Jaws and Teeth of American Cichlids [Pisces: Labroidei]

The morphology of the upper, lower, and pharyngeal jaws is very similar among American cichlids. Common conditions are: (1) the presence of a premaxillary dentigerous arm shorter than the ascending arm (exceptions are Astronotus, Cichla, and Crenicichla sernifasciata), (2) a narrow coulter area; in contrast, a broad coulter area is found in the Crenicichline Group, in certain chaetobranchines, and in Apistograrnrna, (3) the mandibular sensory canal exists to the skin through five or six simple pores; in contrast, it exits through numerous small pores that increase in number during ontogeny in the Chae- tobranchine Group, certain crenicichlines, such as Cichla, Crenicichla lepi- dota, Crenicichla proteus, and Crenicichla uittata, and certain genera of the Cichlasomine Group A, such as Caquetaza, Petenia, Neetroplus, and "Cichlasoma, " and (4) the premaxilla and dentary of American cichlids com- monly bear unicuspid, conical teeth with a few exceptions such as Neetroplus (with scraping blade teeth) and "Ci~hlasoma" facetum, "C. " cyanoguttatum, "C." guttulatum, and "C." spilurum (with bicuspid (hooked) teeth). In con- trast to the near uniformity of the upper and lower jaws, the upper and lower pharyngeal jaws present a great diversity of tooth shapes. At least seven types are found in American cichlids; usually, several types exist on a single tooth plate, but the combination of tooth types differs among some genera. The pharyngobranchial4 tooth plate has significant evolutionary transforma- tions in labroids. The caudal margin of the pharyngobranchial 4 tooth plate bears the frayed zone in cichlids and embiotocids. The presence of a broad frayed zone bearing one to seven concavities represents a synapomorphy for the family Cichlidae, whereas a deep, narrow frayed zone is a synapomorphy of Embiotocidae. The absence of the frayed zone is a synapomorphy of Pomacen- tridae, whereas the loss of the pharyngobranchial 4 is a synapomorphy of Labridae. c 1993 Wiley-Liss, Inc. The family Cichlidae with more than 1,000 species is among the most speciose of perci- form families. Together with the Embiotoci- dae, Labridae, and Pomacentridae, the Cichl- idae comprise the Suborder Labroidei, a taxon that includes -5-10% of all living fishes (Stiassny and Jensen, '87). Cichlids have a widespread distribution, which includes Africa, Madagascar, southern India, the Middle East, Sri Lanka, South and Central America, parts of North America, and the Antilles. On the American conti- nents, cichlids are less speciose than their African relatives and are represented by - 300-350 species (Kullander, '83, '86; Kul- lander and Nijssen, '89) included in 35 gen- era. The monophyly of the Cichlidae is cur- rently recognized. However, authors who have worked with cichlids disagree as to their sistergroup relationships. Cichlidae is the sis- tertaxon of Embiotocidae plus Labridae (Kaufman and Liem, '82; Lauder and Liem, '83), or the sistertaxon of the remaining la- broids (Stiassny and Jensen, '87). The phylo- genetic interrelationships of most genera within the Cichlidae remain obscure; among them, those of American cichlids are mainly unresolved (Stiassny, '91).