Odostomia acuta Jeffreys, 1848

Høisaeter, Tore, 2014, The Pyramidellidae (Gastropoda, Heterobranchia) of Norway and adjacent waters. A taxonomic review, Fauna norvegica 34, pp. 7-78 : 31-34

Odostomia acuta Jeffreys, 1848

Figures 38 -42

Odostomia acuta - Jeffreys, 1848:338

Odostomia acuta Jeffreys - Forbes & Hanley 1850 -51; Jeffreys 1859, 1867, 1870; M. Sars 1870; Friele 1874; G.O. Sars 1878; Collin 1880, 1884; Jeffreys 1884; Petersen 1888; Marshall 1899; Friele & Grieg 1901; Dautzenberg & Fischer 1912; Winckworth 1932; Spärck & Thorson 1933; Warén 1980; van Aartsen & al. 1984; Høisaeter 1986; van Aartsen 1987; Høisaeter 1989; Smith & Heppell 1991; Peñas et al. 1996; Schander et al. 2003; Høisaeter 2009

Chemnitzia acuta Jeffreys (in part) - Clark 1855

Ptychostomon acutum (Jeffreys) - Kobelt 1903

Odontostomia (Nisostomia) acuta (Jeffreys) - Dautzenberg & Fischer 1925

Type material: Twenty-one syntypes, no locality, USNM 753712

Type locality: Not designated, presumably British Isles ( Warén 1980)

Material seen: Norway - Skagerrak , 53 spms ; Hordaland, 104 spms; Møre og Romsdal 20 spms; Nord-Trøndelag, 3 spms; Nordland, 13 spms; Troms 3 shs.

Diagnosis: Shell: Large conical shells. Body whorl large and round. Aperture oval. Distinct umbilicus. Columellar tooth fairly prominent. Protoconch large with completely exposed nucleus. Soft parts: Foot wide. Parallel-sided tentacles with blunt tips (Figures 40 and 41), no tentacular pads. Mentum with upturned edges forming a gutter. Pigmented mantle organ (Figure 41) of varying length, alternatively dark brown and yellow segments in a linear row, elongated light yellow gland (?) further behind. Head-foot region (Figure 40) with characteristic purplish-brown colour pattern. Operculum: With very strong opercular ‘anchor’ (Figure 42).

Biology: According to Fretter et al. (1986) probably feeding on bryozoans. Found in large numbers on the gelatinous tubes of the polychaete Myxicola infundibulum ( Høisaeter 1989) . Most likely also associated with other tube building polychaetes.

Distribution: Reported from all along the coast, with the exception of east Finnmark (G.O. Sars 1878). In my material competing with O. turrita and O. unidentata in being the commonest species of Odostomia (s.s.). The northernmost shells recorded from a station in Andfjorden, east of Andøya (69°17’N, 65-80 m, coarse shell gravel). Otherwise, fairly evenly distributed along the coast. Two samples from Hordaland with respectively 58 and 29 specimens, and a sample in the material from Skagerrak with 21 specimens. Otherwise only one to six specimens in each sample. Outside Norway it is known from the Swedish west coast and Kattegatt and the northern part of the Sound. All along the western coasts of the British Isles and Ireland, scattered also on the the North Sea coast of Britain (probably absent from the southern parts of the North Sea) ( Fretter et al. 1986). Not known from Iceland or the Faroes ( Schander 1995). Found along the Atlantic coasts of France and Spain and into the western Mediterranean (van Aartsen et al. 1984, Peñas et al. 1996). Van Aartsen et al. (1998) extend the distribution to Mauritania, Cape Verde Islands, the Canary Islands, and Madeira.

