Clionolithes palmatus Clarke, 1908

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 : 27-28

Clionolithes palmatus Clarke, 1908

Fig. 6

Clionolithes palmatus Clarke, 1908: 169 , pl. 12, figs 1–2 ( fig. 1 = lectotype).

Clionolithes sollei Talent, 1963: 37 , pl. 9, figs 1–8 .

Clionolithes palmatus – Clarke 1921: 88, figs 92–93 (fig. 92 = lectotype). — Plewes 1996: 176, pl. 25, figs 7–8, pl. 26, figs 3, 5–8 (fig. 5 = lectotype), pl. 27, figs 1–2 .

Clionolithes sollei ? – (?) Talent 1963: 37, pl. 10, figs 1–6 .

Original diagnosis

n/a

Emended diagnosis

Trace developed along a number of principal branches which curve in a regular manner, forming stretched and longitudinally buckled sheet-like fans or terminating in fine ramifications, producing a trace with a jagged or lobed outline. Branches may radiate from only one side of a main axis. Surface texture largely smooth, tips of branches connect to substrate surface.

Original description

[…] a singular form assuming broad sparsely branched palmate hollow fronds and found only in the pelecypods and gastropods of the Pertage group (Upper Devonian).

Supplementary description

A reinvestigation of Clarke’s original material and additional specimens cast in epoxy resin allowed Plewes (1996) to provide the following description and morphometrical figures: “If numerous examples of this trace had not been cast, the different morphologies present could have been included in a number of different ichnospecies or even ichnogenera. Extremes of morphology can exist within a single individual; branches can develop into sheet-like extensions, or be delicately branched, as in the original holotype material. […] Variations in morphology are sometimes confined to different principal axis of one individual; some portions of the trace are delicately branched, others totally devoid of sub-branches. […] The width of the branches is highly variable, between 35 µm and 300 µm, with a mean of 137 µm (n = 24, SD = 67.62). Trace may be a simple rosette up to 3 mm in diameter or may ramify over the surface of the substrate, confined only by its edges; branches can extend for up to 5 mm and be 3–4 mm wide.” Despite this morphological plasticity, the most diagnostic feature appears to be the sheet-like and laterally widening fans. The maximum size of the trace was measured on the lectotype, which is 7 mm in diameter.

Type material, locality and horizon

Clarke (1908) depicted two drawings (syntypes; Fig. 6A, C ), none of which designated as the holotype. Clarke (1921) reproduced both of his original illustrations and again did not explicitly indicate a holotype. Plewes (1996) re-illustrated both of the specimens Clarke based his drawings upon (1908: pl. 12, figs 1–2 ) and both appear to be damaged. The less damaged specimen ( Clarke 1908: pl. 12, fig. 2) was considered as the holotype, whereas the other specimen was qualified as “damaged beyond recognition”. However, since her illustration as well as new images of this specimen indicate that this is not the case, and since the trace depicted by Clarke (1908: pl. 12, fig. 1 ) does match his original description much more closely, it his herein formally selected as the lectotype ( Fig. 6 A–B), rendering the other specimen a paralectotype ( Fig. 6 C–D). The lectotype, a natural cast in a Loxopteria dispar shell from the Portage Beds, Upper Devonian, from Correll’s Point, New York, USA, is housed in the New York State Museum ( NYSM 6697). The paralectotype is a natural cast in a Loxonema danai from the type locality ( NYSM 6698).

Remarks

This ichnospecies is the largest and most variable one of all Clionolithes ichnospecies, but is clearly distinguished from the others by the presence of sheet-like and laterally widening fans, as expressed most prominently in the lectotype. Clionolithes sollei Talent, 1963 shares this diagnostic (and other) features and is thus regarded as a junior synonym.

Figures

Fig. 6. Clionolithes palmatus Clarke, 1908. A. Original drawing of the lectotype, a natural cast in a shell of Loxopteria dispar Sandberger & Sandberger, 1857 from the Upper Devonian of New York State, USA (reproduced from Clarke 1908: pl. 12, fig. 1). B. The lectotype in its present state, either slightly damaged or originally idealised. C. Original drawing of the paralectotype, a natural cast in a Loxonema danai Clarke, 1904 from the type locality (reproduced from Clarke 1908: pl. 12, fig. 2). D. Significantly damaged paralectotype. E–F. A number of natural casts in a shell of Leptostrophia Hall & Clarke, 1892 from the Devonian of Victoria, Australia, including the holotype (close-up in F) and several paratypes of junior synonym Clionolithes sollei Talent, 1963 (compare with Talent 1963: pl. 9, figs 3–8). G. SEM of a specimen cast in epoxy resin by Plewes (1996) from the Devonian of Iowa, USA, illustrating the morphological range within one trace, comprising sheet-like fans and galleries terminating in fine ramifications (reproduced from Plewes 1996: pl. 1, fig. 1).

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.