Cymothooidea Leach, 1814

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Suggested Common Name: Fisheaters
Number of subordinate taxa: 1405 species in 9 families worldwide, 246 species in 7 families in our area
Etymology: after Cymothoa Fabricius, 1787, see that account for more information. Common name refers to this superfamily's propensity to either predate on or parasitize fishes (and other vertebrates), something unique to it over other groups. A name theming based on the Golden Age of Piracy is given to many subordinate taxa to allude to their ravenous carnivory.
Taxonomic History: Cymothooidea Leach, 1814; the superfamily Cirolanoidea is seperated in Bruce & Poore, 2003 and previous papers based on mandibular details but the few details seem to be more signifigant on a family basis rather than a superfamilial basis.
Size Range: up to +250mm
Type taxon: Cymothoidae Leach, 1814
Notes: This large superfamily contains all vertebrate-parasitic and a signifigant precentage of predatory isopods. The two extralimital families, Barybrotidae and Protognathiidae, are very small, with 1-2 species and occur in the West Indopacific and Antarctica respectively.
This superfamily is likely highly polyphyletic, with the most recent genetic evidence (An et. al. 2022) placing families in scattered locations across Isopoda. More research, especially into obtaining genetic information from more taxa, is critical for understanding how members of this superfamily relate with other members of Isopoda.

Subordinate taxa: Aegidae, Anuropidae, Cirolanidae, Corallanidae, Cymothoidae, Gnathiidae, Tridentellidae

Key to families
1 a. Pereonite 1 fused to head; only 5 pairs of pereopods present, the first pair modified into ovate pylopods, pereonite 7 absent; pleon abruptly narrower than the pereon; head sexually dimorphic, with ♂ mandibles often distinctively enlargened; bizarre isopods with vertebrate-parasitic larvae (praniza) and non-feeding adults --> Gnathiidae
b. Pereonite 1 free; all 7 pereopods present, the first pair not modified into pylopods; pleon gradually or moderately narrower than pereon; head not as above; ecology not as above, usually with similar immature and adult stages (except Cymothoidae) --> 2

2 (1) a. Uropods identical to the pleopods, giving the animal the appearance of having no uropods; antenna 1 large and reduced to 2 segments with a distinct groove, making it appear scalloped; bizarre bathypelagic parasites of jelly animals, known species are usually a vivid red --> Anuropidae
b. Uropods sharply differentiated from the pleopods; antenna 1 not as above, with a distinct peduncle and flagellum; highly carnivorous to facultative parasites of vertebrates --> 3

3 (2) a. All pereopods prehensile; body moderately contorted in adults (♀'s); adults obligate parasites on the surface, in the gills or in the mouth of fish, immatures (incl. ♂'s) facultatively parasitic--> Cymothoidae
b. At least some pereopods ambulatory (all ambulatory in some Cirolanidae but then troglobitic); body not contorted in any life stage; free-living carnivorous, facultative vertebrate parasites or obligate jelly animal parasites --> 4

4 (3) a. Maxilliped and maxilla 1 with stout recurved apical spines; maxilla 2 lateral lobe formed into a slender stylet, medial lobe small, lacking stout circumplumose spines  --> Aegidae
b.  Maxilliped and maxilla lacking stout recurved apical spines; maxilla 2 lateral lobed not formed into a slender stylet, medial lobe large with or without stout circumplumose spines --> 5

5(4) a. Mandible incsisor multicuspid, prosterior tooth prominent, lacinia well-developed, spine row set on fleshy lobe, molar large, spinose, blade-like; maxilla 1 biramous; maxilla 2 lateral lobe with 11-14 apical spines, medial lobe large with 3-4 circumplumose spines --> Cirolanidae
b. Mandible incisor weakly or not toothed, with lacinia weakly developed or absent, spine row not set on fleshy lobe, molar absent or small to moderately sized, sparsely spined; maxilla 1 uniramous; maxilla 2 lateral lobe with 1-5 stout apical spines, medial lobe small, lacking circumplumose spines --> 6

6 (5) a. Mandible lacinia absent, molar moderately large; maxilla 1 stout, 2-segmented, endite conical, often with tridentate scale-like spines; maxilla 2 lateral lobe slightly curved, tip with 3-5 stout hooked spines and smaller subapical spines; maxilliped with endite, palp 5-segmented; generally deepwater --> Tridentellidae
b. Mandible lacinia absent or small with a weak spine row, molar absent or small; maxilla 1 small, 1-4 segmented, endite rounded, bifid, trifid or sublinear, lacking tridentate scale-like spines; maxilla 2 lateral lobe sickle-shaped with 1-3 large hooked apical spine and 0-3 smaller subapical spines; maxilliped lacking endite, palp 3-5-segmented; shallow to deepwater --> Corallanidae


An, J., Yin, X., Chen, R., Boyko, C. B., & Liu, X. (2022). Integrative taxonomy of the subfamily Orbioninae Codreanu, 1967 (Crustacea: Isopoda) based on mitochondrial and nuclear data with evidence that supports Epicaridea Latreille, 1825 as a suborder. Molecular Phylogenetics and Evolution, 107681.

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.

Delaney, P. M. (1988). Systematics, Phylogeny and Biogrography of the Marine Isopod Family Corallanidae Hansen, 1890. Contributions in Science, 409, 1-75.

George, R. Y. (2003). Two new species of gnathiid isopod Crustacea from the North Carolina coast. Journal of the North Carolina Academy of Science, 119(2):33-40.

Schultz, G. A. (1977). Bathypelagic isopod Crustacea from the Antarctic and southern seas. Biology of the Antarctic seas V, 23:69-128.

Published: Jan 1, 2023

Edited: 9/28/2023