EVOLUTION OF BODY SIZE IN MUSHROOM CORALS (SCLERACTINIA: FUNGIIDAE) AND ITS ECOMORPHOLOGICAL CONSEQUENCES by BERT W. HOEKSEMA (Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D. C. 20560, U.S.A.) ABSTRACT Most Fungiidae are free-living and therefore they are able to dwell on various kinds of substrata. A large size may facilitate mushroom corals to acquire food and light, but it may also hinder their capacity to move and reject sediments. A cladistic analysis of the Fungiidae suggests that phylogenetic increase in body size may have induced the development of secondary mouths in several independent species lineages.
On a patch reef off Makassar, Sulawesi, Indonesia, corals identified as Fungia (Cycloseris) costulata, Fungia (Cycloseris) tenuis and Fungia (Cycloseris) cf costulata were collected down to a maximum depth of 10 m. The corals lived sympatrically. Mushroom coral clones resulting from fragmentation can be recognized by their equal coloration and close proximity. Therefore, to ensure that no clones were collected, corals of dissimilar colors were selected at a mutual distance of 5 m. The corals were kept alive in two 30 liter sea-water aquariums with an air-pump. They were photographed in detail. Using allozyme electrophoresis in a laboratory close to the field area, it was tested whether the separate coral morphs should be considered three species. Eventually it was concluded that there are only two species, i.e. F. (C.) costulata and F. (C.) tenuis, of which F. (C.) costulata has two distinct morphs, one of which may be an eco-phenotype occurring on reefs off river outlets or inside estuaries.
Research on the evolution of the symbiosis between the boring mussel Fungiacava eilatensis (Bivalvia: Mytilidae) and its mushroom coral hosts (Scleractinia: Fungiidae), which requires phylogenetic reconstructions of both the Mytilidae and the Fungiidae, contributes to the understanding of the complexity of coral reef ecosystems. Previously, Fungiacava was regarded as a genus that had descended from Leiosolenus or as belonging to the subfamily Crenellinae, but no phylogenetic support has been obtained for this hypothesis. In the present study, the 18s rRNA sequences of ten mytilid species and the shell microstructures of 12 mytilids were investigated. The phylogenetic position of F. eilatensis is discussed in relation to its associations with its host species. The results of the molecular phylogenetic analysis indicate that F. eilatensis forms a sister group with Leiosolenus simplex, a livecoral- boring species within the Leiosolenus clade. Scanning electron microscope observations indicate that the shell of F. eilatensis is constructed of 3 layers: the outer shell layer with a homogeneous structure, the middle shell layer as a sheet nacreous structure, and the inner shell layer with an irregular simple prism structure. This shell microstructure of F. eilatensis is similar to that of Leiosolenus malaccanus and L. simplex. These findings show that F. eilatensis has descended from a coral-boring Leiosolenus species and that it would be adequate for Fungiacava to be treated as Leiosolenus. However, because of its extraordinary shell shape it has been kept as a separate genus.
Examination of about 60,000 scleractinian corals of the families Dendrophylliidae, Euphylliidae and Fungiidae for the presence of associated wentletrap snails (Gastropoda: Epitoniidae) revealed various ectoparasitic life history strategies. Twenty Indo-Pacific wentletrap species were found, which were either host-specific or generalist. Most species were associated with mushroom corals, especially free-living species belonging to the Fungiidae. Snails showed different preferences with regard to their position relative to mushroom corals, the host’s size and its substrate. No preferences for depth were found. Infestation rates of mushroom corals in multi-species assemblages were negatively correlated with coral densities, which indicates that epitoniid veliger larvae may actively look for preferential hosts. Indirect proof was found that burrowing shrimps remove any epitoniid that is on or underneath the mushroom coral under which they have their burrow. Fishes like wrasses and damselfishes were seen to eat the snails the moment their host corals were overturned, which suggests that the host corals may provide the snails with protection against predators.
A phylogenetically based comparative analysis of onshore-offshore distribution patterns of mushroom coral species (Scleractinia: Fungiidae) was made to reconstruct an evolutionary scenario for differentiation in fungiid shelf habitats. This phyloecological study integrates data on fungiid distribution patterns along environmental gradients on the Spermonde Shelf, SW Sulawesi, with a recently published phylogeny reconstruction of the Fungiidae. A mushroom coral fauna of 34 species was used to compare their distributions by use of 50-m2 belt quadrats in transects (1) from the mainland to the shelf edge, (2) around reefs with regard to predominant wind directions, and (3) over bathymetrical reef zones. Species association ordinations were made for each of the four shelf zones using both abundance and incidence data to examine whether closely related species cooccurred. Some closely related species or even sister species appeared to show very similar distribution patterns and to coexist in high abundances. These results indicate that there may not be community saturation and competitive exclusion among mushroom corals species, most of which are free-living. In reconstructions of fungiid habitat evolution, offshore reef slopes appear to be original (ancestral), whereas onshore habitats, shallow reef flats, and deep sandy reef bases seem to be derived. The latter is in contrast with an earlier hypothesis, in which deep sandy substrates were considered ancestral mushroom coral habitats.
