Tambja kava Pola, Padula, Gosliner & Cervera, 2014

Tambja kava

No field photograph submitted for this species yet

Description

Body small, elongate and limaciform with a long pointed tail; the living animal measures 15 mm in length and the holotype is the sole known specimen. Ground colour uniformly green, with whitish markings forming a broken line along the mantle edge that joins behind the circular gill. Numerous longitudinal reddish stripes give the body a corrugated appearance. Rhinophores delicate and perfoliate with about 16 lamellae, retractile in their sheaths. Tips, upper lamellae and bases of the rhinophores, oral tentacles, upper half of the branchial plumes and posterior end of the foot are dark violet; the remaining rhinophoral lamellae are reddish; rhinophoral sheaths are the same colour as the body. Five short, non-retractile tripinnate gill branches form a semicircle around the anal papilla; the basal outer and inner branchial rachises are white. Genital pore on the right side, midway between gill and rhinophores. Small lateral slots of unknown function are present on both sides of the body between the rhinophores and the oral tentacles, as in other species of Tambja. Radular formula 16 × 5–6.1.1.1.5–6. The rachidian teeth are rectangular, lacking denticles, and have a smooth upper edge. The innermost lateral teeth are much larger than the outer ones, with a deeply bifid upper cusp bearing two sharp, elongate denticles of similar size; the outer cusp is smaller and rectangular. The outer lateral teeth are simple plates decreasing in size towards the margin. The penis is armed with small, hooked, chitinous spines.

Distribution

Vanuatu Archipelago (Western Aoré Island). Known only from the holotype.

Etymology

Verbatim from the original description (Pola, Padula, Gosliner & Cervera, 2014, p.621):

The specific name 'kava' refers to the most popular drink consumed in Vanuatu, where this species was collected, as well as throughout the western Pacific Ocean cultures of Melanesia.

Remarks

The only previously known species closely resembling this taxon is Tambja amakusana Baba, 1987, from Japan, originally described from a single 8 mm specimen. T. amakusana differs internally in several remarkable features. It bears elongate pouches at the junction of the oral tube and the buccal mass, which are absent in T. kava. The rachidian teeth of T. amakusana are nearly quadrangular and the innermost lateral teeth bear an upper bifid cusp with a wide blunt terminal denticle and a very small inner one, whereas in T. kava the rachidians are rectangular and the innermost laterals bear a deeply bifid upper cusp with two sharp, elongate denticles of similar size. The two species also differ in the number of marginal teeth (five in T. amakusana versus four in T. kava) and in the presence of a small projection between the rachidian and the inner lateral tooth in T. amakusana, which is absent in the new species. Reproductively, T. amakusana has a prostatic portion with a dense network of interconnecting tubules over its surface and lacks a vaginal gland, whereas T. kava lacks a morphologically well-differentiated prostate and bears a well-developed, elongate vaginal gland. Molecular analyses recover T. kava outside the clade containing T. amakusana, Tambja limaciformis and Tambja divae, and place it close to Tambja cf. tenuilineata from Mexico and Tambja brasiliensis Pola, Padula, Gosliner & Cervera, 2014, from Brazil. Specimens previously misidentified as T. amakusana by Gosliner et al. 2008 and online by C. Y. Wong and J. Davies (as Roboastra sp.) may belong to T. kava.