• Corpus ID: 39983358

New Genus And Species Of Ahermatypic Coral Anthozoa Scleractinia From The Western Atlantic

@inproceedings{Cairns1978NewGA,
  title={New Genus And Species Of Ahermatypic Coral Anthozoa Scleractinia From The Western Atlantic},
  author={Stephen D. Cairns},
  year={1978}
}

• S. Cairns
• Published 1978
• Biology

—A new genus and species are described in the subfamily Para.smihinae. Balht/cyathus maculattis Pourtales, 1874 is transferred to the new genus. Both species arc characterized by having paliform lobes before tlie penultimate cycle of septa and an identical method of basal reinforcement. [Scleractinia; Rhizosmilia; Parasmiliinae.l Numerous species have been uncritically placed in the genera Bathycyathus and Coenocijulhus. One of these is Balhycyathus maculatus Pourtales, 1874 (= Caryophyllia maculata, Pourtales, 1880; Wells, 1972; Cairns, 1977; Coenocyathus hort.ichi Wells, 1947). A re-examination of B. maculatus indicates that it has endothecal dissepiments (Plate 1, Fig. 8), which would transfer it from the Caryophylliinae to the Parasmiliinae. It is necessary to describe a new parasmilid genus to contain both B. maculatus and another undescribcd .species. Some of the specimens used in this study were collected by the R/V Gerda in the Deep-Sea Biology Program sponsored by the National Geograpliic Society. Sliip time was supported by a National Science Foundation grant. This is a contribution from the Rosenstiel School of Marine and Atmospheric Science, University of Miami. I would like to thank Dr. Gilbert L. Voss, Rosenstiel School of Marine and Atmospheric Science, for access to the University of Miami collections, and Dr. Frederick M. Bayer, National Museum of Natural History, for the opportiuiity to study the Smithsonian specimens. I am grateful to Dr. John W. Wells, Cornell University, for reviewing the manuscript. All of the specimens listed in this paper are deposited at the National Museum of Natural IIi.story (USNM). Suborder CaryophylHina Vaughan and Wells, 1943 Family Caryophylliidae Gray, 1847 Subfamily Parasmiliinae Vaughan and Wells, 1943 Rhizosmilia, new genus Diagnosis.—Small phaceloid clumped colonies formed by extratentacular budding. Coralhte bases increase in diameter by adding exothecal dissepiments over raised costae producing concentric rings of partitioned chambers. Paliform lobes present before penultimate cycle. Columella prominent, varying from spongy to fascicular (a line of pillars) to lamellar. Endothecal dissepiments present. VOLUME 91, NUMBER 1 217 Type-species.—Rhizosmilia gerdae, n. sp., here designated. Discussion.—Rhizosmilia is easily distinguished from the other genera in the subfamily Parasmiliiuae by a combination of three easily observed characters: it is colonial (clumped phaceloid), has a prominent columella, and has large paliform lobes. The position of the paliform lobes before the penultimate cycle of septa requires explanation. The first paliform lobes to form are the 12 that border the Ss at the 48-septa stage (Fig. la). When a pair of S-, appears within a half-system, one of two things occurs to maintain the paliform lobes before the penultimate cycle: 1) the original P:, may remain stationary before the S-.^ while an independent lobe forms on the accelerated S4 (Fig. lb), or 2) the original ?:) may gradually begin to align with the accelerated S4, maintaining trabecular connections with both S:i and S4 simultaneously (Fig. Ic). With greater development, this transitional paliform lobe becomes completely aligned and attached to the St (Figs. Id, e). (For example, every transitional P4 merges with a P3 lower in the fossa.) When the second pair of Sr, occurs in the half-system, if the P3 is still present (case 1), it becomes a transitional lobe and forms the P4. If the P3 has already aligned with the other S4 (case 2), then an independent lobe is formed of equal size on the second S4. In both cases, the final condition is two equal paliform lobes bordering the S4 (penultimate cycle) and no lobe visible before the 83 (Fig. If). Both species in this genus also have a peculiar method of basal reinforcement. As the corallite increases in size, the edge zone secretes thin costae, up to 2 mm high and 10 mm long, perpendicular to the coralluni wall around the base (Plate 1, Fig. 2). Next, exothecal dissepiments form over the costae, producing a series of chambers around the base. This process may occur several times, producing 4-5 concentric rings of hollow compartments that substantially increase the basal diameter of the corallite and therefore its stability. If a transverse section is made through the base (Plate 1, Fig. 7), these concentric rings appear identical to Durham's (1949) thecal rings of polycyclic development. The rings described here are, however, structurally and ontogenetically different, since they are formed much later in development by raised costae and exothecal dissepiments, whereas polycyclic thecal rings are an early develoi^mental feature involving overlapping of primitive thecal walls. Furthcnnore, there is no extension of the polyp into the compartments of the costal roots, whereas in polycyclic development, the polyp occupies the area created by the last thecal ring. The identical mode of basal reinforcement also occurs in Phi/llangia and Oxijsmilia. Etymology.—The prefix is derived from the Greek rhiza, meaning root, and pertains to the concentric rings of root-like costal chambers around the base. Gender: feminine. 218 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON VOLUME 91, NUMBER 1 219