taxonID	type	description	language	source
477287C0FFF4FFF0D738FF07FBD346CF.taxon	description	Figs 47 – 87 DESCRIPTION: Symmetrical prorocentroid cells, broadly to narrowly elliptic to ovate, 34.8 – 42.9 µm long, 28.6 – 33.5 µm deep and 15.0 – 21.6 µm wide. Smooth thecal surface with pores of two size classes; more densely packed towards the plate margins; posterior central pore cluster; with a narrow central area devoid of pores. Periflagellar area with 10 platelets (1, 2, 3, 4, 5, 6 a, 6 b, 7, 8 a, 8 b) and anterior projections appearing as two opposed wings. Two pyrenoids visible on one lateral side in anterior and posterior position. Encapsulated stage (two hyaline envelopes, one nesting in the other) containing up to four cells with actively beating flagella.	en	Tillmann, U., Gottschling, M., Sunesen, I., Wietkamp, S., Dzhembekova, N., Rodriguez Hernández, F., Tardivo Kubis, J., Sar, E., Kaufmann, M., Hoppenrath, M. (2024): Morphological and molecular characterization of Prorocentrum bidens (formerly known as P. compressum) and description of the closely related Prorocentrum bisaeptum sp. nov. (Prorocentrales, Dinophyceae). Phycologia 63 (5): 431-452, DOI: 10.1080/00318884.2024.2382521, URL: https://doi.org/10.1080/00318884.2024.2382521
477287C0FFF4FFF0D738FF07FBD346CF.taxon	materials_examined	HOLOTYPE: SEM-stub (designated here: CEDiT 2023 H 165) of the clonal strain Madeira deposited at Senckenberg am Meer, German Centre for Marine Biodiversity Research, Centre of Excellence for Dinophyte Taxonomy, Germany. All SEM images from this strain (Figs 67 – 87) were taken from this stub. ISOTYPE: Lugol-fixed sample of the clonal strain Madeira (CEDiT 2024 I 181) deposited at Senckenberg am Meer, German Centre for Marine Biodiversity Research, Centre of Excellence for Dinophyte Taxonomy, Germany. DNA SEQUENCE OF HOLOTYPE STRAIN: GenBank accession number: PP 873957 (ITS + LSU rRNA).	en	Tillmann, U., Gottschling, M., Sunesen, I., Wietkamp, S., Dzhembekova, N., Rodriguez Hernández, F., Tardivo Kubis, J., Sar, E., Kaufmann, M., Hoppenrath, M. (2024): Morphological and molecular characterization of Prorocentrum bidens (formerly known as P. compressum) and description of the closely related Prorocentrum bisaeptum sp. nov. (Prorocentrales, Dinophyceae). Phycologia 63 (5): 431-452, DOI: 10.1080/00318884.2024.2382521, URL: https://doi.org/10.1080/00318884.2024.2382521
477287C0FFF4FFF0D738FF07FBD346CF.taxon	etymology	ETYMOLOGY: Latin: bi = double; saeptum = enclosure, envelope; referring to the two nested, hyaline envelops enclosing the cells in the encapsulated stage.	en	Tillmann, U., Gottschling, M., Sunesen, I., Wietkamp, S., Dzhembekova, N., Rodriguez Hernández, F., Tardivo Kubis, J., Sar, E., Kaufmann, M., Hoppenrath, M. (2024): Morphological and molecular characterization of Prorocentrum bidens (formerly known as P. compressum) and description of the closely related Prorocentrum bisaeptum sp. nov. (Prorocentrales, Dinophyceae). Phycologia 63 (5): 431-452, DOI: 10.1080/00318884.2024.2382521, URL: https://doi.org/10.1080/00318884.2024.2382521
477287C0FFF4FFF0D738FF07FBD346CF.taxon	materials_examined	TYPE- LOCALITY: North-East Atlantic Ocean, south off Funchal, Madeira, Portugal (32 ° 36.36 ’ N; 16 ° 53.54 ’ W).	en	Tillmann, U., Gottschling, M., Sunesen, I., Wietkamp, S., Dzhembekova, N., Rodriguez Hernández, F., Tardivo Kubis, J., Sar, E., Kaufmann, M., Hoppenrath, M. (2024): Morphological and molecular characterization of Prorocentrum bidens (formerly known as P. compressum) and description of the closely related Prorocentrum bisaeptum sp. nov. (Prorocentrales, Dinophyceae). Phycologia 63 (5): 431-452, DOI: 10.1080/00318884.2024.2382521, URL: https://doi.org/10.1080/00318884.2024.2382521
