taxonID	type	description	language	source
03F48792DD1B79025962FCF6549ABE39.taxon	materials_examined	Type species: Calathiscus tantillus	en	Claereboudt, Michel R., Al-Amri, Issa S. (2004): coral (Scleractinia, Poritidae) from the Gulf of Oman. Zootaxa 532: 1-8, DOI: 10.5281/zenodo.157525
03F48792DD1B79025962FCF6549ABE39.taxon	diagnosis	Diagnosis: see under only known species, Calathiscus tantillus Calathiscus tantillus new species (Figs. 1 – 6).	en	Claereboudt, Michel R., Al-Amri, Issa S. (2004): coral (Scleractinia, Poritidae) from the Gulf of Oman. Zootaxa 532: 1-8, DOI: 10.5281/zenodo.157525
03F48792DD1B79025962FCF6549ABE39.taxon	materials_examined	Material examined Holotype: Sultan Qaboos University, SQU 040001, Cemetery Bay­ Pillar Rock, 8 m, Muscat (Oman). Collector: Michel Claereboudt. The holotype consists of a whole colony (1. 7 x 3.4 cm) (Fig. 1, 4). Paratypes: 1 ­ Florida Museum of Natural History, UF 535, Masirah Island, 3 – 4 m (Oman). Collector: Gustav Paulay (Fig. 2, A). 2 Institut Royal des Sciences Naturelles de Belgique, IG 30190, Cemetery Bay, Muscat, 6 m. Collector: Michel Claereboudt (Fig. 2 B).	en	Claereboudt, Michel R., Al-Amri, Issa S. (2004): coral (Scleractinia, Poritidae) from the Gulf of Oman. Zootaxa 532: 1-8, DOI: 10.5281/zenodo.157525
03F48792DD1B79025962FCF6549ABE39.taxon	diagnosis	Diagnosis Corallites are 1.7 mm in diameter with calices small, rarely exceeding 1.5 mm There are two complete and one incomplete, variable, cycles of septa (6 + 6 + 3 — 10). A columella is absent. Living colonies have large polyps, with an elongated column and lanceolate tentacles that are normally extended during the day. Tentacles vary in number from 15 to 22 corresponding to the number of septa. Previous records This species has not been previously recorded.	en	Claereboudt, Michel R., Al-Amri, Issa S. (2004): coral (Scleractinia, Poritidae) from the Gulf of Oman. Zootaxa 532: 1-8, DOI: 10.5281/zenodo.157525
03F48792DD1B79025962FCF6549ABE39.taxon	description	Description Colonies are encrusting or hemispherical, very small, rarely more than 30 mm across. Corallites are rounded and very small (1.7 mm in diameter on average) with calices rarely exceeding 1.5 mm. The wall is thin and consists of rows of irregular, granulated denticles that correspond to septal insertions, and are connected with synapticular links leaving few pores between adjacent corallites, particularly in lightly calcified colonies from deeper water. Calices are shallow. Septa form 2 subequal cycles with a third cycle expressed to varying degrees in different corallites and colonies. Only the first 2 cycles are complete, and show an irregular pattern of septal fusion. There are between 15 and 22 septa, some reduced to a single row of denticles along the corallite wall. A ventral trident (or triplet) is present in some calices and defines with a dorsal septum an axis of bilateral symmetry. The lateral septa do not form regular pairs as in Porites, but are occasionally fused. In most specimens, a single synapticular ring is clearly visible surrounding a central fossa in which there is no columella. Pali formed by large granulated denticles are present on the margin of 6 septa although in some lightly calcified specimens, the pali are poorly defined. There is an additional denticle on some septa between wall and palus. Living colonies have large polyps, with an elongated column and lanceolate tentacles, that are normally extended during the day. All observed colonies were light green with radiating brown marks on the oral cones and a darker ring on the tentacles. Tentacles vary in number from 15 to 22 and correspond to the septal arrangement. Colonies are very sensitive to even slight changes in water pressure or movement and respond readily to the slightest disturbance by retracting the polyps.	en	Claereboudt, Michel R., Al-Amri, Issa S. (2004): coral (Scleractinia, Poritidae) from the Gulf of Oman. Zootaxa 532: 1-8, DOI: 10.5281/zenodo.157525
03F48792DD1B79025962FCF6549ABE39.taxon	discussion	Remarks The series of corallites studied showed considerable variation in the development of the various skeletal features, particularly the number of septa and size of the pali. The number of septa varied from 15 to 22. The development of a ring of synapticulae linking the septa in the center of the corallites and the fusion patterns of the septa (ventral triplets and lateral pairs) was also variable. The appearance of the living polyps on the other hand was very stable, and the species was readily identifiable underwater by its color, number of tentacles and small size.	en	Claereboudt, Michel R., Al-Amri, Issa S. (2004): coral (Scleractinia, Poritidae) from the Gulf of Oman. Zootaxa 532: 1-8, DOI: 10.5281/zenodo.157525
03F48792DD1B79025962FCF6549ABE39.taxon	etymology	Etymology Calathiscus is named after a small woven wicker basket (C alathiscus in Latin) to reflect simultaneously the “ porous ” and delicate nature of the calices of this genus and the small size of the colonies. Gender masculine. The specific epithet tantillus, literally “ ever so small ” in Latin, was chosen to suggest the small size of the calices and the colonies of this species. Habitat and distribution All colonies were found attached to hard substrate: fragments of coral skeleton, large flagstone of limestone and Ophiolite bedrock. Colonies of Calathiscus tantillus have been found in several reef communities between 4 and 22 m in depth in mixed communities dominated by several species of Cyphastrea, Leptastrea, Favites and small colonies of Porites and Goniopora. In the Gulf of Oman, these depths correspond to the lower part of the reefs, as reefs rarely extend below 12 – 15 m. The species has been found in communities established on ancient limestone but also, more commonly, in coral communities growing directly on ophiolite. Although never common and always cryptic, colonies of Calathiscus tantillus can be relatively abundant but never exceed 2 or 3 cm 2 in size. Some specimens observed at the deepest location (Fahl Island, 22 m) where partially discolored with the disk and tentacles taking brown­purple color. Calathiscus tantillus was observed in most coral rich communities in the Muscat Area (Daymaniyat Islands, Cemetery Bay, Bandar Khayran) and one specimen (Paratype 2, FLMNH UF 535) was collected in the Arabian Sea near the Island of Masirah (20 º 0 ’ 40 ” N, 58 º 38 ’ 0 ” E).	en	Claereboudt, Michel R., Al-Amri, Issa S. (2004): coral (Scleractinia, Poritidae) from the Gulf of Oman. Zootaxa 532: 1-8, DOI: 10.5281/zenodo.157525
03F48792DD1B79025962FCF6549ABE39.taxon	discussion	Discussion	en	Claereboudt, Michel R., Al-Amri, Issa S. (2004): coral (Scleractinia, Poritidae) from the Gulf of Oman. Zootaxa 532: 1-8, DOI: 10.5281/zenodo.157525
03F48792DD1B79025962FCF6549ABE39.taxon	description	Several species of Poritidae are also characterized by very small colonies. The largest colonies of Stylaraea for instance are only a few cm across and several small Porites not exceeding a few cm in diameter are being described (J. E. N. Veron, Pers. Comm.).	en	Claereboudt, Michel R., Al-Amri, Issa S. (2004): coral (Scleractinia, Poritidae) from the Gulf of Oman. Zootaxa 532: 1-8, DOI: 10.5281/zenodo.157525