Remarks: Specimens inspected alive are easy to identify, but long dead shells are hard to distinguish from O. unidentata . O. acuta is included in the 16S-analysis of Schander et al. (2003), who concluded that its inclusion in Odostomia (represented by O. turrita and a few species not found in the Norwegian fauna, but not the type species, O. plicata ) is “problematic, as it alternately clusters with ‘ Megastomia’ (i.e. ‘ Odostomia’ conoidea and ‘ O.’ corimbensis ), or is basal to other Odostomia species ”. Morphologically O. acuta is most definitely closer to e.g. O. turrita (and especially to O. unidentatata ) than to O. conoidea , and the table of pairwise differences in Schander et al. (2003) support this relationship, as the character difference between O. acuta and ‘ O.’ conoidea is more than twice the species. I find that the differences between the two shells difference between O. acuta and O. turrita . O. acuta is among figured in van Aartsen (1987) are striking, and in the material the most common pyramidellids along the Norwegian coast, I have seen they seem to be rather constant. Schander (1995) especially as empty shells. presents a photograph of what he calls O. acuta from the Koster

area in western Sweden (centre in Figure 44). This has all the

attributes of Jeffreys’ concept of O. umbilicaris , but Schander Odostomia umbilicaris ( Malm, 1861) does not comment further on the relationship between O. acuta Figure 43-44 and O. umbilicaris . Both Jeffreys (1867) and Marshall (1899b)

describe the distinction between these two species: “This Turbonilla (Odontostomia) umbilicaris Malm , n.sp. – Malm, species [ O. acuta ] may be distinguished from O. umbilicaris by 1861:623 its greater solidity, the periphery being always keeled, the spire Odostomia umbilicaris (Malm) - Jeffreys 1867; Friele 1874; much longer, and the whorls compressed instead of convex” G.O. Sars 1878; Marshall 1899; Winckworth 1932; Høisaeter ( Jeffreys 1867:132).”It [ O. umbilicaris ] is most like a stumpy 1986; Fretter et al. 1986; Graham 1988 O. acuta , but the latter is more solid and conical, the whorls Odostomia acuta var. umbilicaris (Malm) - Smith & Heppell less tumid and the last whorl smaller proportionally.” (Marshall 1991 1899b:231). Fretter et al. (1986) regard O. umbilicaris to be Ptychostomon umbilicare (Malm) - Kobelt 1903 the most easily identified of the British species of Odostomia ,

based on just those characters van Aartsen mentions. Fretter et Type material: Göteborg (?) al. do discuss an additional character, however, not mentioned Type locality: Löken, Western Sweden (?) by van Aartsen (1987), in spite of this character being regarded Material seen: Norway - Skagerrak, 4 spms (tentative as the most important for distinguishing between a number of identification). closely similar pyramidellids, viz. the inclination of the growth Diagnosis: Shell: Cyrtoconoid moderately sized shell. lines. This inclination is shown by Fretter et al. (1986) to be Convex whorls and deep suture. Large umbilicus. Partly from 8 to 10 degrees for O. acuta , and from 24 to 33 degrees submerged protoconch. Prominent columellar tooth. Soft parts: for O. umbilicaris . If these measurements are representative Not known. Operculum: Not known. and correct, there is no possibility that the two are conspecific. Biology: Not known, but reported by ( Malm 1861) together Until living specimens are available for analyses, I regard it as with Modiolus adriaticus on the Swedish west coast. prudent to regard the two as distinct and keep them apart in Distribution: According to Friele (1874) not rare at one of fauna lists. his localities, Biskopshavn, (in Bergen) 55- 75 m. Not recorded by Norman (1879) and a record in G.O. Sars (1878) is only a repetition of the one in Friele (1874). (The two shells depicted ‘Odostomia’ conoidea ( Brocchi, 1814) in Figure 44 are from Friele’s locality, Biskopshavn, and Figures 45 -48 identified by him). This record of Friele seems to be the only one from Norwegian waters (Malm’s record from 150 fathoms, Turbo conoideus Brocchi, 1814:659 ; pl. 16, Figure 2 Eggers Bank is intractable). In my material, four specimens Odostomia conoidea (Brocchi) - Forbes & Hanley 1850 - from the Skagerrak region, and probably several others listed 51; Jeffreys 1867, 1870; G.O. Sars 1878; Norman 1879; as O. acuta (following van Aartsen 1987, see Remarks below). Collin 1880; Jeffreys 1884; Petersen 1888; Marshall 1899; Outside Norway it is recorded from the Swedish west coast, the Winckworth 1932; Høisaeter 1986; Peñas et al. 1996; northern and western coasts of the British Isles and south west Høisaeter 2009; Öztürk et al. 2013 Ireland ( Jeffreys 1867, Marshall 1899b, Fretter et al. 1986). In all Odostomia (Megastomia) conoidea (Brocchi) - van Aartsen newer literature regarded as a synonym of O. acuta , following 1987 van Aartsen (1987). Megastomia conoidea (Brocchi) - Smith & Heppell 1991; Remarks: Authorship is usually attributed to ‘Malm, Schander et al. 2003 1863’, but the species was briefly described already in Malm Chemnitzia conoidea (Brocchi) - Clark 1855:422 (1861). Van Aartsen (1987) expressed as his opinion that the O. Ptychostomon conoideum (Brocchi) - Kobelt 1903 umbilicaris described and figured by Jeffreys (1867) (at left in Odontostomia conoidea (Brocchi) - Dautzenberg & Fischer Figure 43), is a form of O. acuta . He ‘supports’ this opinion by 1925 showing photographs of Jeffreys’ ‘type’ of O. umbilicaris and Odostomia polita (Bivona, 1832) - van Aartsen 1987 a shell of O. acuta from his own collection. He states that “… Turbonilla plicata (Montagu) - Lovén 1846a, b not O. plicata these shells (to) differ only in its more shiny surface and its ( Montagu, 1803) more convex whorls.” He could not compare his O. acuta with Malm’s unavailable type of O. umbilicaris however, so that Type material: In Museo civico di storia naturale di there might still be doubts as to the identity of the two nominal Milano ( Pinna & Spezia 1978:162, pl. 53, Figure 4). Type locality: Tertiary fossil from Toscana, Italy.

