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Family Merulinidae: (L. merus, pure; L. linea, line).... outlining the entirely line-like appearance of the valleys. The genus name is derived from prominent hydnophores, which are conical structures, developed between the corallite centers (monticuloid or hydnophoroid morphology). Skeletal structures are often faviid-like but are highly fused, without paliform lobes. The valleys are superficial and often become obscured as they contort or spread like a fan.

This is a Cenozoic Tethyan family, with most genera now extant. Its affinities with the Mussidae are clear on morphological grounds. The family consists of five extant genera (i.e. Hydnophora, Paraclavarina, Merulina, Boninastrea, and Scaphophyllia). Only species of the genus Boninastrea are not found around PNG. The most diverse genus is Hydnophora with seven species. This genus was sometimes included in the family Faviidae. However, Veron (2000) points out that the close morphological similarities with Merulina and Scapophyllia clearly establish this genus in the family Merulinidae.


Some members of the family Merulinidae (80kB)

All species studied thus far are hermaphroditic broadcast-spawners. Paraclavarina triangularis and Merulina ampliata were observed to spawn during the mass-spawning events on the GBR.
Key to the family Merulinidae Monticules developed: Genus Hydnophora
Monticules not developed Colony consists of branches and/or laminae No basal laminae: Genus Paraclavarina
With basal laminae: Genus Merulina Colony massive: Genus Boninastrea
Colony columnar: Genus Scapophyllia
All genera are restricted to the Indo-Pacific region: ---------------------------------------------------------------------

Hydnophora (Gk. hydnon, tuber; phero, to bear):

Colonies are both branched or massive and brown, green, or yellowish with tips of the monticules paler. The genus name is derived from prominent hydnophores, which are conical structures (projecting discontinuous cones) between the corallite centers (Veron 1986). Skeletal structures are often faviid-like but are highly fused, without paliform lobes. The valleys are superficial and often become obscured as they contort or spread like a fan. Corallites are joined in series but their walls only rarely form a solid ridge. They are seldom over 20mm in length (hydnophoroid). Septa are visible as fine, closely packed, finely dentate or almost smooth. Species are characteristic of protected habitats and is very abundant in lagoonal environments.
PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to southern Pacific.
GENERAL ABUNDANCE: generally common, very conspicuous.
FOSSIL RECORD: Cretaceou, Eocene of the Tethys, Oligocene of the Caribbean.
NUMBER OF EXTANT SPECIES: 6 known species. Paraclavarina (Gk. para, beside; L. clavarius, clublike): The colonies of the only member of this genus P.triangularis consits of a network of anastomosing branches, either compacted or open. Branches are triangular in cross-section. Colonies may be up to 5m across. Color pale yellow or cream. No hydnophores present. Valleys are short and shallow with deep columella and distinct septa.
PRESENT DISTRIBUTION: central Indo-Pacific.
GENERAL ABUNDANCE: generally uncommon, conspicuous.
FOSSIL RECORD: None.
NUMBER OF EXTANT SPECIES: 1 known species. Merulina (L. merus, pure; linea, line): Partly encrusting and partly foliaceous colonies which may be thin and cabbage-like or flatter and plate-like. Colonies are pale-brown in color. Surface structure is meandroid (lines of corallites fan out radially), with the calices arranged in rows and separated by collines (hydnophores are present only rudimentarily). Calices are about 5mm apart and visible. Septa protrude and are closely packed. Septal margins have ragged teeth. Species found on reef slopes.
PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to southern Pacific.
GENERAL ABUNDANCE: sometimes common, conspicuous.
FOSSIL RECORD: Pliocene of the Pacific.
NUMBER OF EXTANT SPECIES: 3 known species. Boninastrea (Japanese island of Bonin; Gk. aster, star): Currently only a single species B.boninensis of thes genus is known from only two disjunct localities, in the Ogasawara (Bonin) Islands of Japan, and in Indonesia. Colonies are massive with short, highly contorted valleys and are yellowish-green in color. Septa have well developed teeth. Calices up to 10mm in diameter. Columella is absent. Status of this coral is still obscure, and could well be an aberant form of Merulina.
PRESENT DISTRIBUTION: western Pacific.
GENERAL ABUNDANCE: rare.
FOSSIL RECORD: None.
NUMBER OF EXTANT SPECIES: 1 known species. Scaphophyllia (L. scapus, stalk, shaft; Gk. phyllon, leaf): The single member of thes genus S.cylindrica forms massive, often columnar colonies that are brown in color and have stout foliaceous edges. Calices are united in series to form a pattern of valleys and ridges. Distance from mid-ridge to mid-ridge is about 5mm while valleys are 3-4mm deep. Callices centers are few mm apart. Septa are slightly exsert and closely packed.
PRESENT DISTRIBUTION: Eastern Indian Ocean to southern Pacific.
GENERAL ABUNDANCE: Generally uncommon, conspicuous.
FOSSIL RECORD: Miocene of the Tethys.
NUMBER OF EXTANT SPECIES: 1 known species.