Scleractinian Coral Family, Mussidae

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Family Mussidae: (L. mus, mouse) This is a Cenozoic Tethyan family, with most genera now extant. It has clear morphological affinities with the Meandrinidae; the fossil record of this affinity is weak. Colonies are solitary or colonial. Skeletal structures are solid. Corallites and valleys are very large. The septa have large teeth or lobes (in contrast to the smoother Faviids). Columellae and walls are thick and well developed with thick and fleshy polyps.
The Mussidae are a relatively small family consisting of roughly 13 genera with wide geographic distribution (i.e. Blastomussa, Micromussa, Acanthastrea, Lobophyllia, Symphyllia, Indophyllia, Scolymia, Australomussa, and Cynarina). Four genera are restricted to the Atlantic (Mussismilia, Mussa, Mycetophyllia, and Isophyllia) while Scolymia is present in both in Indo-Pacific as well as in Atlantic waters. The family is closely related to Pectiniidae, from which it may be easily distinguished by more robust and denser skeleton as well as by large corallites whose septa are usually ornamented by large septal teeth (Veron 1986).	Some members of the family Mussidae (96kB)
Due to the prominent columellae and walls, the polyps are thick and fleshy, and in some species (e.g. Cynarina lacrimalis, Scolymia australis) the body cavity becomes greatly inflated with water during the day, making the underlying skeleton partly visible. At night, Mussidae generally feed on zooplankton - Lobophyllia hemprichii was observed to capture large demersal zooplankton (e.g. mysids, polychaetes, attracted by underwater light during night dives). The expansion of body tissue during the day may have a functional significance, since the surface area of the colorful tissue is considerably enlarged, thus theoretically maximizing photosynthetic efficiency of the zooxanthellae. The two dominant genera on most PNG reefs are Lobophyllia and Symphyllia. However, Acanthastrea echinata may dominate locally. The most abundant mussid by far is Lobophyllia hemprichii, which inhabits a wide range of habitats, often forming monospecific stands, while exhibiting a wide range of polyp sizes and color patterns. L.corymbosa and L.hataii are likewise present, but in less abundant numbers. Symphyllia is an important genus on many PNG reefs and is distinguished from Lobophyllia by its meandroid corallum. All mussids studied so far are hermaphroditic in sexual character; six species spawn gametes and two species brood planulae. Five hermaphroditic species (i.e. Acanthastrea echinata, Lobophyllia hemprichii, L.corymbosa, Symphyllia recta, and S.radians) have been observed to spawn (releasing gametes) during mass-spawning events on the GBR.
Key to the family Mussidae Colonial Corallites <12mm diameter Colony phaceloid: Genus *Blastomussa* Colony Cerioid: Genus *Micromussa* Corallites >12mm diameter Colony cerioid to subplocoid Septal teeth pointed: Genus *Acanthastrea* Septal teeth beaded: Genus *Mussismilia* Colony subplocoid to submeandroid: Genus *Isophyllia* Colony phaceloid to flabello-meandroid Corallites numerous: Genus *Lobophyllia* Corallites not numerous: Genus *Mussa* Colony meandroid Septal teeth very prominent: Genus *Symphyllia* Septal teeth not very prominent Valleys mostly radiate: Genus *Mycetophyllia* Valleys concentric: Genus *Australomussa* Non Colonial Septal teeth pointed: Genus *Scolymia* Septal teeth lobed Septal teeth very large: Genus *Cynarina* Septal teeth not very large: Genus *Indophyllia*
Indo-Pacific genera: ---------------------------------------------------------------------------------------------------------- Blastomussa (Gk. blastos, bud; mussa, a coral genus): Forms small phaceloid colonies that are brown, greenish, or red in color. Corallites form clumps or tufts or becomes united laterally to adjacent corallites by their walls. Coralites are 5-15mm in diameter depending on the species. Septa are prominent with rough margins. Septa are also stout, well spaced and exsert. Columella is solid. B.wellsi usually has phaceloid corallites, but in most high-latitude regions colonies become cerioid. This is environment correlated and can be traced from one extreme to the other over a wide latitudinal range. PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to western Pacific. GENERAL ABUNDANCE: generally uncommon, sometimes inconspicuous. FOSSIL RECORD: Pleistocene of the Pacific. NUMBER OF EXTANT SPECIES: 2 known species. Micromussa (Gk. micros, small; mussa, a coral genus), previously listed under Acanthastrea; Colonies are submassive, encrusting, and usually flat. They ave fleshy tissues but skeletal structures remain visible making them readily confusable with Acanthastrea, which has larger polyps. Tentacles are extended only at night. In-situ, this genus is readily confused with faviid genera Favia and Favites wich have corallites of similar size. Corallites are cerioid or sub-plocoid, either