Bornella excepta Bergh, 1884

Pola, Marta, Rudman, William B. & Gosliner, Terrence M., 2009, Systematics and preliminary phylogeny of Bornellidae (Mollusca: Nudibranchia: Dendronotina) based on morphological characters with description of four new species, Zootaxa 1975, pp. 1-57 : 16

Bornella excepta Bergh, 1884

Bornella excepta Bergh, 1884: 34 –43, Pl. VII, figs 13–22., Pl. VIII, figs 1–13; Bergh, 1902: 202 –204, Pl. III, figs 4–5; Bergh, 1905: 220 –221, Pl. XIX, figs 25–27.

Material examined: No specimens have been recognized as this species since Bergh (1905).

Remarks: Bergh (1884) described Bornella excepta from a 60 mm preserved specimen, from Arafura Sea, in the Pacific Ocean. The color of the animal alive is unknown and no type specimen exists. Nevertheless, the author gave a fully detailed description of the external morphology and the internal anatomy. With such a good description, the species should be easily recognizable within the genus. Eliot (1904) tentatively identified a specimen of Bornella from the east coast of Zanzibar as this species, but there is no way of confirming its identity. There are some similarities between B. excepta and B. hermanni , but we consider the similarities to be outweighed by the following differences: the number of lamellae on the rhinophore is about 20 in B. hermanni and between 40 and 50 in B. excepta ; B. hermanni has three pairs of dorsolateral processes with three gills per dorsolateral process while B. excepta has five pairs of dorsolateral processes with four gills: also the anterior digestive glands of B. hermanni have branches entering the rhinophore sheaths while they do not in B. excepta and, finally, the number of ovotestis follicles is different, from around four in B. hermanni to nine in B. excepta . The shape of the penis and its associated spines, as illustrated by Bergh (1884, Pl. 17, figs 18–22) is also very similar. There are also similarities in the shape of the dorsolateral processes and the penial armature to B. dotoides sp. nov. but the dentition on the central radular tooth of B. excepta appears much coarser. Until new specimens are found which are a closer match to the original description, we have no way of comparing B. excepta to any better known species and so must tentatively retain it as a different and valid species within the genus.