Baeolidia australi

Miller, M. C., 2001, Aeolid nudibranchs (Gastropoda: Opisthobranchia) of the family Aeolidiidae from New Zealand waters, Journal of Natural History 35 (5), pp. 629-662 : 654-658

Baeolidia australi s ( Rudman, 1982)

(®gures 10±12)

Spurilla australis Rudman, 1982: 164 ±169.

Berghia australis ( Rudman, 1982) . Gosliner, 1985: 257.

Morphology (®gure 10)

Extended length up to 40 mm. Body fairly broad, short and low, pericardium inconspicuous, tail approximately one-twelfth of body length. Foot wider than visceral part, tapering very gradually then quite abruptly to posterior end; anterior distinctly two-lipped, upper lip cleft in mid line, corners drawn out as curved processes in length approximately two-®fths width of foot (®gure 11B). Lips and lining of oral tube papillate. Oral tentacles shortish and stout, being one-eighth to one-ninth of body length, tapering gradually to a broad, rounded tip. Rhinophores about same length comprising a very short, sometimes wrinkled stalk and a tall, slightly swollen club tipped with a large, ¯at knob; club covered with upwardly curving papillae arranged roughly in rings (®gure 11A). Cerata arranged in simple arches anteriorly with the anterior limb longer than the posterior, and in rows further back; anterior limb of arch longer than posterior one, limbs of ®rst arch curve anteriorly, becoming less so rearwards as posterior limb reduces gradually until disappearing (®gure 11C); up to 18 cerata in ®rst (largest) arch. At rest a large ceras when viewed from front elliptical to reniform (enlargement facing mesially) with nipple-like apex containing cnidosac, tending to be directed towards dorsal mid line; cerata very mobile and thus shape variable. Proximal part of ceras compressed with convex anterior and concave posterior faces, distal part partially ināted; ceras greatly constricted at point of attachment. Anus lies within second right arch closer to lower end of posterior limb, renal pore immediately anterior and slightly above; reproductive apertures immediately in front and just below tip of rear limb of ®rst right arch (®gure 11C).

Colour

Body between cerata and sides of foot greyish-brown, darkest mid-dorsally. Oral tentacles, side of head, area between mouth and foot deep orange; at front of top of head often a heptagonal outline traced in pale yellow with opaque white spot at centre. Rhinophores pale yellow or orange with papillae and apical knob tipped with opaque white. Large oval spots of opaque white scattered on sides of foot, head, around bases of rhinophores. Ceratal surface faintly yellow or orange with several large elliptical areas of white; digestive diverticulum dark brown, granular; apex transparent, colourless, cnidosac partly visible, below a narrow ring of scattered small, opaque white granules, followed by a fairly broad band of crimson, then a narrow band of light blue. Sole of foot translucent, pale pink or purple.

Alimentary system (®gure 11D±G)

Oral tube very short, wide, leading to buccal bulb, ovate to cordate in outline when viewed from above. Oral glands composite, small, distinctly aciniform, acini evenly compacted around central duct (®gure 11F); outer section of ducts very short, opening low down on inner lips. Salivary glands branched, lobulated (®gure 11G), ducts enter buccal bulb at sides of oesophagus. Oesophagus quickly widens into spacious stomach. Pre-cardiac ducts of digestive gland divide, two branches curve forwards: median post-cardiac duct gives rise to series of 11 or 12 lateral ducts on each side, ®rst of these similar to pre-cardiac pair, but further behind posterior branch gradually shortens, disappearing by sixth or seventh lateral duct; rest a single duct: each secondary duct bears a single row of ceratal diverticula. Intestine arises immediately behind right stomachal duct, at ®rst running laterally, then bending to run ventrally and mesially, then again laterally and dorsally to anus.

Buccal armature

Radular formula 0-1-0; radula of 18 mm specimen had 17 (including one developing) teeth. Teeth comb-like, curved in form of a basket arch; largest (youngest) teeth very broad (®gure 12A), approximately four times width of smallest (oldest) (®gure 12B). Jaws large, ovate, fairly heavy looking, thickened in front (®gure 12C); articulated by a longitudinal ridge on right jaw ®tting into a groove on left. Masticatory process very long, broad, apex drawn out into a point; posterior margin uneven, cutting edge slightly thickened.

Kidney (®gure 11E)

Although compressed, still thick. Lateral and dorso-lateral regions pouched, ®nger-like or rounded; anterior part quite wide, extends to front of pericardium. Renopericardial duct situated near front of pericardium, renal duct near rear end.

Reproductive system (®gure 12D)

Gonad extends posteriorly to between sixth and seventh pairs of post-cardiac ducts of digestive gland; divided into distinct lobes, each consisting of a group of follicles, ducts of follicles of several lobules unite to form a single lateral branch of hermaphrodite duct. Median hermaphrodite duct runs forward to just beyond front end of gonad, there gradually dilating to form ampulla lying in a tight S on top of posterior part of female glands. Ampulla abruptly constricts at front end to form common duct, this running obliquely to right for short distance then dividing. Lower branch enlarges to form a distinct chamber in turn making a T-junction with a narrower duct, to left and posteriorly becoming a longish coiled duct leading to saccate bursa copulatrix, to right and anteriorly directly to genital atrium or by a side branch to female glands. Other branch of common duct, vas deferens, enlarges almost at once after junction into a long, wide sinuate prostatic part terminating at base of glans penis: penis unarmed (®gure 12E).

Localities and habitats

New Zealand, the North Island , East Coast : Bay of Islands , Rawhiti Bay , 3.5±5.5 m, two specimens ( Museum of New Zealand collection B5315), 6 December 1973; Whangarei Heads , Ocean Beach , one specimen on Cystophora on sheltered side of unnamed islet, 19 May 1961, and one specimen in a pool at MTL, 22 May 1967; Hen Island , one specimen, 1958 (collected by E. Milligan); Leigh , Goat Island Bay , Echinoderm Reef ¯at, one specimen crawling across rock in the sublittoral fringe, 18 March 1961, and on inner part of Waterfall Reef, one specimen on Carpophyllum sp. , 8 May 1972 (collected by R. C. Willan) .

Types

Specimens collected at Pilot Beach near Laurieton, northern NSW, Australia, 4 November 1979 holotype (C124692) and paratypes (C118700) deposited in the Australian Museum, Sydney .

Remarks

The New Zealand specimens of this species were ®rst identi®ed as Baeolidia major in Morton and Miller (1968). This was acknowledged by Rudman (1982) when he determined that the New Zealand specimens and some Australian specimens were distinct from those recognized as Baeolidia major , and for the former he created a new species. Consistent diOEerences in colour pattern and anatomy separate these two species, B. australis having its body and cerata more densely pigmented and subapical ceratal bands of orange and blue (always present), and a pair of smallish oral glands, smaller diOEerence in width between the smallest (oldest) and largest (youngest) radular teeth, a smaller number of denticles / tooth, a narrower jaw with a broader masticatory process. All of the specimens examined by me agree with Rudman’s description of B. australis except for some small diOEerences, particularly in colour. The local specimens diOEer in the border of the conspicuous head marking being pale yellow, not white, and the presence of an opaque white spot in the centre, the red (not orange) subapical ceratal ring with a very narrow white band above it, and the cerata having a faint orange tinge. Additional to these colour diOEerences, there are seven ceratal arches not four, 17 radular teeth not 26. All of these diOEerences are explainable as intraspeci®c variation, and in the case of the structural characters, as being diOEerent developmental stages.