Trigonaspis sp.

Thomsen, Helge A. & Østergaard, Jette B., 2015, Coccolithophorids in Polar Waters: Trigonaspis spp. Revisited, Acta Protozoologica 54 (2), pp. 85-96 : 94

Trigonaspis sp. (= Pappomonas garrisonii (HOL) Thomsen and Østergaard 2014b )

A new species of Trigonaspis was encountered in AMERIEZ, EPOS and ANT X/3 samples from the Weddell Sea, Antarctica. A complete cell with flagella and haptonema is shown in Fig. 24 . The tower-shaped coccoliths are present on the entire cell surface and most prominently developed at the flagellar pole. In terms of general appearance of the tower-shaped coccoliths ( Fig. 25 ) it is obvious that these are very reminiscent of those of T. minutissima ( Fig. 13 ). Body coccoliths are rarely observed. However, we believe that the coccolith pointed out in Figs 25 represents a disc shaped body coccolith. The shape of the individual triangle (rounded corners and concave edges) is very similar to what has been described for T. diskoensis and T. minutissima . However, the Trigonaspis sp. triangles are somewhat larger than those found in both T. diskoensis and T. minutissima (see Table 1).

Circumstantial evidence exists that links Trigonaspis sp. with Pappomonas garrisonii Thomsen and Østergaard 2014b . It is obvious from the documentation pro- vided in terms of combination cells (see Thomsen and Østergaard 2014b; l.c. Figs 43–45) that the Trigonaspis counterpart of P. garrisonii possesses tower-shaped coccoliths very reminiscent of those described here for Trigonaspis sp. , and it is furthermore evident that the size of the triangles also matches those of Trigonaspis sp. in overall size (see Table 1) and appearance.

Due to the overarching possibility that Trigonaspis sp. is in fact the life history counterpart of P. garrisonii we have refrained from formally describing the species. We recommend that this taxon is in the future referred to informally as P. garrisonii HOL.

Biogeographical data on P. garrisonii HOL is presented in Table 2.

Figures

Figs 24–26. Trigonaspis sp. (= Pappomonas garrisonii HOL?). TEM whole mounts from the Weddell Sea, Antarctica. 24 – whole cell with curled up flagella and haptonema. Tower-shaped but differently sized coccoliths occur over the entire surface of the cell; 25 – detail (from Fig. 24) of tower-shaped coccoliths showing the triangular crystallite groups. Arrow points to a body coccolith; 26 – part of body coccolith calcification. Reversed printing.

Figs 12–16. Trigonaspis minutissima. TEM whole mounts from West Greenland (Arctic Station). 12 – whole cell with partly detached coccoliths; 13 – detail from Fig. 12 of flagellar pole coccoliths showing triangular crystallite groups and slender towers wreathed with 4–5 of these in a random transect; 14 – detail of body coccolith from the cell shown in Fig. 12; 15 – detail of coccoliths from the cell shown in Fig. 16; 16 – whole cell with flagella and curled up haptonema.