Kornia acia, Korn & Weyer, 2023
publication ID |
https://doi.org/ 10.5852/ejt.2023.882.2177 |
publication LSID |
lsid:zoobank.org:pub:67C909E4-C700-4F8D-B8CE-5FD9B2C5D549 |
DOI |
https://doi.org/10.5281/zenodo.8180628 |
persistent identifier |
https://treatment.plazi.org/id/62D5E824-BACD-4D6F-B03E-2F09A89D9349 |
taxon LSID |
lsid:zoobank.org:act:62D5E824-BACD-4D6F-B03E-2F09A89D9349 |
treatment provided by |
Felipe |
scientific name |
Kornia acia |
status |
sp. nov. |
Kornia acia sp. nov.
urn:lsid:zoobank.org:act:62D5E824-BACD-4D6F-B03E-2F09A89D9349
Figs 27–28 View Fig View Fig ; Tables 17–18 View Table 17 View Table 18
Diagnosis
Species of Kornia with globular to spindle-shaped, involute conch (ww/dm ~1.05; uw/dm ~0.10) at 12 mm conch diameter. Growth lines lamellar with moderately deep, wide ventral sinus.
Etymology
From the Latin ‘ acia ’ = ‘yarn’, as the conch has the shape of a yarn reel.
Material examined
Holotype
GERMANY • Rhenish Mountains , Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 5a2; Weyer 1993–1994 Coll.; illustrated in Fig. 27 View Fig ; MB.C.31073.1.
Paratypes
GERMANY • 1 specimen; Rhenish Mountains , Oberrödinghausen , road cutting; Hangenberg Limestone, P.dorsoplanus Zone ; Korn 1977Coll.; MB.C.31072 • 1specimen; Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone, bed 5a2; Weyer 1993–1994 Coll.; MB.C.31073.2 .
Description
Holotype MB.C.31073.1 is a well-preserved specimen that is fully covered by shell material ( Fig. 27 View Fig ). It has a conch diameter of 12.3 mm and changes from spindle-shaped to globular in the last half whorl (ww/dm = 1.13 at 10 mm dm; ww/dm = 1.05 at 12.3 mm dm); the umbilicus is very narrow (uw/dm = 0.10 at 12.3 mm dm). The peculiar apertural shape shows a pronounced umbilical margin, from where the flanks, which are nearly arranged in right angles, rapidly converge towards the broadly rounded venter. The aperture is very low (WER = 1.47). The shell surface shows lamellar growth lines; they form a pronounced dorsolateral projection and turn back to proceed in a very wide and moderately deep sinus across flanks and venter ( Fig. 28B View Fig ). At a major non-lethal shell damage, the growth lines deviate from this course during the interval of repair.
Paratype MB.C.31072 was sectioned and allows the study of conch ontogeny up to a diameter of 19 mm ( Fig. 28A View Fig ). All whorls have a similar profile, but the ww/wh ratio decreases from about 3.00 at 1.5 mm conch diameter to about 1.80 at 19 mm diameter ( Fig. 28D View Fig ). At the same time, the shape of the profile changes from broad kidney-shaped to C-shaped. At all size stages, the flanks are strongly convergent and the venter is comparatively narrow. The umbilical margin is particularly pronounced between 4 and 10 mm conch diameter.
Remarks
Kornia acia sp. nov. cannot be confused with any other ammonoid from the Hangenberg Limestone because of its peculiar spindle-shaped juvenile conch with raised umbilical margin and the strongly backward directed growth lines. K. fibula sp. nov. has a ball shaped conch with more broadly rounded venter and a wider umbilicus than K. acia (uw/dm ~ 0.10 in K. acia but ~ 0.15 in K. fibula at 11–12 mm dm).
Kornia citrus from the Anti-Atlas has a very similar conch geometry, but differs from C. acia sp. nov. in the shape of the umbilical margin, which in K. citrus is more strikingly raised but more rouded in K. acia .
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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