taxonID	type	description	language	source
03D8878EFFA0C57B5236FBCF7F48FA1F.taxon	description	Small biflagellate coccolithophorids with a short haptonema. Periplast composed of coccoliths which are tower-like near the flagellar pole. Coccolith crystallites small triangular plates composed of three subunits. Small organic scales, always unmineralized, appear below the coccolith base-plates. Type species: Trigonaspis diskoensis The key characteristics are dimorphic (occasionally varimorphic) coccoliths that involves a tuft of tower-shaped coccoliths encircling the flagellar pole, and above all the monolayer of triangular crystallite groups that cover all coccolith surfaces. The most closely related genus is Turrisphaera Manton et al. 1976 b which is distinguished from Trigonaspis based on the presence of hexangular rather than triangular crystallite groups. Circumstantial evidence in support of this distinction has subsequently come from the discovery of combination cells (Thomsen et al. 1991) where Papposphaera spp. share a common life history with Turrisphaera spp., while species of Trigonaspis interact with species of Pappomonas (see also Thomsen and Østergaard 2014 b). Three species of Trigonaspis, viz. T. diskoensis Thomsen, 1980 a, T. minutissima Thomsen, 1980 a and T. melvillea Thomsen in Thomsen et al. (1988) have been described so far. A fourth species (Pappomonas garrisonii HOL = Trigonaspis sp.) is illustrated and discussed here based on material from the Antarctic.	en	Thomsen, Helge A., Østergaard, Jette B. (2015): Coccolithophorids in Polar Waters: Trigonaspis spp. Revisited. Acta Protozoologica 54 (2): 85-96, DOI: 10.4467/16890027AP.15.007.2732, URL: https://www.mendeley.com/catalogue/8583a3fc-c451-3f7e-8d46-3599e9c62572/
03D8878EFFA3C57C522FFE9A7999FA62.taxon	description	Triangular groups of crystallites are shown at high magnification in Figs 4, 7 – 10. In the flagellar pole coccoliths the triangles appear to be organized in a singlelayered helical pattern where one turn occupies 8 – 10 triangles (Fig. 9). The monolayer of triangles on the flattened body coccoliths (BC) also displays clear el- ements of a basic symmetrical layout involving the deposition of triangles in concentric ovals while main- taining a fairly distinct triangular matrix (Figs 4 and 7). The individual triangle, irrespective of coming from a tower-shaped or a flat coccolith, is characterized by rounded to semi-pointed corners and straight or slightly concave edges. It must be emphasized that decalcifica- tion, whether natural or accidental and caused by e. g. preparational procedures, will impact on the shape and appearance of the triangular groups of crystallites. We thus interpret the tiny central hole seen in numerous triangles as a light spot (e. g. Figs 4 and 7) as a phenom- enon caused by dissolution. There is little variation in size among triangles from either end of a single coc- cosphere when measured as the length of the edge (see Table 1). However, slight variability does occur when comparing triangle dimensions across several speci- mens. The overall range in mean value is in T. diskoensis from 0.13 – 0.16 µm with a standard deviation typically one tenth of the mean value (see Table 1). We are still inclined to believe that the interpretation of a triangle being formed by three calcite rhombohedral crystallites (Thomsen 1980 a) is correct. The texture and shadowing of the surface of an individual triangle (see e. g. Figs 4 and 9) often indicates a tripartition of the unit. Organic under layer scales are visible in places where coccoliths become separated (Fig. 4). A shared life cycle between the holococcolithophorid T. diskoensis and the heterococcolithophorid Pappomonas borealis (Manton, Sutherland and McCully 1976 a) Thomsen in Thomsen and Østergaard 2014 b, has been reported previously (Thomsen et al. 1991; Thomsen and Østergaard 2014 b). Biogeographical data on T. diskoensis is presented in Table 2.	en	Thomsen, Helge A., Østergaard, Jette B. (2015): Coccolithophorids in Polar Waters: Trigonaspis spp. Revisited. Acta Protozoologica 54 (2): 85-96, DOI: 10.4467/16890027AP.15.007.2732, URL: https://www.mendeley.com/catalogue/8583a3fc-c451-3f7e-8d46-3599e9c62572/
