ALLOGROMIA SP. REVISITED: A NEW STRAIN OF A WELL-KNOWN FORAMINIFERAN

Organic-walled allogromiids are common members of foraminiferal associations in reef and back-reef settings of the Florida Keys, and many live in cryptic or otherwise protected microhabitats associated with macroalgae and seagrasses. A new strain of Allogromia sp. was isolated from the alga Dasycladus vermicularis (Scopoli) collected from prop-roots of the red mangrove in Zane Grey Creek, Long Key, Florida. Materials brushed from the surfaces of the alga were maintained at 18 - 20° C in incubators with illumination on a 12-hr cycle. This allogromiid, present in the initial collections, reproduced among the algal washings over several months. Specimens were picked individually and placed in clean, artificial seawater and then transferred through new, clean wells over several days, facilitating the removal associated microbiota and ingested food organisms. Allogromiids were then placed in cultures with the mat-forming cyanbacterium, Spriulina major Kützing. Individuals soon extruded extensive reticulopidial nets and burrowed into the mats. These foraminifera opened large areas in these mats and ultimately reproduced. These cultures have been subcultured numerous times and maintained since 2010. This taxon can also be reared on the coccolithophore Isochrysis galbana. This strain, “Allogromia sp., strain ZG”, genetically is a close match to “Allogromia sp., strain NF” that was isolated by John J. Lee and students in the 1960s from an unknown source, as well as several GenBank entries labelled as “Allogromia sp.” from sources in the Mediterranean and Caribbean. Members of these closely related populations apparently are broadly distributed and fairly easy to isolate and rear in culture. Individuals typically have a bright orange cytoplasm, high flexibility, and can assume a wide range of shapes. TEM (using high-pressure freezing followed by freeze substitution) shows that the test varies in thickness with a complex “herringbone” fine structure that microscopically resembles elastin. The number of apertures varies. In culture, this species reproduces asexually by budding and multiple fission, and sexually and by releasing numerous flagellated gametes into the surrounding medium. This life cycle differs significantly from that of Allogromia laticollaris Arnold.