Cymothoida Wägele, 1989

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Suggested Common Name: Wormpods and Fisheaters
Number of subordinate taxa: over 2000 species in 2 superfamilies worldwide, 490 species in both superfamilies in our area
Etymology: after Cymothoa Fabricius, 1787. Common name refers to the two consituent superfamilies, see those for more information.
Taxonomic History: one of the many former members of Flabellifera, which was divided into seperate suborders over the course of the late 1980s to early 2000s.
Size Range: Largest among suborders, ranging from a few millimeters to a quarter of a meter.
Taxonomic History: Body ovate, compact (Cymothooidea) or extremely elongate and cylindrical (Anthuroidea); sexual dimorphism obvious to absent, pleopod dimorphism restricted to presence or absence of appendix masculina. Antenna 1 well-developed or secondarily reduced, scale absent (present in Bathynomus). Antenna 2 without scale. Mandible incisor large, cutting, 1-few-cuspidate; lacinia present or fused with spine row; spine row present; palp present (very rarely absent). Maxilla 1 usually biramous (apparently absent in Gnathiidae). Maxilla 2 present (most of Cymothooidea) or absent (Anthuroidea and Gnathiidae), when present usually with exopod with 2 endites. Maxilliped epipod present in at least a few groups; basis not dominating maxilliped size (moderately dominating size in some Anthuroidea); endite small, rarely reaching past palp segment 1, usually tapering; palp present, generally well-developed. Pereopods 2-7 coxae formed into coxal plates, variously free to fused with tergites. Penes present, shape and separation various. Pleon all segments free or secondarily fused. Pleonite 1 (when free) similar to other pleonites. Pleopod 1 not modified, not sexually dimorphic. Pleopod 2 slightly modified, slightly dimorphic mainly in the presence or absence of the appendix masculina. Pleopod 3 endopod ovate to subrectangular, tip rounded. Telson ventrally flattened, lacking a branchial chamber. Uropods set ventrolaterally or ventrally on telson, forming a tailfan with telson (Cymothooidea) or folding over telson to form a “flower-shaped” shovel-like structure (Anthuroidea).
Type taxon: Cymothooidea Leach, 1814
Notes: Cymothoida is a very loosely-held together suborder containing the superfamilies Anthuroidea, Cymothooidea and formerly the odd clade Epicaridea. It is almost certainly not monophyletic, likely either being paraphyletic or polyphyletic depending on the status of Cymothooidea, although Anthuroidea likely represents a monophyletic group. It is only considered tentative valid here due to the undetermined status of Cymothoidea and will likely be taken apart in the near future.

Subordinate taxa: Anthuroidea, Cymothooidea

Key to larger groups
1 a. Uropod endopod folded over telson to form a flower-shaped "shovel"; maxilla 2 absent; body elongate-cylindrical; benthic burrowers --> Anthuroidea
b. Uropod endopod not folded over telson, forming a retractable tailfan (pleopod-like in Anuropidae); body ovate (highly modified in Gnathiidae); maxilla 2 present (vestigial in Gnathiidae) voracious predators or parasites --> Cymothooidea


Brandt, A., & Poore, G. C. (2003). Higher classification of the flabelliferan and related Isopoda based on a reappraisal of relationships. Invertebrate Systematics, 17(6):893-923.

ohen, B. F. & Poore, G. C. B. (1994). Phylogeny and biogeography of the Gnathiidae (Crustacea: Isopoda) with descriptions of new genera and species, most from south-eastern Australia. Memoirs of the Museum of Victoria, 54:271-397.

Poore, G. C. (2001). Families and genera of Isopoda Anthuridea. Crustacean Issues, 13:63-173.

Published: Jan 1, 2023
Updated: Nov 1, 2023