This review of copepod crustaceans associated with reef-dwelling cnidarians, sponges and echinoderms of the Greater Caribbean is based on published records, systematically arranged by the classification of symbiotic copepods and their hosts, sampling sites, coordinates, depth and date of sampling, literature sources, and three recent surveys (Cuba, St. Eustatius in the Eastern Caribbean and Curaçao in the Southern Caribbean). This resulted in totals of 532 records of 115 species of symbiotic copepods (47 genera, 17 families, three orders) hosted by 80 species of invertebrates, representing scleractinians (47%), octocorals (9%), echinoderms (3%), and sponges (1%). Among ten Caribbean ecoregions, the Greater Antilles (with 64 species of symbiotic copepods) as well as the Southern and Eastern Caribbean (with 46 and 17 species of copepods, respectively) are the most studied and best represented, whereas only six species of copepods are known from Bermuda, one from Southwestern Caribbean and none from the Gulf of Mexico. The absence of poecilostomatoid copepods (Anchimolgidae, Rhynchomolgidae and Xarifidae) on Caribbean stony corals as noted by is confirmed. The results indicate that the diversity and ecology of Caribbean symbiotic copepods are still poorly investigated.
The phylogenetic relationships of the Fungiidae, a family of predominantly free-living, zooxanthellate, reef corals, were studied by sequencing a part of the mitochondrial Cytochrome Oxidase I (COI) and the complete ribosomal Internal Transcribed Spacers (ITS) I & II of specimens from various locations in the Indo-West Pacific. Some sequences were retrieved by using fungiidspecific primers on DNA-extracts from parasitic gastropods living with these corals. The analyses were performed both including and excluding intraspecific variation to investigate the potential effect of saturation. Even though the present molecular phylogeny reconstructions largely reflect those based on morphological characters, there are some distinct differences. Three major clades are distinguished, one of which consists of species with relatively long tentacles. The two other major clades cannot yet be clearly separated from each other morphologically. Several polyphyletic taxa were detected and some genera and species that previously were considered closely related to each other, appear not to be so. Proposed nomenclatorial changes include amongst others the upgrading of subgenera in Fungia to genus level. A few species moved from one genus to another. Among all Fungiidae, the loss of the ability to become free-living appears to have evolved independently as reversals in four separate clades, including two that were previously assumed to be sister groups. The evolution of corals with additional (secondary) mouths leading to polystomatous growth forms from corals with only a single primary mouth (monostomatous growth form) appears to have occurred independently ten times: seven times by extrastomatal budding and three times by intrastomatal budding. In two clades, Herpolitha and Polyphyllia, both mechanisms co-evolved. In general there is no clear relationship between the loss of a freeliving phase and the evolution of multiple mouths.
Ovulid gastropods and their octocoral hosts were collected along the leeward coast of Curaçao, Netherlands Antilles. New molecular data of Caribbean and a single Atlantic species were combined with comparable data of Indo-Pacific Ovulidae and a single East-Pacific species from GenBank. Based on two DNA markers, viz. CO-I and 16S, the phylogenetic relationships among all ovulid species of which these data are available are reconstructed. The provisional results suggest a dichotomy between the Atlantic and the Indo-Pacific taxa. Fully grown Simnialena uniplicata closely resembles juvenile Cyphoma gibbosum conchologically. Cymbovula acicularis and C. bahamaensis might be synonyms. The assignments of Caribbean host species for Cyphoma gibbosum, C. signatum, Cymbovula acicularis and Simnialena uniplicata are revised.
Phyllodiscus semoni is a morphologically variable sea anemone species from the Indo-Pacific with morphotypes ranging from upright and branched to low-lying and rounded. The apparent camouflage strategies of this sea anemone allow it to resemble other species or objects in its environment, such as stony corals, soft corals, seaweeds, or rocky boulders covered by algae, which may help it to avoid recognition by potential predators. Occasionally, it occurs in aggregations that may result from asexual reproduction. A high level of intraspecific morphological variation, including co-occurring aggregations of three different morphotypes, was observed in the Spermonde Archipelago off Makassar, South Sulawesi, Indonesia. The co-occurrence of aggregations with different morphotypes suggests that Phyllodiscus is a highly polymorphic monospecific genus. Sea anemones of this genus are not frequently encountered at other localities and the number of morphotypes seems large. Therefore, it is unlikely that we are dealing with more than one species that are all concentrated in a single area. Phyllodiscus sea anemones are considered dangerous to humans because their nematocysts contain highly toxic venoms that may inflict harmful stings. Therefore they are the subject of recent toxicological studies. The present paper aims to assist in the recognition of these highly variable hazardous animals and to discuss the appearance of their aggregations.
Corallivorous Drupella (Muricidae) snails at Koh Tao are reported to have extended their range of prey species following a major coral bleaching event in 2010. Populations of their preferred Acropora prey had locally diminished in both size and abundance, and the snails had introduced free-living mushroom corals in their diet. Although the coral community largely recovered, the Drupella population grew and reached outbreak proportions. For this study, corallivorous muricids at Koh Tao were studied more intensively to examine their identities, distribution and prey choice four years after the bleaching event. Drupella rugosa was identified as the major outbreak species and occurred at densities > 3 m-2 in depth ranges of 2-5 and 5-8 m. The density of D. rugosa was related to the live coral cover, Acropora colony density, and depth. Resource selection ratios revealed that species of Acropora, Psammocora and Pavona corals were attacked more frequently than would be expected based on their availability. Strikingly, fungiid corals were now avoided as prey in the recovered coral community, despite them being part of the preferred diet directly after the bleaching. Although D. rugosa showed a clear prey preference, it appears to be plastic by changing with prey availability. The muricids Drupella margariticola and Morula spinosa occurred in much lower densities and were less often associated with corals. Snails of the opportunistic corallivore D. margariticola usually co-occurred in D. rugosa aggregations, although they also formed feeding aggregations by themselves. Whether M. spinosa generally associates with corals as a corallivore or a scavenger has yet to be determined. Molecular analyses did not reveal cryptic speciation among snails sampled from different coral hosts and also no geographic variation. The present study also showed that corallivory is more common among D. margariticola and M. spinosa than previously known.