Material seen: Norway - Skagerrak , 30 spms, 7 shs ; Hordaland, 14 spms, 3 shs; Møre og Romsdal, 11 spms, at least 9 shs; Nord-Trøndelag, 3 spms, 4 shs; Nordland, 10 spms.

Diagnosis: Shell: ( Figure 45 ) to 5 mm, milky white, almost opaque; very smooth and polished, with a glossy surface. Usually with a narrow spiral incision around the periphery of the body whorl ( Figure 45 right). Protoconch (Figure 46) partly submerged in first postlarval whorl. Umbilicus usually a narrow chink, but in large specimens a deep hollow. Tooth strong and prominent. Often, but not always, with spiral ridges on inside of outer lip. Soft parts: Mentum deeply cleft and diverging. Eyes small and close together. The front of the foot strongly ciliated (Figure 47 left). Pigmented mantle organ (hard to see clearly through the shell) elongated, almost linear, reddish yellow, with numerous small, yellow-white spots in a row above the gland (Figure 47 right). Operculum: (Figure 48) of same type as O. acuta (underside not studied).

Biology: Usually found at intermediate depths, from 50-60 to 200 m. According to Fretter et al. (1986) usually in association with the starfish Astropecten irregularis . “Food. Presumably the starfish”. This needs verification, as echinoderms are not among the usual hosts for pyramidellids.

Distribution: In Norway reported from the southern and western coast by G.O. Sars (1878) and from the Bergen area by Norman (1879). In my material thirteen samples from Skagerrak, 29 specimens and an additional 54 shells, more or less evenly distributed north to Bindalsfjorden (c. 65°N). Further north nine specimens from around Bodø. A large (5.0 mm) specimen in Saltfjorden (67°10’N, 170- 90 m, Modiolula phaseolina bottom). Outside Norway it is known from the Swedish west coast, the west and south coasts of the British Isles and Ireland and further south along the Atlantic coasts of France and Spain and the Mediterranean ( Fretter et al. 1986, Peñas et al. 1996, Öztürk et al. 2013). Apparently very common in the Mediterranean, and by Öztürk et al. listed as the most abundant Odostomia distributed along the Turkish coast. By van Aartsen et al. (1998) stated to be abundant also along the coast of Mauritania and the Canary Islands.

