Kozurium hindei (Tan, 1927)
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publication ID |
https://doi.org/ 10.35463/j.apr.2022.02.06 |
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persistent identifier |
https://treatment.plazi.org/id/EE35878D-0E60-AA38-54AF-FAC6FCB8FA1B |
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treatment provided by |
Felipe |
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scientific name |
Kozurium hindei (Tan, 1927) |
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Figs. 9 View Fig l-o, t, t1
1927 Holocryptocapsa hindei Tan Sin Hok , p. 53, pl. 10, fig 75.
1970 Holocryptocapsa cf. hindei Tan – Dumitrică, p. 74, pl. 15, figs. 100a-d.
1994 Holocryptocapsa hindei Tan – O’Dogherty, p. 212, pl. 35, figs. 9-17.
2001 Holocryptocapsa hindei Tan – Dumitrică in De Wever et al., fig. 165.8.
2014 Holocryptocapsa hindei Tan – Robertson et al., fig. 10(A), 32.
Description. Shell commonly three-segmented, but originally four-segmented. Cephalothorax bell-shaped, partly to almost completely hidden in the abdominal wall and cavity. Cephalis imperforate and bearing usually an extremely short conical apical horn. Abdomen ovoid or subspherical with distal end flat. Lateral parts of the wall smooth with circular and irregularly disposed pores. Pores are very small on the inner part of wall and larger and cylindrical on the middle and external parts. Near the cephalothorax a wide depression is always present, corresponding to the sutural pore, but a true sutural pore is just a larger pore situated near the cephalis (see Dumitrică, 1970, pl. 15, fig. 100d). Distal part of abdomen completely flat or slightly convex and thinner-walled than the lateral sides. Aperture circular, a little larger than the normal pores, simple or with protruding margins ( Figs. 9 View Fig l-l1). Postabdominal segment absent in the Sardinia assemblages, but present in a Valanginian pyritized specimen from the Murguceva Formation, from Svinița ( Romania) (see De Wever et al., 2001, fig. 165.8). It is a thin-walled tureen-shaped segment that covers the distal part of the abdomen.
Studied material. Numerous specimens in samples OZ824-826, OZ834, OZ836, OZ837 and OZ839 (see Table 1).
Dimensions. Length 115-138 µm, diameter of abdomen 95-126 µm.
Remarks. All specimens assigned to this species have a smooth surface, whereas the original drawing of the holotype illustrated by Tan Sin Hok (1927) shows a faint lineation suggesting a slightly rough surface. Such a surface resembles that of the specimen illustrated on Fig. 9l View Fig of the present paper, which, in our opinion, characterizes a younger ontogenetic stage of skeletogenesis, when the superficial layer of skeleton that narrows the diameter of pores was not completely built.
The large flat base of the abdomen differentiates this taxon from all other species of the Williriedellidae . As mentioned above, Dumitrică (1970, pl. 15, fig. 100a) has also shown that this distal part is not only flat but also thinner and its borders are rather sharp suggesting the initial presence of a fourth segment that was either absorbed during the life of the specimens or very easily dissolved after death. A single specimen with this supposed postabdominal segment was found in the upper Valanginian of the Svinița section ( Romania) [see description in Dumitrică, 1995, and the illustrated specimen in De Wever et al. (2001, fig. 165.8)]. This specimen is comparable with the two species of the Albian-Cenomanian genus Kozurium Pessagno, 1977 [ K. corningensis Pessagno 1977 (recte corningense), and K. zingulai Pessagno 1977 ]; this suggests that these two taxa are not diacanthocapsids. In conclusion, the genus Kozurium Pessagno 1977 is a williriedellid and not a diacanthocapsid as supposed by Pessagno.
Range and occurrence. Upper Valanginian of Sardinia to upper Cenomanian of Romania, but O’Dogherty (1994, p. 213) recorded more than 200 specimens in the early Apti- an .
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