Lambdachitina bipedata, Li & Yan & Wang & Maletz & Liang & Yao & Wu & Chen & Cheng & Fang & Wang, 2025

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 : 21

Angochitina bipedata Geng et al., 1997 ( Fig. 5N–T )

1997 Lambdachitina bipedata sp. nov., Geng et al., p. 98, pl. 10, figs. 1–7.

2020 Angochitina bipedata Geng et al. , Wang et al., p. 120, pl. 7–30, figs. 10–12.

Material: Systematic study was performed based on 35 photomicrographs.

Description: Tis taxon has a total length of 105–161 μm and a chamber diameter of 60–85 μm. Its chamber is cono-spheroidal, with convex flanks, rounded margin and base. Te shoulder is absent or inconspicuous. Te flexure between the neck and the chamber is marked. Te neck is short and cone-shaped, widest near the flexure and narrowing toward the oral pole. However, unlike the neck, the long membranous collar (which can reach 10 μm long), widens toward the oral pole. Except for the collar, the vesicle surface is densely covered with spines. Tese spines are spaced about 3 μm apart. Te spines on the surface of the chamber are wider, with a length of up to 5 μm. Te spines on the neck become thinner, shorter, and disappear at the collar. Most of the spines are bi-rooted. Te distance between the two roots is very short, and no more than 1 μm. A few spines with very short distances between the two roots make it appear to be one-rooted.

Measurements: Measured data based on 15 specimens.

Comparison and remarks: Although its morphology looks like Angochitina sinica Cramer, 1970 , they are different species. A. sinica found in the Yangtze Platform is covered by simple spines ( Geng et al., 1997). While the λ-shaped spines on the vesicle surface is the diagnostic feature of this taxon ( Wang et al., 2020). Although Paris et al. (1999) regarded Lambdachitina ( Lakova, 1986) as a synonym of Angochitina ( Eisenack, 1931) , based on the unique spines of this taxon, Geng et al. (1997) and Huang et al. (2017) still classified them as Lambdachitina . Te current study supports the view of Paris et al. (1999) and assigs it to Angochitina . Some of our specimens are slightly smaller than those reported by Geng et al. (1997), but their morphological diagnostic features are consistent, and therefore they are the same species.

Locality and stratigraphic horizon: Previous reports indicate that this species has only been found in the Telychian Xiushan Formation of western Hunan Province. In this study, four hundred and fifteen specimens were recorded from the Shenxuanyi Member .

Angochitina cf. bipedata sensu Geng et al., 1997

Figures

Fig. 5 Llandovery chitinozoans from the Shenxuanyi Member.Scale bars represent 50 μm (except the scale bar of specimens B, F, J, R, S and T represent 10 μm). A, B Eisenackitina venusta Tsegelnjuk,1982 (A N83-6. B close-up of N47-7 showing the ornaments). C-F Eisenackitina zhangjiajieensis Geng et al., 1997 (C N87-2. C N90-12. E N97-7. F close-up of N97-7 showing the ornaments). G Conochitina (?) sp. 1 (G Ch3-1). H Belonechitina sp. 1 (H N3-5). I Belonechitina sp. 2 (I N103-1). J–M Sphaerochitina palestinaense Grahn et al., 2005 (J close-up of N62-14 showing the ornaments. K N9-15. L N70-6. M N62-14). N–T Angochitina bipedata Geng et al, 1997 (N N55-15. O N55-7. P N39-11. Q N19-4. R close-up of N19-4 showing the ornaments. S close-up of N55-7 showing the ornaments.T close-up of N94-6 showing the ornaments)