Pyrgo Defrance 1824

Mamo, Briony L., 2016, Benthic Foraminifera from the Capricorn Group, Great Barrier Reef, Australia, Zootaxa 4215 (1), pp. 1-123 : 55-56

Pyrgo Defrance 1824

Pyrgo sp. 1

( Fig. 12 :12, 13)

Description. Imperforate, porcelaneous test with inflated chambers separated by very faintly depressed sutures. Test periphery smooth, with weak ‘knife-edge’ margin. Ornament absent. Aperture ovate, subterminal, possessing a wide bifid T-shaped tooth. Aperture boarded by a wide, shallow lip.

Remarks. These specimens were assigned to Pyrgo due to their ovoid test with a slightly angular periphery and adult biloculine chamber arrangement ( Fig. 12 :12, 13). This taxon closely resembles both Pyrgo denticulata ( Brady 1884, pl. 3, fig. 4; Debenay 2012, p. 117, pl. 5) and Pyrgo sarsi published by Parker (2009, fig. 121a–g) in its test form and aperture shape with the hint of a tooth present in some specimens. All the specimens collected from the CG are corroded and damaged making identification below genus level difficult.

Distribution within study area. Pyrgo sp. 1 was collected from the Channel sample between Heron and Wistari Reefs and in One Tree Lagoons 2 and 3. Two of the four total specimens collected were from One Tree Lagoon 2.

Pyrgo sp. 2

( Fig. 12 :14–16)

Description. Test elongately oval in outline and cross section. Glossy test walls smooth, apart from very faint, raised longitudinal ridges spaced around test. Periphery rounded with slightly inflated, biloculine chambers. Sutures shallow to almost indistinct. Terminal aperture is very long, thin, almost three times as long as wide. A single tooth extends entire length of aperture, ending in a bifid tip.

Remarks. This species bears some similarity to the specimens assigned to Pyrgoella tenuiaperta ( Huang 1970) by Loeblich & Tappan (1994) collected from the Timor Sea and Sahul Shelf. However, the specimens reported by Loeblich & Tappan (1994) were collected from greater depths, have a much broader test that is less elongate than Pyrgo sp. 2, an indistinct apertural lip and a more complex dentition. Parker (2009) described Pyrgo sp. 1, which is almost identical to Pyrgo sp. 2 from the CG, but like the specimens collected by Loeblich & Tappan (1994), the apertural tooth does not extend the entire length of the aperture and ends with a thickened tip rather than a bifurcate one. Parker’s (2009) specimens are also more pinched at the apertural end of the test.

Distribution within study area. Pyrgo sp. 2 was only collected from site 40 in Heron Lagoon.

Figures

FIGURE 12. (Unless otherwise specified all scale bars = 100 µm). 1 – 4. Miliolinella sp. 3, QM # G 465973 from OTI 51. 1. Lateral view. 2. Peripheral view, scale bar = 50 µm. 3. Underside view, scale bar = 50 µm. 4. Oral view, scale bar = 50 µm. 5 – 6. Parahauerinoides fragilissima (Brady, 1884), MU 62849 from OTI 47. 5. Lateral view. 6. Peripheral view. 7 – 8. Pseudomassilina australis (Cushman, 1932), MU 62899 from T 2 – 3. 7. Lateral view. 8. Underside view. 9 – 11. Pseudomassilina macilenta (Brady, 1884). 9 – 10. QM # G 465925 from OTI 12, lateral (9) and oral (10) views. 11. QM # G 465947 from WL 15, lateral view. 12 – 13. Pyrgo sp. 1, MU 62903 from CHANNEL. 12. Lateral view. 13. Oral view. 14 – 16. Pyrgo sp. 2, QM # G 465950 from HL 40. 14. Lateral view. 15. Peripheral view. 16. Oral view. 17. Pyrgo sp. 3, QM # G 465956 from CHANNEL, lateral view. 18 – 20. Triloculina barnadi Haig, 1988, QM # G 465791 from ST / HW 2, lateral (18) and oral (19) views. 20. QM # G 465835 from OTI 36, lateral view.