Dendrina dendrina ( Morris, 1851 ) dendrina (Morris, 1851

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 : 16-18

Dendrina dendrina ( Morris, 1851) comb. nov.

Fig. 2

Talpina dendrina Morris, 1851: 87 , pl. IV, figs 6b, 7.

Dendrina crassa Hofmann, 1996: 70 , pl. 5, figs 1–4 .

Dendrina fluensis Hofmann, 1996: 72 , pl. 6, figs 3–6.

Dendrina lacerata Hofmann, 1996 (partim): 78, pl. 8, figs 5–6.

Dendrina – Quenstedt 1849 (partim): 470, pl. 30, figs 36 (upper three dendrinids), 37 (upper two dendrinids); 1885 (partim): 496, pl. 38, fig. 39 (individuals labelled “d”). — Radwański 1972 (partim): 257, figs 1–4 . — Hillmer & Schulz 1973 (partim): pl. 1, figs 1–2 . — Whittlesea 2005 (partim): 18, figs 1 , 3.

Without name – Dacqué 1921 (partim): 457, fig. 214 (reproduced from Quenstedt 1849). — Gravesen & Jakobsen 2011: 77, fig. 8.

Talpina dendrina – Voigt 1929: 122, pl. IV, figs 9–10.

Dendrina belemniticola – Mägdefrau 1937 (partim): 55, pl. IV, figs 1 (bottom individual), 6, 8. — Häntzschel 1962 (partim): W230, fig. 144-2 (reproduced from Mägdefrau 1937); 1975 (partim): W127, fig. 78-7 (reproduced from Mägdefrau 1937). — Pugaczewska 1965: pl. 1, fig. 2. — Nadjin 1969 (partim): 138, fig. 53 (reproduced from Quenstedt 1849), pl. III, fig. 7, pl. IV, figs 1 (bottom trace), 6, 8 (reproduced from Mägdefrau 1937). — Voigt 1972 (partim): 95, pl. 1, figs 3a–c (reproduced from Quenstedt 1849), pl. 2, figs 1c , 2–3c, 6d ( fig. 1d reproduced from Quenstedt 1849, fig. 4 reproduced from Quenstedt 1885). — Kutscher 1972 (partim): 27, figs 3–5. — Nestler 1975 (partim): 108, fig. 159b reproduced from Quenstedt 1849). — Schnick 1992 (partim): 112, pl. 3, fig. 4, pl. 4, fig. 5. — Girod & Rösner 2013 (partim): 280, fig. 12. — Rudolph 2014 (partim): 18, fig. 23.

Rosetten-Form A – Hofmann 1996: (partim;?) 83, pl. 10, fig. 3.

Dendrina ordoplana – Plewes 1996: 166, pl. 22, figs 5–8, pl. 23, figs 1–7 .

? Dendrina belemniticola – Hoşgör & Košt’ák 2012: 38, fig. 4I.

Original diagnosis

n/a

Emended diagnosis

Rosette of irregular to sub-circular outline, with loosely spaced galleries radiating from the centre in meandering fashion, ramifying with widened bi- and trifurcations of various angles, only rarely forming anastomoses. In larger individuals, additional tiers may develop.

Original description

This form has a very dendritic appearance, the branches are compressed, closely aggregated, generally arising from a common centre, and diverging in a somewhat radiating manner, variously dichotomous and rarely anastomosing.

Supplementary description

Plewes (1996) provided the following comprehensive description of the junior synonym D. ordoplana : “Tiers are visible in hole material through the semi-transparent belemnite, but these are more clearly illustrated in cast material. As individuals increase in size and bore more deeply in a series of tiers, the substrate between the branches becomes lighter in colour due to the borings beneath it. Cast material shows this increase in depth and increased complexity of boring in more detail. Borings begin as a small single tiered rosette which bores parallel to the substrate surface. As the trace becomes larger, the diameter and depth of the boring increases until complex tiered traces result. Up to three tiers of branches have developed in the material cast here. As the boring becomes more extensive there is a concomitant increase in the number of small interconnections with the substrate surface.” Also based on SEM observations of epoxy resin casts, Hofmann (1996) provided the complementing information for the junior synonyms D. crassa and D. fluensis that galleries are oval in cross section (parallel to the substrate surface), have diameters of 100 to 250 µm, branching points may be considerably widened (300 to 600 µm), branching angles range from 30° to 70°, the rosette is developed some 50 to 90 µm below the substrate surface and distal connections to the latter measure 25 to 50 µm in diameter. The diameter of the rosette was reported to range from 1 to 6 mm ( Plewes 1996, measured from plates 22–23; Hofmann 1996, for junior synonyms D. crassa and D. fluensis ).

Type material, locality and horizon

The Morris types are found in a belemnite rostrum (broken in two parts) from the Upper Cretaceous Norfolk Chalk near Norwich, Great Britain. The type stratum was not further specified by Morris, but the Upper Cretaceous at Norfolk comprises the Turonian to lower Maastrichtian and the belemnite genus Belemnitella d’Orbigny, 1840 narrows down the stratigraphical range to the upper Campanian to lower Maastrichtian. The type material is deposited at the Natural History Museum in London ( PI A 559). The belemnite contains, apart from many other bioerosion trace fossils, about ten specimens of D. dendrina . Morris did not designate a holotype, but one of the specimens ( Fig. 2 E–G) is encircled with ink and corresponds to the position of trace 6b on figure 6 on the original plate ( Morris 1851: pl. IV, fig. 6). Based on this circumstance, and due to this specimen clearly exhibiting the diagnostic inlet tunnel, it is hereby designated as the lectotype, rendering the other specimens (e.g., Fig. 2 H–I) on the same belemnite paralectotypes.

Remarks

Dendrina dendrina is primarily distinguished from D. belemniticola by the more irregular outline of the rosette and the more loosely spaced galleries that branch in perpendicular to acute angles and often follow a meandering course. In addition, multiple and interconnected tiers are a common phenomenon in D. dendrina that is only rarely observed in D. belemniticola . Distinction is complicated in the case of juvenile specimens or mature specimens with a very dense branching and nearly circular outline.

Figures

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. 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. 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.

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.