Trapania tatsulok Smirnoff, Donohoo & Gosliner, 2022

MORPHOLOGY

The body coloration is opaque white with dark orange pigmentation on the outer three quarters of the extra-rhinophoral and extra-branchial appendages. There is a gradation of colour such that the basal portion is more yellow orange. The extra-rhinophoral and extra-branchial appendages are somewhat curved and cylindrical with a uniform diameter throughout. The conical, perfoliate rhinophores have five to six lamellae and are dark maroon/brown except for an opaque-white base. The oral tentacles are identical to the rhinophore coloration, with black spanning between the oral tentacles colouring the anterior margin of the head with a semicircle protruding posteriorly at the medial line. The anterior margins of the foot extend laterally as elongate appendages and are more translucent than the rest of the body. This specimen has a distinct black, equilateral triangle on its dorsum centred on the body midline, midway between the gill plume and rhinophores, with its tip pointing anteriorly. There are three other black markings adorning each side of the lateral flanks, starting at the middle of the body and extending to the posterior extension of the foot. There is another black spot situated medially, posterior to the gill plume.

DISTRIBUTION

Known only from Calatagan, the Philippines.

ETYMOLOGY

Tatsulok is the Tagalog word for triangle and it refers to the black equilateral triangle found on the dorsum of this species. It is a noun in apposition.

---

References

• Trapania sp. 17, Terrence Gosliner, Ángel Valdés and David Behrens. (2018). Nudibranch and Sea Slug Identification Indo-Pacific 2nd Edition. New World Pubns Inc.
• Trapania tatsulok sp. nov., Smirnoff D.S., Donohoo S.A. & Gosliner T.M. (2022). Extra-branchial processes manifest extra diversity: systematics of the genus Trapania (Nudibranchia: Goniodorididae) and nine new species descriptions. Zoological Journal of the Linnean Society. 196(1): 270-313. https://doi.org/10.1093/zoolinnean/zlac009
• Paz-Sedano S., Moles J., Smirnoff D., Gosliner T.M. & Pola M. (2024). A combined phylogenetic strategy illuminates the evolution of Goniodorididae nudibranchs (Mollusca, Gastropoda, Heterobranchia). Molecular Phylogenetics and Evolution. 192: 107990. https://doi.org/10.1016/j.ympev.2023.107990