Triloculina d'Orbigny 1826
Creators: name: Mamo, Briony L.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Chromista
Foraminifera
Tubothalamea
Miliolida
Hauerinidae
Triloculina

description: Triloculina d’Orbigny 1826
Triloculina barnardi Haig 1988 (Fig. 12:18–20; Fig. 13:1–4)
1971 Triloculina terquemiana (Brady 1884) var. barnadi Rasheed, p. 37, pl. 10, fig. 3, nomen nudum. 1988 Triloculina barnardi Rasheed; Haig, p. 235, pl. 11, figs 9–21.
1997 Triloculina barnardi Rasheed; Haig, p. 273, fig. 4: 23.
2005 Triloculina tricarinata (d’Orbigny); Woodroffe et al., p. 264, pl. 1, fig. 12. 2009 Triloculina barnardi Haig; Parker, p. 358, fig. 260a–m.
2012 Triloculina barnardi Rasheed; Debenay, p. 136, pl. 6.
Description. See Parker (2009, p. 358, fig. 260a–m).
Remarks. Rasheed (1971) first described this species as a new variety of Triloculina terquemiana Brady 1884, but as noted by Parker (2009), in accordance with article 15.2 of the International Code of Zoological Nomenclature (ICZN 2000), varietal names published post 1960 are invalid. Instead of synonymising his specimens with those of Rasheed (1971), Haig (1988, pl. 11, figs 19–21) illustrated this taxon as Triloculina barnardi which made the name officially available and Haig (1988) the first reviser of this taxon. Unfortunately, Haig (1988) did not include a formal description of the taxon, but the description and designation provided by Rasheed (1971) provides some degree of nomenclatural stability.
Triloculina barnardi Haig 1988 is characterised by a triloculine test bearing a short neck, everted lip, oval aperture with single tooth that has a thickened tip and distinct longitudinal striae that vary in definition from deep and strong to weak and shallow. The ornament of this species is highly distinct and in combination with its carinate peripheries, separates it from other triloculine species collected from the CG. This species differs from Triloculina earlandi Cushman 1954 by its broader test, more knife-like peripheral margins and thicker striae. Triloculina barnardi differs from Triloculina striatotrigonula Parker 1865 by having less strongly round and inflated chambers, a smaller aperture and a thinner T-shaped dentition. Triloculina striatotrigonula can be discriminated by its lack of a neck and deeply incised striae. However, all three Triloculina species are similar in bearing longitudinal ornament.
Rasheed’s (1971, p. 37) original description of T. barnardi was based on specimens collected from Papua New Guinea. Haig’s (1988) specimens were collected from the Papuan Lagoon and were abundant in both back-reef settings and channel waters. Haig (1997) also reported this species from the Exmouth Gulf and both these and the Papuan specimens (Haig 1988) bear distinct, deep striate ornament. Woodroffe et al. (2005) reported this species as Triloculina tricarinata d’Orbigny 1826 from intertidal mangrove sediments off Townsville, coastal GBR. Parker (2009) collected specimens from Ninagloo Reef, Western Australia and clearly illustrated two morphotypes defined by their weakly or strongly developed striate ornament. The CG specimens display the same variation in ornament as those collected by Parker (2009). Although the two morphotpyes were originally considered separate species, with the weakly striate form originally thought to be Triloculina tricarinata d’Orbigny 1826, it is now clear that both morphotypes are conspecific. Debenay’s (2012, p. 136) specimens from a bay in the southerwestern lagoon of New Caledonia illustrate weak to moderate striation intensity.
Distribution within study area. Triloculina barnardi is the most abundant Triloculina species collected from the sampled CG reefs. This species prefers deeper water habitats with greatest abundance at site 40 from Heron Lagoon. Markedly lower abundance was observed in shallow water environments and it was absent from Sykes Reef.
Triloculina earlandi Cushman 1954 (Fig. 13:5–7)
1954 Triloculina earlandi Cushman, p. 338, pl. 85, fig. 3.
1988 Triloculina funafutiensis (Chapman); Haig, p. 235, pl. 11, figs 23, 24. 1992b Triloculina earlandi Cushman, Hatta & Ujiié, p. 73, pl. 12, fig. 1. 2009 Triloculina earlandi Cushman; Parker, p. 362, fig. 262a–c.
2012 Triloculina earlandi Cushman; Debenay, p. 136, pl. 6.
Description. See Cushman et al. (1954) and Parker (2009, p. 362, fig. 262a–c).
Remarks. This species has an elongate, slender, fusiform, triloculine test with fine longitundinal striate ornament. The terminal aperture is mounted atop a stout tapering neck and is circular to ovate with short T-shaped bifid tooth (Fig. 13:5–7).
This species differs from other Triloculina having a more elongate and slender test and by its very fine striae. Both T. barnadi and T. striatotrigonula have much broader tests with more inflated chambers.
