Phidiana militaris

Phidiana militaris (Alder & Hancock, 1864)

Phidiana militaris @ Hoi Ha Wan Marine Park, Hong Kong (6m) 20°C, 17-04-2016 by Markus Rummel










































Phidiana militaris  (Alder & Hancock, 1864)

 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 404960).

  • Caloria militaris (Alder & Hancock, 1864)
  • Eolis militaris Alder & Hancock, 1864 (original)
  • Hervia dangeri Risbec, 1953
  • Learchis howensis Burn, 1966

With a maximum length of 30mm (Debelius, 2001), it has an elongate pale flesh or white body terminating behind in a slender tappered tail considerably behind the cerata. A bright orange median line on the head forks anteriorly, with a branch running up the frontal edge of each oral tentacle. Another orange line runs along the posterior edge of each oral tentacle and then runs along each side of the body below the cerata. The cerata are long and smooth, swelling a little in the centre and grow in six groups on the sides of the body, the last groups almost meeting on the back. They are colored brown with a longitudinal orange or red line and with yellowish tips having a bluish line and a terminal tip which is white. The oral tentacles are large, stout and tapering, share the color scheme of cerata. Rhinophores and tentacular foot corners are also tipped with yellow and there is a broad orange band on the rhinophores. The anus is located on the right side of the body.

It feeds on hydroids (George, J.D., 2012). Very similar to Phidiana indica, they can be distinguished by the line between the rhinophores: Phidiana indica has a white line, Phidiana militaris has an orange or red line. Opioid ligands such a “phidianidines” have been obtained from this species (Baker, 2016) for a medical use, although it was later found that they could be easily synthethised.


  • Militaris, from Latin, meaning military man, soldier or warrior, probably related to the orange pattern of the body.

Native to the Indo-Pacific. Originally described from India, it has also been reported from the United Arab Emirates, Sri Lanka, Brunei, Malaysia, Thailand, Hong Kong and Northern Australia. A report on the Scirè U-boat shipwreck, in the Haifa bay, northern Israel, in october 2016 is probably the first cite for the Mediterranean Sea, where it is an alien species.

Known georeferenced records of the species: Phidiana militaris
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions


    Western Mediterranean: ☆☆☆☆☆
    Eastern Mediterranean: ★☆☆☆☆
    Atlantic Ocean: ☆☆☆☆☆

This chart displays the monthly observation probability for Phidiana militaris based on our own records.

More pictures


    Alder J, Hancock A. 1864. Notice of a collection of nudibranchiate Mollusca made in India by Walter Elliot Esq. with descriptions of several new genera and species. Transactions of the Zoological Society of London 5 (3-4): 113-147.
    Baker BJ. 2016. Marine Biomedicine: From Beach to Bedside. CRC Press.
    Ballesteros M, Madrenas E, Pontes M. 2024. OPK - Opistobranquis. Available from
    Debelius H. 2001. Asia Pacific reef guide : Malaysia, Indonesia, Palau, Philippines, tropical Japan, China, Vietnam, Thailand. IKAN-Unterwasserarchiv. 321 p.
    Debelius H. 1996. Nudibranchs and Sea Snails: Indo-Pacific Field Guide. IKAN-Unterwasserarchiv, Frankfurt, Germany, 321 pp, 1000+ color illus.
    Debelius H, Kuiter RH. 2007. Nudibranchs of the world. Frankfurt: IKAN- Unterwasserarchiv. 360 pp. p.
    George JD. 2012. Reef-associated macroinvertebrates of the SE Gulf. p. 253-308 In Riegl, B.M.; Purkis, S.J. (eds) 2012. Coral Reefs of the Gulf: adaptation to climatic extremes. Springer Science.
    Gosliner TM. 1979. The systematics of the Aeolidiacea (Nudibranchia: Mollusca) of the Hawaiian Islands, with descriptions of two new species. Pacific Science 33(1): 37-77.
    Powell AWB. 1979. New Zealand Mollusca. Marine, Land and Freshwater Shells. Collins, Auckland, xiv. 500 p.
    Rothman BS, Mienis HK, Galil BS. 2017. Alien facelinid nudibranchs in the Eastern Mediterranean: first report of Phidiana militaris (Alder and Hancock, 1864) and report of Caloria indica (Bergh, 1896) 30 years after its previous sighting. BioInvasions Records, 6 (2): 125-128.
    Rudman WB. 1980. Aeolid opisthobranch molluscs (Glaucidae) from the Indian Ocean and the south-west Pacific. Zoological Journal of the Linnean Society 68: 139-172.
    Rudman W.B. et al. 1998 2010. Phidiana militaris accessed through: Sea Slug Forum on 2014-12-14. Available from
    Sachidhanandam U, Willan RC, Chou LM. 2000. Checklist of the nudibranchs (Opisthobranchia : Nudibranchia) of the South China Sea. Raffles Bulletin of Zoology.:513–537. Available from ://WOS:000167042900014.
    Venkataraman K, Raghunathan C, Sivaperuman C. 2012. Ecology of Faunal Communities on the Andaman and Nicobar Islands. Springer.
    Willan RC. 1987. Description of a new aeolid nudibranch (Mollusca: Opisthobranchia) belonging to the genus Phidiana. N.Z. J. Zool. 14(3):409-417.
    Willan RC, Coleman N. 1984. Nudibranchs of Australasia, 56 pp. Sea Australia Productions Ltd.
    Willan RC, Morton J. 1984. Marine Molluscs, Part 2; Opisthobranchia. University of Auckland, Leigh Marine Laboratory. Auckland, New Zealand: 106 pp.
    WoRMS Editorial Board. 2023. World Register of Marine Species. WoRMS. Available from

    Bibliography based on the works by Steve Long, 2006. Bibliography of Opisthobranchia 1554-2000 and Gary McDonald, 2009. Bibliographia Nudibranchia, with later updates from other resources.

Further reading

Cite this article as:

Pontes, Miquel, Manuel Ballesteros, Enric Madrenas (2023) "Phidiana militaris" in OPK-Opistobranquis. Published: 14/10/2016. Accessed: 28/05/2024. Available at (

To copy this cite click on the right button.

To Markus Rummel (Euphotic Photography) for his pictures of this species.