Angochitina sp. 2

Li, Yangui, Yan, Chunbo, Wang, Chuanshang, Maletz, Jörg, Liang, Yan, Yao, Huazhou, Wu, Haizhi, Chen, Weixiong, Cheng, Jingqing, Fang, Zichen & Wang, Xiaofeng, 2025, Chitinozoans from the Telychian (Llandovery, Silurian) Shenxuanyi Member, upper Ningqiang Formation of the northwestern Yangtze Platform, China, Swiss Journal of Palaeontology (20) 144 (1), pp. 1-33 : 24

Angochitina sp. 2 ( Fig. 7H–M )

Material: Systematic study was performed based on 17 photomicrographs.

Description: Tis taxon with an ovoid chamber and a long column neck. Te body flanks, margin and base are rounded. Te shoulder is absent, while the flexure between the chamber and the neck is evident. Te distal end of the neck has a short membranous collar. Te vesicle surface is covered with simple spines (2 μm long). Te spines are solid, and no hollow structures are observed. Te spines are dense and randomly distributed on the surface of the chamber (the interval of size is 2–5 μm) but sparse on the neck.

Measurements: Measured data based on nine specimens.

Comparison and remarks: Te spinous ornaments of A. longicollis are hollow and ordered longitudinally ( Geng et al., 1997; Laufeld, 1974; Nestor, 1994), and the neck of A. longicollis is also covered by spinous ornaments ( Mullins & Loydell, 2002; Nestor, 2012; Verniers et al., 1995). But the spinous ornaments of this taxon are solid, mainly distributed on the surface of the chamber, and rarely on the surface of the neck. Terefore, although the vesicle morphology of this taxon is very similar to A. longicollis , the present study distinguishes it from A. longicollis and tentatively assigns it to Angochitina sp. 2 .

Locality and stratigraphic horizon: It was recognized in the Shenxuanyi Member in this study.

Figures

Fig. 7 Llandovery chitinozoans from the Shenxuanyi Member.Scale bars represent 50 μm (except the scale bar of specimens D, E, G, K and M represent 10 μm). A–E Angochitina synaphacantha (Geng et al., 1997) (A N39-27. B N42-8. C N23-7. D, E close-up of N39-27 showing the ornaments). F-G Angochitina sp. 1 (F N4-21. G close-up of N4-21 showing the ornaments). H–M Angochitina sp. 2 (H N5-7. I N2-12. J N7-11. K close-up of N5-7 showing the ornaments. L N3-19. M close-up of N3-19 showing the ornaments). N–S Angochitina sp. 3 (N N3-14. O N10-3. P N8-14. Q N64-7. R N58-67. S N11-1)