Rhaetina rainei MACFARLAN 2023, n. sp.
Creators: name: MACFARLAN, DONALD ALEXANDER BANKIER
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Brachiopoda
Rhynchonellata
Terebratulida
Dielasmatidae
Rhaetina
Rhaetina rainei

description: Rhaetina rainei n. sp.
Fig. 10, 1–8, Fig. 11, 1–11. Fig. 12A–C
1951 Coenothyris sp. Trechmann 1918; Marwick 1953 p. 34, pl. 1: 8, 9.
NON Coenothyris sp. Trechmann, p. 218, pl. 23:7 (fide J.D. Campbell, MS)
Holotype. B876 from NC/f0519 AU 7774, île Hugon. Double-valved shelly specimen with some damage to dorsal valve. Collected by J.A. Grant-Mackie.
Derivation of name. This species is named for Dr Ian Raine of GNS Science.
Material. The data series consists of 129 specimens, 38 from New Caledonia and 91 from Nelson; 23 New Caledonia specimens and 68 from Nelson yielded valid measurements.
New Caledonia. île Hugon: NC/f0004A (AU 7148), NC/f0005 (AU 7146), NC/f0007A (AU 7149), NC/f0008A (AU 7795), NC/f0010A (AU 4155), NC/f503 (AU 7174), NC/f518 (AU 7773), NC/f519 (AU 7774). île Ducos: NC/f0020 (GS 12733), NC/f0023 (? GS 12376), NC/f60A (?AU 7214), NC/f0087A (?AU 6073, AU 7168).
Nelson. Eighty-Eight Valley: N28/f7454 (GS 196), N28/f7455 (GS 197). Ram Creek: N28/f0045 (PGS 40, McF D21), N28/f7860 (AU 7885), N28/f7864 (AU 6521).
Southland Syncline. Oreti Valley: E45/f7484 (? GS 372).
Description. Medium sized to large terebratulide with an elongate-elliptical to rounded-triangular outline. The dorsal valve is moderately and evenly convex posteriorly, and generally has two rounded folds anteriorly. Some large specimens are not folded.
The ventral valve is strongly convex posteriorly, and in some specimens is strongly folded anteriorly. The initiation of folds is variable, from 1/5 of valve length in some specimens to near anterior in others. The folds are often stronger on the dorsal valve. The strength can be accentuated by distortion. The anterior margin is uniplicate or parasulcate.
The shell surface is smooth or has fine closely spaced growth lines. Some specimens have stronger, rounded concentrics, which may be visible on the valve interior. Punctae appear to be fine but are poorly shown on shelly New Caledonia specimens and the remnant shell material on Nelson specimens due to recrystallisation.
The beak is triangular and suberect with a bluntly rounded tip. The foramen is large, subcircular (Fig. 10.1a) and permesothyrid (Fig. 11.6a, 6d, 12A–C), and is surrounded by a large, thick pedicle collar. The beak ridges are blunt and poorly defined. The deltidial plates are large and disjunct (Fig. 12C).
In the dorsal valve the hingeplate has broad inner socket ridges and narrow outer ridges, with a distinct cardinal process (Fig. 11.4a, 6a, 9, Fig. 12A, B). There is a low, ridge-like median septum which is about 1/3 of valve length, with a shallow muscle field on either side of the septum (Fig. 11.6a). The loop was not seen.
Dimensions. Dimensions of the holotype and representative specimens, and statistics for New Caledonia and Nelson specimens are shown in Table 3. A length vs width graph is shown in Fig. 9B.
Range and Distribution. Otapirian of Nelson and New Caledonia (Hugon and Ducos). The Nelson material is late Otapirian, the New Caledonia material is both early and late Otapirian.
Marwick (1953) figured Coenothyris sp., which was originally reported by Trechmann (1918) from the Warepan of Ram Hill, Nelson (N28/f7522, GS 4559). Re-examination of Marwick’s figured specimens (BR 1013 and 1014) show them to belong to the new species (Fig. 11.5). Trechmann’s original Coenothyris sp. was examined at the Natural History Museum, London, by Dr J.D. Campbell. He stated in an unpublished MS on Late Triassic athyrids of New Zealand and New Caledonia that it is an athyrid.
The largest collection is from N28/f7454, GS 196 (Eighty-Eight Valley, Nelson), and the species is common in several collections from shellbeds in the Bouraké Formation in île Hugon, New Caledonia. Fragments of a large terebratulide from one collection in Southland may belong to this species.
Remarks. This species is present in large numbers in the Otapirian of île Hugon and of the Eighty-Eight Valley of Nelson. It is also present in île Ducos, and a few specimens are known elsewhere. The distribution suggests that it may be a shallow water form.
The variation in shape in this species is considerable, with the larger collections from île Hugon and Nelson showing a range from medium-sized forms with strong folding anteriorly to large, elongate-elliptical specimens with blunt, rounded folds developed only on the anterior part.
description: Published as part of MACFARLAN, DONALD ALEXANDER BANKIER, 2023, Otapirian (Rhaetian) Terebratulida (Brachiopoda) of Zealandia, pp. 1-34 in Zootaxa 5374 (1) on pages 13-17, DOI: 10.11646/zootaxa.5374.1.1, http://zenodo.org/record/10148159