in shape, about as large as the seminal receptacle (Fig. 12C).

In the central nervous system (Fig. 12E) the cerebral and pleural ganglia are fused and distinct from the pedal ganglia. There are three cerebral nerves leading from each cerebral ganglion and three pleural nerves leading from each pleural ganglion. There is a separate abdominal ganglion on the right side of the visceral loop. This ganglion appears to have several distinctive portions and one of them seems to be the genital ganglion. The buccal ganglia are near to the rest of the central nervous system, joined to the cerebral ganglia by two relatively short nerves. Gastrooesophageal, rhinophoral and optical ganglia are present. The pedal ganglia are clearly separated, having three nerves leading from the left ganglion and two from the right one. The pedal and parapedal commissures are enveloped together with the visceral loop.

The circulatory system (Fig. 12A) consists of a large heart and a single large blood gland situated in front of the central nervous system.

Remarks

Wägele (1990) revised the genus Austrodoris and concluded that all the Antarctic species previously assigned to it are synonyms of Austrodoris kerguelensis (Bergh, 1884). She also described in detail the anatomy and external morphology of this species.

More recently García et al. (1993) described the new species Austrodoris georgiensis, which is also a synonym of Austrodoris kerguelensis. García et al. (1993) based Austrodoris georgiensis on a single specimen collected from South Georgia, in the Atlantic Antarctic sector. The only difference between A. georgiensis and A. kerguelenensis is the presence of an elongate bursa copulatrix in the former. As other features of both nominal species (e.g. external morphology, radula, other reproductive organs), are identical, it is likely that the single specimen assigned to A. georgiensis is just an aberrant specimen of A. kerguelenensis. Another possibility is that the bursa copulatrix is more variable than assumed until now.