Montastraea, DE BLAINVILLE, 1830: 339

Huang, Danwei, Benzoni, Francesca, Fukami, Hironobu, Knowlton, Nancy, Smith, Nathan D. & Budd, Ann F., 2014, Taxonomic classification of the reef coral families Merulinidae, Montastraeidae, and Diploastraeidae (Cnidaria: Anthozoa: Scleractinia), Zoological Journal of the Linnean Society 171 (2), pp. 277-355 : 342-344

GENUS MONTASTRAEA DE BLAINVILLE, 1830: 339 ( FIG. 27 )

Synonym

Montastrea Vaughan & Wells, 1943: 173 (misspelling).

Type species

Astrea guettardi Defrance, 1826: 379 , fossil (figured in Guettard, 1770, vol. 3, pl. 48: figs 2–4); subsequent designation, Lang & Smith, 1935: 554; holotype: lost; hypotype: MNHN R05933, figured in Michelin, 1842, pl. 12: fig. 3 (dry specimen; Fig. 27A ); type locality: Miocene.

Original description

‘En masses épaisses, composées de cellules tubuleuses assez serrées pour être polygonales, à bords non saillans, à cavité assez profonde, garnie de lamelles nombreuses, remontant le long d’une axe solide plus ou moins saillant.’ ( de Blainville, 1830: 339).

Subsequent descriptions

de Blainville, 1834: 374; Lang & Smith, 1935: 554; Wells, 1936: 120; Vaughan & Wells, 1943: 173; Smith, 1948: 90; Wells, 1954: 463; Wells, 1956: F404; Chevalier, 1971: 278; Veron et al., 1977: 136; Wijsman-Best, 1977: 84; Scheer & Pillai, 1983: 139; Wood, 1983: 49; Veron, 1986: 502; Chevalier & Beauvais, 1987: 714; Veron & Hodgson, 1989: 273; Sheppard, 1990: 24; Budd, 1991: 34 ; Sheppard & Sheppard, 1991: 135; Veron, 2000, vol. 3: 212.

Diagnosis

Colonial, with extracalicular budding only. Corallites monomorphic and discrete (one to three centres); monticules absent. Coenosteum costate, moderate amount (<corallite diameter). Calice width medium (4– 15 mm), with medium relief (3–6 mm). Costosepta not confluent. Septa in ≥ four cycles (≥ 48 septa; including very short free septa). Free septa regular. Septa spaced> 11 septa per 5 mm. Costosepta unequal in relative thickness. Columellae trabecular and spongy (> three threads), ≥ 1/4 of calice width. Paliform (uniaxial) lobes absent. Epitheca well developed and endotheca low−moderate (tabular) ( Fig. 27A, D ).

Tooth base at midcalice elliptical−perpendicular. Tooth tip at midcalice regular (pointed). Tooth height medium (0.3–0.6 mm) and tooth spacing medium (0.3–1 mm), with> six teeth per septum. Granules scattered on septal face; weak (rounded). Interarea smooth ( Fig. 27B, E ).

Walls formed by partial septotheca; abortive septa weak. Thickening deposits fibrous. Costa centre clusters strong; 0.3–0.6 mm between clusters; medial lines absent. Septum centre clusters weak; 0.3–0.5 mm between clusters; medial lines absent. Transverse crosses absent. Columella centres clustered ( Fig. 27C, F ).

Species included

Montastraea cavernosa ( Linnaeus, 1767: 1276) ; holotype: unknown, figured in Seba (1758, pl. 112: fig. 19) (reproduced in Budd, 1991: 37 , fig. 20); type locality: ‘O. Americano’ ( Linnaeus, 1767: 1277); phylogenetic data: molecular and morphology.

Taxonomic remarks

Montastraea de Blainville, 1830: 339 , was initially described as a subgenus of Astrea consisting solely of five fossil species. This name never caught on, partly because of its subgenus status, but also because of its association with the more commonly used name Heliastraea Milne Edwards & Haime, 1857, vol. 2: 456. Forty-five species of both modern and fossil corals were attributed to Heliastraea , including the type Madrepora astroites Forskål, 1775: 133 (= Astrea forskaliana Milne Edwards & Haime, 1849b, vol. 12: 100), as well as Madrepora cavernosa Esper, 1795: 18 , pl. 37: figs 1, 2 (= Madrepora cavernosa Linnaeus, 1767: 1276 ).

