Thalassiosira dolmatovae Oreshkina ex A. Gladenkov, 2013
publication ID |
https://doi.org/ 10.11646/phytotaxa.127.1.12 |
persistent identifier |
https://treatment.plazi.org/id/EB2B87FA-E71E-FF87-58C5-C24CFDE7FA34 |
treatment provided by |
Felipe |
scientific name |
Thalassiosira dolmatovae Oreshkina ex A. Gladenkov |
status |
sp. nov. |
Thalassiosira dolmatovae Oreshkina ex A. Gladenkov sp. nov. ( Figs. 4–29 View FIGURES 4–10 View FIGURES 18–23 View FIGURES 24–29 )
Synonyms:— Thalassiosira sp. 9 Dolmatova 1992b (p. 86, pl. 30, figs. 1–5); Thalassiosira dolmatovae Oreshkina 1992 (p. 129, pl. XL, figs. 7, 8), invalid species name.
Valves circular, slightly convex to almost flat, diameter 12–37 µm. On valve face size of the areolae gradually decreases from the centre (3–5 areolae in 10 µm) towards the margin, in irregular, concentric wavy arrangement. Abrapt change in areolae pattern at marginal zone, up to 19–25 areolae in 10 µm near the margin, arranged in sublinear to tangental rows. Margin is hyaline, 0.7–1.5 µm wide. Simple external (occluded) processes are scattered on the valve face between areolae. One single strutted process occurs near the valve center between two areolae, one of which has a smaller size than other central areolae. 4–6 strutted processes in 10 µm are located along the margin zone near the boundary between valve face and low mantle. Internal openings of central and marginal strutted processes are surrounded by 4 satellite pores. External opening of central process as a simple rounded opening, and marginal processes have external extensions. One single labiate process is located at the margin and enclosed by two strutted processes. External opening of labiate process is simple.
Type:— USA. Alaska: Sandy Ridge stratigraphic section of the Alaska Peninsula, Milky River Formation, 56° 70' N, 159° 92' W, material from 28 m above an angular unconformity with the underlying Bear Lake Formation , ( Circled specimen ( Fig. 4a–c View FIGURES 4–10 ) on slide Slide 608382/1, Sample # CAS 608382 About CAS , ( Geological Institute , Russian Academy of Sciences , Moscow, Russia), holotype, designated here; circled specimen ( Fig. 5 View FIGURES 4–10 ) on Slide #608382/2, Sample # CAS 608382 About CAS , ( Geological Institute , Russian Academy of Sciences , Moscow, Russia), isotype, designated here; material from 139.9 m above an angular unconformity with the underlying Bear Lake Formation , circled specimen ( Fig. 8a– b View FIGURES 4–10 ) on Slide #608400/1, Sample # CAS 608400 About CAS (Geological Institute, Russian Academy of Sciences, Moscow, Russia), paratype, designated here ).
Occurrence: —Marine neritic species. Marine deposits of the latest Miocene to early Pliocene (the North Pacific Neodenticula kamtschatica diatom Zone) of the Alaska Peninsula, southwestern Alaska; the latest Miocene to late Pliocene (the Neodenticula kamtschatica Zone to Neodenticula koizumii Zone ) of Karaginsky Island, northeastern Kamchatka.
Remarks: —This species is distinguished from Thalassiosira baldaufii Bodén (1993: 68) by the presence of one single central strutted process on the valve face, by the absence of prominent marginal occluded processes, and by areolae pattern. It is similar to Thalassiosira labimarginata Bodén (1993: 68) but differs by larger valve diameter, wider hyaline margin, and size of areolae and their arrangement.
Etymology: —The species is named in honour of Dr. Lora M. Dolmatova who studied fossil diatoms from Russian Far East during many years.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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