Xenusiid

Systematics

Order Archonychophora

• Archonychophora Hou & Bergstrom, 1995 – undifferentiated appendages; each segment the same as each other.
• *Luolishaniidae Hou & Bergstrom, 1995 – three small rounded sclerites per segment – these are thorn-shaped spines.
• **Luolishania Hou & Chen 1989
• **Miraluolishania Liu & Shu 2004
• *Paucipodiidae Hou et al., 2004 – with no dorsal sclerites, two claws, fine annulation and few segments.
• **Paucipodia Hou et al. 2004

Order Protonychophora

• Protonychophora Hutchinson, 1930 – spiny legs, reduced tail.
• *Aysheaiidae Walcott, 1911 – many claws on each leg. Anterior grasping appendages with long spines.
• **Aysheaia Walcott 1911
• *Xenusiidae Dzik & Krumbiegel, 1989 – >20 leg-bearing segments; paired, rounded sclerites on each segment; spiny legs.
• **Xenusion Pompeckj, 1927
• **Jianshanopodia Liu et al. – from Chengjiang; two rows of tubercles but no obvious sclerites.
• **Hadranax Budd & Peel 1998 – from the Sirius Passet. Lacks obvious dorsal armature, but bears four 'nodes' per row.

  Order Scleronychophora

• Scleronychophora Hou & Bergstrom, 1995 – paired sclerites; elongated head sclerites.
• *Eoconchariidae Hou & Shu, 1987 – ~10 leg-bearing segments, small head, sieve-like sclerites, varying in shape along body; curved claws on annulated legs; terminal mouth and anus.
• **Microdictyon Bengtson et al.
• **Quadratapora Hao and Shu, 1987
• **Fusuconcharium Hao and Shu, 1987
• *Hallucigeniidae Conway Morris, 1977 – ~10 leg-bearing segments; large sclerites covering head; sclerites on each segment are long spines.
• **Hallucigenia Conway Morris 1977 – from the Chengjiang, Kaili and Burgess Shale.
• *Cardiodictyidae Hou & Bergstrom, 1995 – many segments ; large sclerites cover head; hexagonal sclerite on each body segment.
• **Cardiodictyon Hou et al. 1991 – known from the Chengjiang.

  Order Paronychophora

• Paronychophora Hou & Bergstrom, 1995 – short, downwards facing head; papillae on body and legs, some arranged in rows; shield-like sclerites on head; dorsal armature of spines; claw-like jaws; annulated legs .
• *Onychodictyidae Hou & Bergstrom, 1995
• **Onychodictyon Hou et al. 1991

  Order unassigned

• Orstenotubulus Maas et al. 2007 – from the Furongian Orsten deposits – with retractable dorsal spines.
• Carbotubulus Haug et al. 2012 – from the Mazon creek. Dorwal armature uncertain. Few segments, long limbs.
• Mureropodia from the Stage 2 Murero lagerstatten, Spain.

  'Phylum' Onychophora