Neodendrina carnelia, Wisshak & Neumann, 2018

Wisshak, Max & Neumann, Christian, 2018, Large dendrinids meet giant clam: the bioerosion trace fossil Neodendrina carnelia igen. et isp. n. in a Tridacna shell from Pleistocene-Holocene coral reef deposits, Red Sea, Egypt, Fossil Record 21 (1), pp. 1-9 : 3-6

publication ID	https://doi.org/ 10.5194/fr-21-1-2018
DOI	https://doi.org/10.5281/zenodo.11047605
persistent identifier	https://treatment.plazi.org/id/0B3887D0-FFCE-ED17-7A31-AE88FD3C461F
treatment provided by	Felipe
scientific name	Neodendrina carnelia
status	sp. nov.

Treatment

Neodendrina carnelia isp. n.

Figs. 2–4 View Figure 2 View Figure 3 View Figure 4

Etymology: From Latin carnelia , meaning carnelian, red-coloured variety of chalcedony. Referring to “Diving Carnelia”, a former scuba dive centre situated in the direct vicinity of the type locality, and secondarily referring also to the Red Sea.

Diagnosis: Radial rosette nearly circular in outline, ramifying in a strictly dichotomous fashion. Roofless canals with slight swellings but relatively constant in width; terminations rounded. Particularly near the centre of the trace, canals may be very shallow or discontinuous and then appear as a series of pits.

Description: The prostrate circular to oval rosette of the dendrinid microboring is radiating from its centre in a strictly dichotomous pattern, forming open canals of relatively constant width (within a trace and among traces) and featuring rounded terminations (e.g. Figs. 2c–e View Figure 2 , 3a–c View Figure 3 ). From the roughly orthogonal individual points of bifurcation, the canals make a slight turn in direction of the radial expansion of the trace, resulting in an acute angle between two neighbouring branches ( Fig. 3a–d View Figure 3 ). Particularly in the centre of the trace, the canals may be either very shallow (at same width than the deeper ones) or even discontinuous, i.e. no bioerosion having taken place at these points (e.g. Figs. 2c–e View Figure 2 , 3h, i, j View Figure 3 ). In the latter case, the trace appears as an array of short grooves or pits, whereas confined and shallow pits may also be found situated within the shallow canals ( Fig. 3h View Figure 3 ). The presence and degree of these different morphological expressions varies markedly between different specimens, the by far most common morphology being the deep and continuous canals. The surface texture is smooth ( Fig. 3e and k View Figure 3 ). The substrate surface in the direct vicinity of the canals may either be a bit different in colour ( Fig. 2b View Figure 2 ) or morphologically slightly elevated ( Fig. 4c View Figure 4 ). Several traces on the Tridacna shell that bears the holotype contain authigenic gypsum crystals, calcite spar, and clay minerals within the boring as well as on the surrounding shell surface ( Fig. 3f–g View Figure 3 ).

Morphometrical measurements obtained from 55 complete specimens on a single Tridacna host shell, including the holotype and comprising a range of initial traces to late ichnogenetic stages, show a maximum diameter of the rosette-shaped trace ranging from 1025 to 3770 µm, with a mean of 1931 ± 651 µm (n = 55), and individual galleries of relatively constant width ranging from 59 to 153 µm, with a mean of 100 ± 16 µm (n = 275). The angle of the dichotomous bifurcations ranges from 43 to 141 ◦ with a mean of 90 ± 15 ◦ (n = 246) at the branching points. One to six orders of bifurcations were observed (mean = 3 ± 1; n = 55), leading to a number of peripheral gallery terminations ranging from 4 to 43 (mean = 13 ± 7; n = 55). Type material, locality and horizon: The holotype ( Figs. 2b–e View Figure 2 , 3a–c View Figure 3 ) is preserved on a piece cut from a Tridacna maxima ( Röding, 1798) shell, and is housed at the Museum für Naturkunde Berlin, Germany ( MB.W 5640 ) . All other specimens preserved on the same slab are defined as paratypes ( Fig. 2b View Figure 2 ). The type locality is 25 km south of El Quseir, between Ras Abu Aweid and Mersa Um Gheig, just south of the former Carnelia Beach Resort (25 ◦ 54 Į 13 ĮĮ N, 34 ◦ 24 Į 45 ĮĮ E). The type shell bed is highly time averaged, and hence the exact age remains unresolved, either from the reefal limestones of the Samadai Formation, Pleistocene, or from a late Pleistocene to early Holocene archaeological shell midden, or (least likely) from the recent reef top.

Additional material: More than a hundred microboring specimens remained preserved on the inner shell surface of the same Tridacna maxima bivalve shell that bears the holotype ( Fig. 2a View Figure 2 ). In addition, a number of specimens were identified on the outer surface of a large recent Tridacna squamosa de Lamarck, 1819 valve ( Fig. 4 View Figure 4 ) stored at the Museum für Naturkunde Berlin, Germany ( ZMB /Mol 102671), originating from Nosy-BØ, northern Madagascar.

Remarks: Spot checks of morphometrical measurements taken from the additional Madagascar material plot in the range of the specimens from the type material.