Deltocyathus rotulus ( Alcock, 1898 )

Kitahara, Marcelo V. & Cairns, Stephen D., 2009, A revision of the genus Deltocyathus Milne Edwards & Haime, 1848 (Scleractinia, Caryophylliidae) from New Caledonia, with the description of a new species, Zoosystema 31 (2), pp. 233-248 : 238-239

Deltocyathus rotulus ( Alcock, 1898) ( Fig. 1B)

Trochocyathus rotulus Alcock, 1898: 16 , pl. 2, figs 1, 1a.

Deltocyathus fragilis Alcock, 1902a: 99 , 100; 1902c: 21, pl. 1, figs 15, 15a.

Deltocyathus rotulus . — Van der Horst 1931: 6. — Gardiner & Waugh 1938: 196. — Yabe & Eguchi 1937: 129. — Keller 1982: 50. — Cairns & Keller 1993: 245, pl. 5, fig. I. — Cairns 1994: 55, 56, pl. 24, figs j, k; 1999: 91, 92; 2004: 280. — Cairns & Zibrowius 1997: 125, 126, fig. 16a-c. — Cairns et al. 1999: 22.

TYPE MATERIAL. — The holotype of Trochocyathus rotulus is presumed to be deposited at the IM. Six syntypes of Deltocyathus fragilis are deposited at the ZMA (Coel. 1188).

TYPE LOCALITY. — North Maldive Atoll, 1408-1756 m ( Trochocyathus rotulus ). 7°24’S, 118°15.2’E ( Flores Sea), 794 m ( Deltocyathus fragilis ).

NEW RECORDS. — BATHUS 3, stn CP 842, 2 specimens (MNHN-Scl.2008-0002); stn DW 786, 1 specimen (MNHN-Scl.2008-0003). — BATHUS 4, stn CP 950, 62 specimens (MNHN-Scl.2008-0004); 10 specimens ( USNM 1114141 ) .

DISTRIBUTION. — New Caldonia waters from 20°31’S to 23°54’S, 699- 830 m. Elsewhere:Indian Ocean off Durban, off Mozambique, off Zanzibar ( Cairns & Keller 1993),

510-1986 m, including Maldive islands ( Alcock 1898; Gardiner & Waugh 1938), Gulf of Aden ( Gardiner & Waugh 1938), off Sri Lanka ( Van der Horst 1931), and off Tanzania ( Gardiner & Waugh 1938); Pacific Ocean off southeastern Japan ( Cairns 1994), 799-1187 m, off Philippines, Indonesia ( Flores and Celebes Sea), Malaysia ( Alcock 1902a, c; Cairns & Zibrowius 1997), 210-1719 m, Vanuatu and Wallis and Futuna region (Cairns 1999), 1050-1160 m, Australia region off Queensland ( Cairns 2004), 143-1192 m.

DESCRIPTION

Corallum circular to slightly elliptical with lancetted calicular margin. Each apex correspond to those C4 flanked by C5. Base normally slightly conical and pointed in centre. However, largest specimen examined (BATHUS 3, stn CP 842), with 19 mm in calicular diameter and 4 mm in height, shows a flat base with upturned edges. Costae more prominent near calicular edge as low serrated ridges. C1-3 originates in centre of the base, C4 present only near calicular edge, and C5 slightly wider than C4. Corallum white to reddish-brown.

Septa hexamerally arranged in 5 cycles (S1-2>S3> S4>S5). S1-2 do not fuse to any adjacent septa, each bearing a palus about 1-2.5 mm wide. S3 less exert with irregularly shaped paliform lobe, sometimes P3 wider than P1-2, but some specimens present P3 very small. Adjacent to the P3, near columella, sometimes 2 or 3 small paliform teeth are present. S4 less wide and exsert than S3 but bear a wide and tall palus, producing a prominent palar crown encircling columella. Each P4 fuses to the flanked P3 near columella. S5 fuses to the axial edge of adjacent P4 close to basal theca through a long and porous lamella.

Fossa extremely shallow containing a welldeveloped papillose columella composed of several interconnected rods.

REMARKS

Among the Deltocyathus species from New Caledonia with five septal cycles, D. rotulus is easily distinguished from D. suluensis by having a scalloped calicular edge, a pigmented columella and paliform lobes, and paliform lobes that reach the same high of the septa. For comparation with D. magnificus see previous remarks.