Pleurobranchus albiguttatus (Bergh, 1905)

Description

A medium pleurobranch, about 3.5 cm long alive. The dorsal ground colour is reddish-brown, lighter and slightly more yellowish along the mantle border, densely covered with small islets bordered by darker outlines, and bearing scattered small white nodules — these conspicuous white dorsal nodules are diagnostic in the field. The everted oral tube is reddish-yellow, bluish at its base. The handsome long gill, narrower anteriorly and tapering posteriorly, projects free only in its posterior quarter. The thin chalk-white dorsal shell lies internally over the gill.

Distribution

Type locality: the reef at Pulu-Pasi-Tanette and the neighbouring "Süd-Insel" in the Selayar group, south of Sulawesi, Indonesia (Siboga Expedition station 213, October 1905). The species is now known to range widely across the tropical Indo-West Pacific on rocky and rubble bottoms of coral reefs.

Etymology

The specific epithet albiguttatus is a Latin compound of albus ("white") and guttatus ("spotted, dotted"), meaning "with white spots", referring to the conspicuous white nodules on the dorsum.

Remarks

Originally described as Oscaniella albiguttata. Oscaniella is now treated as essentially synonymous with Pleurobranchus, and the species is accordingly placed in Pleurobranchus; the parentheses in the author citation reflect this transfer. The scattered white dorsal nodules provide a useful external character for field identification.

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References

• Oscaniella albiguttata Bgh. n. sp., Bergh R. (1905). Die Opisthobranchiata der Siboga-expedition. https://doi.org/10.5962/bhl.title.11223
• ナイワンフシエラガイ（仮称）, 小野篤司. (1999). ウミウシガイドブック. TBSブリタニカ.
• ナイワンフシエラガイ（新称）, 小野篤司. (2000). ウミウシガイドブック. 第2版. TBSブリタニカ.