Bairdianella cuspis Buschmina 1970
- Dataset
- Late Devonian-early Carboniferous ostracods (Crustacea) from South China: taxonomy, diversity and implications
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Arthropoda
- class
- Ostracoda
- order
- Podocopida
- family
- Bairdiidae
- genus
- Bairdianella
- species
- Bairdianella cuspis
description
Dimensions RV: L = 460 – 575 µm, H = 188 – 247 µm, H / L = 0.37 – 0.45. LV: L = 460 – 587 µm, H = 201 – 255 µm, H / L = 0.38 – 0.48.
description
Fig. 11 P
discussion
Remarks Our material is smaller than the holotype shown in Buschmina (1970: pl: 5 fig. 2) with L = 625 µm, H = 325 µm, H / L = 0.52. Specimens shown in Kotschetkova & Janbulatova (1987: pl. 24 fig. 1) from Mugodzhary, Western Kazakhstan and Sobolev (2020: figs 5, 9 – 10 )) from Pechora Uplift, Russia, have a similar size to our material with respectively L = 532 µm, H = 250 µm and H / L = 0.47 and L = 580 µm, H = 280 µm, H / L = 0.48. However, the specimen shown in Zhuravlev & Sobolev (2019) from North Ural is slightly larger than the present material with L = 580 µm, H = 275 µm and H / L = 0.47 but still smaller than the holotype in Buschmina (1970). The size variations in our material indicate that at least two stages are present and may correspond to juveniles, compare to the holotype in Buschmina (1970), but the wide distribution of the dimensions of the specimens does not allow to clearly discriminate them. Five species have been mentioned as Bairdianella aff. cuspis in papers discussing Devonian – Carboniferous ostracod faunas, they are summarized in Table 3. Based on specimens shown in these different contributions, the main differences between these species and Bairdianella cuspis Buschmina, 1970 seem to be weak variations of the length of the carapace, concavity at VB, degree of postero-dorsal angulation, posterior end more or less rounded and AVB sometimes truncated (visible only on Bairdianella sp. A, aff. cuspis Buschmina, 1970 in Casier et al. 2004). Specimens of Bairdianella aff. cuspis Buschmina, 1970 sensu Kotschetkova & Janbulatova 1987 in Casier et al. (2002), Bairdianella sp. A, aff. cuspis Buschmina, 1970 in Casier & Préat (2003) and Bairdianella sp. B, aff. cuspis Buschmina, 1970 in Casier et al. (2004) are also larger than the holotype but others had sizes similar to our material so may also correspond to juveniles. These differences do not seem sufficient to reasonably distinguish these forms from the species described by Buschmina (1970). However, only one specimen is shown in each of these papers with no discussion on possible other specimens, ontogenetic and intraspecific variations within the material or comparisons between these different species. Only a complete review of these taxa, based on close observations of all these specimens, can clarify this major issue. For this reason, they are kept as distinct species.
distribution
Occurrence Gengis horizon, Yeltsov synclinorium, South of Occidental Siberia, early Carboniferous (Buschmina 1970). Berchogur section, Mugodzhary, Western Kazakhstan, Devonian – Carboniferous transition (Kotschetkova & Janbulatova 1987). Kamenka River section, North Urals, Russia, Famennian – Tournaisian, late Devonian – early Carboniferous (Zhuravlev & Sobolev 2019). Yjid-Kamenka river section, Pechora Uplift, Russia, Famennian – Tournaisian, late Devonian – early Carboniferous (Sobolev 2020). Samples 19 BAI 01 - 03, 19 BAI 05, 19 BAI 37, 19 BAI 39, 19 BAI 44, Tangbagou Formation, Blue Snake section, Tournaisian, early Carboniferous (this work).
materials_examined
Material examined CHINA • 1 complete carapace (Fig. 11 P); Blue Snake section, Tangbagou Formation, sample 19 BAI 03; P 6 M 3973 • 25 complete carapaces; Blue Snake section, Tangbagou Formation, samples 19 BAI 01 - 03, 19 BAI 05, 19 BAI 37, 19 BAI 39, 19 BAI 44. All from the Tournaisian, early Carboniferous.
Name
- Homonyms
- Bairdianella cuspis Buschmina 1970