circular or angular in shape, and up to 8mm in diameter. Septa with teeth are thickened at the corallite wall. Paliform crown present. Columella absent. PRESENT DISTRIBUTION: central Indio-Pacific, southern Japan, Sri Lanka, Gulf of Aden. GENERAL ABUNDANCE: rare. FOSSIL RECORD: none. NUMBER OF EXTANT SPECIES: 3 known species. Acanthastrea (Gk. akantha, thorn, prickle; aster, star): Several species (A.hillae, A.bowerbanki, A.lordhowensis and possibly A.amakusensis) are much more common in high-latitude non-reef localities than in the tropics. A.echinata is the only widespread common species of the genus. Large encrusting colonies or flat to rounded heads that are red or greenish in color. Corallites are seldomly separate and distinct (plocoid) but rounded and mostly united by the walls (cerioid), usually polygonal, irregular, and rarely semi-meandering with 2-3 mouths in a row (from 10-20mm in diameter). Septa are prominent and usually run from one calice to the next without interruption. Septa are separated by a small grove and are thicker on the wall than in the fossa. Septa are numerous, stout, exsert and have sharp teeth (3-4mm in length, which is in contrast to Faviids). PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to southern Pacific. GENERAL ABUNDANCE: generally uncommon, Favites-like. FOSSIL RECORD: Miocene (?) of the Pacific. NUMBER OF EXTANT SPECIES: 15 known species. Lobophyllia (Gk. lobos, lobe; phyllon, leaf): Some of the more uncommon species of this genus are well-defined, others, including the very common L.hemprichii appear to be species complexes which show little geographic variation. Colonies are massive, convex or rounded and green or brown, pinkish or red in color. Corallites are covered by numerous fleshy protuberances. Stalked corallites are either single or joined to form irregular lobes or sinuous meanders, which are joined at their base (phacelo-flabello-meandroid structure). The stalks vary in length (up to 20cm or more). Corallites are 1-4cm in diameter but may be larger and are separated by a gap of 0.5-2cm. Small and large septa alternate, most of them are exsert - the larger ones as much as 1cm. PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to southern Pacific. GENERAL ABUNDANCE: very common, very conspicuous. FOSSIL RECORD: Miocene of the Tethys. NUMBER OF EXTANT SPECIES: 9 known species. Symphyllia (Gk. syn-, together; phyllon, leaf): Massive heads that are rounded, convex, or flattened and is usually brown, green, and white in color. The valleys and walls have contrasting colors. Similar in appearance, but unlike the stalked corallites in Lobophyllia, its corallites are fused which are separated by wide valleys containing numerous mouths, giving the genus (e.g. Symphyllia recta) a brain-like appearance. A characteristic feature of this genus is a narrow (ambulacral) groove that usually runs along the top of walls, which is absent in Lobophyllia (Veron 1986). Valleys can also be short or even monocentric rather than meandering. Septa are numerous, with the larger ones being exsert by several mm. Septal margins are pointed with spines and finally serrated. PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to southern Pacific. GENERAL ABUNDANCE: generally common, very conspicuous. FOSSIL RECORD: Pliocene of the Pacific. NUMBER OF EXTANT SPECIES: 7 known species. Indophyllia (first recorded in Indonesia; Gk. phyllon, leaf): This genus, formerly thought long extinct, was rediscovered alive in Indonesia. I.macassarensis is a solitary, free-living, brown coral that may reach 45mm in diameter. Walls are indistinct beneath septo-costae which are present in 3 cycles. Septal teeth are large and lobed. Columella is compact submerged and composed of tiny pinules. A paliform crown may be present. PRESENT DISTRIBUTION: Indonesia only. GENERAL ABUNDANCE: Rare, inconspicuous. FOSSIL RECORD: Oligocene. NUMBER OF EXTANT SPECIES: 1 known species. Australomussa (L. australis, Australia; Gk. mussa, a coral genus): A.rowleyensis is the only member of this genus and has only recently been described (1985). PRESENT DISTRIBUTION: Central Indo-Pacific. GENERAL ABUNDANCE: sometimes common, very conspicuous. FOSSIL RECORD: Pliocene of the Pacific. NUMBER OF EXTANT SPECIES: 1 known species. Cynarina (Gk. kinara, an artichoke; L. -ina, suffix denoting likeness): C.lacrymalis is the only member. It is a solitary coral that is attached or free-living and tinged with green and red. Corallum is 5-6cm tall, rounded or slightly irregular in cross-section and does not exceed 8cm in diameter. Septa are prominent and arranged in cycles. 