PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 109(3):419-429. 1996. A new Atlantic species of Acanthemblemaria (Teleostei: Blennioidei: Chaenopsidae): Morphology and relationships Glenn R. Almany and Carole C. Baldwin (GRA) Division of Fishes, MRC 159, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A. (Present address: Department of Zoology, Oregon State University, 3029 Cordley Hall, CorvaUis, Oregon 97331-2914); (CCB*) Division of Fishes, MRC 159, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A. (*Corresponding author) Abstract. — Acanthemblemaria johnsoni is described from six specimens col-lected from shallow coral reefs at the north end of the Caribbean island of Tobago. The new species differs from all other Atlantic species of Acanthem-blemaria by the combined spinous and soft dorsal-fin ray count of XXIV, 12-13. Evolutionary relationships of the new species are discussed in relation to the phylogeny of the genus proposed by Hastings (1990). Shallow-water rotenone collections of fishes were made at the Caribbean island of Tobago in September 1990 by members of the Division of Fishes, National Museum of Natural History, and the Marine Fisheries Section, Tobago Fisheries, in a collabora-tive survey of the shorefishes of Tobago. Among the fishes collected were six spec-imens of the chaenopsid genus Acanthem-blemaria that could not be identified using published descriptions and keys for the At-lantic members of the genus (Smith-Vaniz & Palacio 1974, Johnson & Brothers 1989). The small blennioid fishes of the genus Acanthemblemaria typically inhabit tubes in shallow-water coral reefs and are distin-guished from other chaenopsids by having spiny cranial bones and two rows of teeth on the palatine (Stephens 1963, Smith-Van-iz & Palacio 1974). Our investigation of At-lantic Acanthemblemaria indicates that the six Tobago specimens represent an unde-scribed species. The addition of the new species brings the number of known species in the genus to 17 (18 including "new species A" from the eastern Pacific, see Hastings 1990); 10 in the tropical western Atlantic and 7 in the eastern Pacific, making Acanthemblemaria the most speciose genus in the family Chaenopsidae. The evolutionary history of the genus appears to show the influence of the emergence of the Isthmus of Panama, with two species pairs following the eastern Pacific-Caribbean distributional track (Has-tings 1990). Using the characters examined by Hastings (1990), we hypothesize the phylogenetic relationships of the new spe-cies to other members of the genus and comment on its historical biogeography. Methods Counts and measurements generally fol-low Stephens (1963). Pore terminology is that of Smith-Vaniz & Palacio (1974) as modified by Johnson & Greenfield (1976) and Rosenblatt & McCosker (1988). All measurements were made to the nearest tenth of a millimeter using an ocular mi-crometer. Vertebral counts were made from radiographs. Tooth and gill-raker counts, as well as assessments of Hastings' (1990) os-
BioStor
