Heterostegina d’Orbigny 1826

Mamo, Briony L., 2016, Benthic Foraminifera from the Capricorn Group, Great Barrier Reef, Australia, Zootaxa 4215 (1), pp. 1-123 : 109-110

Heterostegina d’Orbigny 1826

Heterostegina depressa d’Orbigny 1826 ( Fig. 25 :16, 17)

1826 Heterostegina depressa d’Orbigny , p. 305, pl. 17, figs 5–7.

1965 Heterostegina sp.; Jell et al., p. 273, pl. 44, fig. 8.

1984 Heterostegina depressa d’Orbigny ; Hallock, p. 251, fig. 1: 9.

1991 Heterostegina depressa d’Orbigny ; Van Marle, p. 195, pl. 21, fig. 4.

1992a Heterostegina depressa d’Orbigny ; Hatta & Ujiié, p. 204, pl. 50, fig. 4. 1993 Heterostegina depressa d’Orbigny ; Hottinger et al., p. 157, pl. 228, figs 1–11; pl. 229, figs 1–8, pl. 230, fig. 9. 1994 Heterostegina depressa d’Orbigny ; Loeblich & Tappan, p. 171, pl. 389, figs 1–6; pl. 390, figs 1–3. 1999 Heterostegina depressa d’Orbigny ; Harney et al., p. 64, fig. 1.

1999 Heterostegina depressa d’Orbigny ; Hohenegger et al., p. 157, fig. 30.

2002 Heterostegina depressa d’Orbigny ; Yordanova & Hohenegger, p. 201, pl. 34, figs 7–11. 2004 Heterostegina depressa d’Orbigny ; Saraswati et al., p. 340, pl. 1, fig. 6. 2009 Heterostegina depressa d’Orbigny ; Parker, p. 625, fig. 443a–j.

2012 Heterostegina depressa d’Orbigny ; Debeny, p. 222, pl. 20.

Description. See Hohenegger et al. (1999, p. 157, fig. 30); Hottinger et al. (1993, p. 157, pl. 228, figs 1–11; pl. 229, figs 1–8, pl. 230, fig. 9); Van Marle (1991, p. 195, pl. 21, fig. 4) and Yordanova & Hohenegger (2002, p. 201, pl. 34, figs 7–11).

Remarks. Heterostegina depressa d’Orbigny 1826 has a large, smooth, lamellar, planispiral, compressed and involute test. The chambers become semi-involute and flat as the test grows and the chamberlets are divided by imperforate, slightly raised sutures. Interiosutural areas are finely perforate and the aperture is an arched slit at the base of the apertural face ( Fig. 25 :16, 17).

Röttger & Hallock (1982) and Van Marle (1991) noted that H. depressa displays strong variation in size and the arrangement of the honeycomb-like rectangular chamberlets that develop across the flattened, outermost part of the test. Inspection of specimens collected by Brady (1884) during the Challenger expedition on legs 172 and 219A show this variation and an affinity with CG specimens. Specimens from leg 172, collected off Tongatobu Friendly Islands from a depth of 33 m (British NHM reg. no. ZF1575) appeared almost identical to those collected from the CG. Yet specimens from leg 219A collected from the Admiralty Islands at a depth of 31 m (British NHM reg. no. ZF1576) had some specimens identical to CG specimens and others with differing size and breadth in chamber arrangement. Some specimens from Admiralty Island possessed broad, square-shaped chambers, whilst the chamber arrangement of other specimens was so narrow and compressed that the chambers appeared as tightlypacked rectangles.

Initial descriptions reported H. depressa as a key tropical to subtropical species that increased in size with increasing water depth and inhabited warm, clear, quiet marine waters in carbonate-rich sediments with limiting factors including light intensity and energy levels ( Röttger 1976; Hottinger 1977; Hallock 1984; Crouch & Poag 1987). Heterostegina depressa has a global distribution and is abundant throughout the Indo-Pacific region (Heron Island—Jell et al. 1965; Hawaiian and Western Caroline Islands—Röttger & Hallock 1982, Hallock 1984, Harney 1999; Ryukyu Island Arc—Van Marle 1991, Hatta & Ujiié 1992a, Hohenegger et al., 1999, Yordanova & Hohenegger 2002, Saraswati et al. 2004; Gulf of Aqaba—Hottinger et al. 1993; Timor Sea—Loeblich & Tappan 1994; Ningaloo Reef—Parker 2009; New Caledonia between 15–50 m—Debenay 2012).

Distribution within study area. Across the CG there is a distinct preference by H. depressa for comparatively deeper water environments (~ 35 m depth) with forty of the fifty collected specimens from the channel sample between Heron and Wistari Reefs. This distribution pattern conforms with the known distribution of H. depressa in terms of depth ( Loeblich & Tappan 1994) and quiet energy regimes within the photic zone ( Van Marle 1991).

Figures

FIGURE 25. (Unless otherwise specified all scale bars = 100 µm). 1 – 4. Elphidium advenum (Cushman, 1922). 1 – 2. QM # G 465779 from ST / HW 2 lateral (1) and peripheral (2) views. 3 – 4. QM # G 465897 from ST / HW 10 lateral (3) and peripheral (4) views. 5 – 8. Elphidium craticulatum (Fichtel & Moll, 1798). 5 – 6. QM # G 465797 from T 2 – 3 lateral (5) and peripheral (6) views. Scale bar = 200 µm. 7 – 8. QM # G 465997 from T 1 – 10, lateral (7) and close-up (8) view. Scale bar for 7 = 200 µm. 9 – 10. Elphidium macellum (Fichtel & Moll, 1798). 9. QM # G 466018 from OTI 20, lateral view. 10. MU 61803 from T 1 – 10, alternate lateral view. 11 – 13. Elphidium maorium Hayward, 1997, from WL 15. 11. QM # G 465926, lateral view. 12 – 13. QM # G 465927 lateral (12) and peripheral (13) views. 14 – 15. Elphidium miletti (Heron-Allen & Earland, 1915), QM # G 465943 from OTI 34. 14. Lateral view. 15. Peripheral view. 16 – 17. Heterostegina depressa d’Orbigny, 1826. Scale bars = 500 µm. 16. QM # G 466134 from ST / HW 10, lateral view. 17. QM # G 465869 from CHANNEL, alternate lateral view. 18 – 20. Operculina? ammonoides (Schröter, 1783) from CHANNEL. 18 – 19. QM # G 465870 lateral (18) and peripheral (19) views. Scale bar = 500 µm. 20. QM # G 465871, alternate lateral view. Scale bar = 1 mm.