Hallaxa cryptica Gosliner & S. Johnson, 1994
- Location
- HIsui Beach, Etchumiyazaki, Toyama, Japan
- Date
- 2020/05/28
- Length
- 30mm
- Depth
- 8.0m
- Water temperature
- 17.0℃
Description
Body length 7-25 mm, round in outline. Two colour forms occur: a creamy yellowish-white form and, less commonly, a light purple-brown form. Both forms have scattered opaque white spots that appear as low tubercles, not strongly elevated from the notum. The white form may also bear light tan streaks and spots running perpendicular to the notal margin.The rhinophores and gill are the same colour as, or slightly darker than, the body. In purple specimens the rhinophore apex is white. The gill consists of 8-11 unipinnate leaflets; the rhinophores are bulbous with 5-9 lamellae. The foot is concavely curved anteriorly with broad, anteriorly directed corners. A small pit is present on either side of the mouth and head.
Distribution
Marshall Islands and Philippine Islands.Etymology
The specific epithet cryptica refers to the cryptic coloration of this species on its sponge prey.Remarks
Like other Hallaxa, this species likely feeds on sponges.Whitish-bodied Hallaxa cryptica resembles Hallaxa translucens and Hallaxa paulinae, but is distinguished by its large opaque white spots (vs reticulate networks). Reproductive characters place it close to Hallaxa indecora, Hallaxa hileenae and Hallaxa michaeli.
References
A Kindle field guide by the site author
Kimoto N. (2026). Sea Slugs of Japan & the Indo-Pacific, 2nd Edition.
Kindle Edition
View on Amazon PR (Amazon Associates)Seasonality
Shooting Locations
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Photos of Hallaxa cryptica
Same Genus Nudibranchs
Similar Colors Nudibranchs
Academic Database
Sea slug observation data is available in international marine biodiversity databases.