The original specimens reported by Cushman et al. (1954) were collected from the northeastern part of Rongerik Lagoon, Marshall Islands from a depth of 34 m along with several other lagoons and atolls in the area. Triloculina earlandi has an Indo-Pacific distribution (Papuan Lagoon—Haig 1988; Ryukyu Island Arc—Hatta & Ujiié 1992b; Ningaloo Reef—Parker 2009; Lizard Island, GBR—Baccaert 1987; New Caledonia from 20 m— Debenay 2012).
Distribution within study area. Triloculina earlandi was not found in high abundance anywhere from the CG. Sites of highest abundance include sites 25 and 43 in One Tree Lagoon 1 and site 47 in One Tree Lagoon 3, but no more than four specimens were collected per sample. The taxon is absent from Sykes Reef, the channel sample, Heron Lagoon and occurs at only four sites on Heron Reef flat and two at Wistari.
Triloculina striatotrigonula Parr 1941 (Fig. 13:8–13)
1884 Miliolina insignis Brady, pl. 4, fig. 10a–b (non fig. 8). 1932b Triloculina insignus (Brady); Parr, p. 9, pl. 1, fig. 12.
1941 Triloculina striatotrigonula, Parr, p. 305.
1977 Triloculina striatotrigonula Parr; Quilty, p. 89, fig. 17.
1988 Triloculina cf. T. schreiberiana d’Orbigny; Haig, p. 235, pl. 11, figs 29–31. 1999 Triloculina striatotrigonula Parr; Hayward et al., p. 105, pl. 5, figs 25, 26. 2009 Triloculina sp. 5; Parker, p. 376, fig. 273a–e.
2012 Triloculina striatotrigonula Parr; Debenay, p. 138, pl. 6.
Description. See Hayward et al. (1999, p. 105, pl. 5, figs 25, 26) and Parker (2009, p. 376, fig. 273a–e).
Remarks. This species is characterised by its broad, squat test that is only slightly taller than wide, greatly inflated chambers with rounded peripheries and truncated oral end. The sutures are depressed, curved and the test wall is ornamented by weak, widely spaced longitudinal striae. The aperture is terminal and contains a large, broad T-shaped bifid tooth that is raised slightly above the aperture at the tip (Fig. 13:8–13).
Triloculina striatotrigonula Parr 1941 differs from both T. barnadi and T. earlandi by having a test that is significantly more rounded, broad and inflated. In addition, the striae are spaced further apart and neither T. barnadi nor T. earlandi possess such a proportionately large, produced T-shaped bifid tooth.
Triloculina striatotrigonula was established by Parker & Jones (1865) without a formal description or illustration to describe a striate form of Triloculina trigonula (Lamarck 1804). This taxon was subsequently incorrectly published by Brady (1884, figs 8, 10) as Miliolina insignis Brady 1884 but the illustrations provided actually represented two different species published under this name. Parr (1932b) mentioned this discrepancy and the similarity to the specimens of Parker & Jones (1865), but retained Brady’s assignation. Parr (1941) later officially rectified this situation by referring the second species (Brady, 1884; Fig. 10), which came from Bass Strait, to T. striatotrigonula. In providing the first formal description of this taxon, authorship has therefore been attributed to Parr (1941).
Brady’s (1884) illustrations of T. striatotrigonula show much thicker, more closely spaced striate ornament similar to the specimens described by Hayward et al. (1999) and Debenay (2012). However, this type of ornament is unlike the ornament found in other publications (Quilty 1977, fig. 17; Haig 1988, pl. 11, figs 29–31; Parker 2009, fig. 273a–c) where the striae are the same thickness, but are significantly more widely spaced apart. Like the varying intensity of the striate ornament in T. barnadi, this variation in T. striatotrigonula represents intraspecific variation which may relate to geographic location. The morphotype with broadly spaced striae has been found in Western Australia, the GBR (CG specimens) and north to Papua New Guinea and New Caledonia (Quilty 1977; Haig 1988; Parker 2009; Debenay 2012) and the closely-spaced striate form the southern regions of Australia across to New Zealand and surrounding islands (Brady 1884; Parr 1932b; Hayward et al. 1999).
Parker & Jones (1865) originally reported this species from coastal sands near Melbourne and has since been largely reported from the southwest Pacific (Bass Strait from 69–73 m—Brady 1884; Victorian and South Australian coastline—Parr 1932b; Hardy Inlet, south Western Australia—Quilty 1977; Papuan Lagoon—Haig 1988; Stewart Island and the Chatham Islands, New Zealand—Hayward et al. 1999; Ningaloo Reef—Parker 2009; New Caledonia at 200 m—Debenay 2012).
Distribution within study area. Triloculina striatotrigonula was the least abundant Triloculina species from the CG with no more than six specimens collected per site. The site of greatest abundance was site 42, Heron Lagoon and it was absent from Sykes Reef, Wistari Lagoon and Heron Reef flat.
description: Published as part of Mamo, Briony L., 2016, Benthic Foraminifera from the Capricorn Group, Great Barrier Reef, Australia, pp. 1-123 in Zootaxa 4215 (1) on pages 56-58, DOI: 10.11646/zootaxa.4215.1.1, http://zenodo.org/record/272923