Nododendrina paleodendrica ( Elias, 1957 ) 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 : 58-60

Nododendrina paleodendrica ( Elias, 1957) comb. nov.

Fig. 21

Cliona paleodendrica Elias, 1957: 382 , pl. 39, figs 3–10, pl. 40, fig. 1 .

Original diagnosis

n/a

Emended diagnosis

From one side of an irregularly-shaped node below the point of entry, a single fan-shaped plexus of strongly branching and anastomosing galleries emerges. Galleries show pronounced swellings connected to the substrate surface by thin apophyses. Proximal plexus fused and with smooth surface texture, whereas distal plexus more irregular to spiny in texture.

Original description

This form is comparable to the excavations of the extant species of Cliona Grant, 1826 , as it consists of branches coming out from the common center, each branch usually swelling into lobes, and with the lobes of the neighboring branches anastomosing. Parts of a few branches remain without lobate swellings, especially near their apical or distal portion. The pattern thus composed is a miniature replica of living Cliona spinosa or C. corallinoides Hancock (1849 : p. 339, pl. 13, pl. 15, fig. 1 ) being about ten to twenty times smaller. Hancock considered width of lobes one of the important characteristics of a species; to this specific character may be added the counting of lobes per given length of a branch as a complementary characteristic. Comparison of C. spinosa and C. paleodendrica in regard to these two characters is as follows: width of lobes is 2 to 2.5 mm and 0.1 mm, the number of lobes along a branch 5 per 10 mm, and 5 to 7 per 1 mm corresponding in C. spinosa and C. paleodendrica . C. spinosa has numerous papillae that arise from the lobes, and similar papillae cover the lobes in C. paleodendrica ; instead of one to three on each side of a lobe in C. spinosa there is a much larger number of papillae covering densely the lobes in C. paleodendrica . Another difference is the presence of a considerable thickening of the initial central part in C. paleodendrica , a feature neither illustrated nor mentioned in the description of C. spinosa by Hancock. The overall size of the borings does not seem to exceed 6 mm across in the plane of its anastomosing branches in C. paleodendrica , while it measures about 35 mm across or more in C. spinosa as seen in the sketch by Hancock (1849: pl. 13, fig. 5).

Type material, locality and horizon

Various syntypes ( Fig. 21A ) are preserved in a natural cast of a dorsal valve of a Buxtonia semicircularis brachiopod from the Late Mississippian Redoak Hollow Formation, exposed in the vicinity of the village of Milo, Carter County, Oklahoma, USA. The type material used to be deposited in the collections of the Geological Survey of Nebraska, but the empty drawer contains a note only, with the information that the collection was “scrutinised” in the 1990s; the current whereabouts of the material is unknown (Robert Diffendal, pers. comm.). Without the original material at hand, a designation of a lectotype is not feasible, and without other specimens being available, the establishment of a suitable neotype is impossible.

Remarks

The trace was originally described as a new species within the sponge biotaxon Cliona , but is actually a dendrinid boring with close affinity to Nododendrina and is thus herein transferred to the latter ichnogenus as a new combination.

Nododendrina paleodendrica is considerably larger than N. europaea or N. nodosa and is primarily distinguished from these ichnospecies by more pronounced swellings along their anastomosing plexus and by a higher degree of fusion in the proximal part of the plexus, with a smooth surface texture. In contrast to N. nodosa , the plexus emerges from one side of the main node only, a feature that is shared by the smaller N. europaea and the much smaller N. incomposita .

Figures

Fig. 21. Nododendrina paleodendrica (Elias, 1957). A. Original illustration of holotype (actually syntypes) in the dorsal valve of the brachiopod Buxtonia semicircularis (Sutton & Wagner, 1931) from the Late Mississippian Redoak Hollow Formation of Oklahoma, USA (reproduced from Elias 1957: pl. 39, fig. 9). B–C. Original illustrations of further specimens in two shells of the brachiopod Chonetes Fischer de Waldheim, 1830 from the Late Mississippian Redoak Hollow Formation of Oklahoma, USA (reproduced from Elias 1957: pl. 39, figs 4 and 3, respectively).

Fig. 1 (page 7). Morphological characters of dendrinid microborings with respect to overall shape and symmetry of the trace, its vertical profile, openings to the substrate surface, orientation of entrance tunnel (where present), branching pattern and surface texture (in order of decreasing relevance as ichnotaxobase).