Triceratium hardmannianum (spelt hardmanianum on the slide) from Joe’s River, Barbados. Single example on the slide. Prepared by Samuel Henry Meakin. Mounted in Styrax, December 1933. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 43 images stacked in Zerene (Pmax).
I have another example of this rare and unusual looking diatom on this site and it is worth providing some additional information about it. There seems to historically be two possible spellings for this diatom – T. hardmannianum and T. hardmanianum. It was reported in Greville, R.K. (1865). Descriptions of new and rare diatoms. Series XVI . Transactions of the Microscopical Society, New Series, London 13: 43-57 [last page as “75”], 2 pls [pls V, VI]. It is also known as Crawfordia radiata and Crawfordia hardmanniana and is discussed in; Sims, P.A., Witkowski, J. & César, E.A. (2021). Crawfordia gen. nov.: solving the riddle of Triceratium hardmannianum Grev. (Bacillariophyta). Nova Hedwigia, Beiheft 115: 205-221, 7 pls, 2 tables. The complexity around naming seems to come from it being found attached to frustules of C. radiata so it is perhaps one half of a complete C. radiata and should be referred to as ‘hardmanniana valves’.