Calliacantha longicaudata (Leadbeater, 1975) Leadbeater, 1978. Choanoflagellates, lorica of which consists of a single chamber, 15-17 microns long x 6-8 microns wide, composed: of 5 (sometimes locally 4 or 6) longitudinal costae, each of 2 linearly attached slender cylindrical costal strips overlapping where they join, delimited anteriorly by 2 transverse costae, one terminal and the other parallel to it at about one sixth I of the length of the chamber behind it, transverse costal strips of both rings joined by their ends to the subtending longitudinal costae, at the posterior end, the longitudinal costae converging to subtend a caudal appendage of exceptional length (up to 100 microns) composed of up to 13 linearly attached costal strips overlapping at their ends and becoming thinner distally. The cell is enclosed by a conical membrane within the lorica chamber, attached to its base and equalling it in length, width when full 3-5 microns, the single flagellum exceeding 20 microns in length, surrounded by a ring of about 40 tentacles up to 6 microns in length, sometimes with terminal swellings.
