Figure 7. Typical Trilobatus immaturus and intergradation with Trilobatus quadrilobatus. A–K in Systematic taxonomy of the Trilobatus sacculifer plexus and descendant Globigerinoidesella fistulosa (planktonic foraminifera)

Figure 7. Typical Trilobatus immaturus and intergradation with Trilobatus quadrilobatus. A–K, Trilobatus immaturus (LeRoy, 1939); L–N, Trilobatus quadrilobatus (d'Orbigny, 1846). A–C, I–K, ODP Site 926, Ceara Rise, western tropical Atlantic, 11H/04/ 50–52 cm (A, B, umbilical view; C, detail wall texture and infilled pores; I, spiral view; J, detail of final chamber wall texture; compare with K, detail of penultimate chamber where primary wall texture is obscured by thick gametogenic calcite); D–H, GLOW-3, south-west Indian Ocean (D, detail of wall texture and imperforate lip on first supplementary aperture; E, H, umbilical view; F, G, spiral view). L–N, GLOW-3, south-west Indian Ocean (L, spiral view; M, umbilical view; N, detail of wall texture including clear spine holes). Scale bars = 100 Lm, except for close-up images C, D, J, K, N, where scale bars = 20 Lm.