Cymbaloporetta

Mamo, Briony L., 2016, Benthic Foraminifera from the Capricorn Group, Great Barrier Reef, Australia, Zootaxa 4215 (1), pp. 1-123 : 91

Cymbaloporetta sp. 1 ( Fig. 22 :1–4)

Description. Test trochospiral, moderately high, conical. Thin periphery rounded, test circular in outline and planoconvex in profile. Crescentic shaped chambers coarsely perforate on spiral side with flush sutures. Test wall imperforate on umbilical side. Final whorl with 4–6 mushroom shaped chambers incised with bent, radial sutures. Usually 3–5 slit-like apertures per chamber, each with a thin lip, arranged along depressed sutures. Two to four apertures extend along the radiating suture and the third or fifth aperture, at the centre, extends into the umbilicus.

Remarks. All collected specimens of Cymbaloporetta sp. 1 were substantially damaged making an accurate identification difficult. The specimens are assigned to Cymbaloporetta due to the trochospiral test, crescentic chambers, the spiral side with coarsely perforate wall and imperforate umbilical side, radiating sutures and mushroom shaped umbilical chambers ( Fig. 22 :1–4). The lack of numerous apertures and large, rounded deep chambers around the test’s periphery rule out any affinity with Cymbaloporella . The lack of limbate spiral-side sutures and the absence of planktonic chambers rule out an affinity with Millettiana .

Cymbaloporetta sp. 1 bears some resemblance to Cymbaloporetta poeyi ( d'Orbigny 1839) , a taxon later assigned to Cymbaloporetta squammosa ( d'Orbigny 1839) by Cushman (1931) based on its circular outline, moderately high conical test with flush sutures and similar umbilical chamber shape. However, the specimens of C. poeyi illustrated by Brady (1884, pl. 102, fig. 13 non fig. 14) have a nodule-like apex on the spiral side of the test where the angle of inclination increases and the chambers are much smaller and compressed. This feature is absent in the CG specimens. Similarly, a high-domed specimen assigned to C. poeyi by Heron-Allen (1915) strongly resembles the CG specimens in shape and by the presence of flush sutures, but discussion is otherwise limited apart from the observation that specimens have a highly variable lobate morphology. Debenay’s (2012) C. squammosa bears strong similarity to CG specimens, yet the sutures are more depressed giving the dome-shape of the test a more knobbled appearance. This could be considered intraspecific morphology and allow assignment to C. squammosa , but the distinct aperture Debenay’s (2012) specimens possess at the centre of their umbilical side cannot be found as CG specimens are too damaged and this portion of the test is absent ( Fig. 22 :12, 4).

Specimens similar to Cymbaloporetta sp. 1 described by Brady (1884) were collected from the Admiralty Islands from a depth of 31 m. Heron-Allen’s (1915) specimens were based on those collected by Sir John Murray in 1875 from Honolulu, Hawaii.

Distribution within study area. Cymbaloporetta sp. 1 was collected from all sampled reefs, except for the channel sample and Heron Reef flat. Average site abundance was highest in One Tree Lagoons and the highest abundance was at site 33 in One Tree Lagoon 1. Cymbaloporetta sp. 1 was not as abundant as C. bradyi or M. milletti , but was more abundant than C. tabellaeformis .

Figures

FIGURE 22. (Unless otherwise specified all scale bars = 100 µm). 1 – 4. Cymbaloporetta sp. 1. 1 – 2. QM # G 465969 from OTI 45 peripheral (1) and umbilical (2) views. 3 – 4. QM # G 465971 from OTI 48 peripheral (3) and umbilical (4) views. 5 – 6. Cymbaloporetta? sp. 1, QM # G 466024 from T 1 – 4. Spiral view (5) and close-up spiral view (6). Scale bar for 5 = 200 µm. Scale bar for 6 = 20 µm. 7 – 17. Millettiana milletti (Heron-Allen & Earland, 1915). 7. QM # G 465789 from ST / HW 2, spiral view. 8 – 9. QM # G 465788 from ST / HW 2, peripheral (8) and umbilical (9) views. 10 – 12. QM # G 466032 from ST / HW 8, spiral (10) close-up spiral (11) and peripheral (12) views. Scale bar for 10 = 200 µm. Scale bar for 11 = 50 µm. Scale bar for 12 = 20 µm. 13 – 14. QM # G 466027 from T 1 – 2 spiral (13) and peripheral (14) views. Scale bar for 14 = 50 µm. 15. QM # G 466140 from OTI 50, umbilical view. Scale bar = 50 µm. 16 – 17. QM # G 466088 from OTI 50 spiral (16) and peripheral (17) views. Scale bar for 17 = 50 µm. 1 8 – 20. Acervulina mabahethi (Said, 1949). 18 – 20. QM # G 466003 from OTI 53 spiral (7), umbilical (8) and peripheral (20) views.