1st cycle is strongly exsert and thickened, which may protrude as much as 10mm (may also be toothed). Smaller septa are thinner. Typical genus of shaded areas. PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to western Pacific. GENERAL ABUNDANCE: generally uncommon, very conspicuous. FOSSIL RECORD: Oligocene (?), Pliocene of the Pacific. NUMBER OF EXTANT SPECIES: 1 known species). Circum-tropical genus: ------------------------------------------------------------------------------------------------------- Scolymia (Gk. skolymos, an artichoke): This genus is readily confused with Mussa, the only difference between these genera in the Atlantic being whether they are free living or not; and this appears to be confused with extant corals. S.lacera of the Indo-Pacific is relatively distinct. Range from small solitary to large colonial types, with the former more typical. Solitary are flattened and disk-like, between 3-14cm in diameter, rounded or slightly irregular in shape. Colonial corals are 20cm in diameter with more than 10 mouths. Septa may be hidden, are arranged in cycles with the larger one radiating from the columella to the perimeter. Corals typical in deeper or more shaded parts of the reef. PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to southern Pacific; Caribbean and Gulf of Mexico. GENERAL ABUNDANCE: generally uncommon, conspicuous. FOSSIL RECORD: Oligocene of the Tethys, Miocene of the Caribbean. NUMBER OF EXTANT SPECIES: 3 known species. Atlantic genera: --------------------------------------------------------------------------------------------------------------- Mussa (L. mus, mouse): he distinction between Mussa and the Atlantic Scolymia is somewhat arbitrary. The only member of this genus, M.angulosa forms massive, usually rounded, colonies that consist of a clump of large corallites rising from a common base. The fleshy olyps may combine shades of pink, purple, red, green, or brown. C orallites are monocentric, are either rounded or slightly elongate, and 40-100mm in diameter. The spiny corallite stalks arise 10-20cm from the base (phaceloid morphology). Corallites are separated by a gap of at least 5mm. Septa are numerous with spines at their margins (polyps with fleshy warts). Etymology obscure. PRESENT DISTRIBUTION: Caribbean and Gulf of Mexico. GENERAL ABUNDANCE: uncommon, very conspicuous, but confused with Scolymi. FOSSIL RECORD: Miocene of the Caribbean. NUMBER OF EXTANT SPECIES: 1 known species. Mussismilia (L. mus, mouse; similus, equal), sometimes termed Protomussa; Genera of massive colonies of relatively small size and bluish to violet, sometimes greenish in color. Corallites are distinct often exhibiting ceroid growth (with a faintly visible ambulacral groove) while one even phaceloid growth (M.harttii). Rounded, elongate, or polygonal calices are about 8-10mm in diameter. Septa are sometimes stout and exsert by several mm, but often smooth as they pass over the wall. In M.harttii septa continue as costae along the phaceloid coenosteum. Septal and costal margins vear slender, sharply pointed and often ragged teeth. Septa are porous. Columella is usually well developed (reduced in M.braziliensis). PRESENT DISTRIBUTION: Brazil only. GENERAL ABUNDANCE: generally uncommon, conspicuous. FOSSIL RECORD: Miocene of the Tethys. Recorded from the Tethys (southern France and Spain) of the Early and Middle Miocene, now endemic to Brazil. The genus is in need of revision; two of the three species qualify for inclusion in Acanthastrea. NUMBER OF EXTANT SPECIES: 3 known species. Isophyllia (G. isos, equal; phyllon, leaf): Small hemispherical colony forming genera that seldom exceed 20cm in diameter and usually green, brown, bluish, purple, or yellow in color. Corallites are joined in a longitudinal series to give a distinct pattern of elongate, Y-shaped, or irregular ridges and valleys. An ambulacral groove is present at the top of the wall. Usually three mouths per U-shaped valley. Septa run vrom the calice centers and are exsert by several mm as they pass over the walls. Septal margins bear strong, long, and sharp spines. The columella is spongy. PRESENT DISTRIBUTION: Caribbean, Gulf of Mexico and Bermuda. GENERAL ABUNDANCE: Generally common, conspicuous. FOSSIL RECORD: Miocene of the Caribbean. NUMBER OF EXTANT SPECIES: 2 known species. Mycetophyllia (Gk. mycetos, knobbed; phyllon, leaf): May form massive, flattened heads, but more often it is encrusting with broad, leafy extensions. The living tissue is fleshy and green, bluish, or brown in color. Calice centers and ridges are often paler. The slightly immersed calices are separate and spread over the surface of the corallum (distance between calice centers ranges from 5-15mm). Septa are continuos and appear as lines or as rows of warts linking adjacent calice centers. Spines are present at the septo-costal margin. The surface of the corallum is flat but in many cases collines are present; these vary from low (few mm) and rounded to high (20mm) and leafy. They may be widely spaced or enclose only a single row of calices. In general discontinuous collines radiate from the center of the colony toward the margin. PRESENT DISTRIBUTION: Caribbean and Gulf of Mexico. GENERAL ABUNDANCE: generally common, conspicuous. FOSSIL RECORD: Oligocene of the Tethys, Miocene of the Caribbean. NUMBER OF EXTANT SPECIES: 5 known species.