On the evolution and morphology of the rotiferan trophi, with a cladistic analysis of Rotifera

Abstract

The phylogeny of Rotifera was examined in different computer‐generated cladistic analyses, including Seisonidea, Bdelloidea, Flosculariacea, Collothecacea and all ploimids treated on family level. The analyses were based on a character matrix solely dealing with morphological characters, primarily based on the trophi morphology. Limnognathia maerski (Micrognathozoa), Rastrognathia macrostoma and Gnathostomula paradoxa (Gnathostomulida) were used as outgroups. The cladistic analysis performed by paup produced 288 most parsimonious trees. peewee analyses produced between 140 and 432 trees, depending on the concavity value. The monophyly of Eurotatoria, Monogononta and Ploima was confirmed in all obtained trees. All analyses suggested a division of Ploima into major clades. One clade corresponded to Transversiramida while the other contained all other ploimid taxa and recognized Antrorsiramida as a monophylum. Based on the obtained results a scenario for the trophi evolution is proposed. The analyses suggested that the presence of an incus is synapomorphic for Gnathifera while mallei are synapomorphic for Micrognathozoa and Rotifera. The ancestral rotifer trophi probably resembled those in Harringia (Asplanchnidae).

A modern approach to rotiferan phylogeny: Combining morphological and molecular data

“…All analyses of morphological, molecular, and combined data supported monogonont monophyly, which agrees with nearly all previous studies (Wallace and Colburn, 1989;Nogrady et al, 1993;Melone et al, 1998a;Sørensen, 2002). The clade is well supported morphologically, and obtains the highest possible jackknife support and posterior probability in the combined analyses of all data (Figs.…”

“…The morphological analysis could not resolve the overall relationships within Ploima (55% JF). However, the strict consensus tree shows monophyly for all taxa with malleate trophi, which form a clade that corresponds to the Transversiramida of Markevich (1989) (see also Sørensen, 2002). Furthermore, monophyly is supported for several clades at the generic and/or family level, i.e., Lindiidae, Dicranophoridae, Trichocercidae, Lecanidae, Mytilinidae, Euchlanidae, Lepadellidae, Trichotriidae, and Brachionidae.…”

“…Three major clades are usually recognized within Rotifera: Seisonidea, Bdelloidea, and Monogononta (Wallace and Colburn, 1989;Wallace and Snell, 1991;Melone et al, 1998a;Sørensen, 2002). Seisonidea comprises only three species in the genera Seison and Paraseison .…”

“…Since 1970, only three studies, Markevich (1989), Melone et al (1998a), and Sørensen (2002), have dealt with the relationships of bdelloid and/or monogonont rotifers, and only the two latter were based on modern numerical methods. Melone et al (1998a) focused solely on bdelloid interrelationships, whereas Markevich (1989) and Sørensen (2002) included most families of rotifers. Both studies produced some congruent results, especially concerning the relationships within the diverse and species-rich monogonont clade Ploima.…”

Application of the minute monogonont rotifer proales similis de Beauchamp in larval rearing of seven-band grouper epinephelus septemfasciatus

“…Food quantity was determined by counting the number of undigested rotifer bodies as well as the trophi of digested rotifers (Akazawa et al, 2008). Trophi are the calcified jaws located at the beginning of the digestive tracts of rotifers (Kleinow et al, 1990;Kleinow, 1998;Sorensen, 2002), and they remain undigested after the other relatively soft parts of the rotifer have been digested, thus providing a more accurate estimation of food quantity. The survival rate of the larvae in all treatments was estimated by counting the number of surviving larvae at the end of the experiment.…”