Angochitina longicollis, 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 : 22-23

Angochitina longicollis Eisenack, 1959 ( Fig. 6M–Q )

1959 Angochitina longicollis sp. nov., Eisenack, p. 13, pl. 2, figs. 8–9.

1974 Angochitina longicollis Eisenack, Laufeld et al. , p. 56, figs. 19(A–C).

1985 Angochitina longicollis Eisenack, Li and Geng , p. 603, pl. I, figs. 1–19. P. 605, pl. II, figs. 1–6, 8. p. 607, pl. III, figs. 5–9.

1988 Angochitina longicollis Eisenack, Geng and Cai , p. 256, pl. I, fig. 3.

1994 Angochitina longicollis Eisenack, Nestor , p. 179, pl. 7, figs. 1–4.

1995 Angochitina longicollis Eisenack, Verniers et al. , p. 658, figs. 5(m–n).

1996 Angochitina longicollis Eisenack, Chen , p. 69, pl. II, figs. 5–10.

1997 Angochitina longicollis Eisenack, Geng et al. , p. 163, pl. 11, figs. 2–10.

2001 Angochitina longicollis Eisenack, Mullins and Loydell , p. 737, pl. 3, figs. 1–8.

2002 Angochitina longicollis Eisenack, Mullins and Loydell , p. 92, fig. 3 (r).

2003 Angochitina longicollis Eisenack, Loydell et al. , p. 224, figs. 16 (X).

2004 Angochitina longicollis Eisenack, Mullins and Aldridge , p. 759, pl. 3, figs. 3, 5.

2005 Angochitina longicollis Eisenack, Loydell and Nestor , p. 373, fig. 4 (d).

2006? Angochitina longicollis Eisenack, Hints et al. , p. 136, pl. I, fig. 24.

2010 Angochitina longicollis Eisenack, Loydell et al. , p. 271, figs. 13 (h).

2012 Angochitina longicollis Eisenack, Nestor , p. 246, fig. 4 (k).

2015 Angochitina longicollis Eisenack, Männik et al. , p. 233, fig. 6 (H).

2015 Angochitina longicollis Eisenack, Tang et al. , p. 224, figs. 3 (C–I).

2021 Angochitina longicollis Eisenack, Li et al. , p. 11, pl. IV, fig. 1.

Material: Systematic study was performed based on 217 photomicrographs.

Description: Tis chitinozoan is very slender, with a total length of 135–194 μm and a L/Dp ratio of about 1.34. Te chamber is cylindro-ovoid or cono-ovoid, with broad round flanks, margin, and base. Te flexure between the chamber and the neck is marked. Te columned neck (including a very shortly membranous collar) occupies more than 1/3 of the total length. Te spinous ornaments that cover the vesicle surface (including the basal region) are dense but become sparse near the aperture. Te spines are regular and distributed longitudinally. Broken spines indicate that these ornaments are hollow.

Measurements: Measured data based on 25 specimens.

Comparison and remarks: According to Eisenack (1959), A. longicollis is slender, with an ovoid chamber and a long neck, and it is covered by regular spines ( Nestor, 1994). Tis species is common in the Telychian. Several specimens were found in the Yangtze Platform. According to Li and Geng (1985), its neck occupies 1/2 of the total length (minimum length 193.3 μm) and widens in the direction of the aperture. Geng et al. (1997) also reported some specimens (mean length 178 μm) slightly smaller than those of Li and Geng (1985). According to Geng et al. (1997), Te Dc/Dp ratio of A. longicollis was about 0.61, which was slightly larger than those reported by Li and Geng (1985). Te spines are longitudinal, and the base of the spines may be bifurcated ( Geng et al., 1997). It should be noted that Mullins and Loydell (2001) reported that some specimens had surface ornaments showing membranes connecting the spines.

Te size and morphological features of the specimen we obtained are consistent with those of Geng et al. (1997) and some typical specimens reported by Laufeld et al. (1974), Loydell and Nestor (2005), Nestor (2012), and Verniers et al. (1995). Terefore, they are assigned to Angochitina longicollis Eisenack, 1959 .

Locality and stratigraphic horizon: A. longicollis is a globally distributed species common in the middle and upper Telychian deposits of Avalonia, Baltica, Gondwana and Laurentia ( Verniers et al., 1995), such as the Jūrmala Formation of Latvia ( Loydell & Nestor, 2005; Loydell et al., 2010), the Adavere Formation of Sweden ( Männik et al., 2015), and the Tarannon Shale Formation of Wales ( Mullins & Loydell, 2001). In the Yangtze Platform, it was found in the Shamao Formation of Hubei Province (Chen, 1996; Li et al., 2021), the Xiushan Formation of Guizhou and Hunan provinces ( Geng & Cai, 1988; Geng et al., 1997), the Fentou Formation of Jiangsu Province ( Li & Geng, 1985), and the Shenxuanyi Member of Sichuan Province ( Geng et al., 1997 and this study).

Angochitina synaphacantha ( Geng et al., 1997)

Figures

Fig. 6 Llandovery chitinozoans from the Shenxuanyi Member.Scale bars represent 50 μm (except the scale bar of specimens E, F and L represent 10 μm). A–E Angochitina cf. bipedata Geng et al., 1997 (A N40-1. B N42-2. C N39-12. D N46-23. E close-up of N39-12 showing the ornaments). F-L Angochitina hansonica Soufiane & Achab, 2000 (F close-up of N56-22 showing the ornaments. G N39-18. H N55-26. I N56-22. J N56-19. K N58-76. L close-up of N56-19 showing the ornaments).M–Q Angochitina longicollis Eisenack, 1959 (M N55-14. N N100-11. O N100-17. P N96-13. Q N91-13)