Haccourtaster nattestadae Gale & Jagt, 2025, sp. nov.

Haccourtaster nattestadae sp. nov. urn:lsid:zoobank.org:act: 74BB38E5-CFFA-45EF-9A49-0988DE70E146 Fig. 2L–O Type material. A group of associated and partly articulated ossicles (MGUH 34867, holotype) from the Arnager Limestone (lower Coniacian) of the coastal cliff southwest of Arnager (Bornholm, Denmark; compare Kennedy & Christensen 1991; Tröger & Christensen 1991; Christensen & Schulz 1997). Diagnosis. Medium-sized Haccourtaster (R approximately 8 mm) in which the superomarginals are strongly convex and have a central ridge. Marginals possess evenly spaced granule pits some of which are large and deeply impressed on the median ridges of the superomarginals. Etymology. Named after local non-professional palaeontologist, Marianne Falbe Nattestad, who collected this and other material of early Coniacian echinoderms from the cliffs near Arnager, Bornholm. Description. The holotype comprises numerous ossicles, some articulated, in a small piece of chalk. The median superomarginals (Fig. 2L–O) are rectangular in abactinal view, and twice as broad as long. The abactinal surface is tumid (Fig. 2N, O); in some ossicles this is symmetrical (N), whereas in others the distal margin is sharply depressed (O). The central area of the median superomarginals is sharply defined by a narrow ridge. The central area carries rather evenly spaced granule pits, some of which are deeply impressed (Fig. 2N); in one case (Fig. 2O) larger pits are present on the lateral-abactinal part of the tumidity. The ultimate superomarginals are triangular with a steep lateral surface which carries evenly sized granule pits (Fig. 2O); the abactinal face bears large, widely spaced crater-like pits. The inferomarginals are gently convex and carry evenly sized and evenly spaced granule pits. The median inferomarginal (Fig. 2M, left) is rectangular in outline, the enlarged penultimate inferomarginal (Fig. 2M, right) tapers distally. A very small 3 rd inferomarginal is present distal to the enlarged 2 nd ossicles. Intramarginal cavities are present (Fig. 2L, upper right). Remarks. Haccourtaster nattestadae sp. nov. differs from its closest relative, H. liticola sp. nov. in the presence of a raised median ridge on the superomarginals which bears deeply impressed, crater-like granule pits. Additionally, the inferomarginals are less broad (compare Fig. 1B with Fig. 2M) and H. liticola sp. nov. lacks the narrow ridge surrounding the central area on the superomarginals in H. nattestadae sp. nov. The Arnager Limestone was interpreted by Svennevig & Surlyk (2018) to represent a relatively deep chalk environment, dominated by hexactinellid sponges and the other invertebrate fauna is of very low diversity. The only other asteroid described previously from the Arnager Limestone is Metopaster cf. thoracifer (Wienberg Rasmussen 1950; Svennevig & Surlyk 2018). However, recent collecting from the cliff southwest of Arnager by Ms Nattestad has yielded additional material of what Wienberg Rasmussen (1950) referred to as M. cf. thoracifer, inclusive of (semi-articulated) specimens. These, and comparative material of late Cenomanian–early Turonian M. thoracifer from the Dresden area (eastern Germany) and the Bohemian Cretaceous Basin (Czech Republic) as described by Geinitz (1871) and Niebuhr & Seibertz (2016) casts doubt over this specific assignment. This matter will be discussed in full in a forthcoming paper. The Arnager locality is less than 2 km from outcropping Palaeozoic basement (Svennevig &Surlyk 2018, fig. 1c), so it is possible that the two currently known asteroid taxa, both characteristically nearshore species, were washed into the region from a coastal environment, perhaps a rocky shoreline.