Laxtorum breve Tekin, 2020

Tekin, Kagan, Krystyn, Leopold, Okuyucu, Cengiz, Bedi, Yavuz & Sayit, Kaan, 2020, Late Triassic to Early Jurassic radiolarian, conodont and ammonite assemblages from the Tavuscayiri block, Mersin Mélange, southern Turkey: Time constraints for the T / J boundary and sedimentary evolution of the southern margin of the northern Neotethys, Geodiversitas 42 (27), pp. 493-537 : 524-525

Laxtorum breve Tekin , n. sp.

( Fig. 12 D-J)

urn:lsid:zoobank.org:act:AAC22989-AF44-439E-8E99-6493848E6229

Laxtorum sp. – Aita & Spörli 1992: pl. 5, fig. 12.

HOLOTYPE. — Sample Orbuk-32, HU.JMB.0157 ( Fig. 12D ).

PARATYPES. — HU.JMB.0158 ( Fig. 12G ), HU.JMB159 ( Fig. 12H ), JMB.0160 ( Fig. 12I ), HU.JMB161 ( Fig. 12J ).

TYPE LOCALITY. — Orbuklukeli section, Mersin Mélange, NW of Mersin city, southern Turkey.

ETYMOLOGY. — From the Latin brevis-e – short, brief, due its short shell.

OCCURRENCE. — Lower Jurassic, lower Sinemurian of Auckland, New Zealand and Orbuklukeli section, Mersin Mélange, NW of Mersin city, southern Turkey.

DIMENSIONS (based on seven specimens, in µm). — Length of horn: 84-120 (holotype: 100, average: 105.7); Maximum length of test: 132-158 (holotype: 158, average: 141.1); Maximum width of test: 120-168 (holotype: 125, average: 136.1).

DESCRIPTION

Test short with three post-abdominal segments. Cephalis hemisphaerical with a long horn. Horn needle-like, subcircular in transversal section, slightly decreasing in width distally and terminated in a sharp end. Rest of the test increasing in width very slowly, and decreasing in width at last segment. Collar, lumbar and following strictures not prominent, not visible at the surface of test. Surface of test covered with thick layer of silica with irregular surface. Test bears circular to subcircular pores of different sizes.

REMARKS

This species differs from Laxtorum hemingense Whalen & Carter in Carter et al. (1998: 80 , pl. 25, figs 6-8, 13, 14,

24, 25; pl. 27, figs 5, 6, 16, 20) by having a shorter test with

very long horn and indistinct circumferential ridges. It can be differentiated from Laxtorum obscurum Tekin , n. sp. by possessing a thin, long horn and longer test with more segments.

Figures

FIG. 12. — Photomicrographs of the radiolarians from the Orbuklukeli section; A, B, Canoptum rhaeticum Kozur & Mostler,1981, Orbuk-15;C, Canoptum striatum (Kozur & Mostler, 1990), Orbuk-27; D-J, Laxtorum breve Tekin, n. sp.; D, Holotype, Orbuk-32; E-J, Paratypes, Orbuk-32; K-L, Laxtorum obscurum Tekin, n. sp., K, Holotype, Orbuk-27; L, Paratype, Orbuk-27; M-N, Atalantria emmela (Cordey & Carter, 1996), Orbuk-32; O, Atalantria sp. A, Orbuk-27; P-Q, Pseudoeucyrtis