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Rotifer Identification: The Brachionidae
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Rotifer Identification: the Brachionidae
Classification Morphology:
Trophi Lorica
Identification Notes on biogeography and ecology Problems
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Brachionidae: classification
Brachionidae Ehrenberg, 1838 Anuraeopsis Lauterborn, 1900 (5 spp.) Brachionus Pallas, 1766 (63 spp.) (Kellicottia Ahlstrom, 1938 (2spp.)) Keratella Bory de St. Vincent, 1822 (48spp.) (Notholca Gosse, 1886 (40 spp.)) Plationus Segers et al., 1993 (3 spp.) Platyias Harring, 1913 (3 spp.)
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Some general features
Morphological diagnosis: Malleate trophi Trunk lorica present, dorsal and ventral plate,
fused or separate (corona features) Weak diagnosis (esp. against Epiphanidae)
strong morphological adaptability (spine production and length, size)
Identification: Ahstrom 1940, 1943, Koste 1978, Koste & Shiel 1987 and scattered literature
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Key to the genera of Brachionidae:
No foot: Lorica dorsal and ventral plate
Anterior spines: Keratella, (Kellicottia) No anterior spines, large,
drop-shaped eggs: Anuraeopsis Lorica plates fused, unci teeth differentiated:
(Notholca)
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Key to the genera of Brachionidae:
Foot present: Foot annulated, crescent-shaped manubria shaft:
Brachionus Foot pseudosegmented
Lorica flat, rounded, foot ventrally: Platyias Lorica high, foot terminally: Plationus
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Keratella Bory de St. Vincent, 1822
Morphology: Diagnosis = Lorica
Elongate, stiff Dorsal plate: transversally arched 6(4) dorso-anterior spines, median largest and curved Ventral plate bilobate anteriorly
Trophi: malleate
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Features: morphologically well-defined, ecologically diverse: pelagic and littoral; filter feeders - small algae
Identification
Dorsal lorica facettation (foundation pattern): middorsal ridge or middorsal row of facets facets, extra facets, marginal facets,…
Caudal spines: 0, 1 or 2 but beware!
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Ecology
Pelagic (no foot) to littoral Oligotrophic to Dystrophic (rarely) low to high pH freshwater to marine filter feeders on small unicellular algae Very common and numerous in eutrophic
and polluted waters
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Biogeography
Cosmopolitanism important Latitudinal variation: Northern-hemisphere
centered, Gondwanan Endemism: important, less so in Africa;
strong in Australia, South America Historical!
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Problems
Cryptic speciation?: see Keratella cochlearis - tecta group
Huge morphological variability Confused taxonomy and nomenclature
(infrasubspecific variants)
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Anuraeopsis Lauterborn, 1900
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Features: Small (!), Pelagic, microphages;Dorsal and ventral lorica plate, no spinesTypical egg mophology
Anuraeopsis Lauterborn, 1900
Key to Southeast Asian species: Lorica ornamented: A. coelata Lorica smooth
Head aperture margin smooth, body shape: A. fissa
Head aperture margin with fine serration, body shape: A. navicula
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Ecology
Pelagic (no foot) Meso- to eutrophic freshwater, thermophilic filter feeders on (very) small unicellular algae
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Brachionus Pallas, 1766
Morphology: Diagnosis = Trophi (except B. budapestinensis, B. murphyi) Lorica: trunk, not subdivided (corona)
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Features: DIVERSE: pelagic and littoral; filter feeders - algae
Identification
Number of anterior dorsal spines
(0, 2, 4, 6)
relative size and shape of anterior spines
Shape of ventral head aperture margin
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Identification
Position of foot aperture (terminal, ventral) Dorsal projection over foot aperture presence and
shape Special features
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Ecology
Pelagic to littoral Oligotrophic to Dystrophic (rarely) low to high pH freshwater to brackish filter feeders on small unicellular algae Very common and numerous in eutrophic
and polluted waters
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Biogeography
Cosmopolitanism important Latitudinal variation: tropic-centered Endemism: strong in Australia, South
America Historical!
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Problems
Cryptic speciation: see Brachionus plicatilis group (papers:)
Huge morphological variability Confused taxonomy and nomenclature
(infrasubspecific variants)
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Plationus Segers et al., 1993
One Southeast Asian species: P. patulus Lorica asymmetrical 10 anterior spines 2 postero-lateral, 2 postero-median
spines of variable length
(phenotypic plasticity!)
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Features: littoral/pelagic, filter feeders
Ecology and distribution
Littoral to (rarely) Pelagic Meso- to eutrophic cosmopolitan very common in rice fields
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Features: Lorica: Dorsoventrally compressed, round Foot: ventral, pseudosegmentedTrophi: malleate
Platyias Harring, 1913
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Features: Dorsoventrally compressed, round lorica, ventral pseudosegmented foot
Platyias Harring, 1913
Two Southeast Asian species: Platyias quadricornis and P. leloupi
Difference: dorsal lorica facettation: anterior pentagonal facet: P. quadricornis middorsal ridge: P. leloupi
Hue University Rotifer Taxonomy workshop 6-12 March 2010
Ecology and distribution
Littoral / benthonic freshwater browsers, grazers (?) P. quadricornis: cosmopolitan P. leloupi: tropical
Hue University Rotifer Taxonomy workshop 6-12 March 2010