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Trapania naeva

Species Profile

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Trapania naeva

Author: Gosliner & Fahey, 2008

Order: Nudibranchia  Family: Goniodorididae

Maximum Size: 5-15 mm (To 50 mm in Japan)

Sightings: Sunshine Coast

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Trapania naeva Gosliner & Fahey, 2008

This species is widespread in the Indo-Pacific region from East Africa across to Fiji and from Japan down to Southern Queensland, Australia but is not common. One of the earliest records is from NW Western Australia in 1998. It has recently (June 2024) been recorded on the Gneering Shoals off the Sunshine Coast, SE Queensland, Australia. The splendid images above, of the find, have been kindly contributed by Harvey Braun.

This nudibranch’s appearance is of elegant simplicity and stark beauty. To quote Dave Behrens: “Probably the easiest of the Trapania’s to ID. Just two color to worry about – black and white. The body is white with large round or oval black spots. The rhinophores, large gill, oral tentacles, extrabranchial and extrarhinophoral appendages are black. That’s about it. 

As with all Trapania the body is elongate, lacking a notal margin, widest at the region of the gill and sharply tapering posteriorly. The non-retractile lamellate rhinophores are unusual for Trapania in possessing a rounded apex that lacks a noticeable extension. The gill is proportionally large and consists of three tripinnate branches.

The body is a semi-translucent white in colour with several large and dark, round to oval spots or blotches. The spots appear to be black or of a very dark brown. Their arrangement is fairly consistent and somewhat symmetrical, with a large spot dorsally on the midline posterior to the gill on the “tail”, a pair posterior to the gill but on the sides of the body, another pair on the sides of the body at the level of the gill, and a third pair on the sides of the body anterior to the gill. This anterior most pair may be replaced by a single large spot midline dorsally anterior to the gill. The total number of spots therefore is most usually from 6 to 7. Variations to this common theme have been recorded.

The rhinophores, extrarhinophoral processes, oral tentacles, gill and extrabranchial process are all black or dark brown. The bases of all these appendages may be translucent white. The entire length of the propodial tentacles (anterior tentacular foot corners) are white.

Trapania are known to feed on the tiny filter-feeding colonial entoprocts. They were long considered spongivores until it was realised they were feeding upon the entoprocts that lived in association with the sponge.

The spawn has been recorded as being laid upon the substrate in a crisscross lace-like pattern.

The etymology of the specific epithet is explained by the authors: “….naeva is from the Latin word meaning ‘mole’ or ‘birthmark’ to describe the large blotches of black pigment on the dorsum of this species.”

It is the Trapania sp. 2 of Nakano, 2004; p. 93, No. 182.

It is the Trapania sp. 5 of Debelius & Kuiter, 2007.

It was the Trapania sp. 1 of the Sea Slug Forum prior to its description in 2008.

David A. Mullins – June 2024

References:
– Nakano, R. (2004). Opisthobranchs of Japan Islands. Rules Inc. Tokyo.

– Debelius, H. & Kuiter, R. H., (2007). Nudibranchs of the World. IKAN-Unterwasserarchiv, Frankfurt.

– Gosliner, T. M. & Fahey, S. H. (2008). Systematics of Trapania (Mollusca: Nudibranchia: Goniodorididae) with descriptions of 16 new species. Systematics and Biodiversity, 6 (1): 53-98.

– Rudman, W. B., (March, 2008) Trapania naeva Gosliner & Fahey, 2008. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/trapnaev and associated messages.

– Gosliner, T. M., Valde ́s, A ́. & Behrens, D. W. (2018). Nudibranch & Sea Slug Identification – Indo-Pacific, 2nd Edition. New World Publications, Jacksonville, Florida, USA.

– Behrens, D. W. (Image Sutton, A.) (2019) Mike Miller’s Slug Site; Week 1113. Available at: http://slugsite.us/bow2007/nudwk1113.htm

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