Dendrina lacerata Hofmann, 1996

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 : 21-23

Dendrina lacerata Hofmann, 1996

Fig. 4

Dendrina lacerata Hofmann, 1996 (partim): 78, pl. 8, figs 3–6.

Piatella-Form – (?) Bundschuh 2000: 69, pl. 10, figs 1–3 .

Original diagnosis

Rosettenförmiges Gangsystem mit sehr breiten und zerlappten Gangformen, häufigen Verschmelzungen einzelner oder mehrerer Gänge und nur wenigen Gangverzweigungen. [Translation: Rosetted boring system with very wide and lobed galleries, common fusion of individual or multiple galleries, and only few ramifications]

Emended diagnosis

Rosette of irregular outline and with wide and lobed galleries, common fusion, and only few ramifications. Inlet tunnel relatively short and often entirely obscured by the rosette.

Original description

The trace shows, similar to Dendrina orbiculata nov. ichnosp., a distinct central area of 0.5 to 1.2 mm in diameter (mean 0.67 mm). For the entire rosette diameters of 1.1 to 2.5 mm (mean 1.72 mm) were measured. Characteristic for this form are the very thick, in planar view irregularly-shaped galleries emerging from the central area. These have a distinctly oval cross section with a 240 to 500 µm lateral diameter. Anastomoses and fusion of individual or several galleries are common, whereas branching points are rare. If present, branching is dichotomous. Gallery terminations are rounded. Due to the anastomoses and gallery fusion, the distal galleries of Dendrina lacerata nov. ichnosp. often have larger diameters compared to the proximal ones. Typical for this boring system is furthermore their stacked occurrence and interconnection with tunnels. Galleries connecting to the substrate surface are present at least at the periphery of the rosette (diameter 20 to 40 µm). The entire rosette is developed about 40 to 100 µm below the surface of the belemnite rostrum. [Translated from German]

Supplementary description

Dendrina lacerata is often found connected to the periphery of Calcideletrix anomala or C. flexuosa , forming a composite trace fossil ( Fig. 4C and separate section below).

Type material, locality and horizon

The holotype ( Fig. 4A ) is preserved in an epoxy resin cast of a Belemnitella mucronata rostrum from the upper Campanian stobaei/basiplana Zone, sampled in the Germania IV quarry near Misburg, Germany. One paratype ( Fig. 4B ) is found on the same and further paratypes (e.g., Fig. 4C ) on three other epoxy casts from belemnite rostra sampled at the type locality and from an outcrop near Lägerdorf , Germany.

Remarks

A similar form, but either with or without a very thick inlet tunnel, was informally described as Piatella- Form by Bundschuh (2000), potentially extending the stratigraphic record of this ichnospecies and for the ichnogenus to the Silurian, although this assignment is made only tentatively here.

Dendrina lacerata is somewhat smaller in diameter than the two other ichnospecies of Dendrina and in contrast to them it exhibits only a few and much wider lobes, rather than individual or fused galleries. The inlet tunnel usually is less pronounced and shorter than in the other two ichnospecies.

Figures

Fig. 4. Dendrina lacerata Hofmann, 1996. A. SEM of holotype in an epoxy cast of an upper Campanian belemnite from Misburg, Germany. B. Paratype on the same cast as the holotype. C. Several paratypes in the periphery of a Calcideletrix anomala from the type locality. D. Oblique view of a specimen in a belemnite from the upper Campanian of Kronsmoor, Germany, illustrating a tubular inlet tunnel on the left and peripheral connections to the substrate surface on the right. E. Surface view of a solitary specimen with inlet canal in a belemnite from the upper Campanian of Misburg, Germany.

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).

Fig. 2. Dendrina dendrina (Morris, 1851) comb. nov. A. Original illustration of belemnite with various traces, including D. dendrina (arrows; reproduced from Quenstedt 1849: pl. 30, fig. 36); provenance unresolved. B. Original amalgam, including D. dendrina (arrows and label “d”; reproduced from Quenstedt 1885: pl. 38, fig. 39). C. Re-illustration of original Quenstedt Dendrina (reproduced from Plewes 1996: pl. 22, fig. 5). D. Original illustrations of Talpina dendrina (= D. dendrina; reproduced from Morris 1851: pl. IV, figs 4–7; 5 = Talpina ramosa; 6a = Trypanites solitarius). E. Morris’ original belemnite from the Upper Cretaceous of Norfolk, UK, including the lectotype of D. dendrina (encircled). F–G. Close-up of lectotype under incipient and transparent light; the inlet canal is clearly visible. H–I. Three paralectotypes in the same belemnite. J–K. Planar and oblique views of the holotype of junior synonym D. fluensis Hofmann, 1996, illustrating the typical multi-tier occurrence, irregular branching, and meandering galleries; SEM of epoxy cast of a belemnite from the lower Maastrichtian at Kronsmoor, Germany. L. Holotype of junior synonym D. crassa Hofmann, 1996, within the morphological range of D. dendrina; SEM of epoxy cast of a belemnite from the lower Maastrichtian at Kronsmoor, Germany.

Fig. 3. Dendrina belemniticola Mägdefrau, 1937. A. Original illustration of belemnite with various traces including D. belemniticola (arrow; reproduced from Quenstedt 1849: pl. 30, fig. 36); provenance unresolved. B. Original amalgam, including D. belemniticola (arrow; reproduced from Quenstedt 1885: pl. 38, fig. 39). C. Re-illustration of original Quenstedt Dendrina (reproduced from Plewes 1996: pl. 22, fig. 3); inlet tunnel roughly at 11h in this and the following four sub-figures. D. Lectotype of D. belemniticola in an upper Senonian belemnite from Rosenthal near Peine, Germany (compare to Mägdefrau 1937: pl. IV, fig. 1). E. Holotype of junior synonym D. orbiculata Hofmann, 1996. SEM of epoxy cast of an upper Campanian belemnite from Lüneburg, Germany. F. Paratype of junior synonym D. constans Hofmann, 1996. SEM of epoxy cast of a lower Maastrichtian belemnite from Lüneburg, Germany. G. Holotype of junior synonym D. constans. SEM of epoxy cast of a lower Maastrichtian belemnite from Lüneburg, Germany. E–G illustrate the morphological range of D. belemniticola from almost completely fused radiating galleries, to partially fused galleries forming anastomoses, to rarely fused radiating galleries. H. Detail of partly obscured inlet tunnel connecting to centre of a paratype of junior synonym D. orbiculata. SEM of epoxy cast of an Upper Cretaceous belemnite from Lüneburg, Germany. I. Rarely observed overlap of D. belemniticola in a lower Maastrichtian belemnite from Rügen, Germany. J. Specimen of D. belemniticola (left) next to a D. dendrina (right) at the very tip of a lower Campanian belemnite from Höver, Germany.