Crispatotrochus septumdentatus, Kitahara & Cairns, 2008

Kitahara, Marcelo V. & Cairns, Stephen D., 2008, New records of the genus Crispatotrochus (Scleractinia; Caryophylliidae) from New Caledonia, with description of a new species, Zootaxa 1940 (1), pp. 59-68 : 65

Crispatotrochus septumdentatus , sp. nov.

Plate 1 , figs. K–L, N–R

Holotype. Norfolk 2 station DW 2124 (MNHN-Scl.2008-0046)

Paratypes. Bathus 4 station DW 894, 1 (MNHN-Scl.2008-0047); Norfolk 2 stations DW 2041, 2 (USNM 1115444), DW 2093, 1 (MNHN-Scl.2008-0048), DW 2117, 1 (MNHN-Scl.2008-0049), DW 2123, 1 (MNHN-Scl.2008-0050), and DW 2125, 1 (MNHN-Scl.2008-0051)

Description. Corallum ceratoid, elongate, curved, and usually slightly flared distally. Corallum attached through a robust pedicel (PD:GCD = 0.32–0.47) and a thin encrusting base of approximately 0.2–0.4 mm in width. Largest specimen analysed (USNM 1115444) 9.4 x 9.0 mm in calicular diameter and 21.5 mm in height. Calice circular to slightly elliptical even in small coralla (GCD:LCD = 1.04–1.15), calicular margin jagged, with high lancets corresponding to fusion of each pair of S4 with their adjacent S1 and smaller lancets to fusion of each pair of S4 with their adjacent S2. All costae ridged near calicular edge, slightly convex, and separated by thin intercostal striae. C1–2 more prominent and usually wider than C3–4, sometimes extending to pedicel. Theca uniformly covered by small pointed granules. Almost all specimens analysed bear some very thin, not uniform, continuous transverse ridges (more prominent in worn specimens). Corallum white.

Septa hexamerally arranged in four cycles according to the formula S1>S2>S3>>S4. S1 most exsert septa (up to 2 mm), and much thicker than higher cycle septa, with straight axial edges that reach and fuse to columella deep in fossa. Some specimens bear septal teeth (?) on S1 just above the fusion point with columella. S2 less exsert (about 1 mm) also with straight axial edges that sometimes fuse to columella. If S2 fuse to columella they also bear septal teeth, however, if not fusing, S2 disappear deep in fossa. S3 about one fourth to half width of S2, slightly sinuous, and commonly have lacerate axial edges. S4 rudimentary, composed of a row of granules, and dimorphic in exsertness. A pair of S4 fuse with each S1–2 near calicular edge forming lancets that alternate in height. Those fused with S1 are almost as exsert as S2, and those fused to S2 are the least exsert septa. Septal faces bear sparse, low, pointed granules.

Fossa deep, containing a large elliptical columella composed of closely grouped, slender ribbons, usually fused into a solid mass.

Remarks. Among the 14 Recent species of Crispatotrochus , C. septumdentatus is most easily distinguished by the unusual presence of septal teeth on the lower axial edges of S1 and S2, the latter only when fused with the columella. The presence of transverse ridges in some specimens is probably related to the expansion of the tissue over the external part of theca (e.g.: the specimen Bathus 4 station DW 894 has lower 3/4 of corallum very encrusted, being separated from the unencrusted higher part by thin transverse ridges).

Etymology. The species name septumdentatus (Latin septum, fence, edge, wall, partition + dentatus, toothed) refers to the small teeth structures present on the primaries’ axial septal margins.

Type locality. New Caledonia region (Norfolk 2 station DW 2124– 23º18’S, 168º15’E, 260–270 m) .

Distribution. Known only in the New Caledonia region, ranging from 20º15.77’S, 163º52.03’E to 24º44’S, 168º09’E, 187– 400 m.

Figures

PLATE 1. Crispatotrochus rubescens (A–D, F–G): A—calicular view X 1.6, B—oblique calicular view X 1.6, C— detail of columella X 3.5, and D—lateral view X 0.7 of USNM 1115428; F—calicular estereo pair X 2.4, and G—lateral view X 1, of MNHN-Scl.2008-0041. Crispatotrochus rugosus (E, H–J, M, S): E—oblique calicular view showing septal exsertnes X 2.8, H—calicular estereo pair X 3.1, I—lateral view X 1.9, and J— lateral view of same specimen showing the attachment near calicular edge of older coralla X 0.9, of USNM 1115430, M—lateral view X 1.9, and S—lateral view showing septal and costal pigmentation X 1.1, of MNHN-Scl.2008-0043. Crispatotrochus septumdentatus (K–L, N–R): K—calicular estereo pair of holotype (MNHN-Scl.2008-0046) X 3.7, L—oblique calicular view of holotype X 3.7, N— calicular view of paratype (USNM 1115444) X 3.7, O—calicular view of paratype X 4.6, P, Q, R—lateral views of paratypes (P and Q), and holotype (R), X 1.4, 1.5, 2.1 respectively.