Family Faviidae: (L. favus, honeycomb).... relating to the regular appearance of the corallites.
The Faviidae contains more genera than any other scleractin-ian family and is second only to the Acroporidae in number of extant species, as well as overall abundance throughout the Indo-Pacific and Caribbean. With few exceptions the genera are well-defined and widely distributed. Two genera (Favia and Montastrea) are common to both the Indo-Pacific and Atlantic; two (Astreosmilia and Eryihrastrea) are restricted to the western Indian Ocean.
Because of their solid construction and wide geographic distribution, most faviid genera are readily preserved as fossils and have a good fossil record. The Faviidae is the only family to have been a dominant reef-builder in both the Mesozoic and Cenozoic eras. It fared better than any other family in the Cretaceous/Tertiary extinctions.
Most species are also widely distributed, both longitudinally and latitudinally. They usually exhibit less inter-regional variation within the central GBR than other major groups of corals and this, combined with the rarity of endemic species, gives a relatively uniform Indo—west Pacific fauna. Some species of faviids are restricted to inter-tidal habitats and upper reef slopes, but most occur over a wide range of environments. These species have similar, correspondingly wide, range of skeletal variation. Coralla from high energy environments exposed to strong sunlight have heavily calcified skeletal structures and corallites. Those from deep or turbid water, with poorly illuminated environments, are always lightly calcified and have relatively small corallites separated by a blistery coenosteum. This similarity in response to environmental gradients frequently results in coralla of different species from the same environment looking superficially more alike than coralla of the same species from very different environments.
Intra-specific geographic variation is very great between high-latitude and tropical locations of the same region. Coralla from high-latitude regions are usually heavily calcified. Coralla from different tropical regions frequently show minimal geographic variation. Many species show major variation in the relative abundance in the tropics.
    
Hypothetical taxonomic affinities between the genera of the Faviidae. The diameter of the circles is proportional to the number of species.
 
With only one exception (Symphyllia) does this family include all the "brain coral"-like genera. Taxonomic identification of most faviid genera is relatively straightforward. All species are zooxanthellate and colonial with large corallites with sturdy walls. Septa, paliform lobes, columellae and wall structures (when present), all appear to be structurally similar. Septal structures are simple, columellae are a simple tangle of elongate septal teeth with thickened septal walls composed of cross linkages.
The structure of septa, paliform lobes, columellae and wall structures (when present) appear to be structurally similar. Septal structures are simple, columellae are a simple tangle of elongated septal dentated teeth that do not spread into the coenosteum (peritheca - far less conspicous than in Mussidae) with somewhat thickened septal walls.
However, according to Veron (1986), Favia, Barabattoia, Favites, and Montastrea may be confused. A number of genera (e.g. Platygyra, Oulophyllia, Leptoria, and Goniastrea australiensis) have a characteristic brain-like corallum morphology, easily recognizable on the reef. Of the meandroid species, Leptoria has the narrowest valleys (2-3mm) between the relatively regular meandering ridges, while Oulophyllia has the widest valleys (10-12mm), with meanders being short and irregular. The mouth of these species are located at the base of the valleys. Platygyra has the longest continous meanders, and septa that are very rounded, compared to the ragged edges and equal-size septa of Oulophyllia and Leptoria, respectively. The two most difficult faviid species to separate underwater are Goniastrea australiensis and Platygyra lamellina. In comparison to P.lamellina, G.australiensis has steeper and deeper valleys as well as corallites with well-developed columella and paliform lobes (Wood 1983).

This family comprises one of the most successful groups of scleractinians (24 genera, i.e. Faviids that exhibit extratentacular budding: Montastrea, Plesiastrea, Oulastrea, Parasimplastrea¹, Diploastrea, Leptastrea, Cyphastrea, Solenastrea², and Moseleya;
Faviids exhibiting intratentacular budding: Caulastrea, Erythrastrea¹, Cladocera², Manicina², Favia, Barabattoia, Favites, Goniastrea, Platygyra, Australogyra, Oulophyllia, Leptoria, Diploria², Colpophyllia², and Echinopora,);
Annotation: ¹ two genera of the Arabic gulf region, ²while five genera are only found in the Atlantic (Wood 1983).
With regards to geographic distribution and diversity and in terms of species numbers Faviids are only surpassed by the Acroporids in overall abundance. Faviids display a wide habitat distribution (i.e. from intertidal to a depth of 90m), they are one of the most important components of PNG reefs. Two genera found throughout the Indo-Pacific region, Favia and Montastrea, also occur in the Atlantic, where M.annularis (along with Acropora palmata) is a dominant reef-builder.

