Pyrgiscus rufescens (Forbes, 1846)

Høisaeter, Tore, 2014, The Pyramidellidae (Gastropoda, Heterobranchia) of Norway and adjacent waters. A taxonomic review, Fauna norvegica 34, pp. 7-78 : 68-69

Pyrgiscus rufescens (Forbes, 1846) Figures 111-113.

Chemnitzia rufescens Forbes, 1846:66

Chemnitzia scalaris (Philippi) (in part) - Clark 1855; Jeffreys 1859; Petersen 1888

Turbonilla scalaris (Philippi) - G.O. Sars 1878

Pyrgiscus scalaris (Philippi) (in part) - Ankel 1936

Odostomia scalaris (Philippi) (in part) - Jeffreys 1848

Odostomia scalaris var. rufescens (Forbes) - Jeffreys 1867, 1870; Friele 1874; Jeffreys 1884; Marshall 1900

Pyrgulina (Pyrgisculus) scalaris var. rufescens (Forbes) - Monterosato 1884

Turbonilla (Dunkeria) scalaris forma rufescens (Forbes) - Nordsieck 1972

Chemnitzia rufescens Forbes - Jeffreys 1847 ; Forbes & Hanley 1850 -51; McAndrew & Barrett 1856; Norman 1879

Parthenina (Pyrgostelis) rufescens (Forbes) - Kobelt 1903

Turbonilla (Pyrgisculus) rufescens (Forbes) - Winckworth 1932

Turbonilla rufescens (Forbes) - McKay & Smith 1979; van Aartsen 1981; Fretter et al. 1986; Graham 1988; Høisaeter 2009

Turbonilla (Pyrgiscus) rufescens (Forbes) - Høisaeter 1986

Turbonilla (Dunkeria) rufescens (Forbes) - Smith & Heppell 1991

Turbonilla interrupta (Totten) - Lovén 1846a, b; Asbjørnsen 1854 (not Turritella interrupta Totten, 1835 )

Type material: Not known.

Type locality: Arran or Oban, western Scotland.

Material seen: Norway - Skagerrak , 32 spms, at least 7 shs ; Hordaland, 12 spms, at least 4 shs; Møre og Romsdal, 1 spm, 8 shs; Nord-Trøndelag, 1 spm, 6 shs; Nordland, 5 spms, at least 9 shs.

Diagnosis: Shell: Pyrgiscus with distinctly cyrtoconoid shell, apical angle 16º or more. Total shell length not exceeding 8.5 mm. Number of whorls 9 or less. Shell semisolid, tawny, semitransparent, with three spiral bands of orange brown as in jeffreysii , but these are darker and all are of more regular occurrence. Lower part of the fairly convex whorls more flattened than the upper part. Shell sculpture slightly prosocline, equidistant axial ribs with numerous spiral grooves in the interspaces. No columellar fold. Prominent heterostrophic protoconch of 1 3/4 whorls, its diameter less than 340 µm and its axis length less than 290 µm, with nucleus inclined to, but not immersed in the teleoconch. Soft parts: Described by Forbes & Hanley (1850 -51): “The specimen is white, slightly tinged with brown. The tentacula are rather long, lanceolate, set well apart, and bearing the eyes nearly centrally at their bases. The mentum is rather narrow and bilobed: the foot is oblong-lanceolate, obtusely angled in front, triangular behind.” I have made a sketch of a specimen from Raunefjorden, W of Fleslandskj., 80- 60 m (Figure 112, bottom). The pigmented mantle organ is long (about ten times as long as broad) and bright yellow in colour. Mentum broad and squarely cut in front, bilobed. Operculum: No ‘tooth’-shaped internal process, at most a narrow, spiral ridge. It is thin and semitransparent of a dark yellowish horncolour, drawn out into a tip at the lower end, and evenly cut at the similarly narrowed upper end. Spire small and terminal at the upper corner (Figure 112).

Biology: Not known. Dredged from ca. 20 to 150 m, but most common from ca. 50 to around 100 m on rather coarse shell gravel bottoms.

Distribution: In Norway P. rufescens is reported from Oslofjorden ( Jeffreys 1870), north to at least 67°15’N. There are a few, scattered records in the old literature. G.O. Sars (1878) reports it from his three southern regions (‘Ora occident., ‘Ora meridion.’, and ‘Sinus Christianensis’) but with no further information. Friele (1874) reports it as rare from two localities just north of Bergen, while Norman (1879) mentions two localities in Korsfjorden and Raunefjorden. In my material 21 specimens and one shell from Skagerrak, 16 specimens and 36 shells from the Espegrend area north to Fugløyfjord (67°01’N, 70- 50 m, stones and shells of Modiolula phaseolina ), and empty shells to 67°15’N. Outside Norway it is reported by Lovén (1846a) from Bohuslän, while Petersen (1888) reported a single empty shell from Kattegatt. There are a few records from British and Irish localities, the most recent ones from north-western areas ( Fretter et al. 1986). On the eastern coast of Scotland it seems to be represented by dead shells only ( McKay & Smith 1979). I have not been able to find any verified records from south of the Irish coast.

Remarks: Concerning the specific distinctness from P. jeffreysii (Forbes) , opinions are divided. Forbes & Hanley (1850 -51) express no doubts as to the specific distinctness of the two forms, while Clark (1855:411, 439) regarded them as two varieties of the same species. This latter conclusion was based on studies of living specimens of what he regarded as the two forms, taken at the same locality. Forbes & Hanley (1853:276) in an appendix to their work did not agree. Jeffreys (1867) and, following him, most later authors adopted the view of Clark, mainly because Clark had found a specimen with the upper whorls like P. jeffreysii , and the lower whorls like P. rufescens . However Monterosato (1884, 1889), Tryon (1886), Kobelt (1903), and later Winckworth (1932) all disagreed with Jeffreys, and readopted the view of Forbes & Hanley (1850 -51), that this is a distinct species. If the illustrations in van Aartsen (1981) and Rolan Mosquero (1983) are representative, the south European P. jeffreysii is very distinct, with its Epitonium -like lamellae. Van Aartsen also seems to accept the specific distinctness of P. rufescen s without question, although Nordsieck (1972), had again subjugated it as a form of P. jeffreysii . According to Fretter et al. (1986), P. jeffreysii is clearly separable from rufescens , having a much more turreted profile to the spire, a relatively broader shell, and more costae per whorl. They do not specifically mention the lamellae-like costae (ribs), which probably is the most reliable character. However, as shown above, the Norwegian forms of P. rufescens are very variable (compare Figure 111 with Figure 113), and both of the drawings presented by Fretter et al. (1986), the one presented as P. rufescens and the one called P. jeffreysii are certainly only two growth varieties of P. rufescens , as was obviously also the opinion of Thorson, who originally gave names to these drawings by Winther. I agree with most recent authors that P. rufescens is specifically different from P. jeffreysii , the last not recorded from Norwegian waters.

Incertae Sedis