Colobocephalus costellatus M. Sars 1870

• Main Authors: Ohnheiser, Lena Tina, Malaquias, Manuel António E.
• Format: Text
• Language: unknown
• Published: Zenodo 2014
• Subjects: Biodiversity; Taxonomy; Animalia; Mollusca; Gastropoda; Cephalaspidea; Diaphanidae; Colobocephalus; Colobocephalus costellatus; Bergen; Christiania; Norway; Sneli; Arktis*
• Online Access: https://dx.doi.org/10.5281/zenodo.6128212; https://zenodo.org/record/6128212

Colobocephalus costellatus M. Sars, 1870 (Fig. 9 A–G) Colobocephalus costellatus M. Sars 1870: 54 –57, tab. 11 figs 7–14. Odhner 1939: 8 –10, fig. 1. Høisaeter 1986: 100. Høisaeter et al . 2001: 249. Høisaeter 2009: 78. Diagnosis. Shell internal, transparent, wavy growth lines and thin spiral ridges. Body whitish translucent. Foot anteriorly lobed, cephalic shield with short stumpy tentacular lobes. Type locality. Drøbak, Oslofjorden, Norway. Material examined. Aurlandsfjorden, Hordaland, Norway, 1 spc (dissected), ZMBN 91084, H = 2.1 mm. Marstein, Bergen, 60 °08’08’’ N, 005°00’00’’ E, Norway, 1 spc, ZMBN 82283, H = 1.4 mm. Shell (Fig. 9 D–F): Maximum H = 2.1 mm. Internal (see Remarks), thin; transparent; globose in shape, aperture wide with thin parietal callus covering umbilicus partly, spire elevated but apex obtuse; shell surface costellate with faint wavy growth lines and thin elevated spiral ridges. Animal (Fig. 9 A–C): Body whitish transparent, eyes visible, foot anteriorly indented with groove, cephalic shield lobed with short stumpy tentacles formed by the rolled up shield, larval kidney visible. Radula : 2.1. 0.1. 2 (G. O. Sars 1878, tab. 12, fig. 16). Rachidian tooth absent. Inner lateral teeth curved with broad base, inner edge smooth. Outer lateral teeth with broad base, curved, smooth. Male reproductive system (Fig. 9 G): Short unbranched prostate emerging from short tubular penial sheath. Ecology. On shell sand, sand and pebbles between 55–336 m (G. O. Sars, 1878; Høisaeter 2009; present study). Distribution. Aurlandsfjorden (present study), Kopervik (59 ° 15 ’ N), Oslofjorden, Korsfjorden south of Bergen (Brown 1979; Høisaeter 2009). Remarks. M. Sars (1870) described Colobocephalus costellatus to have an external shell. Odhner (1939) observed that the mantle of smaller specimens in fact do not completely cover the shell, but in adults the shell is totally enclosed by the mantle. The specimens studied here had the shells slightly exposed but this was due to damage of the mantle edges. The mantle is very thin and easily torn apart. Several authors (e.g. Odhner 1939; Høisaeter 2009; Høisaeter et al . 2001) considered Colobocephalus costellatus and Colpodaspis pusilla distinct species, while others (e.g. Brown 1979; Thompson 1988) list them as synonyms because of anatomical similarities. The latter authors considered the different shape of the head and mantle to be either due to young age or damage, but Odhner (1939) showed that C. costellatus has distinct and consistent features. The shell in C. costellatus is sculptured with a globose spire, while C. pusilla has an almost smooth shell with a keeled angulated shoulder. Furthermore C. pusilla possesses a siphon formed by the mantle (not present in Colobocephalus ) and unlike Colobocephalus can retreat into its shell completely. : Published as part of Ohnheiser, Lena Tina & Malaquias, Manuel António E., 2014, The family Diaphanidae (Gastropoda: Heterobranchia: Cephalaspidea) in Europe, with a redescription of the enigmatic species C olobocephalus costellatus M. Sars, 1870, pp. 501-522 in Zootaxa 3774 (6) on page 512, DOI: 10.11646/zootaxa.3774.6.1, http://zenodo.org/record/227215 : {"references": ["Sars, M. (1870) Bidrag til Kundskab om Christianiafjordens fauna. II. Nyt Magazin for Naturvidenkaberne, 172 - 225.", "Odhner, N. H. (1939) Opisthobranchiate Mollusca from the western and northern coasts of Norway. Kongelige Norske Videnskabers Selskabs Skrifter, 1939, 1 - 92.", "Hoisaeter, T. (1986) An annotated check-list of marine molluscs of the Norwegian coast and adjacent waters. Sarsia, 71, 73 - 145.", "Hoisaeter, T., Sneli, J-A. & Brattegard, T. (2001) Subclass Heterobranchia (phylum Mollusca) non-prosobranch gastropods, includes shelled opisthobranchs and sea slugs (N: bakgjellesnegler). In: Brattegard, T. & Holthe, T. (Eds.), Distribution of marine, benthic macroorganisms in Norway. A tabulated catalogue, Oppdatering av utredning for DN 1997 - 1. Research report for DN- 2001 - 3, Directorate for Nature Management. Directorate for Nature Management, Trondheim, pp. 248 - 261.", "Hoisaeter, T. (2009) Distribution of marine, benthic, shell bearing gastropods along the Norwegian coast. Fauna Norvegica, 28, 5 - 106.", "Sars, G. O. (1878) Bidrag til kundskaben om Norges arktiske fauna: 1. Mollusca regionis Arcticae Norvegiae. Oversigt over de i Norges arktiske region forekommende bloddyr. Brogger, A. W., Christiania, 466 pp.", "Brown, G. H. (1979) An investigation of the anatomy of Colpodaspis pusilla (Mollusca: Opisthobranchia) and a description of a new species of Colpodaspis from Tanzanian coastal waters. Journal of Zoology, 187, 201 - 221. http: // dx. doi. org / 10.1111 / j. 1469 - 7998.1979. tb 03944. x", "Thompson, T. E. (1988) Molluscs: Benthic Opisthobranchs (Mollusca: Gastropoda). Linnean Society, Synopses of the British Fauna (new series) No. 8. (Second Edition). Brill, E. J. & Dr Backhuys, W., Leiden, New York, Copenhagen, Cologne, 356 pp."]}