Nudi Notes

THE STORY BEHIND A NAME

Dec 14, 2023

THE STORY BEHIND A NAME

Chromodoris elisabethina

Definitive information about the taxonomic history of Chromodoris elisabethina together with some attractive (dare I say pretty) and some not so attractive pictures, but nevertheless informative.

A story of misspelling, incomplete descriptions and wrong assumptions based on insufficient material, creating a tangled web of almost incomprehensible complexity that is finally unravelled through good detective work and access to and direct examination of live subjects.

Above: A pair of Chromodoris elisabethina

 

Chromodoris elisabethina is sighted quite commonly on the offshore reefs of the Sunshine Coast, Queensland, Australia. It is one of the black-lined species of the Chromodorididae family of cryptobranch nudibranchs. It has had an interesting but tortured taxonomic history. For such a well-known, attractive and a  species with a much-displayed image, its early taxonomy was a tangled mess. Take the time to be informed about the labyrinthine taxonomy and not just dwell on the pretty pictures. Let’s follow the trail.

– The name Chromodoris elisabethina first appears in a list of Chromodoris species published by the famous taxonomist Rudolph Bergh in 1875 as: Chr. elisabethina. Bgh. n. sp. (translated as: Chromodoris elisabethina. Bergh. nova species.). Bergh did not include an illustration or a description of his new species. Although this was the first use of that name, without an accompanying description it is considered a nomen nudum (naked name) meaning the name has no status and therefore neither does the publishing date of 1875 in relation to priority.

Above: The first publication of the name Chromodoris elisabethina in a list by Bergh, 1875 but not accompanied by a description or illustration. [Bergh, L. S. R. (1875). Neue Nacktschnecken der Sudsee. III. Journal de Museum Godeffroy, 3(8): Page 73. “Image from the Biodiversity Heritage Library. Contributed by Smithsonian Libraries. www.biodiversitylibrary.org”]

– In 1877 Bergh published a description of Chromodoris elisabethina so the date of species authorship is correctly taken as 1877. That description was based upon a preserved specimen (lacking any colour other than the black lines) and apparently no live colour notes were supplied by the collector. So Bergh just used a black and white line drawing and no colour description in his text. The same situation exists for another new species he described in the same paper – Chromodoris annae. In their black and white form these images do, in some manner, make a reasonable attempt at representing the visual external differences between these two species. The C. annae drawing shows a short black line running between the rhinophores and stippling, at least on the posterior portion of the mantle, that could represent the well-known mantle punctations of this species. The C. elisabethina drawing has a pinching in and thickening mid-length of the black line that loops around the mantle and a continuous line from anterior to the rhinophores back to the gill pocket. From here though, the real confusion reigns, mostly created by Bergh himself.

Above: The black and white drawings in Bergh’s 1877 paper. Plate 51 Figs 6 & 21. Upper: Chromodoris elisabethina Lower: Chromodoris annae                                                                                     [Bergh, L. S. R. (1877). Malacologische Untersuchungen. In: C.G. Semper, Reisen im Archipel der Philippinen, Wissenschaftliche Resultate, 11: Plate 51. “Image from the Biodiversity Heritage Library. Contributed by Smithsonian Libraries. www.biodiversitylibrary.org”]

– In 1904 Eliot used the incorrect spelling of Chromodoris elizabethina (with a z) instead of Chromodoris elisabethina (with an s). This error in spelling was promulgated for many years by several authors (Willan & Coleman, 1984 and Debelius & Kuiter, 2007 for example). Eliot also created additional confusion as he considered what became known as Chromodoris africana Eliot, 1904, that he had called Chromodoris elizabethina var. africana, to be identical to Bergh’s C. elisabethina, although a variety thereof. 

