Clade for ASCHELMINTHES=PSEUDOCOELOMATES
The ASCHELMINTHES. A grouping of convenience; probably not monophyletic; tree & most characters from Nielson 1994 p. 62, 235, 262.
==T=======(placement uncertain)== Tardigrada (water bears) | | ===3=============== Rotifera (rotifers= "wheel bearers") |====2========| <<==1===| ===4=============== Acanthocephala (spiny headed worms) | | =============6=============== Gastrotricha (gastrotrichs, hairy-belly worms) | | =5==| ===9=============== Nematoda (round worms) | ===8==| | | ==10=============== Nematomorpha (horsehair worms) | | =7==| ==12==(uncertain)== Priapula (penis worms) | | ==11==| ===14======== Kinorhyncha (spiny-snout propelled worms) ==13==| ===15======== Loricifera (corset-bearer worms)
(** plesiomorphic- a primitive state, not unique to clade): b) tri-radiate, myo-epithelial sucking pharynx c) cleavage not spiral or radial b) pseudocoelom c) bilaterally asymmetrical, determinate cleavage d) mesoderm from blastopore rim e) direct development without ciliated primary larva f) protonephridia** b) sperm structure b) one ventral nerve cord b) apical proboscis with intracellular hooks c) two lateral nerve cords b) radial pharynx c) tripartite epipharyngeal brain b) pseudocoelom lost c) two lateral nerve cords |
b) cuticle molted c) introvert with cuticular spines, teeth or scalids b) protonephridia lost c) circular trunk muscles lost d) non-ciliated sperm b) four nerve cords (dorsal, ventral, 2 lateral) b) no amphids c) one ventral nerve cord b) rings of scalids on introvert c) chitinous cuticle d) one ventral nerve cord b) circular trunk muscles lost b) tri-radiate, myo-epithelial sucking pharynx |
Back to Zool 250 version of tree for animal phyla