Bornella pele Pola, Rudman & Gosliner, 2009

Description

The body is elongate and limaciform, with a long tapering posterior foot. Living adults are small, up to 20 mm in length. The general colour pattern consists of a translucent whitish body with scattered subepithelial opaque white granules. Two parallel red marks run along the inner side of each dorsolateral process and of each rhinophore sheath. There is also a pair of red marks on the head, between the oral tentacles and the base of the rhinophore sheaths. An irregular, elongate red patch runs along the dorsal midline from behind the last pair of dorsolateral processes to the posterior tip of the foot. The oral tentacles bear no red pigmentation.
On either side of the mouth is a lobe-like oral tentacle bearing 9 to 13 finger-like papillae of unequal length arranged in three rows; the outer row usually carries seven papillae. Each rhinophore sheath has a tall stalk with the rhinophore protruding from its tip. The translucent whitish rhinophores are perfoliate with about 15 to 19 lamellae. Around the upper edge of the rhinophore sheath are three elongate anterior and anterolateral papillae and a taller, distinctly bifid posterior papilla. Behind the rhinophores there are three pairs of dorsolateral processes followed by two single processes along the dorsal midline. Each dorsolateral process has a stout base topped with three acutely pointed papillae, with the central one larger and more elongate than the other two. Two bipinnate translucent gills sit on the inner surface, at the base of the lateral papillae of each paired process. The bases of the most posterior pair of dorsolateral processes are joined.
The radula has rachidian teeth with seven denticles on either side of a strong median cusp; outside the blade-like laterals are three or four plate-like outer denticles, which lack any cusp. The posterior chamber of the stomach is smaller than in other species in the genus and bears about 20 longitudinal rows of brown chitinous spines, straight and spatuliform at the tip. The penis is a fleshy lobed structure armed with a single circular row of chitinous hooked spines.

Distribution

Known from Hawaii (type locality: Molokini Island), eastern Australia, and Japan.

Etymology

Verbatim from the original description (Pola, Rudman & Gosliner, 2009, p.34):

This species is named after the Hawaiian goddess

Pele", goddess of fire, lightning, dance, volcanoes and violence. This species was first collected in Hawaii and the red markings of the animal remind the fire and violence of the Hawaiian goddess."

Remarks

This is a relatively small species with a very characteristic colour pattern: the translucent white body with red markings clearly distinguishes it from all other species of the genus. Internally, the rachidian teeth are elongate with denticles on either side of a strong median cusp, and at least three conspicuous plate-like outermost lateral teeth are present — these plate-like outer laterals are well developed in B. pele but inconspicuous or absent in other congeners.
Bornella pele resembles Bornella dotoides in several internal features, including its compact salivary glands, small buccal bulb, less numerous labial cuticle rodlets and a single circular row of penial spines. The two species can be separated by the upper branches of the anterior digestive glands, which run into the rhinophore sheaths in B. dotoides but do not reach them in B. pele.

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References

• ユビウミウシ, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
• Bornella pele sp. nov., Pola M., Rudman W.B. & Gosliner T.M. (2009). Systematics and preliminary phylogeny of Bornellidae (Mollusca: Nudibranchia: Dendronotina) based on morphological characters with description of four new species. Zootaxa. 1975(1): 1-57. https://doi.org/10.11646/zootaxa.1975.1.1
• ホムラユビウミウシ（新称）, 中野理枝. (2018). 日本のウミウシ. 文一総合出版.
• Bornella pele, Terrence Gosliner, Ángel Valdés and David Behrens. (2018). Nudibranch and Sea Slug Identification Indo-Pacific 2nd Edition. New World Pubns Inc.