異蟲綱（學名：Xenusia）是一類生存在古生代海洋中的已滅絕動物，是葉足動物的代表演化支，可能包括有爪動物的祖先。模式屬是異蟲屬（_Xenusion_）。它們具有相對較大的環狀圓柱形的身體，它們的葉足基部有結節。有些附肢較大，這些埋藏的化石生物資訊能夠做為其代表。它們的口器在軀體末端或接近末端，它們曾經生活在全球各地的海洋中。它們可能是一個並系群，而不是單系群。



分類

異蟲綱包括以下目和科:

始有爪目 Archonychophora


* 始有爪目 Archonychophora Hou & Bergstrom, 1995– undifferentiated appendages; each segment the same as each other.
  
* 囉哩山蟲科 Luolishaniidae Hou & Bergstrom, 1995 – three small rounded sclerites per segment – these are thorn-shaped spines.
    
* _囉哩山蟲屬 Luolishania_ Hou & Chen 1989
    
* _神奇囉哩山蟲屬 Miraluolishania_ Liu & Shu 2004
  
* 貧腿蟲科 Paucipodiidae Hou _et al._, 2004– with no dorsal sclerites, two claws, fine annulation and few segments.
    
* _貧腿蟲屬 Paucipodia_ Hou et al. 2004

These taxa are only known from the Chengjiang (Cambrian Stage 2 Series 3).

原有爪目 Protonychophora


* 原有爪目 Protonychophora Hutchinson, 1930 – spiny legs, reduced tail.
  
* 埃謝櫛蠶科 Aysheaiidae Walcott, 1911 – many claws on each leg. Anterior grasping appendages with long spines.
    
* _埃謝櫛蠶屬 Aysheaia_ Walcott 1911
  
* 異蟲科 Xenusiidae Dzik & Krumbiegel, 1989 – >20 leg-bearing segments; paired, rounded sclerites on each segment; spiny legs.
    
* _異蟲屬 Xenusion_ Pompeckj, 1927
    
* _尖山葉足蟲屬 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.

堅有爪目 Scleronychophora


* 堅有爪目 Scleronychophora Hou & Bergstrom, 1995 – paired sclerites; elongated head sclerites.
  
* 始小貝科 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.
    
* _微網蟲屬 Microdictyon_ Bengtson et al.
    
* _Quadratapora_ Hao and Shu, 1987
    
* _Fusuconcharium_ Hao and Shu, 1987
  
* 怪誕蟲科 Hallucigeniidae Conway Morris, 1977 – ~10 leg-bearing segments; large sclerites covering head; sclerites on each segment are long spines.
    
* _怪誕蟲屬 Hallucigenia_ Conway Morris 1977 – from the Chengjiang, Kaili and Burgess Shale.
  
* 心網蟲科 Cardiodictyidae Hou & Bergstrom, 1995 – many segments (~23); large sclerites cover head; hexagonal sclerite on each body segment.
    
* _心網蟲屬 Cardiodictyon_ Hou et al. 1991 – known from the Chengjiang.

等有爪目 Paronychophora


* 等有爪目 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 [Note: diagnosis modified in ].
  
* 爪網蟲科 Onychodictyidae Hou & Bergstrom, 1995
    
* _爪網蟲屬 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.

' 門 ' 有爪動物門

Onychophora are distinguished by their terrestrial habit, their ventral mouth; their antennae, jaws and oral papillae; they seem to be most closely related to the Paronychophora. Their first fossils are Carboniferous (_Helenodora_), although they may have had a cryptic earlier history.



參考文獻