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Species identified:

Trigonium arcticum (Brightwell) Cleve 1868: 663

Genus: Trigonium
Taxonomic classification:

Phylum: Heterokontophyta
Subphylum: Coscinodiscophytina
Class: Coscinodiscophyceae
Subclass: Coscinodiscophycidae
Order: Stellarimales
Family: Trigoniumaceae
Genus: Trigonium (Guiry and Guiry 2024)

Type species: Trigonium arcticum (Brightwell) Cleve 1868: 663

Summary:

Trigonium is marine diatom genus that forms zig-zag chains and is most often attached to seaweeds, eelgrass and other substrates, however it is occasionally found free-floating in coastal plankton. A cosmopolitan genus found in temperate waters, but more widely distributed in warm waters. In valve view, cells are tri- to multiangular and rectangular in girdle view. Valves are slightly convex or concave and elevated at the corners; with deep, steep vertical mantles. The areolae are more-or-less simple, arranged in rows radiating from the centre, becoming smaller at the rounded angles where they form pseudocelli; closed externally by a layer of silica in which there is a ring of usually six pores, each closed by rotae. A septum is found at each corner. At high magnification small granules can often be observed. Rimoportulae low lying, clustered in the centre of the valve; their external openings are not obvious. The girdle is often deep, closed bands, containing simple pores. Plastids discoid. (Cleve 1873: 8-9; Gran and Angst 1931: 492-493, fig. 79; Hendey 1962: 109-110; Round et al. 1990: 254-255; Tiffany 2003)

Species Descriptions:

Trigonium arcticum (Brightwell) Cleve 1868: 663

Species morphology: Trigonium arcticum (Brightwell) Cleve 1868: 663
Image files: Trigonium arcticum on Z. marina-Sidney Isl-ECH-MWJuly 2021-TM4000-300x_3.tif

Characteristics and morphometric data: Found in chains, Triangular valves 77.0-84.9 µm broad. Valves with deep, steep vertical mantles. Areolae arranged in radiating rows, 6 in 10 µm in mid valve, finer towards the slightly elevated pseudocelli. Coarse striae 5-6 in 10 µm. Rounded pseudocelli at the corners with fine pores. Girdle is deep, closed bands, containing simple pores.

Found on Z. marina. Collected at Sidney Island, Southern Gulf Islands, British Columbia, Canada, July 2021.

Trigonium arcticum was previously reported in the Salish Sea by:

1. Bailey and MacKay, 1915: 172.
2. Gran and Angst, 1931: 492-493; Fig. 79.
3. Shim, 1976: 156-157, 214 & 239, Pl. 18, fig. 3.

Methods:

The collected eelgrass leaf, Zostra marina was sun dried on the deck of a sailboat. A few days later it was mounted with a carbon sticky to an SEM stub and imaged with a Hitachi table top TM4000 SEM at Advanced Microscope Facility (AMF) at the University of Victoria, B.C. Thanks go to Elaine Humphrey of the AMF, UVIC. SEM imaging by Elaine Humphrey, taxonomy and identifications by M. Webber.

References:

Bailey, L.W., and MacKay, A.H. (1915). Diatoms from the eastern coast of Vancouver Island. Trans. Roy. Soc. Can. Series 3, Vol. 9(sec. 4).

Cleve, P.T. (1867). Diatomaceer från Spetsbergen. Öfversigt af Kongl. Vetenskaps-Akademiens Förhandlingar, Stockholm 24(10): 661-670.

Cleve, P.T. (1873). On diatoms from the Arctic Sea. Bihang till Kongliga Svenska Vetenskaps-Akademiens Handlingar 1(13): 1-28, 4 pl.

Gran, H. H. and Angst, E.C. (1931). Plankton diatoms of Puget Sound. Publ. Puget Sd. Mar. Biol. Sta. 1929-1931. 7.

Guiry, M.D. in Guiry, M.D. & Guiry, G.M. 2021 & 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on October 1, 2024.

Hendey, N.I. (1964). An introductory account of the smaller algae of British coastal waters. Part V: Bacillariophyceae (diatoms). pp. [i]-xxii, 1-317. London: Ministry of Agriculture, Fisheries and Food, Fishery Investigations. Her Majesty’s Stationery Office.

Round, F.E., Crawford, R.M. and Mann, D.G. (1990), The Diatoms, Biology & Morphology of the Genera, pp. 238-239. Cambridge University Press, Cambridge, UK.

Shim, J. H. (1976). Distribution and Taxonomy of Planktonic Marine Diatoms in the Strait of Georgia, B.C. Phd. Thesis, UBC.

See https://www.planetscott.com/speciesdetail/12224/geometer-moth-geometridae-sppng12 for more info.
PLEASE NOTE: Some of my observations may not have photos. These are casual observations where a photo was not possible but the data potentially useful.

I saw these in the ground and took pics as best I could. On my way back, a kind couple was investigating and had uprooted them, and let me take pics.
The last pic is more that were growing right next to the others.