477287C0FFF4FFF0D738FF07FBD346CF.taxon	biology_ecology	HABITAT: Open subtropical surface water. The species is part of the plankton community.	en	Tillmann, U., Gottschling, M., Sunesen, I., Wietkamp, S., Dzhembekova, N., Rodriguez Hernández, F., Tardivo Kubis, J., Sar, E., Kaufmann, M., Hoppenrath, M. (2024): Morphological and molecular characterization of Prorocentrum bidens (formerly known as P. compressum) and description of the closely related Prorocentrum bisaeptum sp. nov. (Prorocentrales, Dinophyceae). Phycologia 63 (5): 431-452, DOI: 10.1080/00318884.2024.2382521, URL: https://doi.org/10.1080/00318884.2024.2382521
477287C0FFF4FFF0D738FF07FBD346CF.taxon	materials_examined	PHYCOBANK REGISTRATION: http: // phycobank. org / 104624	en	Tillmann, U., Gottschling, M., Sunesen, I., Wietkamp, S., Dzhembekova, N., Rodriguez Hernández, F., Tardivo Kubis, J., Sar, E., Kaufmann, M., Hoppenrath, M. (2024): Morphological and molecular characterization of Prorocentrum bidens (formerly known as P. compressum) and description of the closely related Prorocentrum bisaeptum sp. nov. (Prorocentrales, Dinophyceae). Phycologia 63 (5): 431-452, DOI: 10.1080/00318884.2024.2382521, URL: https://doi.org/10.1080/00318884.2024.2382521
477287C0FFF4FFF0D738FF07FBD346CF.taxon	description	MORPHOLOGICAL DESCRIPTION Cells of P. bisaeptum were symmetrical and broadly to narrowly elliptic to ovate (narrowing slightly in the posterior cell half) in lateral view (Fig. 47 – 53). Cell size ranged from 34.8 to 42.9 µm in length and 28.6 to 33.5 µm in depth (Table 2) with a length / depth ratio of c. 1.28. Cells were laterally compressed and lens-shaped in ventral or dorsal view. Cell width ranged from 15.0 to 21.6 µm with a mean length / width ratio of c. 2.33. Cells had both a longitudinal and a wavy transverse flagellum arising from the apical periflagellar area (Fig. 47). In LM, the surface was smooth, and no ornamentation of the theca was visible except for scattered thecal pores (Fig. 50). The apical area was slightly flattened and terminated with characteristic anterior projections appearing as two opposed wings and additional central structure (s) (Fig. 47, 48). A large, round and hyaline area, the pusule, was visible in the anterior part of the cell (Fig. 47). Cells had two retiform chloroplasts (Fig. 51, 52). Two round pyrenoids per chloroplast in the anterior and posterior half of the cell were visible in LM of cells in lateral view (Fig. 49, 51, 52). A large U-shaped nucleus (Fig. 48, 54) with thick, dinokaryotic chromosomes was located in the posterior half of the cell (Fig. 47, 48, 54). Fig. 23. Right lateral view. Fig. 24. Left lateral view. Fig. 25. Ventral right-lateral view. Fig. 26. Ventral left-lateral view. Fig. 27. Apical right-lateral view. Fig. 28. Apical dorsal view. Fig. 29. Dorsal view. Fig. 30. Apical view. Fig. 31. Antapical lateral view. In culture, cells occurred in two different stages (Suppl. video V 2). The cells were either freely motile (Fig. 47) with a typical helical swimming path or in an encapsulated stage, they were enclosed with actively beating flagella in two hyaline envelopes, one nesting in the other. Each envelope was bounded by a thin, barely visible surface layer that was most distinct under phase contrast. The smaller inner envelope contained one to four cells (rarely three; Fig. 55 – 61). Single cells surrounded by only a single, narrow envelope were rarely seen (Fig. 55). Encapsulated cells, which were sometimes seen to undergo cell division by desmoschisis along the sagittal suture (Fig. 62 – 66), exhibited reduced motility (Suppl. video V 2). The flagella of these cells continued to beat, at times rotating the cells within the envelope (Suppl. video V 2). The spherical outer envelope was much larger, and of different sizes (Suppl. video V 2). Cells were occasionally observed to abandon their envelopes (Suppl. video V 2). The general appearance of the cell (Fig. 67 – 76) was confirmed by SEM revealing ultrastructural details of thecal plates and the microarchitecture of the periflagellar area. The surface of both thecal plates was smooth (rarely with faint depressions, Figs 76, 77). The intercalary bands were of varying