Difference between revisions of "Stylocheilus longicauda"

Latest revision as of 16:03, 22 May 2012

Taxonavigation

Familia: Aplysiidae
Genus: Stylocheilus

Name

Stylocheilus longicauda (Quoy & Gaimard, 1824) – Wikispecies link – Pensoft Profile

• Aplysia longicauda Quoy & Gaimard, 1824: 421, pl 66 Fig. 8 (New Guinea); Rang 1828: 73, pl. 22 figs 8 - 10 (Quoy & Gaimard specimen, on “fucus”).
• Aplysia citrina Rang, 1828: 71, pl. 22 figs. 1, 2 (Atlantic Ocean on Sargassum).
• Aplysia nudata Rang, 1828: 72, pl. 22 figs. 3-5 (Sandwich Islands on “fucus”).
• Aplysia striata Quoy & Gaimard, 1832: 315 (New Guinea).
• Stylocheilus longicauda. – Bebbington 1974^[1]: 87, figs. 7G, 14, 15 (Kenya and Zanzibar); Gosliner 1987^[2]: 49, fig. 30 (South Africa); Yonow and Hayward 1991^[3]: 5, fig. 3E (Mauritius); Yonow 2008^[4]: 104 (Red Sea).
• Stylocheilus striatus. – Yonow 2008^[4]: 108 (Red Sea); Apte 2009^[5]: 167, fig. 1k (Laccadive Islands); Richmond 2011^[6]: 278 (East Africa).

Material

Maldives: 6 mm in length pres., 2 m depth on algal-covered stone, Kuredu, Lhaviyani Atoll, 10-24 March 1998, leg. J Hinterkircher; three specimens collected of many, 50-70 mm live lengths (28-32 mm preserved), on algae growing on floating grouper cage near surface, Kiadhu Tila, Felidhoo Atoll, 23 July 1994, leg. RC Anderson (striations still visible on preserved specimens). – Zanzibar: numerous specimens 10-50 mm pres. lengths, Mazzini, intertidal and low water forming chains on sand and rocks in sea grass beds, 09 September 1993, leg. MD Richmond (numerous villi, very long rhinophores and oral tentacles). – Mauritius, La Réunion, Mayotte, and Madagascar: photographs of numerous individuals http://seaslugs.free.fr/nudibranche/a_intro.htm. – Oman: Muscat, 01-12 April 2009, photos of several individuals, S Kahlbrock.

Description/Distribution

Benthic form of this circumglobal species distinguished by fine longitudinal brown-to-black lines usually interrupted by ‘eyespots’ with bright blue centres; tail long, swelling present in middle of body where parapodial lobes enclose large gill and anal siphon; rhinophores and oral tentacles long and slender. Specimens in any given population may have few or numerous villi, and this variation is still visible in the preserved material. It can be locally common in sea grass beds and shallow water, especially during the breeding season, but this does not happen every year (P Bidgrain, pers. comm. and http://seaslugs.free.fr/nudibranche/a_intro.htm).

Remarks

There is probably only one species of Stylocheilus occurring in two forms, the benthic striated form described and illustrated here, which was known as striatus, and the yellow pelagic form associated with seaweeds currently known as longicauda.
This may be an appropriate location to discuss the problems posed by the aplysiids distributed in the Indo-West Pacific: all species covered in this work are complex and appear to comprise colour forms identified as separate species, as well as having different habitat preferences. Aplysia parvula occurs consistently in at least two forms, the larger pale-coloured shallow water one associated with algae and the tiny black reef form although other colour forms are recorded (http://seaslugs.free.fr/nudibranche/a_intro.htm and http://www.nudipixel.net/species/aplysia_parvula/). It is noted that the radulae and shells were similar, with slight differences. Dolabrifera dolabrifera has been described under many names but has long been recognised as a single species. Many species of Dolabella have been described but were historically resolved to two species, with different external and (possibly) internal morphologies and shells; these are synonymised as one species in this work. The history of Stylocheilus is also complicated, with two very different forms inhabiting very different environments. Clearly the aplysiids are in need of revision, entailing comparison of specimens from different regions and habitats as well as a very thorough review of the literature; it is probable that the numerous species names currently listed will dissolve into fewer, variable species.

Taxon Treatment

• Yonow, N; 2012: Opisthobranchs from the western Indian Ocean, with descriptions of two new species and ten new records (Mollusca, Gastropoda) ZooKeys, 197: 1-130. doi

Other References

1. ↑ Bebbington A (1974) Aplysiid species from East Africa with notes on the Indian Ocean Aplysiomorpha (Gastropoda: Opisthobranchia). Zoological Journal Linnean Society 54: 63-99. doi: 10.1111/j.1096-3642.1974.tb00793.x
2. ↑ Gosliner T (1987) Nudibranchs of Southern Africa. A guide to Opisthobranch molluscs of Southern Africa. EJ Brill, Leiden, Netherlands, 136 pp.
3. ↑ Yonow N, Hayward P (1991) Opisthobranches de l’lle Maurice, avec la description de deux espèces nouvelles (Mollusca: Opisthobranchia). Revue française d’aquariologie herpétologie 18 (1): 1-30.
4. ↑ ^{4.0 4.1} Yonow N (2008) Sea Slugs of the Red Sea. Pensoft Publishers, Sofia-Moscow, 304 pp.
5. ↑ Apte D (2009) Opisthobranch fauna of Lakshadweep Islands, India, with 52 new records to Lakshadweep and 40 new records to India: part 1. Journal Bombay Natural History Society 106 (2): 162-175.
6. ↑ Richmond M (2011) A Field Guide to the Seashores of Eastern Africa and the Western Indian Ocean Islands, 3rd edition. Sida/SAREC-UDSM, Sweden, 464 pp.

Images

Plate 13. Stylocheilus longicauda form striata, 10–50 mm pres., Zanzibar, photo: MD Richmond.