Bornella hermanni Angas, 1864

Location: Taredo, Hachijo Island, Tokyo, Japan
Date: 2016/09/10
Length: 10mm
Depth: 7.0m
Water temperature: 27.0℃

Description

The body is elongate and limaciform, up to 50 mm in length. The ground colour is translucent cream-white with a network of broken red-orange lines and scattered subepidermal opaque white granules on the back and both sides; this colour pattern can extend to the stalk of the rhinophore sheaths and the dorsolateral processes. Each lobe-like oral tentacle bears 13–14 finger-like papillae of unequal length arranged in three rows; smaller specimens usually carry 9 to 12 papillae. The rhinophore sheath stalk is tall, with 15 to 20 lamellae on the rhinophore at its tip. At the upper edge of each sheath are three long, narrow anterior and anterolateral papillae and a taller, sail-like posterior papilla bearing two or three secondary papillae. Behind the rhinophores there are three pairs of dorsolateral processes, followed by two unpaired processes along the dorsal midline. The first and second pairs of dorsolateral processes have three or four branches; the third pair usually has three branches. In paired processes with four branches, three tripinnate translucent gills sit at the junction of each lateral papilla and the central one.
The radula generally bears about eight to ten denticles on either side of a median cusp. The posterior chamber of the stomach is armed with about 20 to 30 longitudinal rows of brown chitinous spines that are straight, cylindrical and spatuliform at the tip. The penial bulb is large and contains a fleshy, irregularly lobed structure armed with a single circular row of chitinous hooked spines.

Distribution

Distributed across the Indo-West Pacific, with the type locality in Sydney Harbour, eastern Australia. The Japanese populations previously reported as B. japonica are referable to this species. Also recorded from the Marshall Islands, Malaysia, Korea and the Indian Ocean (Christmas Island and elsewhere).

Etymology

The specific epithet hermanni is the genitive of the personal name Hermann; the original description by Angas 1864 does not state the dedicatee explicitly.

Remarks

Pola, Rudman & Gosliner 2009 treated Bornella japonica Baba, 1949, originally described from Japan, as a new junior synonym of Bornella hermanni. Baba had separated B. japonica from Bornella stellifera on the basis of four supra-marginal papillae on the rhinophore sheaths (the hindmost subdivided into two or three smaller papillae) and three pairs of dorsolateral processes, but Angas's B. hermanni from eastern Australia shows exactly the same features.
This species has often been misidentified as Bornella stellifera in field guides. It differs from B. stellifera in always having branched posterior papillae on the rhinophore sheaths, in lacking the orange subapical rings on the papillae (which are cream-white instead), in having more numerous and spatuliform stomach spines, and in having the penial spines arranged in a single ring around a large fleshy lobe rather than in several rows.

Photographed by 名谷朋浩

Description

Distribution

Etymology

Remarks

References

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Seasonality

Shooting Locations

Photos of Bornella hermanni

Same Genus Nudibranchs

Similar Colors Nudibranchs

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