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Alterbidinium daveyi
From Fensome et al., 2019:
Alterbidinium daveyi (Stover and Evitt, 1978, p.93) Lentin and Williams, 1985, p.14.
Name not validly published: holotype not designated.
Originally Alterbia (name not validly published), subsequently Alterbidinium (name not validly published).
Age: Albian–Cenomanian.
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Dodsworth et al., 2020:
Alterbidinium daveyi basionym nov.
Derivation of name. In honour of the palynologist Roger J. Davey.
Designation of holotype. Davey (1970, plate 1, fig. 3). Location, International Yarbo Borehole no. 17, SE Saskatchewan, Canada (coordinates supplied by Davey 1969, p. 115, fig. 8, are; ‘east of Regina at Lsd. 1, Sec. 24, Twp. 20, Rg. 33, W1st Meridian’). Sample depth 254.5 m (835 ft) below Kelly Bushing, Second White Specks Shale, Colorado Group. The slide is curated at the Natural History Museum, London (slide/specimen reference number V.51979).
Description. See Davey (1970, p. 338).
Discussion. Davey (1970, pl. 1, figs 3, 4, p. 338) described. specimens from Cenomanian deposits in Saskatchewan that he assigned to Deflandrea (now Subtilisphaera) pirnaensis. He pointed out differences with the type material of S. pirnaensis, as described by Alberti (1959) from Turonian deposits in Germany, including a smaller size, length 46 (62.7) 87 μm (compared with 80–106 μm) and width, 34 (45.5) 63 μm (compared with 58–64 μm), and presence of an archaeopyle in many Saskatchewan specimens but absence of one in the type specimens. It is also noted here that the holotype of S. pirnaensis (Alberti 1959, pl. 8, fig. 1) has possible pre- and postcingular tabulation that is absent from the Saskatchewan specimens. Stover and Evitt (1978) proposed a new species, Alterbia daveyi, based on the specimens illustrated in Davey (1970) but did not designate one of the specimens as a holotype. The name was therefore not validly published (Fensome et al. 2019). Subsequently, the genus Alterbia has been considered an illegitimate name and its species have been transferred to the genus Alterbidinium (Fensome et al. 2019). Alterbidinium ‘daveyi’ has become widely accepted as a separate but informal species. The designation herein of one of the specimens illustrated in Davey (1970) as a holotype, gives it formal status.
Alterbidinium daveyi and Eurydinium saxoniense have comparable morphology, and both possess a single intercalary (2a) plate archaeopyle that is steno- to iso-deltaform. Alterbidinium daveyi may be slightly larger (cf. length, 52– 66 μm, and width, 37–54 μm for E. saxoniense; Marshall and Batten 1988) and appears to have a more strongly developed apical horn and cingulum than E. saxoniense, but intergradations may occur. The cingulum in A. daveyi is marked by low ridges that sometimes possess pustules distally and is occasionally crossed by low ridges delimiting plate boundaries (Davey 1970, p. 338); the latter features are not reported in E. saxoniense. The holotype of A. daveyi appears to show some anterior dorsal intercalary tabulation (2a and 3a plate boundaries). Dorsal tabulation is usually restricted to the archaeopyle in E. saxoniense (Marshall and Batten 1988), though our illustrated specimen (Fig. 5.6) may possess sutures around both 2a and 3a intercalary plates.
The eastern England specimens inspected in this paper and previous studies have been assigned to E. saxoniense, although the additional presence of A. daveyi cannot be ruled out. The dinoflagellate cyst distribution charts of Marshall and Batten (1988) indicate an absence of A. daveyi and the common to abundant occurrence of E. saxoniense from the (post-Plenus) CTB interval in NW Germany. Conversely, in coeval deposits from North America, A. daveyi (sometimes recorded as S. pirnaensis) is prominent (Bloch et al. 1999, fig. 23; Dodsworth 2000, 2016; Harris and Tocher 2003; Dodsworth and Eldrett 2019). In the Shetland Group of Northern Europe, both A. daveyi and E. saxoniense are common, e.g. in Norwegian well 35/6-2 S, where confident differentiation between the species can be problematic for some specimens.
