Limacina sp. 2

Janssen, Arie, Sessa, Jocelyn & Thomas, Ellen, 2016, Pteropoda (Mollusca, Gastropoda, Thecosomata) from the Paleocene-Eocene Thermal Maximum (United States Atlantic Coastal Plain), Palaeontologia Electronica (Athens, Greece) 19 (3), pp. 1-26 : 15

Limacina sp. 2

Figure 13.1-2

Description. A single specimen (H 0.54, W 0.90 mm) in poor preservation of c. three whorls, resembles juvenile Heliconoides mercinensis , but is relatively higher and has a perfectly rounded whorl shape. It has a slightly raised apical shell part. Its umbilicus is very small, occupying only one tenth of the shell diameter.

Material examined. Cambridge-Dorchester section ( Table 4) (1 specimen, Figure 13.1-2 ; RGM 777 345) .

Discussion. This specimen does not align with any of the known limacinid species, and there is no sign of apertural reinforcements. The species Heliconoides texana (Garvie and Hodgkinson, in Hodgkinson et al., 1992, p. 20, pl. 4, figures 3-6) and Limacina wechesensis Hodgkinson , in Hodgkinson et al., 1992, p. 21, pl. 5, figures 1-7, pl. 6, figures 1- 4) roughly have a similar shape but seem to differ in proportions. Considering the poor condition of our specimen we prefer to only identify it in open nomenclature. More and better-preserved specimens are needed for a final interpretation. Because of its fragility, this specimen was not subjected to CT scanning.

Distribution. Currently only known by the specimen described here.

Figures

FIGURE 13. Limacina sp. 2. 1-2, Cambridge-Dorchester section, sample 26, depth 222.61-222.62 m, RGM 777 345; 1: apical view, 2: apertural view.