Ondina de Folin, 1870

Høisaeter, Tore, 2014, The Pyramidellidae (Gastropoda, Heterobranchia) of Norway and adjacent waters. A taxonomic review, Fauna norvegica 34, pp. 7-78 : 42-43

Ondina de Folin, 1870

Type species, by subsequent designation: Ondina semiornata de Folin, 1872 [= Ondina warreni ( Thompson, 1845) ]; designated by van Aartsen (1984:134). Atlantic coast of France.

Synonyms: Auriculina J.E. Gray, 1847 not Grateloup, 1838. Evalea auct., not A. Adams, 1860.

Menestho Møller, 1842 (in part).

Pyramidellids with small (<5.5 mm long), oblong-ovate to rather conical shells, of not more than six whorls. Sculpture none, or fine to moderately strong spiral lirations. Body whorl rather long and dominating. Growth lines opisthocline. Aperture mostly oblong, regularly rounded below, and acute-angled above. Columellar tooth may be absent, if present it is retracted and inconspicuous. Protoconch medium-sized to small, intorted so that usually only its base is visible. Operculum without an ‘anchor’ or indentation, of a more or less regular outline and with a distinct though small excentric spire. Eyes very close together.

Ondina is here used for the group of European pyramidellids which is named Evalea A. Adams, 1860 in e.g. Fretter et al. 1986 and Graham 1988. Originally this group was named Auriculina Gray, 1847 , with Odostomia obliqua Alder, 1844 as type species. This name was, however, preoccupied by Auriculina Grateloup, 1838 . Thiele (1929) in splitting the large and heterogeneous “genus” Odostomia (sensu Dall & Bartsch, 1904) into smaller units, chose Menestho Møller, 1842 as the oldest of the sections of Dall & Bartsch with only spiral sculpture. This name was accepted by Winckworth (1932) (with Evalea as a subgenus) and, following him, Høisaeter (1986). The type species of Menestho is Turbo albulus Fabricius, 1780 , an arctic species with a heavy shell and strong spiral sculpture. I agree with van Aartsen (1984, 1987), Smith & Heppell (1991) and Warén (1991) that this species has little in common with the thin-shelled, oval species from Europe. According to van Aartsen (1987), Evalea , based on Odostomia (Evalea) elegans A. Adams, 1860 , is neither a suitable genus for this group of European species. The type species is described from Japan, it has a distinct, if small, columellar tooth, and has rather distinct spiral grooves. Kobelt (1903) was apparently the first to use Ondina for this group of European pyramidellids, although he excluded the smooth ones. I follow van Aartsen (1987) in adopting Ondina de Folin, 1870 , with Ondina semiornata de Folin, 1872 as type species, for the European species formerly included in Auriculina J.E. Gray, 1847 .

The European members of Ondina have been revised by van Aartsen (1987), and the Scandinavian ones by Warén (1991). Warén included five species in the Scandinavian fauna. He did not mention the record of Jeffreys (1870) of O. warreni from Oslofjorden, however, and he disagreed with van Aartsen’s opinion of O. perezi as a taxon specifically distinct from O. diaphana . By accepting both of these as species found in Norwegian waters, the number of species was increased to seven in Høisaeter (2009). A final complication not adressed by neither Warén nor Høisaeter (2009) is the taxonomic status of G.O. Sars’ (1878) variety, nobilis of O. divisa .

As will be evident from the discussion below the variability of the recognized species within this group is large, and the number of shell characters is limited, so correct delimitation of species based solely on shell characters is rather contentious. The species recognized from northeast Atlantic waters do either have smooth shells, or are variously decorated with incised spirals on part of, or the whole of the whorls. The density and distribution of these spirals is usually accepted as the main distinguishing character for the different species, but the variability of this character is high. The species described as being smooth sometimes have weak spirals, while the spirally striated ones are said to have smooth varieties (e.g. Marshall 1900). The species in the ‘smooth’ group are O. diaphana , O. perezi , O. obliqua and O. normani . Those in the group with spiral sculpture are O. divisa , O. coarctata and O. warreni . Species with spirally incised shells from Norwegian waters may be divided, based on the records we have so far, into northern forms ( O. coarctata and O. divisa forma nobilis) and southern forms ( O. warreni ), with O. divisa being the only species common to both the northern and southern region.

The key below is, due to the extreme variability in members of this group, especially preliminary, and should be followed up with close scrutiny of photographs and diagnoses.

Key to the species of Ondina , based on shell morphology

1a. Shell with sculpture of spiral lines ...................................2

1b. Shell smooth .....................................................................5

2a. Spirals confined to lower part of the whorls ...................3

2b. Spirals covering more or less the whole shell .................4

3a. Shell not exceeding 3.5 mm, yellowish colour

................................. Ondina divisa 3b. Shell narrow conical with somewhat flattened whorls, reddish colour, from the North Sea

................. Ondina divisa cf. rubra 3c. Shell not exceeding 4.6 mm, broadly conical, yellowish colour, northern form

.......... Ondina divisa forma nobilis

4a. Shell with fine spirals covering the whole shell, northern species .................................... Ondina coarctata

4b. Shell with coarse spirals on lower half of the whorls, and very dense, fine spirals above, southern species ...................................................... Ondina warreni

5a. Protoconch planorboid almost disjunct, body whorl

dominating ............................................... Ondina obliqua 5b. Protoconch intorted, type B ............................................6

6a. Convex whorls, rather deep suture ......... Ondina normani 6b. Flattish whorls, shallow suture ........................................7

7a. Shell narrow, shiny, no umbilicus ........ Ondina diaphana 7b. Shell like O. diaphana , but flatter whorls with dull

surface ........................................................ Ondina perezi