width and striated transversally (Figs 73 – 76, 79). Thecal pores were abundant on both thecal plates, more densely packed towards the plate margins, and a narrow, central area was (nearly) devoid of pores (Fig. 67 – 76). A posterior pore cluster in the central marginal area was recognizable (Figs 70, 71, 81). Two types of pores were distinguished. Large pores with an outer round opening, a counter-sunk short cavity and at its bottom an inner round opening of smaller diameter (Fig. 77, 78). In addition, there were small pores with a round opening (Fig. 77, 78). Some pore tubes of small pores with oblique outlet ports were visible on the plate surface (Fig. 77, 78) and in some cases, these ports were V-shaped. Internal views of thick plates revealed inner pore openings of two size classes (Fig. 80, 81). The periflagellar area (Fig. 82 – 87), which was 6.0 – 7.5 µm deep and 3.0 – 4.0 µm wide (n = 13), was located in a small excavation mainly of the right thecal plate (Figs 67, 68, 73, 87). It was composed of 10 platelets (pattern: 1, 2, 3, 4, 5, 6 a, 6 b, 7, 8 a, 8 b) surrounding the fp and an ap (Fig. 82 – 87). A number of platelets had characteristic structures. Wings were the most conspicuous extensions on platelets 1 and 4 (Fig. 83, 85, 87) and sometimes platelet 8 b (Fig. 83 – 85). Platelet lists were present on the narrow platelets 2 and 6 a (Fig. 82 – 85), sometimes reaching the size of wings (Fig. 87). Platelets 3, 5 and 6 b had a protrusion at their fp margin (Fig. 82 – 84). Platelet 7 could have a platelet list bordering the ap (Fig. 82, 85). Platelet 6 was consistently split into two parts (6 a and 6 b), and platelet 8 was also split into two parts (8 a and 8 b, Fig. 85, 86), although platelet 8 a was often covered by the wing of platelet 8 b (Fig. 83, 84). The fp was irregular in shape, generally longer than wide, and surrounded by platelets 3, 5, 6 b, and 8 b (Fig. 82, 83, 86). The ap was elliptic and smaller than the fp, and was surrounded by platelets 7 and 8 a (Fig. 83, 85, 86). Molecular phylogenetics The SSU + ITS + LSU alignment was 1800 + 739 + 3490 bp long and composed of 305 + 537 + 840 parsimonyinformative sites (28 %, mean of 20.51 per terminal taxon) and 2654 distinct RAxML alignment patterns. The ML tree (– ln = 56,602.26), was highly similar to the Bayesian tree, with many nodes having high if not maximal support (Fig. 88). With respect to Dinophysales and Gymnodiniales, the studied ingroup was monophyletic (82 LBS, 1.00 BPP) and segregated into four supported monophyletic lineages, namely Adenoides Balech (100 LBS, 1.00 BPP), Plagiodinium M. A. Faust & Balech (100 LBS, 1.00 BPP) and the clades PRO 1, including the type species of Prorocentrum P. micans (93 LBS, 1.00 BPP), and PRO 2 (93 LBS, 1.00 BPP). The PRO 1 clade consisted of six well-supported lineages, two of which comprised benthic species such as Prorocentrum tsawwassenense Hoppenrath & B. S. Leander and P. emarginatum Fukuyo. Three sublineages constituted the P. cordatum (Ostenfeld) J. D. Dodge species group, the P. micans species group and the Prorocentrum triestinum J. Schiller species group. The P. bidens species group comprised P. bidens (78 LBS, 0.99 BPP) and P. bisaeptum (single accession) and showed low sequence divergence. ITS 1 sequences of P. bidens differed from those of P. bisaeptum in four positions and ITS 2 sequences in five positions and LSU sequences in four positions. No compensatory base-pair changes (CBCs) could be detected.	en	Tillmann, U., Gottschling, M., Sunesen, I., Wietkamp, S., Dzhembekova, N., Rodriguez Hernández, F., Tardivo Kubis, J., Sar, E., Kaufmann, M., Hoppenrath, M. (2024): Morphological and molecular characterization of Prorocentrum bidens (formerly known as P. compressum) and description of the closely related Prorocentrum bisaeptum sp. nov. (Prorocentrales, Dinophyceae). Phycologia 63 (5): 431-452, DOI: 10.1080/00318884.2024.2382521, URL: https://doi.org/10.1080/00318884.2024.2382521