Astrea guettardi Defrance, 1826: 379 , is one of the species originally assigned to Montastraea , but it was only chosen as ‘genolectotype’ more than a century later by Lang & Smith (1935) and Wells (1936). The authors elevated this taxon to genus, and continued its restriction to fossil corals albeit spanning Cenozoic to Palaeozoic. Shortly after, Vaughan & Wells (1943: 173) redefined the genus and included as synonyms Heliastraea and Orbicella amongst several fossil genera, effectively incorporating the Recent Atlantic ( Madrepora cavernosa and Orbicella ) and Red Sea ( Astrea forskaliana ) within its range, although the latter was not explicitly stated. Note that an ‘a’ was omitted from the genus name in the process, a practice that has propagated until today ( Veron, 2000, vol. 3: 212; but see Chevalier, 1971: 278; Budd et al., 2012). Wells (1956: F404) followed a similar treatment, but excluded Heliastraea as a synonym, thus restricting the living Montastraea to the Atlantic.

Subsequent workers expanded on the definition of this genus, characterizing it mainly with the trait of extracalicular budding, and consequently incorporat- ed Indo-Pacific species such as Astrea curta Dana, 1846: 209 , Astrea annuligera Milne Edwards & Haime, 1849b, vol. 12: 103, Phymastrea valenciennesi Milne Edwards & Haime, 1849b, vol. 12: 124, and Montastraea magnistellata Chevalier, 1971: 293 ( Chevalier, 1971; Veron et al., 1977; Wijsman-Best, 1977; Veron, 1986, 2000). It is also clear that Heliastraea is a synonym of Echinopora instead of Montastraea because its type Astrea forskaliana (holotype: MNHN IK-2010-406) undoubtedly belongs in Echinopora ( Wijsman-Best, 1980; Veron, 2000), even against the broader definition of Montastraea .

This genus is a challenge to define, and it has been argued that confusion with Plesiastrea Milne Edwards & Haime, 1848a, vol. 27: 494, is causing this taxonomic uncertainty ( Veron et al., 1977). Recent molecular phylogenetic analyses have shown that the problem is far worse than previously thought. Fukami et al. (2008) and Kitahara et al. (2010) initially showed that Montastrea (sensu Veron, 2000) is polyphyletic and present in at least three separate clades, but more extensive samplings of the group placed it in up to six distinct lineages ( Huang et al., 2011; Arrigoni et al., 2012). All species examined to date, with the exception of Madrepora cavernosa Linnaeus, 1767: 1276 (clade XVI), and Montastrea multipunctata Hodgson, 1985: 284 (clade XVIII, XIX or XX; Lobophylliidae ), are nested within Merulinidae and have been dealt with above.

Montastraeidae is restricted to Montastraea cavernosa on the basis of molecular data that place it in one of the deepest branching lineages of clades XV to XXI ( Budd et al., 2012), either sister to Merulinidae + Lobophylliidae + Mussidae ( Fukami et al., 2008) , or to Diploastraeidae ( Huang et al., 2011; Arrigoni et al., 2012).

‘ Montastrea’ multipunctata has been placed outside of the Merulinidae clade based on molecular and morphological data (Fig. 2; Huang et al., 2011; Arrigoni et al., 2014). It is in close alliance with Lobophylliidae species, although the precise relationship is unknown. There is however little evidence to suggest that it has any affinity to Montastraea cavernosa . Here, we place it in the family Lobophylliidae Dai & Horng, 2009: 59 that awaits detailed taxonomic revision.

Montastraea is distributed on reefs of the Atlantic, specifically in the Caribbean, Brazil, and West Africa.

Morphological remarks

Montastraea is an outgroup for the morphological phylogeny and thus no apomorphies were inferred. It can be distinguished from Orbicella , which co-occur in the Caribbean, in having larger (4–15 mm) and deeper (3– 6 mm) calices, more septa (≥ 48), spongy columellae, larger and more widely spaced septal teeth (0.3– 0.6 mm high, 0.3–1 mm apart) with ellipticalperpendicular bases and regular (pointed) tips, weak (rounded) granules, presence of weak abortive septa, strong costa centre clusters, and absence of medial lines.

FAMILY DIPLOASTRAEIDAE CHEVALIER & BEAUVAIS, 1987: 721

Synonym

Diploastreidae Budd et al., 2012: 469 (misspelling).

Figures

Figure 27. Montastraea de Blainville, 1830, has discrete corallites that bud extracalicularly, septa in ≥ four cycles (≥ 48 septa) spaced> 11 septa per 5 mm, regular free septa, and large (≥ 1/4 of calice width) spongy columellae. Septal teeth elliptical−perpendicular at base. Walls formed by partial septotheca and weak abortive septa, with strong costa centre clusters. A, Astrea guettardi Defrance, 1826, type species of Montastraea; macromorphology, hypotype MNHN R05933, Miocene, Turin, Italy. B–F, Montastraea cavernosa (Linnaeus, 1767), the only living species of Montastraea; macromorphology (D) and micromorphology (scanning electron microscopy; B, E), hypotype SUI 122829 (FA1109), Carrie Bow Cay, Belize; microstructure (transverse thin section), hypotype SUI 48763 (FA1110), Discovery Bay, Jamaica (C), and hypotype SUI 122828 (FA1093), Bocas del Toro, Panama (F).