Limacina sp. 1

Cotton, Laura J., Janssen, Arie W., Pearson, Paul N. & Driel, Rens van, 2017, Pteropoda (Mollusca, Gastropoda, Thecosomata) from the Eocene / Oligocene boundary interval of three cored boreholes in southern coastal Tanzania and their response to the global cooling event, Palaeontologia Electronica 20 (3), pp. 1-21 : 13

Limacina sp. 1

Figure 11.1-2

Material examined. Five specimens, all from the same sample TDP 17.37.1, 0-13 cm; 106.90- 107.03 m below surface, 118.90-119.03 composite depth; RGM 777440 a-c ( Table 3) .

Description. Low conical limacinid of 3.75 moderately convex whorls attaching on periphery of foregoing whorls. Aperture semicircular, slightly more than half shell height, Base regularly rounded, umbilicus c. 1/6th of shell diameter.

Discussion. Three of the available specimens are juveniles in poor preservation. In specimen RGM 777440b ( Figure 11.2 ) the first whorl is missing. The two more adult specimens show a striking resemblance with a limacinid illustrated by Lokno and Kumar (2008, figure 3-2) from the Upper Disang Formation (Bartonian - Priabonian) of the Phek District, south-central Nagaland (Assam - Arakan Basin), northeastern India, indicated by these authors as “ Limacinidae type A.” As these specimens were recorded from Indian Ocean Basin rocks of more or less similar age they could very well represent the same species as the Tanzanian ones. However, the material is insufficient for a reliable identification. Lokno and Kumar compared their specimens with “ Limacina pygmaea , ” as illustrated by Hodgkinson et al. (1992, pl. 3, figures 14-15), correctly stating that that name “most certainly is incorrect,” as Hodgkinson et al.’s species seems to be closely related to L. gormani ( Curry, 1982) (see above) and not to Limacina pygmaea .

Figures

FIGURE 11. Limacina sp. 1. 1: RGM 777440c; apical view; 2: RGM 777440b; apertural view. Bar equals 100 μm.