Above: The illustration in Eliot’s 1904 paper labelled Chromodoris elizabethina Var. africana. Plate 24 Fig 4. [Eliot, C. N. E. (1904). On some nudibranchs from East Africa and Zanzibar. Part 1V. Proceedings of the Zoological Society of London, 1904: Vol. 1 Plate 24. “Image from the Biodiversity Heritage Library. Contributed by Smithsonian Libraries. www.biodiversitylibrary.org”]

– In 1905 Bergh published a re-description of Chromodoris quadricolor (Ruppell & Leuckart, 1830). The reference to its image is Plate 2 Fig. 7, but that image is actually labelled as Chromodoris elisabethina (and has the appearance of what we now call Chromodoris lochi Rudman, 1982). In the same paper on Plate 4 there is a Fig. 3 labelled Chromodoris elisabethina var. (Chr. annae) and a Fig. 4 labelled Chromodoris annae. There is no illustration labelled C. quadricolor but in the text Bergh synonymises C. annae and C. elisabethina var. under C. quadricolor. He also synonymises C. annae and C. elisabethina. Confused yet?

Above: An illustration from Bergh’s 1905 paper Plate 2 Fig. 7. Bergh refers to this illustration as Chromodoris quadricolor in the text but labels it Chromodoris elisabethina. It is later revealed not to be either but rather an entirely new species by Rudman, 1982 who names it Chromodoris lochi.  [Bergh, L. S. R. (1905). Die Opisthobranchiata der Siboga Expedition. Siboga Expeditie Report, 50: Plate 2. “Image from the Biodiversity Heritage Library. Contributed by Smithsonian Libraries. www.biodiversitylibrary.org”]

Above: Two further illustrations from Bergh’s 1905 paper Plate 4 Figs 3 & 4. Upper: Captioned Chromodoris annae Lower: Captioned Chromodoris elisabethina var. (Chr. annae). In the text Bergh synonymises these two under Chromodoris quadricolor.  [Bergh, L. S. R. (1905). Die Opisthobranchiata der Siboga Expedition. Siboga Expeditie Report, 50: Plate 4. “Image from the Biodiversity Heritage Library. Contributed by Smithsonian Libraries. www.biodiversitylibrary.org”]

– In 1977 Bill Rudman, in one of his notable papers on the chromodorids, is misled by Bergh and uses specimens from Fiji that match Bergh’s 1905 Plate 2 Fig. 7 labelled Chromodoris elisabethina (but as we will see later these are actually Chromodoris lochi). Rudman’s colour description is based on colour photographs and transparencies, but interestingly, no colour images are reproduced in his paper. Rudman, at the time, also keeps C. annae as a junior synonym of C. elisabethina.

– In 1982 Rudman revisits this group and in finally having access to sufficient living material recognises the earlier mistakes made from preserved material and corrects the record. He describes as Chromodoris lochi, (a new species), the species he misidentified as Chromodoris elisabethina in 1977. Chromodoris elisabethina is redescribed and matched with Bergh’s 1877 Chromodoris elisabethina. Until this point no colour description of C. elisabethina had ever been published. Rudman also resurrects Chromodoris annae  as a good species, matched with Bergh’s 1877 C. annae. Clarity at last.

Modern taxonomists spend an inordinate amount of time assessing past descriptions (review of the literature), more than they probably spend upon examining their new species. The constraints placed upon them by previous good taxonomy is immense let alone the frustration of bad taxonomy.

So, enjoy the pretty pictures, but don’t ignore the often fascinating story behind them.

David A. Mullins – December 2023

References:
– Bergh, L. S. R. (1875). Neue Nacktschnecken der Sudsee. III. Journal de Museum Godeffroy, 3(8): 53-100, [185-232], Pls.7-11.

– Bergh, L. S. R. (1877). Malacologische Untersuchungen. In: C.G. Semper, Reisen im Archipel der Philippinen, Wissenschaftliche Resultate, 11: 429-494, Pls.49-57.

– Eliot, C. N. E. (1904). On some nudibranchs from East Africa and Zanzibar. Part 1V. Proceedings of the Zoological Society of London, 1904: Vol. 1, 380-406.

– Bergh, L. S. R. (1905). Die Opisthobranchiata der Siboga Expedition. Siboga Expeditie Report, 50: 1-248.

– Rudman, W . B. (1977). Chromodorid opisthobranch Mollusca from East Africa and the tropical West Pacific. Zoological Journal of the Linnean Society. 61: 351-397.

– 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.

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