325 Neogene paleontology in the northern Dominican Republic: 3. The family Poritidae (Anthozoa: Scleractinia)

Various multivariate statistical procedures are used to distinguish species in the reef-coral family Poritidae through a continuous Neogene sequence (five myr time interval) in the Cibao Valley of the northern Dominican Republic. Some older (by approximately 10 myr) material from the same region is also included in the analyses. The material consists of approximately 450 colonies (120 of which are measured) from 92 localities in four river sections. The colonies are first sorted into three genera, and approximately 30 characters measured on five calices per colony. The data are analyzed using cluster and canonical discriminant analyses to group the colonies into clusters representing species. Five species are so defined into Porites and three in Goniopora. These groupings are then used statistically to reclassify type specimens for 22 of the 25 described species of Neogene Caribbean poritids. Eight described species are thereby synonymized with four previously- described species in Porites and one new species of Porites, Porites convivatoris, n. sp., is discovered. Five described species are synonymized with two previously-described species in Goniopora. The stratigraphic range of three species of Porites and three species of Goniopora is also shown to extend back to the late Oligocene, thereby diminishing the significance of any presumed early Miocene adaptive radiation. Only one species was found to be endemic to the Dominican Republic and only one confined to the norther Caribbean. The rest are widely distributed throughout the Caribbean. Thus, the endemism previously believed common during the Neogene is shown to be far less extensive.

Evolutionary trends within each species are preliminarily analyzed for various characters using nonparametric statistical procedures. In general, the results show that seven species experienced little or no evolutionary change (= stasis) through the sequence. Slight increases in corallite size are detected in two species, and increase in colony height in one species, and a more rounded colony shape in one species. These trends may be related to the general deepening of the environment; however, little correction is found between lithology and morphology within species. Preliminary analyses of the relationship of the relationship between intraspecific variation and poritid abundance and diversity yield significant results, suggesting that intraspecific trends may be environmental and that future study of the coral species associations may offer insight into paleoenvironmental interpretations.

Statistical comparisons with the Miocene Mediterranean poritids show that no species co-occur in the two provinces during the Neogene. Similarly, none of the studies Neogene species of Porites resemble modern Caribbean species of Porites, signifying that all nine poritid species studied must have become extinct and the modern Caribbean species of Porites radiated during the late Pliocene or early Pleistocene.

This study represents part of a multidisciplinary project on the stratigraphy of the northern Dominican Republic, coordinated by P. Jung and J. B. Saunders of the Naturhistorisches Museum Basel, Switzerland.

Year published: 1986