Hinea brasiliana (Lamarck 1822)

Hinea brasiliana (Lamarck, 1822)

Buccinum brasilianum Larnarck, 1822:272.

Planaxis mollis Sowerby, 1823:209, pl. 209: fig. 2.—Tryon, 1887:279, pl. 52: figs. 34, 35.

Planaxis brasilianus (Lamarck).—Sowerby, 1877, pl. 5: fig. 35.

Hinea brasiliana (Lamarck).—Hedley, 1904:186; 1918:51.—McMichael, 1960:66, fig. 128.

Planaxis (Hinea) mollis (Sowerby).—Thiele, 1929:204.—Wenz, 1940:722.

Planaxis (Hinea) brasilianus (Lamarck).—Cernohorsky, 1972:59, pl. 12: fig. 20.

Hinea brasiliana has a geographic distribution from South Australia to southern Queensland and also occurs at Lord Howe Island, Norfolk Island, the Kermadecs, and northern New Zealand. The species is gregarious and occurs in discrete populations among rocks and rubble in the midlittoral zone along exposed, rocky, high-energy coastlines. Populations usually live in somewhat protected areas not in direct contact with large waves. Individuals are found in clusters under rocks, in moist, dark places during low tide, but become very active and rapidly disperse when submerged by incoming tides. Hinea brasiliana lives well under laboratory conditions and needs little care. Coleman (1975:8) kept specimens alive for a year in a jar of unchanged sea water to which no food was added.

SHELL MORPHOLOGY (Figure 10).—The adult shell (Figure 10A–D,F) is thick, smooth, and turreted, reaching 20 mm in length, and is covered with a thick, brownish yellow periostracum. The whorls are slightly inflated and the suture adpressed. The protoconch comprises 3 whorls, each sculptured with a suprasutural spiral cord and subsutural axial plaits (Figure 10E). A distinct sinusigeral notch is present. The aperture is ovate, white inside, and has a short anterior canal. The outer lip is thick, smooth, and denticulate within. The thick upper edge of the outer lip extends onto the middle of the penultimate whorl folding over the anal canal. Operculum thin, having attachment scar a little less than half the operculum length.

EXTERNAL ANATOMY.—Animal is cream colored with a yellowish head. The head, snout, tentacles, and propodium are covered with a network of fine black lines. A large red buccal mass is seen through the snout. The eyes, located at the bases of the tentacle peduncular stalks, are black and smaller than in other planaxid taxa. The sole of the foot is white and has a propodial mucus gland that extends halfway around the foot. Although no sign of a ciliated groove for egg transport was found, a small brood pouch on the right side of the head-foot is highlighted by a raised, white pigmented area. The mantle edge is smooth. Gonads are orange in females and brown in males.

MANTLE CAVITY ORGANS.—Within the mantle cavity, the osphradium (Figure 13C, os) separates from the ctenidium distally and runs into the inhalant siphon. In contrast to Planaxis sulcatus, the ctenidium is comprised of narrow, tall filaments. The hypobranchial gland, although wide and covering the mantle roof, is very thin and underdeveloped in comparison to other planaxid taxa and in section is seen to comprise numerous, granular, secretory, elongate cells (Figure 13B, hg).

ALIMENTARY TRACT (Figure 12A).—The body wall of the snout is thin and the buccal mass (Figure 12A, bm) of moderate size.

Radula (Figure 11). The radula is small, about one-sixth the shell length and has about 16 rows of teeth per mm. The semilunar rachidian tooth (Figure 11B) has long lateral extensions and is much wider than tall. It has a concave top with a single triangular cusp that is serrated along its cutting edge by 3–5 minute denticles. The basal plate of the rachidian has a shallow central extension and a pair of sharp cusps along its base. The dental formula of the rachidian tooth is . The rhomboidal lateral tooth (Figure 11D) has a long lateral extension and a concave cutting edge with a large central pointed cusp, flanked by 2 or 3 proximal (inner) denticles and 3 or 4 distal (outer) denticles. The marginals (Figure 11C) are elongate with curved spatulate tips. The inner marginals have about 10 sharp denticles, while in the more spatulate outer marginals the denticles are not as clearly separated and the distal portion is smoother. The tips of the outer and inner marginals appear to be fused to each other.

