Author: (van Hasselt, 1824)

Order: Nudibranchia  Family: Chromodorididae

Maximum Size: 30 mm

Sightings: Whitsundays

________________________________________________________________________

Chromodoris lineolata (van Hasselt, 1824)

The mantle is broadly oval in shape overhanging the foot apart from the tail. The rhinophores are lamellate and can retract into pockets that have slightly raised sheaths. The gill can also retract into a pocket beneath the mantle and is arranged in a circle around the anus. Gill branches depend on specimen size, ranging from 6 to 15 in number. In smaller specimens the gill is simple but larger specimens show bifurcation and will often be fully extended and spreading, not unlike a flower.

The mantle of Chromodoris lineolata is black with numerous thin white longitudinal lines. Many of the lateral lines run completely around the mantle while the medial lines run between the rhinophores stopping at the gill. The very edge of the mantle carries a, just perceivable, extremely thin, white line but most noticeable is the broader yellow to orange band on the margin. Just inside this yellow/orange margin a black band lies adjacent. This arrangement, according to Rudman, will often assist in separating Chromodoris lineolata from Chromodoris striatella, that species having a white band adjacent to the yellow/orange margin. The sides of the body are black with longitudinal white lines. The edge of the foot is mostly white beneath the mantle but yellow/orange posteriorly. Rhinophore stalks are black with white lines while the club changes from black to orange with opaque white spots on the edge of the lamellae. The low sheaths carry a white band to the rim. The colour of the gill branches changes from watery orange to translucent grey with maturity. Regardless of age, they carry opaque white spots. The white lines of the medial notum run up the low gill pocket sheath but there is no white rim as in the rhinophore sheaths.

Chromodoris lineolata feeds upon sponges of the Dysideidae family with some species being identified by Rudman & Bergquist, 2007, as Lamellodysidea herbaria and Dysidea sp. Also Spongia sp. (Rudman, 1999).

Spawn is a spiral ribbon laid flat upon the substrate.

Distribution is from tropical Australia north through Indonesia and the Philippines to Hong Kong and Japan. Many of the specimens in Rudman’s 1982 redescription were sourced from the tropical coast, islands and reefs of Queensland, Australia.

– Originally described as: Doris lineolata. That description by van Hasselt, 1824 was not accompanied by an illustration, however, we are fortunate that, in Engel & Nijssen-Meyer, 1964, van Hasselt’s unpublished illustration is reproduced.
– Chromodoris funerea is a synonym by Collingwood, 1881.
– It may be the Glossodoris lineolata of Allan, 1947, however, the description, the black & white drawing, the confusion at the time between Chromodoris striatella and Chromodoris lineolata and that Chromodoris burni was described much later, together with the Clarence River Heads location, sheds doubt on the identification.
– The Glossodoris lineolata by Baba, 1949 is most likely Chromodoris striatella.
– The Chromodoris lineolata by Thompson, 1972, plate IV (a), is Chromodoris burni that was not described until 1982.
– Rudman, 1982, states that Bergh incorrectly synonymized Chromodoris striatella and Chromodoris lineolata.  This resulted in much subsequent confusion and misidentifications.
– In the classification based upon the molecular sequencing of the chromodorid nudibranchs, Johnson & Gosliner, 2012, Chromodoris lineolata is listed as a hypothesized member of Chromodoris.

David A. Mullins – November 2023

References:
 – van Hasselt, J. C. (1824). Uittreksel uit eenen brief van Dr J.C. van Hasselt, aan Prof van Swinderen. Algemeene Konst- en Letter-Bode. 1824: [2] 20–24.

– Collingwood, C. (1881). On some new species of nudibranchiate Mollusca from the eastern seas. Transactions of the Linnean Society of London, Zoology, series 2. 2(2):123-140, pls. 9-10.

– Allan, J. (1947). Nudibranchia from the Clarence River Heads, north coast, New South Wales. Records of the Australian Museum 21(8): 433–463, plates xli–xliii and map.

– Baba, K. (1949). Opisthobranchia of Sagami Bay. Tokyo: Iwanami Shoten.

– Engel, H. & Nijssen-Meyer, J. (1964). On Glossodoris quadricolor (Ruppell & Leuckart, 1828) (Mollusca, Nudibranchia). Beauforfia.11: 27-32.

– Thompson, T. E. (1972). Chromodorid nudibranchs from eastern Australia (Gastropoda, Opisthobranchia). Journal of Zoology, London. 166: 391-409.

– Rudman, W. B. (1982). The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Chromodoris quadricolor, C. lineolata and Hypselodoris nigrolineata colour groups. Zoological Journal of the Linnean Society. 76: 183-241.

– Willan, R. C. & Coleman, N. (1984). Nudibranchs of Australia, Neville Coleman, AMPI: 24-25.

– Rudman, W. B., (1999, June 19) Chromodoris lineolata (van Hasselt, 1824). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/chroline and associated messages.

– Debelius, H. (2001). Nudibranchs and Sea Snails Indo-Pacific Guide (3rd Edition). IKAN – Unterwasserarchiv.

– Wilson, N. G. (2002). Egg Masses of Chromodorid Nudibranchs (Mollusca: Gastropoda: Opisthobranchia). Malacologia, 2002, 44(2): 289-305.

– Rudman, W. B., Bergquist, P. R. (2007). A review of feeding specificity in the sponge-feeding Chromodorididae (Nudibranchia: Mollusca). Molluscan Research, 27(2): 60-88.

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

– Coleman, N. (2008). Nudibranchs Encyclopedia. Neville Coleman’s Underwater Geographic Pty Ltd, Springwood, Qld.

– Johnson, R. F., Gosliner, T. M. (2012). Traditional taxonomic groupings mask evolutionary history: A molecular phylogeny and new classification of the chromodorid nudibranchs. PLoS One 7 (4): e33479.

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