Pyritonema belua, Wisshak, 2017

Wisshak, Max, 2017, Taming an ichnotaxonomical Pandora’s box: revision of dendritic and rosetted microborings (ichnofamily: Dendrinidae), European Journal of Taxonomy 390, pp. 1-99 : 65-66

Pyrodendrina belua isp. nov.

urn:lsid:zoobank.org:act:D5F00DD3-FFAF-4C73-B044-0F3C8C9248BD

Fig. 25

? Semidendrina pulchra – Wisshak et al. 2008: 43, fig. 9C–E.

Diagnosis

Prostrate galleries slender, with bi- or trifurcations and rare anastomosis. Additionally, sub-vertical tunnels reach straight into the substrate. All galleries end in widened terminations and are ornamented with short spiny protrusions.

Etymology

From the Latin ‘belua’, monster (for the most part in the sea), referring to the former working name “the beast” this trace had earned because of its “fur” and “vertical teeth”.

Type material, locality and horizon

The holotype ( Fig. 25 A–E) is cast in epoxy of a bivalve shell from the Buckhorn Asphalt, Boggy Formation, Deese group, Desmoinesian, middle Pennsylvanian, sampled at the Buckhorn Asphalt Quarry, Oklahoma, USA. The epoxy cast is stored in the Bayerische Staatssammlung für Paläontologie und Geologie München , Germany ( BSPG 2007 XII 12 d). For further details about the type locality and its ichnological record, see Wisshak et al. (2008) .

Description

The basal dendritic network of straight galleries displays uni- or bilateral ramification at 45° to 55° and rare anastomoses ( Fig. 25A, E ). All galleries end in slightly widened terminations ( Fig. 25 A–E). From these basal galleries, additional tunnels of slightly larger diameter, with or without perpendicular side branches, penetrate the substrate sub-vertically and likewise end in widened terminations ( Fig. 25 B–D). The entire trace has a bulged surface texture and is ornamented with short spiny protrusions ( Fig. 25D ). The holotype measures 594 µm in length and 296 µm in width, and has a maximum penetration depth of 235 µm. The horizontal galleries measure 20.9 ± 6.5 µm in thickness (n = 10) and the vertical tunnels are slightly thicker, 24.3 ± 5.8 µm (n = 10). The spiny protrusions measure up to 15 µm in length.

Remarks

Originally tentatively assigned to Nododendrina europaea (as Semidendrina pulchra ), this trace is now recognised as a different ichnospecies. It is clearly distinguished from N. europaea by the lack of a vertically oriented main node, by the almost complete lack of anastomosis, and by the presence of many vertically oriented galleries.

Distinguished from other ichnospecies of Pyrodendrina by its straight and slender galleries, which always widen near their termination. The central node is least distinct in this species, and the hairy ornament is less pronounced than in P. villosa isp. nov.

Figures

Fig. 25. Pyrodendrina belua isp. nov. A. SEM planar view of holotype, surrounded by a carpet of other microborings in an epoxy cast prepared from a bivalve shell sampled from the Middle Pennsylvanian Buckhorn Asphalt Lagerstätte in Oklahoma, USA. B–C. Lateral views of holotype illustrating vertically oriented galleries, parts of which bearing perpendicular side braches. D. Detail of terminal widening and spiny ornamentation. E. Detail of slender prostrate galleries with terminal swellings and typical branching pattern; an anastomosis is developed at the lower right.