03D8878EFFA4C57F5236FED77991FDDD.taxon	description	The appearance of the whole cell including appendages and the overall distribution of coccoliths is accounted for in Figs 12 and 16. Numerical facts have been assembled in Table 1. The tiny cell (Fig. 12) carries a corona of slender and tower-shaped flagellar pole coccoliths while the remaining part of the cell appears to be covered by fairly identical disc-shaped and oval body coccoliths. Trigonaspis minutissima in contrast to T. diskoensis thus appears to be strictly dimorphic. The slender individual FPC is in principle still a double-flared tube (Figs 13 and 15). The triangular groups of crystallites in this species also appear to be organized in a helical pattern. A single turn of the helix in the narrowest middle part of the FPC involves only 4 – 5 triangles. The 2 D-matrix of triangles on the individual body coccolith (Fig. 14) appears in the undisturbed BC to be similarly well organized as previously reported for T. diskoensis. In contrast to T. diskoensis there is in T. minutissima a slight difference in the size of triangles among flagellar pole and body coccoliths (see Table 1), with triangles from the body coccoliths being marginally larger. A life cycle counterpart of T. minutiussima remains to be discovered. Considering the convincing similar- ity between T. diskoensis and T. minutissima in all crucial morphological features, the life cycle counterpart is likely to be a species of Pappomonas. Pappomonas flabellifera Manton and Oates 1975 which is also abun- dantly present in the Disko Bay area (Thomsen and Østergaard 2014 b) is from all perspectives a strong candidate. Biogeographical data on T. minutissima is presented in Table 2.	en	Thomsen, Helge A., Østergaard, Jette B. (2015): Coccolithophorids in Polar Waters: Trigonaspis spp. Revisited. Acta Protozoologica 54 (2): 85-96, DOI: 10.4467/16890027AP.15.007.2732, URL: https://www.mendeley.com/catalogue/8583a3fc-c451-3f7e-8d46-3599e9c62572/
03D8878EFFA7C570522FF9587AE7FE5F.taxon	materials_examined	This taxon was first described from the Weddell Sea, Antarctica, based on material from the AMERIEZ cruise (Thomsen et al. 1988). The species is here re- examined based on supplementing Antarctic material (EPOS and ANT X / 3). The appearance of the cell emphasizing appendages (flagella and haptonema) and the overall layout of the coccolith coverage is accounted for in Figs 17 and 18. Numerical facts have been assembled in Table 1. Trigonaspis melvillea has dimorphic coccoliths, viz. a tuft of highly distinct spear-shaped flagellar pole coccoliths, and oval, disc-shaped body coccoliths elsewhere. Both types of coccoliths are in accordance with the Trigonaspis genus concept covered by triangular plates of crystallites. Whereas the triangles of both T. diskoensis and T. minutissima are generally found to have either a straight or a slightly concave edge, the situation is different in T. melvillea where most triangles have slightly convex edges which endows the individual triangle with a roundish appearance (Figs 19, 20, 22). However, when examining e. g. a decalcified specimen, as illustrated in Fig. 21, it is very evident from the organic matrix remaining, that the basic geometry is a distinct triangular shape. The triangle edge length in T. melvillea is markedly smaller than observed in both T. diskoensis and T. minutissima (see Table 1). The organization of triangles in the FPC is strictly pyramidal when examining the distal spear-shaped termination of the coccolith, while the shaft seems to be carrying triangles organized in the same helical pattern that has previously been described for both T. diskoensis and T. minutissima. The organization of triangles on a BC deviates in T. melvillea from the concentric and closely abutted layout that characterizes both T. diskoensis and T. minutissima. In T. melvillea the triangles are thus organized in an open mesh structure comprising interwoven pentagonal (see Thomsen et al. 1988, l. c. Fig. 29) or hexagonal rings (Fig. 22). Unmineralized under layer scales are fre- quently observed (e. g. Figs 20 and 23). So far there is no evidence for life history events implicating a phase shift between the holococcolithophorid T. melvillea and a species from the heterococcolithophorid genus Pappomonas. Two candidate species of Pappomonas occur (Thomsen and Østergaard 2014 b) within the geographic realm of T. melvillea, viz. P. weddellensis Thomsen in Thomsen et al. 1988 and P. garrisonii Thomsen and Østergaard 2014 b. It is ar- gued below that P. garrisonii enters into a shared life history with an undescribed Trigonaspis sp. that deviates markedly from T. melvillea, thus leaving P. weddellensis as a strong candidate for sharing a life history with T. melvillea. Biogeographical data on T. melvillea is presented in Table 2.	en	Thomsen, Helge A., Østergaard, Jette B. (2015): Coccolithophorids in Polar Waters: Trigonaspis spp. Revisited. Acta Protozoologica 54 (2): 85-96, DOI: 10.4467/16890027AP.15.007.2732, URL: https://www.mendeley.com/catalogue/8583a3fc-c451-3f7e-8d46-3599e9c62572/
