Protoperidinium quadrioblongum Sarai

Krakhmalnyi, Aleksandr F., Krakhmalnyi, Maxim A., Terenko, Galyna V. & Goncharenko, Igor V., 2023, Dominant Species Of The Genus Protoperidinium Bergh (Peridiniales: Protoperidiniaceae) In The Black Sea, Zootaxa 5339 (5), pp. 427-448 : 441

Protoperidinium quadrioblongum Sarai , Yamaguchi, Kawami & Matsuoka 2013. Rev. Palaeobotany and Palynology 192: 117, Type C; Plate III, Table 4. ( Figs. 5, 10 ) .

Basionym: Peridinium oblongum var. symmetricum Dangeard 1927: 7–10 , Fig. 5 , Figs. 1a–1c .

Description: Cells pentagonal, with an apical and two large antapical horns. The apical pore structure of Bʹ– type ( Toriumi & Dodge 1993). The epithecal plate pattern comprises seven precingular plates (7ʹʹ), four apical plates (4ʹ), three anterior intercalary plates (3a), 1ʹ plate – “ortho”, 2a – “quadra”. The thecal surface finely reticulated, with scattered pores. The cingulum median, descending (displaced by 1.0 cingular width). The sulcus straight, broad, bears lists. Dimensions: 70–106 μm long and 50–65 μm wide.

Nomenclatural note: Sarai et al. (2013) proposed to split up Protoperidinium oblongum into three separate taxa of species rank: a) Protoperidinium quadrioblongum Sarai et al. 2013 (2a – “quadra” type), which incorporates Peridinium oblongum var. symmetricum Dangeard 1927: 7–10 , Fig. 5 and Peridinium oblongum (Aurivillius) in Lebour 1925: 121, pl XXIV, Figs. 1a–1c; b ) Protoperidinium paraoblongum Sarai et al. 2013 (2a – “penta”) incorporating Peridinium oblongum var. inaequale Dangeard 1927 , 7–10, Fig. 6 ; c) Protoperidinium latidorsale (Balech) Balech 1974 (1a – “hexa”) – Peridinium oblongum var. latidorsale Dangeard 1927 , 7–10, Fig. 7 .

Unfortunately, in publications pertaining to the Black Sea, only the species name “ Protoperidinium oblongum ” was mentioned, without specifying the variety, and presenting neither drawings nor photographs. In specimens of P. oblongum (Aurivillius) Parke & Dodge found by us, the first apical plate (1ʹ) is “ortho”, and 2a – “quadra”. Thus, taking into account the study of Sarai et al. (2013), the specimens should be assigned to P. quadrioblongum Sarai et al. 2013 . We did not observe other types of epitheca morphology in this species in the Black Sea.

Protoperidinium quadrioblongum ( P. oblongum ) is close to P. oceanicum , which is primarily distinguished by larger size (120–300 μm long and 60–150 μm wide) and relatively longer apical and antapical horns.

Distribution ( P. oblongum ): Neritic, oceanic; cosmopolitan in cold temperate to tropical waters ( Steidinger & Tangen 1997). Data on the distribution of P. oblongum are given from the GBIF.org (2022) ( Fig. 95 ).

Figures

FIGURES 1–10. Protoperidinium of the Black Sea. 1–2—P. achromaticum; 3–4, 7—P. brevipes; 5, 10—P. quadrioblongum; 6, 8–9—P. excentricum. Designations: 1ʹ—first apical plate, 2a—second intercalary plate. 4, 6–9—epifluorescence; 5, 10— transmitted light. Scale bars: 10 µm.

FIGURES 95–98. Global distribution maps of some Protoperidinium species. 95—P. oblongum; 96—P. solidicorne; 97—P. steinii; 98—P. subinerme.