Neomonoceratina columbiformis Kingma, 1948

Fig. 6J

Neomonoceratina columbiformis – Kingma 1948: 95, pl. 10 fig. 8a–f.

Neomonoceratina columbiformis – Keij 1979: 61, pl. 1 figs 1–4, pl. 2 figs 5–6. — Zhao & Whatley 1988: 565, pl. 1 fig. 1.

non Neomonoceratina columbiformis – Keij 1979: 166, pl. 1 fig. 11.

Dimensions

L = 0.440 millimeters, H = 0.240 millimeters, H/L = 0.55.

Distribution

Modern distribution: Malacca Strait (Zhao & Whatley 1988); Jakarta Bay, Indonesia (Fauzielly et al. 2013); Klong Thom, Krabi, Andaman estuary, Thailand (Yamada et al. 2014).

Fossil distribution: Pliocene, Sumatra (Kingma 1948; Keij 1979); Bangkok Clay (sample 20SS04A), whale excavation site, Samut Sakhon Province, Thailand, Late Holocene (this work).

Remark

Neomonoceratina columbiformis Kingma, 1948 is very rare in our material but it can be recognized by its non-ornamented carapace with curved posterodorsal rib and oblique median rib.