Odostomiinae Pelseneer, 1928

Høisaeter, Tore, 2014, The Pyramidellidae (Gastropoda, Heterobranchia) of Norway and adjacent waters. A taxonomic review, Fauna norvegica 34, pp. 7-78 : 13-14

Subfamily Odostomiinae Pelseneer, 1928

Pyramidellids with comparatively short, more or less conical or pupoid shells with (at most) a single columellar ‘tooth’ and protoconch either exposed (type A) or more or less concealed (type B and C) in first teleoconch whorl.

Based on a few easily observed shell characters, the northeast Atlantic species have been classified as belonging to either Odostomia (without macroscopic sculpture), Chrysallida (with mainly axial sculpture) or Menestho (with only spiral sculpture). These three genus names were used by Winckworth (1932) and adopted by Høisaeter (1986). The three genera were subdivided into subgenera, however. Chrysallida was divided into Partulida and Parthenina , Menestho into Evalea and Liostomia , and Odostomia into Odostomia s.s. and Brachystomia . These subgenera have all been elevated to full generic rank by later authors (e.g. Fretter et al. 1986), although Evalea and Partulida have since been changed to Ondina and Spiralinella respectively. Fretter et al. (1986) also removed Jordaniella from Odostomia and re-established it as an independent genus. Van Aartsen (1977, 1987) disagreed and re-established Chrysallida , Odostomia and Ondina as the only European odostomine genera. Warén (1991), used Chrysallida , Ondina and, as did Fretter et al. (1986), found Liostomia , sufficiently distinct to separate it from Odostomia (he did not include Odostomia s.l. in his revision). Smith & Heppell (1991) accepted the generic taxonomy of Fretter et al. (1986). Schander (1995) in his revision of the pyramidellids of the Faroes, used van Aartsen’s (1987) taxonomy as a basis for his small sample, but accepted Brachystomia as a genus, not a subgroup of Odostomia . Høisaeter (2009) adopted the current use of names in CLEMAM, and used Chrysallida , Odostomia , Ondina and Liostomia , but mentioned briefly also the rare Rissopsetia and Aartsenia .

In this review, I include the following Norwegian ‘genera’ in this subfamily (but see Discussion on p. 125):

Odostomia - Shells smooth or with microscopic striation, protoconch angle usually 90° (exceptionally 110° to 135°), operculum with notch and internal process; no tentacular pads.

Brachystomia - Shells with at most microscopic sculpture, protoconch more or less intorted, operculum without notch or internal process; tentacles with tentacular pads.

(‘Brachystomia’ lukisi ) - Shell smooth and polished, protoconch intorted and extremly flat, no tentacular pads.

(‘Odostomia’ conoidea ) - Shell smooth and polished, protoconch angle 110° and partly submerged, sometimes with inside of outer lip with several spiral ridges, columellar tooth prominent.

Ondina - Thin-shelled forms with opisthocline growth lines, intorted protoconch, with or without fine spiral sculpture.

Liostomia - Small, smooth, almost cylindrical shells lacking a columellar tooth.

Jordaniella - Shell small, almost cylindrical with indistinct spiral sculpture. Blunt apex.

Parthenina - Shell sculptured with axial ribs and a limited number of spiral lirae on lower part of each whorl, protoconch intorted, tentacles with tentacular pads. At least some species with spermatophores.

Spiralinella - Shell sculptured with axial ribs, spiral cords limited to the base of body whorl, protoconch intorted, tentacles with tentacular pads.

(‘Chrysallida’ eximia ) - Shell small, with prominent axial, prosocline ribs and three spiral cords. Whorls convex with deep suture. (Three species in Norway. ‘ C.’ bjoernssoni , ‘ C.’ brattstroemi and ‘ C.’ hoeisaeteri are probably closely related to ‘ C’ eximia ).

(‘ Chrysallida’ sublustris ) - Shell sculptured with wavy axial ‘ribs’, no spiral sculpture.

Rissopsetia - Shell cylindrical, small, high and solid. Protoconch inflated

Aartsenia - Large shell with dominating body whorl, smooth and glossy shell.

Of these, Parthenina , Spiralinella , Chrysallida s.l., Brachystomia , Ondina and Liostomia , based on protoconch morphology (intorted), general colouration of pigmented mantle organ, type of operculum and the presence of tentacular pads (missing in all other genera in the Norwegian fauna) belong in a separate clade, corresponding to the informal group, Liostomini in Schander et al. (2003). Lack of observations of living specimens of Jordaniella , Rissopsetia and Aartsenia prevents placement of these groups. Based on molecular data (mitochondrial 16S partial gene), Jordaniella should, however, belong in the same clade as Liostomia ( Schander et al. 2003) .

In the list above, four groups are singled out as belonging to so far unnamed genera. I refrain from naming these, as the possibility of further confusing the already chaotic generic taxonomy of the family is too great.

To facilitate the practical work of identifying members of this ‘difficult’ subfamily, keys are given for the genera, and also for the species within each of the species-rich genera.

Key to the genera of Odostomiinae , based on shell morphology

1a. Shell smooth or with fine spiral sculpture ......................2

1b. Shell with prominent axial sculpture ...............................6

2a. Protoconch angle usually around 90° (Type A)

(exceptionally 110° to 135°) ............................. Odostomia 2b. Protoconch more or less intorted (type B and C) ...........3

3a. Protoconch intorted, completely flat, 180° (type C), shell smooth and polished (porcellaneous)

................... (‘Brachystomia’ lukisi ) 3b. Protoconch intorted, around 150°-170° (type B) .............4

4a. Shell delicate, thin, with fine spiral sculpture or completely smooth, opisthocline growth lines, elongated aperture.................................................. Ondina

4b. Shell different....................................................................5

5a. Shell solid, no sculpture............................... Brachystomia

5b. Small, smooth, almost cylindrical shells, lacking a columellar fold ................................................... Liostomia

5c. Shell cylindrical, with a few or many indistinct (low and wide) spiral ridges .................................... Jordaniella

5d. Shell with very weak axial ribs or growth lines, protoconch inflated ......................................... Rissopsetia

6a. Shell with wavy, poorly defined, axial ribs, no

spiral sculpture. Protoconch inflated ............... (‘ Chrysallida’ sublustris )

6b. Shell with clearly defined axial ribs, from three to

many spiral cords .............................................................7

7a. Spiral cords restricted to base, below axial ribs ..................................... Spiralinella

7b. Two to several spiral cords on lower parts of

whorls, usually seen only in interspaces between

the axial ribs .................................................... Parthenina

7c. Three spiral cords crossing prosocline axial ribs

below periphery of each whorl ‘ Chrysallida’ eximia (and ‘relatives’)