Parasorites

Mamo, Briony L., 2016, Benthic Foraminifera from the Capricorn Group, Great Barrier Reef, Australia, Zootaxa 4215 (1), pp. 1-123 : 65-67

Parasorites sp. 1 ( Fig. 15 : 8–13)

Remarks. This species is assigned to Parasorites due to the embryonic apparatus with a proloculus and flexostyle, and possession of peneropline chamber arrangement during the initial test development that becomes reniform to discoidal with annular final chambers ( Fig. 15 :8, 9). Specimens collected from the CG have an imperforate test with depressed sutures between the discoidally layered chambers. Pitting increases from a nearly imperforate test at the suture to distinct, scattered perforations before the next suture marked by a sharp contact. The apertures consist of a single row of rounded, rimmed openings that become more vertically elongate as the test expands during growth. Internally, the chambers are divided by robust intradermal plates ( Fig. 15 :12) in the final, annular chambers of the test.

Similar taxa have been published by various authors under differing names, but none directly match the specimens collected from the CG. Parasorites sp. cf. P. orbitolitoides ( Hofker 1930) from Ningaloo Reef ( Parker 2009) and P. orbitolitoides from New Caledonia ( Debenay 2012) both have a similar chamber arrangement to Parasorites sp. 1, but the Ningaloo and New Caledonian specimens are far less pitted and the annular stage of test development is far more variable than specimens collected from the CG. In addition, the Ningaloo and New Caledonian specimens have more annular rings than the 3–4 usually found in the CG specimens.

Parasorites orbitolitoides ( Hofker 1930) described by Loeblich & Tappan (1987) from Puerto Rico, Rivera and Indonesia have large, distinct pitting and an extensive annular test development compared to Parasorites sp. 1 from the CG. The apertures along the peripheral margin of P. orbitolitoides have an alternating “upper-lower” arrangement that are occasionally merged to become elongate apertures that lie horizontally to, or parallel with, the test.

Similarly, Sorites orbitolitoides ( Hofker 1930) described by Gudmundsson (1994) from the Caribbean has a similar chamber arrangement to the CG tests, but again the Caribbean specimens have a far more extensive annular test stage and also bear apertures which align parallel with, or horizontal, to the test as opposed to the vertical or perpendicular orientation of CG specimen apertures ( Fig. 15 :9; 13).

Specimens described by Brady (1884) as Orbitolites marginalis Lamarck (1816) from the Honolulu Reefs and Fiji, have the same vertically-oriented, elongate apertures along the peripheral margin as the CG specimens. However, the initial stage of test development appears to coil into several whorls before the chambers expand and flare into the style of Parasorites . Furthermore, the chambers are raised above the reniform and annular test sections. Lacroix (1940) reassigned Brady’s (1884, pl. 15, figs 1–5) specimens of S. marginalis to Praesorites orbitolitoides Hofker 1930 , the type species for Parasorites . Then after noting a distinct difference in the initial test structure, Lacroix (1940) reassigned some of Brady’s (1884, pl. 15, figs 1–3, 5) specimens to Sorites hofkeri Lacroix 1940 and the remaining specimen ( Brady 1884, pl. 15, fig. 5) to Sorites hofkeri subsp. orbitolitoides Hofker 1930 . Although Lacroix (1940) noted Brady’s (1884) specimens possessed a different test structure compared to his own specimens from Indochina, Australia and east Africa, he considered such differences to be of varietal significance only ( Barker 1960).

It is clear from examining previous synonymy lists for this genus that a confident identification of the CG specimens remains quite difficult. The specimens from the CG lack a well-developed annular test stage and this may be due to a dominance of juvenile specimens, but additional material is required to determine the true scope of intraspecific variation displayed by this taxon. Without this, a definitive species identification cannot be made.

Distribution within study area. Parasorites sp. 1 was found in low abundance with only one to three specimens being collected per site. This taxon was most common at site 20 in One Tree Lagoon 3 and site 38 in One Tree Lagoon 1. Specimens were also collected at three sites from Heron Reef flat and Heron Lagoon and was only found at site 18 in Wistari Lagoon. Parasorites sp. 1 was not collected from Sykes Reef, or the channel between Wistari and Heron.

Figures

FIGURE 15. (Unless otherwise specified all scale bars = 100 µm). 1 – 5. Peneroplis pertusus (Forskål, 1775). 1 – 3. QM # G 465896 from ST / HW 10, lateral (1, 2) and oral (3) views. 4 – 5. QM # G 465805 from T 2 – 3, lateral (4) and oral (5) views. 6 – 7. Peneroplis planatus (Fichtel & Moll, 1798) QM # G 465995 from T 1 – 10, lateral (6) and oral (7) views. Scale bar = 500 µm. 8 – 13. Parasorites sp. 1. 8 – 9. QM # G 465802 from T 2 – 3, lateral (8) and oral (9) views. Scale bar = 200 µm. 10. QM # G 465781 from ST / HW 2, lateral view. Scale bar = 200 µm. 11 – 13. QM # G 465982 from OTI 54, lateral (11), close up of intradermal plates (12) and oral (13) views. Scale bar for 12 = 50 µm. 14 – 20. Marginopora vertebralis Quoy & Gaimard, 1830. 14 – 16. QM # G 465793 from T 2 – 1, lateral view (14), scale bar = 200 µm. 15. Oral view. 16. Close-up oral view, scale bar = 50 µm. 17 – 18. QM # G 466030 from T 2 – 5, lateral (17) and close-up oral (18) views. Scale bar for 17 = 1 mm. 19 – 20. QM # G 466020 from T 1 – 2, lateral (19), oral (20) views. Scale bar for 19 = 2 mm. Scale bar for 20 = 1 mm.