Raphitoma purpurea ( Montagu, 1803 )

Raphitoma purpurea ( Montagu, 1803) View in CoL

Figures 18 View Figure 18 - 20

Murex purpureus Montagu, 1803:260 , Tab. 9, f. 2 Defrancia purpurea ( Montagu, 1803) View in CoL - Jeffreys 1867; Friele 1874; Norman 1879

Defrancia purpurea var. oblonga Jeffreys 1867:374 View in CoL (?) Clathurella purpurea, Mont. - G.O. Sars 1878

Philbertia purpurea ( Montagu, 1803) View in CoL - Monterosato 1884; Hubendick & Warén 1976; Høisaeter 1986

Raphitoma purpurea ( Montagu, 1803) View in CoL - Rolán 1983; Fretter & Graham 1985; Graham 1988; Sabelli et al. 1990; Smith & Heppell 1991; Heppell et al. 1997; Cachia et al. 2001; Høisaeter 2009

Type material. Lectotype and two paralectotypes, designated by Rolán et al. (1998), BMNH 1995089. (Figure 20C). Holotype of Defrancia purpurea var. oblonga, USNM 190029 ( Warén 1980, Pusateri et al. 2012) (Figure 20B).

Type locality. Salcombe Bay , Devon, England .

Material examined. Six empty shells from: Hjartøysundet, Bodø, 67°17.5’N, 75- 64 m ; W of Svinøy , 64°55’N, 11°22’E, 175- 20 m GoogleMaps , shell sand; Lamholmen north of Gjerdingen, 64°57.30’ N, 11°25’E, 80- 30 m GoogleMaps ; Outer part of Foldafjorden 64°40.20’ N, 11°07.30’E, 60- 20 m GoogleMaps ; Near Lillesand , 58°15’N, 08°26’E, 8 m GoogleMaps , and a shell from Bergen ( ZMBN 28685 View Materials ) .

Description. (Based mainly on an, immature, specimen from Hjartøysundet, Figure 18 View Figure 18 , with additional details from Fretter & Graham 1985). Shell long and narrow (height from 2.26 to 2.35 times the diameter), with up to 12 whorls at 20 mm height. No shells longer than c. 12 mm so far found in Norwegian waters. Shell colour impossible to ascertain from my empty shells, but stated to be brownish to purplish with scattered whitish specs and ribs (see shell from Bretagne, Figure 20A). Sculpture of numerous axial ribs and almost equally strong spiral cords. ‘Valleys’ between spiral cords only slightly wider than the cords. Five to six fully developed spiral cords on penultimate whorl, but with secondary, narrower cords between the uppermost primary spirals. Body whorl 65 to 66 % of total height. Siphonal canal short and wide. Sculpture on siphonal canal of thickened spirals sectioned into numerous nodules by the axial ribs. Outer lip thickened and (usually) with eleven coarse denticles on the inside. Fairly deep and narrow anal sinus. Protoconch (only conserved in the specimen from Hjartøysundet, Figure 18 View Figure 18 ) short and narrow, with three whorls and apical angle 40° to 45°. Protoconch W/L: 0.97. The protoconch is smaller than in any of the other species found in Norwegian waters. Microsculpture hard to tell from old, worn shells, but appear to consist of rather coarse granulation ( Figure 18 View Figure 18 ).

Variability. The six shells seen (Figure 19) have a fairly constant morphology. The denticulation inside the thickened outer lip is present only in mature shells, as is the secondary spiral cords on body whorl.

Distribution. In older Norwegian literature reported as rare around Bergen (M. Sars according to Jeffreys 1867, Friele 1874, Norman 1879, Hubendick & Warén 1976), and from Kristiansund (Danielssen according to Jeffreys 1867). In my material three empty (old) shells from 65°N, and one fresh shell from around 67°N, in addition to a single shell from the Skagerrak coast. Also reported from Bohuslän in Sweden (Malm according to Jeffreys 1867). Around the British Isles, it occurs everywhere except on the North Sea coast. Most common in the southern part, but also found occasionally around Shetland ( Seaward 1990). Elsewhere found from the Atlantic coast of France and southwards to the Strait of Gibraltar. According to Cachia et al. (2001) also in the Mediterranean at least as far east as Malta, although Monterosato (1884) and van Aartsen et al. (1984) claim that it does not occur in the Mediterranean. Not included in newer check-lists of Mollusca from the Mediterranean.

Remarks. Characterized by thickened outer lip with heavy denticulation, short and narrow protoconch and very prominent tubercles where axial ribs are crossed by spiral costae. The species is reported to reach 23 mm in length ( Rolán 1983), so the shells in my material are small, although the heavy teeth on the inner lip on all but one of the shells seen, indicate that they are mature. Jeffreys (1867:374) described a ‘variety’, Defrancia purpurea var. oblonga from the Channel Islands (Figure 20B above) which is distributed along the southern and western coast of the British Isles as well as the Atlantic coast of France. The ‘variety’ is accepted as a valid species, Raphitoma oblonga ( Jeffreys, 1867) by Pusateri et al. 2012. Compared with the sympatric form of R. purpurea (Figure 20A) it is less solid and turreted and with significantly more ribs and cords. According to Jeffreys (1867:374) the colour and other characteristics of the soft parts are different for the two species. R. oblonga has not been recorded from Norwegian waters.