Bursachitina sp. 1

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 : 15-16

Bursachitina sp. 1 ( Fig. 4D–F )

Material: Systematic study was performed based on 31 photomicrographs.

Description: Small specimens with square-like or conical vesicle, its length is 53–84 μm. Some specimens’ length is slightly less than width, the L/Dp ratio is 0.79– 1.18, and the Dp/Dc ratio is 1.07–1.30. Its chamber (with slightly convex flanks) gradually transitions into the aperture, and the chamber wall is reduced to form a very short membranous collar at the distal aperture, where it may preserve a round-shaped operculum. Tere is no flexure or neck observed. Te base is convex and with an evagination. Tere is a short and papillary mucron, with an orifice in the center of the base. Its chamber wall is smooth. Te specimens can be preserved as a chain or single individual. Connected individuals link with each other by mutual operculum and basal region.

Measurements: Measured data based on 15 specimens.

Comparison and remarks: Smooth wall surface and conical vesicle are the main morphological features of Bursachitina ( Armstrong & Brasier, 2005; Paris et al., 1999). According to Zaslavskaya (1983), B. rectangularis occurs in isolation rather than in chains. However, Bursachitina sp. 1 can be preserved as a chain. Besides, the total length of B. rectangularis is larger than its chamber width ( Geng et al., 1997), which is different from Bursachitina sp. 1 because the total length of Bursachitina sp. 1 may be less than its chamber width. Some reported species are also different from Bursachitina sp. 1 , including Bursachitina baqaensis ( Paris et al., 2015) , Bursachitina nestorae ( Mullins & Loydell, 2001) and Bursachitina sp. A ( Mullins & Loydell, 2001). Compared with Bursachitina sp. 1 , the vesicle of flattened B. baqaensis is conical (with a reduced aperture), and the morphology of B. nestorae and Bursachitina sp. A is more slender.

Locality and stratigraphic horizon: Te Shenxuanyi Member of Majia section.

Figures

Fig. 4 Llandovery chitinozoans from the Shenxuanyi Member.Scale bars represent 50 μm (except the scale bar of specimens M and P represent 10 μm). A–C Bursachitina rectangularis (Zaslavskaya, 1983) (A N62-4. B N54-12. C N66-7). D–F Bursachitina sp. 1 (D N21-11 & 12. E N39-26. F N37-1). G–I Bursachitina (?) sp. 1 (G N91-4. H N56-5. I N39-3). J-M Eisenackitina causiata Verniers, 1999 (J N59-9. K N60-16. L N87-6. M close-up of N59-9 showing the ornaments). N-P Eisenackitina rimosa Umnova, 1976 (N N45-5. O N43-3. P close-up of N43-3 showing the ornaments).P-Q Eisenackitina venusta Tsegelnjuk, 1982 (P N47-7. Q N47-7)