Remarks: Best identified by the combination of the partly submerged protoconch (nucleus partly hidden by first postlarval whorl) and the spiral incision around the periphery of each whorl, in addition to the solid, glossy shell. Sufficiently different from Odostomia plicata to be placed in another genus. This is supported by the molecular analysis of Schander et al. (2003). In this analysis O. conoidea is (following van Aartsen) placed in the (sub)genus Megastomia at the outset, a decision they find to be supported by their molecular data. There is however no convincing reason to put it in the nominal genus Megastomia , which is based on Odostomia conspicua which, in my opinion is a typical Odostomia s.s. and has few traits in common with O. conoidea . According to Schander et al., O. corimbensis Schander, 1993 is another member of this genus. Yet another is O. polita (Bivona, 1832) described from Palermo, Sicily, but listed as a synonym of O. conoidea by van Aartsen (1987). A final possible congener is O. harveyi van Aartsen & Smith, 1996 from the upper slope in the northeast Atlantic, a species lacking a columellar tooth. The spiral ridges (or list like ‘teeth’) on the inside of the outer lip have been noted as an important character, and even of generic significance (distinguishing Megastomia from Odostomia s.s., see van Aartsen 1987). This character is very unreliable, however, as many shells are completely smooth inside the outer lip.

Figures

Figure 2. Head-foot complex of (from top and left to right) Odostomia turrita, ‘Brachystomia’ lukisi, and Ondina divisa.

Figure 38. Odostomia acuta. Two specimens from Grimseidpollen, W of Pålsholmen, 60°16’N, 5°16’E 20-23 m, 2.4 and 1.45 mm (ZMBN 82595). Figure 39. Odostomia acuta, protoconch of specimen from the same locality as in Figure 36, three orientations Figure 40. Odostomia acuta. A specimen from Bukkasundet, Raunefjorden, 60°14.2 N, 05°12.3’E, 15 m, 3.8 mm. Figure 41. Odostomia acuta, head-foot complex and pigmented mantle organ (not to scale). Figure 42. Odostomia acuta, operculum, two views. Scale bar = 400 µm. Figure 43. Odostomia umbilicaris. Two illustrations from the literature. From van Aartsen (1987) at left and Fretter et al. (1986) at right. The shell at left is Jeffreys’ ‘type’, USNM 132020, the one at right is a shell from the Hebrides. Figure 44. Odostomia umbilicaris. A specimen from the Swedish west coast (Schander 1995, as O. acuta) between two specimens from Biskopshavn, Bergen, 60°25.4’N, 05°17.6’E, 50-60 m, (ZMBN 35030), both 2.95 mm, coll, and det. Friele.

Figure 45. Odostomia conoidea. At left two specimens from Lamholmen W of Gjerdingen (Nord-Trøndelag), 64°57.5’N, 11°25’E, 80-30 m, 4.65 and 2.85 mm (T 69077). At right a shell from Håøya, Grimstad (Aust-Agder), 58°18’N, 8°36.5’E, 60 m (G 115-71). Figure 46. Odostomia conoidea. Three protoconchs. Figure 47. Odostomia conoidea, head-foot complex and pigmented mantle organ (not to scale). Figure 48. Odostomia conoidea. Operculum, two illustrations. Photo from operculum in situ within aperture (left) and copied from G.O. Sars (1878) (right). Figure 49. Odostomia conspicua. A specimen from SE of Portør, Telemark, 58°47’N, 09°29’E, 60 m (S 17-88) (left) and one from between Store and Lille Torungen, Aust-Agder, 58°24’N, 08°47.5’E, 70 m (S 66-88), 4.6 and 2.5 mm respectively. Figure 50. Odostomia conspicua, protoconch of the specimen from between Store and Lille Torungen. (Cf. Figure 55). Figure 51. Odostomia plicata. Three illustrations from the literature. From left: a SEM-photo of a specimen 1.7 mm long from van Aartsen et al. (1984), one (size not given) from Fretter et al. (1986), and a LM photo of a specimen 2.4 mm long from van Aartsen (1987).