The paired salivary glands (Figure 12A, sg) are long thin tubes having a proximal origin on the left side of the esophagus, far behind the nerve ring. The glands pass through the nerve ring and empty into the mid-dorsolateral part of the buccal mass. Unlike those of other planaxids, they are uncoiled.

The esophagus is wide, with a distinct dorsal food groove. The esophageal gland (Figure 12A, eg) arises as a series of lateral longitudinal folds in the sides of the esophagus.

The stomach has a small, bilobed posterior pad, but in other respects it is similar to that of Planaxis sulcatus.

REPRODUCTIVE SYSTEM.—The male pallial gonoduct is a simple open duct lined with transverse thin glandular folds at its basal attachment. The free portions of the medial lamina are composed of thick, white, glandular tissue proximally and medially, but become thin distally. These thickened portions of the gonoduct appear to delineate the prostate-spermatophore gland. In the female pallial oviduct, the lateral lamina (Figure 12B, ll) is closely fused to the mantle wall, while the medial lamina (Figure 12B, ml) has a long, thin-walled, highly ciliated, sperm gutter (Figure 12B, sg) along its distal edge, which runs into a moderate sized median-proximal spermatophore bursa (Figure 12B, sb). The seminal receptacle (Figure 12B, sr) is proximal to the spermatophore bursa and connected to it by a tiny opening. A ciliated tract leading from the oviduct to the brood pouch is present, but no groove is present as in Planaxis, Supplanaxis, and Fissilabia species. The brood pouch is lined with ciliated epithelium and arises as an invagination of the outer epithelium of the head-foot. It is located in the lower right portion of the head-foot. It is not large, about 1.5 mm in length (one-third the foot width), and lies only in the right side of the head-foot, adjacent to the extensions of the right pedal ganglion (Figure 13A, bp, exp). Thin, convoluted, heavily ciliated lamellae of connective tissue that stain darkly in section arise from the inner walls of the chamber (Figure 13D, E). These lamellae occur throughout the lumen, separate the larvae, and may provide some kind of fluid medium in the brood pouch. In section, the interior surface of the brood pouch consists of tall columnar epithelial cells bearing long cilia (Figure 13D). The latter cells are not present in the part of the brood pouch closest to the birth pore. A thick branch of the right pedal ganglion appears to innervate the brood pouch. Advanced embryos and newly hatched larvae range in size from 0.2–0.3 mm and are intermediate in size between typical planktotrophic larvae and lecithotrophic larvae. Moreover, the protoconch does not have a deep sinusigeral notch, suggesting that development is lecithotrophic, perhaps with a brief demersal stage.

NERVOUS SYSTEM (Figure 12A).—The subesophageal ganglion (Figure 12A, ueg) is joined to the left pleural ganglion (Figure 12A, lpg). The pedal ganglia have elongate extensions (Figure 12A, pg) with a series of smaller ganglia extending anteriorly and innervating the brood pouch (Figure 13A, exp). The RPG ratio is 0.65 (n = 4), indicating a looser concentration of ganglia than in other planaxid taxa.

Angiola Dall. 1926:63.—Thiele, 1929:204.—Wenz, 1940:722.—Rehder, 1980:48.

TYPE-SPECIES.—Planaxis periscelida Dall, 1926, by original designation.

DIAGNOSIS.—Shell small, thick, mostly smooth, glossy, and colored white, with numerous spiral bands of brown, tan and black. Periostracum thin, hispid. Rachidian tooth wider than tall, with single serrated triangular cusp and basal plate with two cusps. Luminous organ near edge of middorsal mantle. Seminal receptacle in proximal part of outer lamina. Brood pouch small, in right side of head-foot. Larvae brooded to veliger stage, released, and undergo planktotrophic phase. Paired salivary glands coiled posterior to nerve ring. Esophageal gland moderately developed. Low intertidal rubble habitat.

Hinea brasiliana, common name the yellow-coated clusterwink, is a species of small sea snail, a gastropod mollusc in the family Planaxidae. It is native to New Zealand and southeastern Australia where it is found in the littoral zone of rocky shores. It is one of only a few sea snail species able to bioluminesce.