Parthenina indistincta ( Montagu, 1808 )

Høisaeter, Tore, 2014, The Pyramidellidae (Gastropoda, Heterobranchia) of Norway and adjacent waters. A taxonomic review, Fauna norvegica 34, pp. 7-78 : 15-16

Parthenina indistincta ( Montagu, 1808)

Figure 5

Turbo indistinctus Montagu, 1808:129

Parthenia indistincta (Montagu) - Thompson 1844; Collin 1884; Petersen 1888

Chemnitzia indistincta (Montagu) - Alder 1848; Forbes & Hanley 1850 -51; Clark 1855; M. Sars 1870; Friele 1874; Jeffreys 1884; Marshall 1900

Odostomia indistincta (Montagu) - Jeffreys 1867

Turbonilla indistincta (Montagu) - G.O. Sars 1878

Turbonilla (Chemnitzia) indistincta (Montagu) - Malm 1861

Parthenina indistincta (Montagu) - Kobelt 1903

Chrysallida indistincta (Montagu) - van Aartsen 1977; Fretter et al. 1986; Graham 1988; Smith & Heppell 1991; Warén 1991; van der Linden & Eikenboom 1992; Micali et al. 1993; Peñas et al. 1996; Høisaeter 2009

Chrysallida (Parthenina) indistincta (Montagu) - Winckworth 1932; Høisaeter 1986; van Aartsen et al. 2000

Type material: Not found ( Warén 1991)

Type locality: “ Found in the Boysian cabinet”. Probably the coast of Kent (fide Parker & Jones 1860:335)

Material seen: Norway - Skagerrak , 2 spms ; Hordaland, several shs; Møre og Romsdal several shs; Nord-Trøndelag, several shs; Nordland, 2 spms and several shs.

Diagnosis: Shell: Fairly long (max. length 3.7 mm), narrow, almost cylindrical shells, superficially Turbonilla -like, with

slightly convex whorls, and with 11 or 12 (visible) flexuous axial ribs crossed by four to seven spiral cords on the body whorl. Very weak columellar fold, not visible within aperture. Protoconch small, intorted. Soft parts: The colour of preserved specimens as seen through the shell is reddish orange, and the eyes are very small and close together. Operculum: Not studied.

Biology: Not known.

Distribution: Reported as rare from the Bergen area by Friele (1874) (not refound by Norman 1879 in the same area), from Oslofjorden by G.O. Sars (1878) (also reported by M. Sars 1865, and Brøgger 1872, but not recorded by Jeffreys 1870), while Warén (1991) only records two specimens (Bergen) and one shell (Raunefjorden) as Norwegian material. In my material two specimens and three shells from Skagerrak, two specimens and an additional 18 shells (or fragments) of which two specimens and 16 shells from between 65°30’N and 67°05’N. Except for the two specimens, beautifully preserved, from outer Vefsnfjorden (65°53’N, 12°32’E, 12-15 m, Desmarestia and Lithothamnion and other red algae) the shells are often worn, with much of the spiral sculpture hard to see. As shells are easily confused with C. interstincta , the identifications of the 10 samples included can not all be trusted. The material from Vefsnfjorden and two shells from Sjonafjorden, just south of Sila (66°17’N, 160- 80 m, gravel) are perhaps the most reliable. The material from Sjonafjorden is also the northernmost record of this species so far. Outside Norway it is reported as common in the Koster area in the Swedish part of Skagerrak ( Warén 1991). Further south the species is distributed along the Atlantic coasts of Europe, from the North Sea to Portugal and the Canary Islands, and all around the Mediterranean (van der Linden & Eikenboom 1992).

Remarks: One of several pyramidellids whose identity is not supported by type material. According to Forbes & Hanley (1853:255) ‘The identity of this shell with the T. indistinctus of Montagu is rather traditional than positive, since the language of the “Testacea Britannica” does not precisely correspond with the characteristics of the present species.’ However the interpretation of the species has been stable, at least since the time of Jeffreys (1867). Empty shells might be mistaken for P. interstincta , but is most easily distinguished by the lack of a columellar tooth.

Figures

Figure 5. Parthenina indistincta. Two specimens from Vefsnfjorden 65°53’N, 12°32’E, 12-15 m, (ZMBN 82368) 3.5 and 3.15 mm. The specimen at left is a SEM photo of the second one from left Figure 6. Parthenina interstincta. Bukkasundet, Raunefjorden, 60°14’N, 5°12.5’E, 20-4 m, 2.0 mm (ZMBN 82305). Figure 7.Parthenina interstincta.From left: Vikkilen, Grimstad, 58°20.1’N, 8°36.3’E, 35 m, 2.2 mm; Bukkasundet, Raunefjorden, 60°14’N, 5°12.5’E, 20-4 m, 2.0 mm (ZMBN 82305); and Hjertøysund, Bodø, 67°17’N, 14°19.5’E, 30 m, 2.15 mm. Figure 8. Parthenina interstincta, postlarva. Scale bar = 300 µm. Figure 9. Parthenina interstincta, head-foot complex and pigmented mantle organ (not to scale). Figure 10. Parthenina interstincta, operculum, two views. Figure 11. Parthenina interstincta, body whorl and aperture with spermatophore attached (from Høisaeter 1965). Figure 12. Parthenina sarsi. Syntype (left) and specimen from Swedish west coast. Both from Warén (1991).