Alterbidinium daveyi (Stover and Evitt, 1978, p.93) Lentin and Williams, 1985, p.14.
Name not validly published: holotype not designated.
Originally Alterbia (name not validly published), subsequently Alterbidinium (name not validly published).
Age: Albian–Cenomanian.
---------------------------------------------------------------------------------------------------
Dodsworth et al., 2020:
Alterbidinium daveyi basionym nov.
Derivation of name. In honour of the palynologist Roger J. Davey.
Designation of holotype. Davey (1970, plate 1, fig. 3). Location, International Yarbo Borehole no. 17, SE Saskatchewan, Canada (coordinates supplied by Davey 1969, p. 115, fig. 8, are; ‘east of Regina at Lsd. 1, Sec. 24, Twp. 20, Rg. 33, W1st Meridian’). Sample depth 254.5 m (835 ft) below Kelly Bushing, Second White Specks Shale, Colorado Group. The slide is curated at the Natural History Museum, London (slide/specimen reference number V.51979).
Description. See Davey (1970, p. 338).
Discussion. Davey (1970, pl. 1, figs 3, 4, p. 338) described. specimens from Cenomanian deposits in Saskatchewan that he assigned to Deflandrea (now Subtilisphaera) pirnaensis. He pointed out differences with the type material of S. pirnaensis, as described by Alberti (1959) from Turonian deposits in Germany, including a smaller size, length 46 (62.7) 87 μm (compared with 80–106 μm) and width, 34 (45.5) 63 μm (compared with 58–64 μm), and presence of an archaeopyle in many Saskatchewan specimens but absence of one in the type specimens. It is also noted here that the holotype of S. pirnaensis (Alberti 1959, pl. 8, fig. 1) has possible pre- and postcingular tabulation that is absent from the Saskatchewan specimens. Stover and Evitt (1978) proposed a new species, Alterbia daveyi, based on the specimens illustrated in Davey (1970) but did not designate one of the specimens as a holotype. The name was therefore not validly published (Fensome et al. 2019). Subsequently, the genus Alterbia has been considered an illegitimate name and its species have been transferred to the genus Alterbidinium (Fensome et al. 2019). Alterbidinium ‘daveyi’ has become widely accepted as a separate but informal species. The designation herein of one of the specimens illustrated in Davey (1970) as a holotype, gives it formal status.
Alterbidinium daveyi and Eurydinium saxoniense have comparable morphology, and both possess a single intercalary (2a) plate archaeopyle that is steno- to iso-deltaform. Alterbidinium daveyi may be slightly larger (cf. length, 52– 66 μm, and width, 37–54 μm for E. saxoniense; Marshall and Batten 1988) and appears to have a more strongly developed apical horn and cingulum than E. saxoniense, but intergradations may occur. The cingulum in A. daveyi is marked by low ridges that sometimes possess pustules distally and is occasionally crossed by low ridges delimiting plate boundaries (Davey 1970, p. 338); the latter features are not reported in E. saxoniense. The holotype of A. daveyi appears to show some anterior dorsal intercalary tabulation (2a and 3a plate boundaries). Dorsal tabulation is usually restricted to the archaeopyle in E. saxoniense (Marshall and Batten 1988), though our illustrated specimen (Fig. 5.6) may possess sutures around both 2a and 3a intercalary plates.
The eastern England specimens inspected in this paper and previous studies have been assigned to E. saxoniense, although the additional presence of A. daveyi cannot be ruled out. The dinoflagellate cyst distribution charts of Marshall and Batten (1988) indicate an absence of A. daveyi and the common to abundant occurrence of E. saxoniense from the (post-Plenus) CTB interval in NW Germany. Conversely, in coeval deposits from North America, A. daveyi (sometimes recorded as S. pirnaensis) is prominent (Bloch et al. 1999, fig. 23; Dodsworth 2000, 2016; Harris and Tocher 2003; Dodsworth and Eldrett 2019). In the Shetland Group of Northern Europe, both A. daveyi and E. saxoniense are common, e.g. in Norwegian well 35/6-2 S, where confident differentiation between the species can be problematic for some specimens.