1 Journal of the Ocean Science Foundation, 32, 1–16 (2019) Enneanectes favus, a new endemic species of triplefn blenny from the southeastern Caribbean (Teleostei: Tripterygiidae) BENJAMIN C. VICTOR Ocean Science Foundation, 4051 Glenwood, Irvine, CA 92604, USA and Guy Harvey Research Institute, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL 33004, USA E-mail: ben@coralreeffsh.com Abstract A review of collections of triplefn blennies of the genus Enneanectes from the tropical western Atlantic Ocean reveals a new species, Enneanectes favus n. sp., belonging to the unscaled-abdomen subgroup. The species is distinguished by having mature adults with black spinous dorsal fns and mature males with a bright yellow rear body and tail; other distinctive features include the third and fourth body bars closer together than the fourth and ffth, the last dark body bar usually extending onto the basal third of the caudal fn, three dark blotches along the anal fn, and two black blotches on each side of the anterior body. The species is apparently limited to the southeastern corner of the Caribbean Sea, i.e. northeast Venezuela and Tobago (and photographs from St. Vincent), where it replaces the widespread Redtail Triplefn, Enneanectes matador. This species is added to the small set of endemic marine species in this corner of the tropical western Atlantic Ocean, likely adapted to unusual local oceanographic conditions. The mtDNA-barcode COI sequence of the new species is 2.4% divergent from the two related allopatric lineages of E. matador in the Caribbean. A revised key to the 9 species of Enneanectes in the Greater Caribbean is presented. Key words: taxonomy, ichthyology, systematics, coral reef fshes, Yellowtail Triplefn, DNA barcoding, Venezuela Citation: Victor, B.C. (2019) Enneanectes favus, a new endemic species of triplefn blenny from the southeastern Caribbean (Teleostei: Tripterygiidae). Journal of the Ocean Science Foundation, 32, 1–16. doi: https://doi.org/10.5281/zenodo.2533400 urn:lsid:zoobank.org:pub:ECAFBDF1-8238-45B5-8509-B9D6181480B6 Date of publication of this version of record: 7 January 2019 Introduction The triplefn blenny genus Enneanectes Jordan & Evermann, 1895 is a group of tiny blennioid fshes endemic to the New World tropics and includes all the known triplefn species (Family Tripterygiidae) in the western Atlantic Ocean (Williams 2003). After a long period of stasis, the number of species has recently increased, with three new species described from the eastern Pacifc Ocean by Rosenblatt, Miller & Hastings (2013) and 4 more