Amphistegina bicirculata Larsen, 1976

Symphonia, Tabita K. & Senthil, Nathan D., 2019, Taxonomic notes on Recent Foraminifera from the Continental Shelf-Slope Region of Southwestern Bay of Bengal, East Coast of India, Palaeontologia Electronica (55 A) 22 (3), pp. 1-89 : 26

Amphistegina bicirculata Larsen, 1976

Figure 7.1-2

1976 Amphistegina bicirculata Larsen , p. 10, pl. 2, figs. 1-5; p. 16, text-figs. 9.2, 10.2.

2002 Amphistegina bicirculata Larsen ; Yordanova and Hohenegger, p. 178, pl. 31, figs. 9-12.

2007 Amphistegina bicirculata Larsen ; Yordanova and Hohenegger, p. 1276, fig. 1.11.

2012 Amphistegina bicirculata Larsen ; Debenay, p. 215.

2014 Amphistegina bicirculata Larsen ; Hohenegger, p. 723, fig. 17.

2014 Amphistegina bicirculata Larsen ; Panchang and Nigam, pl. 32, figs. 9a-b, 10a-b.

Description. Test flat, lenticular, unequally biconvex or slightly spiroconvex, wall calcareous, surface smooth; chambers initially radiate, later nicely curved at the periphery, chamber arrangement low trochospiral, coiling involute; peripheral margin acute, slightly keeled, sutures slightly depressed; aperture interiomarginal, a slit-like opening, surrounded by pustules, bordered by a lip.

Figures

FIGURE 7. 1-2, Amphistegina bicirculata Larsen, 1976 in dorsal view (scale equals 1 mm) (1) and in ventral view (scale equals 1 mm) (2). 3-4, Amphistegina gibbosa d’Orbigny, 1839 in dorsal view (scale equals 500 μm) (3) and in lateral view (scale equals 500 μm) (4). 5, Amphistegina lessonii d’Orbigny in Guerin-Meneville, 1843 in dorsal view (scale equals 400 μm). 6-7, Amphistegina papillosa Said, 1949 in dorsal view (scale equals 500 μm) (6) and in lateral view (scale equals 300 μm) (7). 8-10, Amphistegina radiata (Fichtel and Moll, 1798) in dorsal view (scale equals 500 μm) (8); in ventral view (scale equals 500 μm) (9); and in lateral view (scale equals 500 μm) (10). 11, Astrononion stelligerum (d'Orbigny, 1839) in dorsal view (scale equals 300 μm). 12, Nonion commune (d'Orbigny, 1846) in dorsal view (scale equals 200 μm). 13, Nonion costiferum (Cushman, 1926) in dorsal view (scale equals 200 μm). 14, Nonionella basispinata (Cushman and Moyer, 1930) in dorsal view (scale equals 200 μm). 15, Nonionellina labradorica (Dawson, 1860) in dorsal view (scale equals 200 μm). 16, Nonionoides elongatum (d'Orbigny, 1852) in dorsal view (scale equals 200 μm). 17, Nonionoides grateloupii (d'Orbigny, 1839a) in dorsal view (scale equals 200 μm). 18, Nonionoides turgida (Williamson, 1858) in ventral view (scale equals 100 μm). 19, Nonionoides boueana (d'Orbigny, 1846) in dorsal view (scale equals 200 μm). 20, Haynesina depressula (Walker and Jacob, 1798) in dorsal view (scale equals 100 μm).