Rubicundus Explained

Rubicundus is a genus of hagfishes, the only extant member of the subfamily Rubicundinae. All species in it were formerly classified in Eptatretus. R. eos, R. lakeside, and R. rubicundus are known from single specimens caught in the Tasman Sea, Galápagos, and Taiwan, respectively. They are named after the distinctive red coloration that all species share.^[1]

They represent the sister lineage to all other extant lineages of hagfishes, and may represent the sister group to the Cretaceous fossil hagfish Tethymyxine, from which they potentially diverged during the Late Jurassic or Early Cretaceous. Both Rubicundus and Tethymyxine share an elongate snout, indented barbels, and numerous slime glands.^[2] Phylogenetic studies indicate that the Rubicundinae lineage may have diverged from other extant hagfishes during the Permian, making them an extremely old lineage.^[3]

Species

Four recognized species are placed in this genus:^{[4] [5]}

• Rubicundus eos (Fernholm, 1991) (pink hagfish)
• Rubicundus lakeside (Mincarone & J. E. McCosker, 2004) (Lakeside hagfish)
• Rubicundus lopheliae (Fernholm & Quattrini, 2008) (lophelia hagfish)
• Rubicundus rubicundus (C. H. Kuo, S. C. Lee & H. K. Mok, 2010)

Notes and References

1. Web site: Rubicundus rubicundus . 2023-03-15 . www.fishbase.se.
2. Miyashita . Tetsuto . Coates . Michael I. . Farrar . Robert . Larson . Peter . Manning . Phillip L. . Wogelius . Roy A. . Edwards . Nicholas P. . Anné . Jennifer . Bergmann . Uwe . Palmer . A. Richard . Currie . Philip J. . 2019-02-05 . Hagfish from the Cretaceous Tethys Sea and a reconciliation of the morphological–molecular conflict in early vertebrate phylogeny . Proceedings of the National Academy of Sciences . en . 116 . 6 . 2146–2151 . 10.1073/pnas.1814794116 . free . 0027-8424 . 6369785 . 30670644. 2019PNAS..116.2146M .
3. Brownstein . Chase Doran . Near . Thomas . 2024-06-13 . Colonization of the ocean floor by jawless vertebrates across three mass extinctions . BMC Ecology and Evolution . 24 . 1 . 79 . 10.1186/s12862-024-02253-y . free . 2730-7182 . 11170801 . 38867201.
4. Van Der Laan . Richard . Eschmeyer . William N. . Fricke . Ronald . Family-group names of Recent fishes . Zootaxa . 11 November 2014 . 3882 . 1 . 1–230 . 10.11646/zootaxa.3882.1.1 . 25543675 . free .
5. Web site: Froese . R.. Pauly. D.. 2017. Petromyzontidae. FishBase version (02/2017). 18 May 2017.