Protoperidinium pentagonum (Gran) Balech 1974

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 : 439-441

Protoperidinium pentagonum (Gran) Balech 1974 . Hydrobiolog. 4 (1): 59. ( Fig. 58 ).

References: Paulsen 1908: 59, Fig. 76 ; Lebour 1925: 112, Pl. XX, Fig. 1 a–e ; Schiller 1937: 242, Fig. 243 a–j; Kiselew 1950: 198, Fig. 337 a–g; Wood 1968: 107, Fig. 321 (as Peridinium pentagonum ); Balech 1988: 88, Lam. 27, Figs. 1–6 ; Steidinger & Tangen 1997: 545, Pl. 53; Okolodkov 2008: 122, Pl. 7, Fig. 1–2 ; Krakhmalnyi 2011: 205, Table 87, 1–12; Phan-Tan et al. 2016: 529, Fig. 7 a–f ; Al-Yamani & Saburova 2019: 320, Pl. 178.

Basionym: Peridinium pentagonum Gran 1902 . Rep. Norw. Fisch. 2 (5): 185, 190, Fig. 15 .

Synonyms: Peridinium sinuosum (Lemmermann) Lemmermann 1905 .

Description: Cells pentagonal. The epitheca flattened in dorsal view and strongly concave in ventral view; broadly triangular, with almost straight sides. The apical pore structure of Aʹ– 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 – “hexa”. The thecal surface reticulate, with pores. The cingulum convoluted, descending (displaced by about 1.5 cingular width), bordered. The sulcus curved to the left, broadens towards the antapex, slightly invades the epitheca. The hypotheca inverse trapeziform, with straight or concave sides, bears two low conical antapical horns ending in two small spines. The cytoplasm granulated, pale pink to pale reddish. Dimensions: 47.0–110.0 μm long and 58.0–111.0 μm wide.

Nomenclatural note: Protoperidinium pentagonum can be confused with P. latissimum Kofoid ( Balech 1974) , which was originally identified as a variety of this species. Protoperidinium latissimum differs from P. pentagonum by the 1ʹ plate being “meta” or “para” type instead of “ortho”, and circular or slightly descending cingulum ( Phan-Tan et al. 2016).

Distribution: Principally coastal but found in estuarine environments. Cosmopolitan in temperate to tropical waters ( Steidinger & Tangen 1997). Data on the distribution of P. pentagonum are given from the GBIF.org (2022) ( Fig. 93 ).

Figures

FIGURES 47–58. Protoperidinium of the Black Sea. 47–52—P. pellucidum; 53–54—P. subinerme; 55—P. solidicorne; 56– 57—P. pyriforme; 58—P. pentagonum. Designations: 1ʹ—first apical plate, 2a—second intercalary plate. Hypothecal pore in plate 1ʹʹʹ is marked with an arrow (47, 50). 47–49—DIC; 50–52, 56–58—epifluorescence; 53–55—transmitted light. Scale bars: 47–54 = 10 µm; 55–58 = 20 µm.

FIGURES 65–76. Protoperidinium of the Black Sea. 65–76—P. steinii. Designations: 1ʹ—first apical plate, 2a—second intercalary plate. 66–68—DIC; 69–76—epifluorescence; 65—transmitted light. Scale bars: 20 µm.

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 11–22. Protoperidinium of the Black Sea. 11–12—P. bipes; 14–15—P. brochii; 13, 16—P. crassipes; 17–19—P. claudicans; 20–22—P. depressum. Designations: 1ʹ—first apical plate, 2a—second intercalary plate. 11, 13, 15–16—DIC; 12, 14, 18–19, 22—epifluorescence; 17, 20–21—transmitted light. Scale bars: 11–12, 14–15 = 10 µm; 13, 16–22 = 20 µm.

FIGURES 86–94. Global distribution maps of some Protoperidinium species. 86—P. excentricum; 87—P. granii; 88—P. knipowitschii (Krakhmalnyi, 2011); 89—P. leonis; 90—P. mediterraneum; 91—P. pallidum; 92—P. pellucidum; 93—P. pentagonum; 94—P. pyriforme.