Caulostrepsis penicillus, Gaaloul & Uchman & Ali & Janiszewska & Stolarski & Kołodziej & Riahi, 2023

Gaaloul, Nadia, Uchman, Alfred, Ali, Syrine Ben, Janiszewska, Katarzyna, Stolarski, Jarosław, Kołodziej, Bogusław & Riahi, Sami, 2023, In vivo and post-mortem bioerosion traces in solitary corals from the upper Pliocene deposits of Tunisia, Acta Palaeontologica Polonica 68 (4), pp. 659-681 : 669

Caulostrepsis penicillus isp. nov.

Fig. 8E–G .

Zoobank LSID: urn:lsid:zoobank.org:act:5763EFEE-14D2-4B02-8706-ECA3A601B402 .

Etymology: From Latin penicillus , brush, in reference to the overall shape.

Type material: Holotype INGUJ265 P158 ( Fig. 8E : a) well preserved, straight, U-shaped surface structure with several grooves branching out fom the apertures ( Fig. 8E : a) . Paratypes: INGUJ265 P158 ( Fig. 8E : b) well preserved, curved, U-shaped surface structure with several grooves branching out fom the apertures ( Fig. 8E : b), INGU- J265P174 incomplete, straight, U-shaped surface structure with several grooves branching out fom the apertures; marginal tunnel almost invisible ( Fig. 8F ) from the type locality and horizon .

Type locality: El Melah stream, north-east of Hammamet town , Tunisia . Type horizon: Coral level II, Argiles de Sidi Barka Formation (upper Pliocene) .

Material.— Type material and INGUJ265 P172 ( Fig. 8G ), NGUJ265 P185, surface, slightly lobate depression, with several grooves in the apertural part, from the type locality and horizon .

Diagnosis.— Caulostrepsis with a vane, characterized by the possession of several commonly overlapping grooves branched out from the aperture, forming a fan-like structure. The grooves are generally longer than the tripled width of the boring.

Description. —Surface depressions or shallow subsurface galleries, straight, curved, or slightly winding tongue-like depression with a vane, up to 4.5–8 mm long, up to 0.8– 1.8 mm wide. It can be slightly wider in the distal part. The surface depressions can transit into a roofed gallery in the distal part. Several slightly curved or slightly winding groves run out from the proximal part (aperture). They overlap and form a symmetric or an asymmetric fan-like structure, which is up to 7 mm wide and up to 7 mm long. With the remaining part of the boring, it looks like a brush. The groves, about 0.1 mm wide, can bifurcate at the end under low angles, become gradually shallower, emerge, and disappear.

Remarks. —Similarly to the other described ichnospecies of Caulostrepsis , it is interpreted that C. penicillus isp. nov. was originally a subsurface gallery, whose roof was eroded or collapsed. It is most similar to C. avipes , but its grooves branch out from the aperture, and they are much more numerous and distinctly longer. The grooves were probably produced by the tentacles of spionid, cirratulid, or similar bioeroding polychaetes, but the tracemaker presumably had them much more than the tracemaker of C. avipes . There were no transitions between C. penicillus isp. nov. and C. avipes observed in the material studied.

Stratigraphic and geographic range.—Upper Pliocene, Tunisia.

Figures

Fig. 8. Caulostrepsis, a domichnion produced by polychates, in the skeleton of caryophylliid coral Ceratotrochus (Edwardsotrochus) duodecimcostatus Goldfuss, 1826), from the El Melah stream section, the upper part of the Argiles de Sidi Barka Formation (upper Pliocene) of Tunisia. A. Caulostrepsis cretacea (Voigt, 1971), INGUJ265P156. B. Caulostrepsis taeniola Clarke, 1908 and Pinaceocladichnus onubensis Mayoral, 1988 (Pn), INGUJ265P154. C.Caulostrepsis avipesBromleyand D’Alessandro,1983,INGUJ265P176.D.A clusterofCaulostrepsis taeniolaClarke,1908,INGUJ265P162.E–G.Caulostrepsis penicillus isp. nov. E. INGUJ265P158 holotype (a), and paratype (b). F. INGUJ265P174 paratype. G. INGUJ265P172, partial views (G1, G2).