Archaeothamnulus verticillatus (Dumitrica) Dumitrica, 1982a, p. 418
(Pl. 5, figs. 3, 4; pl. 7, fig. 4)
[Form without apical verticil illustrated here]
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Remarks:As specified in the original description, the apical spine has sometimes a verticil of commonly short thin spinules. This fact allows to recognise two types within the species:
- a type without apical verticil (Pl. 5, fig. 4; also Dumitrica 1978b, p1. 2, fig. 5);
- a type with an apical verticil of commonly three to four spinules (Pl. 5, fig. 3; also Dumitrica 1978b, pl. 1, fig. 1, the same as Pl. 7, fig. 4 in the present paper).
The former type is generally more frequent than the latter. Both of them represent probably extreme terms of the same species rather than independent species or subspecies because:
- the presence or absence of the apical verticil is not correlated with other morphological changes;
- the length of the spinules is variable, from very short to moderately long;
- the species was found in only two samples of the Buchenstein Formation, so there is no stratigraphic or paleogeographic control of the distribution of these two morphological types.
The apical verticil, when present, arises at a distance of 70-85µm from the centre whereas the verticils of the basal spines are situated at a distance of 100-110µm. It results that the centre of the spicule is slightly eccentrical as in all the Triassic spicule-bearing Spumellaria.
Repository:Holotype: no. 103749, paratype: no. 103749, Collection of the Institute of Geology and Geophysics, Bucharest, Romania. Type locality:Sample Rc4, Buchenstein Limestone, Recoaro area, Vicentinian Alps, 500m Northeast of Monte Anghebe, along the road descending to Recoaro, Italy. Stratigraphic range:Uppermost Illyrian to Fassanian, Middle Triassic, Mesozoic. Etymology:[No information given] Subsequent descriptions:? |
Literature cited:- Dumitrica, P. (1978b). Triassic Palaeoscenidiidae and Entactiniidae from the Vicentinian Alps (Italy) and eastern Carpathians (Romania). Deri di Seama ale sedinfelo 64: 39-54.
- Dumitrica, P. (1982a). Middle Triassic spicular Radiolaria. Revista espanola de micropaleontologia 14(1-3): 401-428.
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