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Updated: May 26, 2026
Laboratory Protocol for Genetic Gut Content Analyses of Aquatic Macroinvertebrates Using Group-specific rDNA Primers
Published on: October 5, 2017
A contemporary evaluation of the acrasids (Acrasidae, Heterolobosea, Excavata)
Matthew W Brown1, Jeffrey D Silberman, Frederick W Spiegel
1Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, USA. protist@live.com
Abstract:
Sorocarpic protists are organisms that individually aggregate and work together to form a fungus-like fruiting body (sorocarp). The amoeboid forms are often colloquially referred to as "cellular slime molds" or "acrasids". We argue the latter term should be used only to refer to members of Acrasidae in Heterolobosea. Here we study the diversity of two Acrasidae genera, Acrasis and the closely similar Pocheina, using a combination of morphological characteristics and small subunit rRNA gene sequences. A total of eight isolates of Acrasis and an example of Pocheina were examined. Acrasis/Pocheina form a well-supported monophyletic group that is the highly supported sister to a clade containing Allovahlkampfia and several other amoebae. Four molecular lineages of Acrasis were resolved, each of which is characterized by a distinctive fruiting body morphology. Each lineage represents a species, two of which are novel, Acrasis kona n. sp. and Acrasis takarsan n. sp. An isolate identified as Pocheina rosea is nested within the clade containing isolates of the taxon Acrasis rosea, into which P. rosea is tentatively subsumed. One member of the tightly knit allovahlkampfid clade was induced to form a simple sorocarp, leading us to include this clade in Acrasidae.
Insights
This study reveals new species of sorocarpic protists, Acrasis kona and Acrasis takarsan, expanding our understanding of cellular slime mold diversity. The research clarifies the Acrasidae family classification using molecular and morphological data.
Area of Science:
- Protistology
- Mycology
- Evolutionary Biology
Background:
- Sorocarpic protists, or cellular slime molds, form complex fruiting bodies.
- The classification of the Acrasidae family requires further molecular and morphological investigation.
Purpose of the Study:
- To investigate the diversity within the Acrasidae genera Acrasis and Pocheina.
- To clarify the taxonomic placement of Pocheina within the Acrasidae family.
Main Methods:
- Morphological characterization of sorocarp formation.
- Small subunit rRNA gene sequencing for molecular phylogenetic analysis.
- Examination of eight Acrasis isolates and one Pocheina isolate.
Main Results:
- Four distinct molecular lineages of Acrasis were identified, each with unique fruiting body morphology, representing new species: Acrasis kona n. sp. and Acrasis takarsan n. sp.
- Pocheina rosea was found to be nested within the Acrasis rosea clade, suggesting its subsumption into Acrasis.
- A related allovahlkampfid clade was induced to form sorocarps, leading to its inclusion in Acrasidae.
Conclusions:
- The Acrasis/Pocheina group forms a well-supported monophyletic clade, sister to Allovahlkampfia.
- The study expands the known diversity of Acrasis and refines the classification of the Acrasidae family.
- The findings support the use of "acrasids" specifically for members of Acrasidae in Heterolobosea.
