A Morphologically Simple Species of Acrasis (Heterolobosea, Excavata), Acrasis helenhemmesae n. sp.

Abstract

In the course of a large-scale global survey of mycetozoans, amoeboid organisms that form fruiting bodies, a new species of Acrasis was discovered from several subtropical locales in Hawaii, Australia, Bermuda, and South Africa. We isolated four strains from dead, still attached, plant material, and one strain from attached bark of a tree. Each isolate forms simple uniseriate multicellular fruiting bodies typically consisting of two bottle-shaped, basal stalk cells and a chain of <20 spores. The isolate from Bermuda often forms dichotomous simple branches, each consisting of <10 spores. Amoebae from these new isolates are limax with eruptive pseudopodial formation and display rapid locomotion-characters indicative of amoebae in the excavate taxon Heterolobosea. These isolates form simpler fruiting bodies than is typical of the well-known Acrasis rosea. Although in the original description, A. rosea is known to form uniseriate fruiting bodies similar to our isolates, A. rosea isolates typically form more complex fruiting structures along side simple ones, but never strictly simple ones. Nuclear-encoded 18S rRNA gene phylogenies demonstrate that our five isolates form a highly supported clade that is sister to A. rosea. Given the differences both in gene sequences and fruiting body morphology between our isolates and A. rosea, we propose the new species, Acrasis helenhemmesae n. sp.

Molecular characterization of a new member of the lariat capping twin-ribozyme introns

“…BA as a very close relative to Allovahlkampfia spelaea , owing to almost identical SSU rRNA gene sequences, and as a sister species to the Acrasid slime moulds, but clearly distinct from the free-living Naegleria amoeboflagellates [26,27]. Thus, we renamed the Heterolobosea sp.…”

“…Asp.S516 appears optional in Allovahlkampfia sp. since only the BA isolate harbours an intron at the S516 site [27]. …”

Coprophilic amoebae and flagellates, including Guttulinopsis, Rosculus and Helkesimastix, characterise a divergent and diverse rhizarian radiation and contribute to a large diversity of faecal‐associated protists

“…Amplification utilised 200 ng of gDNA, 0.3 lM final concentration of each primer and Q5 DNA polymerase (New England Biolabs) in a total volume of 25 ml and the following cycling conditions: initial denaturation of 988C 10 s, followed by 32 cycles of 98 C 30 s, 428C 45 s, 728C 3 min, following the manufacturer's recommended reaction conditions. The PCR reaction was electrophoresed through 1% agarose and product purified from gel slice as described in Brown et al (2010). Sanger sequencing on an ABI 3130xl and BigDye v3.1 chemistry was used to sequence the amplicon in both directions with specific internal primers.…”

Diversity of Heterolobosea

“…When starving, the amoebae aggregate to form sorocarps (Bonner, 2003). Both slightly different cell types of the fruiting body (basal stalk cells and distal spore cells) are capable of germination through excystment (Bonner, 2003;Brown M.W. et al, 2010).…”