Zeilleria minima, MACFARLAN, 2023

MACFARLAN, DONALD ALEXANDER BANKIER, 2023, Otapirian (Rhaetian) Terebratulida (Brachiopoda) of Zealandia, Zootaxa 5374 (1), pp. 1-34 : 21-24

publication ID	https://doi.org/ 10.11646/zootaxa.5374.1.1
publication LSID	lsid:zoobank.org:pub:072341AB-7693-4DF3-9286-D69D0BBD8FAD
DOI	https://doi.org/10.5281/zenodo.10574164
persistent identifier	https://treatment.plazi.org/id/073F87AD-FFBB-5A6A-FF4B-FA69FEA6FE5B
treatment provided by	Plazi
scientific name	Zeilleria minima
status	sp. nov.

Treatment

Zeilleria minima n. sp.

Fig. 15 View FIGURE 15 : 1–15. 16 A–C.

Holotype C81, a double-valved internal mould from E44/f6635, JDC 241 , South Taringatura Hills. Collected by J.D. Campbell, May 1949.

Derivation of name. This is the smallest of the Zeilleria species from the Zealandian Mesozoic.

Material. The data series consists of 19 specimens; 12 of these came from the South Taringatura Hills locality E45/f6635, six from late Otapirian localities in New Caledonia, the Kawhia Syncline and Nelson , and one from E44/f8637, a Warepan locality in the South Taringatura Hills. All yielded valid measurements .

New Caledonia. Ducos NC/f0018A (AU 6074).

Kawhia Syncline. Coast north of Marokopa R 16/f6899A ( GS 10010). Marokopa coast R 16/f0050 (McF A19). Awakino Gorge R 18/f6562B (AU 8986).

Nelson. Eighty-Eight Valley N28/f7454 ( GS 196).

Southland Syncline. South Taringatura Hills, Southland, E44/f6635, JDC 241. E44/f8637, JDC 655 (Warepan).

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Description. Small terebratulide with robust shells and elongate-elliptical outline. Both valves are moderately, evenly and about equally convex with no definite fold or sulcus. The anterior commissure is rectimarginate or with a shallow, poorly-defined uniplication. The beak is sharply rounded, erect, and large in proportion to the shell. The foramen is elliptical and permesothyrid. There is no pedicle collar. Deltidial plates are small, triangular and conjunct. The beak ridges are strong and sharply rounded. The shell is coarsely punctate.

The dorsal valve has a narrow hingeplate, with a small poorly defined cardinal process. The median septum is high, wall-like, and generally 0.2 – 0.5 of valve length ( Fig. 16A, C View FIGURE 16 ). Adductor muscle scars are paired ( Fig. 15.6a View FIGURE 15 ) and of variable strength at the anterior end of median septum.

The ventral valve has short, thick slightly divergent dental plates ( Fig.15.1a View FIGURE 15 , 6a View FIGURE 6 , 10a, b View FIGURE 10 , Fig. 16 View FIGURE 16 A-C). Diductor muscle scars are prominent in some specimens ( Fig. 15.6b View FIGURE 15 , 10b View FIGURE 10 , 16B View FIGURE 16 ), located to the anterior of the beak and between the dental plates.

Dimensions. Dimensions of the holotype and representative specimens, and statistics for all measurable specimens are shown in Table 5. A length vs width graph is shown in Fig. 9D View FIGURE 9 .

Range and Distribution. Otapirian of New Caledonia, and the Murihiku Terrane of New Zealand. One Warepan specimen from Southland.

Remarks. This new species forms part of a group of small rectimarginate Zeilleria which include the Early Jurassic Z. terezowae MacFarlan, 2019 and the Middle to Late Jurassic Z. opuatiaensis MacFarlan, 2016 . The new species most closely resembles Z. terezowae but is smaller. The larger specimens are proportionately more elongate and more inflated.

Specimens from R16/f050 and R18/f6562 are wider and closer to Z. terezowae in shape. They could represent a different species.