The « Pale Triton » is a small but lovely ranellid with an extremely wide distribution in subtropical and tropical waters around the globe. Compared to other species in genus Septa, it has a more stout shell with rougher surface. When alive, the shell is covered entirely by a thick periostracum with finely reticulate surface. An uncommon carnivorous and predatory gastropod, it inhabits rubble bottoms of shallow water from low intertidal down to about -50m. A small-sized Septa species, its shell length averages at around 25mm. while the largest individuals may exceed 40mm. The Hawaiian population was recognised for some time as a separate subspecies S. occidentalis beui (Garcia-Talavera, 1985), but is now considered a synonym by most. In the western Pacific there appears to be a long confusion between this species and the name Septa limbata (Roding, 1798), with many specimens of S. occidentalis labelled as S. limberta. The issue with the name S. limbata was in fact discussed and solved by Alan Beu in 1986, who noted that the figure cited in the description is in fact S. flaveola (Roding, 1798). As S. limbata and S. flaveola was described in the same work by Roding and S. flaveola was in prevailing use, Beu selected the name S. flaveola to be the senior synonym as first reviser and designated a single specimen to be the neotype for both names. In addition, Beu clarified that the only modern use of the name S. limbata (as Tritonium limbatum) was actually applied to a mis-identified specimen of Monoplex gemmatus (Reeve, 1844). Specimens of Septa from western Pacific in collections identified as S. limbata (often mis-spelt as S. limberti; Japanese name Hime-Jyuseira) usually have nothing to do with the name S. limbata but are in fact mostly S. occidentalis and sometimes either M. gemmatus or M. mundus (Gould, 1849). Although merely a speculation, treating the western Pacific populations of S. occidentalis under a different name probably roots in disbelief that the same species is shared across Pacific and Atlantic Oceans.

TYPE DATA
Triton rubecula occidentale: Holotype ANSP 36874. (ex Swift collection). Type locality: St. Thomas, Virgin Islands, western Atlantic. - Septa blacketi: Holotype AMS C60662. Type locality: Nielsen Park, Watson's Bay, Sydney Harbour, NSW. - Cymatium beui: Holotype MICN. Type locality: Ohau. Hawaiian islands.
DISTRIBUTION
Indo-West Pacific (Mauritius. Philippine Islands. Ryukyu Islands, eastern Australia. Coral Sea and Hawaii). Western Atlantic (from Florida to Brasil where it is not uncommon). In eastern Atlantic it is only reported from western Canary Islands (Tenerife and La Palma) with several records.
DESCRIPTION
From 30 to 40 mm. Typical pattern of Septa genus with a medium spired shell. Sculpture formed with narrow spiral cords and a lot of finer axial ridges closely spaced. Strong varices slightly shouldered. Siphonal canal straight and short. Aperture oval and narrow with numerous plicae in columellar wall and simple teeth in the outer lip. Operculum corneus. Periostracum green to brownish, cespitous. Protoconch wide and very flat spired with 3 embrionic whorls. Basic color uniform pale brown with a while band in the middle of the whorl. Varices have 2 white blotches. Cream columella with white plicae and white outer lip.
REMARKS
A species included in the "rubeculum complex". It is clearly distinguished by the pale color rather than the reddish color of the other species and has a finer sculpture. Garcia-Talavera, 1981 and Vega-Luz report live specimens from Tenerife. I also can confirm a few records from La Palma. but there are no more citations in other islands. Anyway it should be considered as a very rare species in the eastern Atlantic, despite its confirmed amphiatlantic presence could indicate an establishment in the Canary Islands. There were no earlier records from Lanzarote. but while finishing this work I found one dead specimen in Puerto del Carmen. It is probably a shell carried by a boat and there is no reason to consider it as established in the island.

Although described by both Morch (1877, p. 29) and Clench & Turner (1957) from Western Atlantic specimens, this species has proved to be relatively common in Hawaii (by far the most common species of the subgenus there) and to occur rarely throughout the rest of the Indo-West Pacific. Cymatium occidentale is easily recognised by its almost uniform pale yellow-brown to faintly reddish brown colour, by its unusually widely extended varices and small aperture for the subgenus, by its relatively prominent shoulder nodule on each varix and, in particular, by its extremely fine, low, close, numerous collabral costae (33 to 46 in each invervariceal space), almost twice as fine and numerous as in C rubeculum rubeculum, C hepaticum, and C closeli Two white splashes are present on the varices, as in all C septa species except C peasei n. sp.; pale reddish brown specimens seen from Ceylon and New South Wales have a pale spiral interspace between the fourth and fifth cords on the last whorl, but this is scarcely discernible on most specimens.