Alectona spp.
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publication ID |
https://doi.org/ 10.4202/app.00612.2019 |
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persistent identifier |
https://treatment.plazi.org/id/AE74871F-B871-B726-FFBD-FEA1FD25FB6E |
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treatment provided by |
Felipe |
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scientific name |
Alectona spp. |
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Fig. 4I–K, O, P, R, T View Fig .
Material.—Middle–upper Eocene, south-central Ukraine.
Remarks.—The spiny triactines (also called acanthotriods) with long rays covered with spines regularly arranged in whirls ( Ivanik 2003: pl. 21: 3, 4; Fig. 4I–K View Fig ) resemble those of Alectona triradiata Lévi and Lévi, 1983 (compare Bavestrello et al. 1998: fig. 2a–c). However, the spicules of modern Alectona possess very well developed spines also on the ray tips while those from Ukraine lack the spines on the tips. Although, this difference in spines arrangement may be due to the poor preservation state of the fossil spicules.
In turn, the long, bent oxeas that are rather irregularly covered by minute spines ( Fig. 4P View Fig ) show great resemblance to spicules of modern Alectona primitiva Topsent, 1932 compare Vacelet and Vesseur 1971: fig. 22).
The smaller acanthoxeas ( Fig. 4O, R, T View Fig ) are less bent in the middle of its shaft and regularly covered with minute spines. They are almost identical with the spicules of modern Alectona millari Carter, 1879 (compare Carter 1879: pl. 17: 3). The acanthorhabds ( Fig. 4S View Fig ), in turn, might be of alectonid affinity because similar spicules (diactines) have been described by Bavestrello et al. (1998) and assigned to Alectona sp. (see Bavestrello et al. 1998: fig. 7). Still, these spicules also resemble sanidasters of Crellastrina alecto Topsent, 1898 and spicules of some species of Halicnemia Bowerbank, 1864 ( Stelligeridae ; van Soest 2017: fig. 34).
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