Faviids exhibiting extratentacular budding (130kB)

The majority of faviids, however, are massive or heavily encrusting plocoid or cerioid colonies. Environmentally stressful habitats favor the broad distribution range of massive growth forms with Goniastrea attaining their largest size. The variety of corallum morphologies is a result of different colony growth, which can be either through intratentacular or extratentacular budding. Corallum morphology is thus one of the main diagnostic features separating the various genera. For example, Favia exhibits mainly plocoid morphology, while Favites is distinctly cerioid in character.
Nonetheless, Faviids are taxonomically a difficult group, and a number of genera show affinities with considerable overlap in terms of corallum morphology. Phaeotypic plasticity in this group of scleractinians is to a large extent related to environmental factors. Different Faviid species from the same locality can be very similar in terms of their corallite morphologies. For example, Favia pallida, F.matthai, and F.rotumana collected from exposed shallow-water habitats showed amazing morphological resemblance in their corallite structure. Similar plasticity occurs in Favites, which is mainly cerioid, but some species (e.g. Favites complanata and Favia rotundata) often exhibit ploco-cerioid morphology.

Some species of Goniastrea, such as G.retiformis, G.palauensis, and G.aspera, exhibit distinct cerioid morpology, while other species, such as G.australiensis, are ceroid to meandroid, and G.favulus and G.pectinata are submendroid.
All Goniastrea species form massive colonies and are dominant corals on many intertidal reef flats. G.aspera, in particular, forms large microatolls on intertidal reef flats and large rounded colonies in subtidal habitats. The presence of large Goniastrea and Heliopora coerulea microatolls (up to 5m in diameter and 1m in height) are characteristic of reef flat areas, even though the reef flat has been colonized by mangrooves. In addition to Goniastrea, other abbundant faviids in the magroove were Favia maxima and F.favus. However, these colonies usually are less than half a meter in diameter. In terms of sheer numbers, the most abundant coral species throughout mangrooves are the fungiid Heliofungia actiniformis which occured in association with the pipefish Siokunichthys nigrolineatus.
One of the most distinct Faviids is the cerioid Diploastrea heliopora, which can grow to a large size (>5m in diameter) and can rival even some massive Porites spp. In contrast to massive Porites species, D.heliopora has a very dense skeleton, which makes the large corallum almost indestructible. Therefore, its rugged nature makes it the most resistant species against earthquakes and volcanic eruptions. In the case of damage, many D.heliopora colonies recover by a process that proceeds from the bottom up. The hard skeleton probably makes it even less susceptible to skeleton boring sponges or other endofauna as well as epiphytic flora and epizoic fauna.
The vast majority of faviids are hermaphroditic broadcast-spawners, showing similar sexual patterns as the acropoids. Only a few species are gonochoric. Planula brooding occurs in two Indo-Pacific species (i.e. Cyphastrea ocellina and Goniastrea aspera) and three Atlantic species (i.e. Favia fragum, Manicina areolata, and Diploria labyrinthiformis. Note that Goniastrea aspera was reported to be both a broadcast-spawner (GBR) as well as exhibiting a brooding mode of reproduction releasing planulae during the new moon (Samama Island). It has been demonstrated that the newly released planulae of most faviids settle in the vicinity of parent colonies.

Plesiastrea (Gk. plesios, recent; Gk. aster, star):

Montastrea (L. montis, mountain; Gk. aster, star):

Solenastrea (Gk. solen, channel; aster, star):

Parasimplastrea (Gk. para, besides; L. simpel, simple):

Caulastrea (L. kaulis, stalk; Gk. aster, star):

Favia (L. favus, honeycomb):

Erythrastrea (Arabic region only Gk. erythros, ?; aster, star):

Cladocora (incl. Mediterranean - Gk. klados, branch; keras, horn):