logo

Micromussa

Veron, 2000, vol. 3, p. 8

Type Species

Acanthastrea amakusensis Veron, 1990, p. 137, fig. 42; Original Designation Veron, 2000, vol. 3: 8

Type Specimen: Holotype; MTQ G32485; Verified; Dry Preserved

Type Locality: Amakusa Is., Japan (Recent)

Classification

Diagnosis

Colonial; encrusting or massive. Budding intracalicular and extracalicular. Corallites monomorphic; discrete. Monticules absent. Coenosteum spinose; usually limited (includes double wall). Calice width medium (4–15 mm), with medium relief (3–6 mm). Costosepta mostly not confluent. Septa typically in three cycles (24–36 septa), although M. pacifica may contain more than 36 septa. Free septa irregular. Septa spaced 6–11 septa per 5 mm. Costosepta unequal in relative thickness. Columellae trabecular and spongy (> three threads), < 1/4 of calice width, and discontinuous among adjacent corallites with lamellar linkage. Internal lobes usually absent. Epitheca well developed. Endotheca low-moderate (tabular). Tooth base at midcalice elliptical-parallel. Tooth tip orientation parallel. Tooth height medium (0.3–0.6 mm). Tooth spacing medium (0.3–1.0 mm), with > six teeth per septum. Tooth shape equal between first and third order septa. Tooth size equal between wall and septum. Granules scattered on septal face; strong (pointed). Interarea smooth. Walls formed by dominant paratheca and partial septotheca. Thickening deposits in concentric rings with extensive stereome. Costa centre clusters strong; 0.3–0.6 mm between clusters; medial lines weak. Septum centre clusters weak; > 0.5 mm between clusters; medial lines weak.

Description

'Colonies are submassive or encrusting and usually flat. Corallites are cerioid or subplocoid, either circular or angular in shape and up to 8 millimetres diameter. Septa are thickened at the corallite wall, and have conspicuous teeth. Colonies may have fleshy tissue over the skeleton, but skeletal structures remain visible. Tentacles are extended only at night.' (Veron, 2000, vol. 3: 8)

Comparisons

Two unambiguous synapomorphies support the Micromussa clade (bootstrap value of 58)—limited coenosteum (likelihood of 0.92 based on the Mk1 model) and strong (pointed) granules on the septal face (likelihood 0.98). Micromussa is the sister genus to Homophyllia based on molecular characters, but forms a paraphyletic group with Homophyllia and Australophyllia when analysed using morphological data. Micromussa is easily distinguished from these closely-related genera by their less numerous septa (24–36), costosepta that are not confluent, shorter distance between costa centre clusters (0.3–0.6 mm), and the two synapomorphies.

Remarks

Micromussa was established recently by Veron (2000, vol. 3: 8) to contain the designated type Acanthastrea amakusensis Veron, 1990: 137, as well as Acanthastrea minuta Moll and Best, 1984: 53, and a new species Micromussa diminuta Veron, 2000, vol. 3: 9. No data exist for the latter two species, but detailed observations by Arrigoni et al. (2016a) indicate that Acanthastrea minuta should not have been moved into Micromussa, while Micromussa diminuta actually belongs to Goniopora. Molecular analyses have also demonstrated that Acanthastrea lordhowensis Veron and Pichon, 1982: 138, and Montastrea multipunctata Hodgson, 1985: 284, are closely related to Micromussa amakusensis (Arrigoni et al., 2014b, c, 2015, 2016a). Specifically, Montastrea multipunctata is closely related to M. amakusensis and M. indiana, while Acanthastrea lordhowensis and M. pacifica are basal to the three species; these have all been placed in Micromussa (Arrigoni et al., 2016a). Our analyses using both molecular and morphological data support the clade grouping these five species, whose macromorphological characters are also shared with Acanthastrea regularis Veron, 2000, vol. 3: 16 (Appendix S2). We note that subcorallite morphology and molecular data have not been sampled for the latter species. Superficially, it resembles Favites valenciennesi (Milne Edwards and Haime, 1849b, vol. 12: 124), though possessing thicker walls and more exsert septal teeth. Based parsimoniously on the characters examinable for the holotype, it is clear Acanthastrea regularis has no affinity to Acanthastrea, and is herein transferred into Micromussa. Consequently, the described diversity of this genus currently stands at six species. Micromussa is widely distributed on the reefs of Indo-Pacific, present from the southern Red Sea (Arrigoni et al., 2016a) to as far east as the Marshall Islands in the Northern Hemisphere and Fiji in the Southern Hemisphere (Veron, 2000).

Distribution

  • East Asia; Pleistocene
  • Indian Ocean; Recent
  • Western Pacific; Recent
  • Central Pacific; Recent
Source: Paleobiology database (accessed 6/5/12), Veron (2000). Distribution compiled by Matthew Tibbits.

This page has been in preparation since 20-Jul-2010 03:40

This version was contributed by Danwei Huang on 29-Jan-2016 14:02.

Page authors are: Ann Budd Danwei Huang. Please contact the editor if you would like to contribute to the diagnosis of this taxon.

The editor is: Ann Budd


holotype of Acanthastrea amakusensis Veron
info