Deltocyathus inusitatus, Kitahara & Cairns, 2009

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 : 245-246

Deltocyathus inusitatus n. sp.

( Fig. 1J)

HOLOTYPE. — NORFOLK 2, stn DW 2097 ( MNHN- Scl.2008-0034).

PARATYPES. — NORFOLK 2, stn DW 2025, 2 specimens (MNHN-Scl.2008-0035, MNHN-Scl.2008-0036); stn

DW 2034, 1 specimen (MNHN-Scl.2008-0037); 1 specimen ( USNM 1114137 ) ; stn DW 2086, 1 specimen (MNHN-Scl.2008-0038); stn DW 2087, 1 specimen (MNHN-Scl.2008-0039); 1 specimen ( USNM 1114138 ) ; stn DW 2097, 1 specimen (MNHN-Scl.2008-0040).

TYPE LOCALITY. — Bank Kaimon Maru (24°44’S, 168°06’E), 580- 583 m.

ETYMOLOGY. — The species name inusitatus (from Latin inusitatus , meaning unusual, extraordinary, strange, rare) refers to the unusual septal arrangement presented in this species.

DISTRIBUTION. — New Caledonia region from 23°27’S, 167°51’E to 24°56’S, 168°22’E (Bank Brachiopode, Bank Stylaster, Bank Éponge, and Bank Kaimon Maru).

DESCRIPTION

Corallum free and patellate, with flat to very slightly convex base. Well-preserved coralla show a small and usually convex epicentre boss in base. Specimens range from 11 to 13.4 mm in GCD and 2.9 to 4 mm in HT. Holotype measures 13.3 × 13.2 mm in CD and 3.6 mm in HT. Well-preserved specimens have a circular calice, and worn specimens appear to have a polygonal margin. Calicular margin not lancetted or serrate, projection of all septa being equal. Costae granular being more conspicuous near calicular edge, where they are separated by shallow intercostal grooves. Granules small and low, becoming more slender and taller near calicular edge. All specimens analyzed show a reddish-brown to purple calicular edge, including all septal edges and approximatelly 3 mm of base edge in direction to centre.

Septa always hexamerally arranged in 5 incomplete cycles (S1≥S2>S3≥S5>S4), normally having 69 to 72 septa. All systems present two dimorphic half systems, one composed of 1 S 1, 1 S 2, 1 S 3, 2 S 4, and 4 S5, and the other composed of 1 S 1, 1 S 2, 1 S 3 and 2 S4. All specimens contain 3 half-systems. S5 oriented to the right of half systems with less septa, and 3 to left. S1 about 1.8 mm exsert and only independent septa, extending half distance to columella. P1 well developed and separated from S1 by a wide notch which contains a slender paliform tooth. S2 similar in shape and exserteness, but sometimes slightly less wide than S1. Notch separating S2 from their paliform lobes less wide than those of S1, and sometimes bearing a small paliform tooth. At the site that S3 join S2 there are usually 1 to 3 paliform teeth. S3 dimorphic in width, those in the half-system with no S5 equal to slightly less wide than the flanking S4 (specially S4 near S1), extending ¼ to ⁄ distance to columella. P3 as wide as S3, being separated by a small notch. However, those S 3 in the half-system with S5 are bigger than the flanking S4, extending about ⅓ distance to columella. Before joining columella, all P3 usually bear 1 to 4 paliform teeth. Axial edges of each pair of S5 solidly fused as a thick lamella to outer edge of adjacent P4. Usually S5 beside a primary or secondary septa is wider than other S5. P4 of crowded half system join P3 at approximately ⁄ distance from columella and in half systems without S5, P4 fuse P3 as thick lamella. P3 join P2 near columella and axial eges of P1 and P2 are fused to columella. All septa and palar faces bear sparse, pointed granules.

Fossa extremely shallow to nonextant, containing a well-developed papillose columella, consisting of 7 to 20 often fused granular rods.

REMARKS

Among the other 24 Recent species belonging to the genus Deltocyathus , D. inusitatus can most easily be distinguished by its unusually dimorphic septal cycles, one half system composed of 1 S 1, 1 S 2, 1 S 3, 2 S 4, and 4 S5, and the other composed of 1 S 1, 1 S 2, 1 S 3 and 2 S4. All specimens consist of 3 half-systems with S5 oriented to the right of the half systems with less septa, and 3 to the left. Other distinctive characters are its flat base, all septa extending the same distance beyond the calicular margin, and usually a small paliform tooth present between S1 and P1.

Two coralla from NORFOLK 2 expedition, stn DW 2087 showed evidence of calicular regeneration.