Monohedotrochus capitolii Kitahara & Cairns, 2005

Cairns, Stephen D. & Polonio, Virginia, 2013, New records of deep-water Scleractinia off Argentina and the Falkland Islands, Zootaxa 3691 (1) : -

Monohedotrochus capitolii Kitahara & Cairns, 2005

Figs. 3 C–G, 11

Monohedotrochus capitolii Kitahara & Cairns, 2005: 117 –121, fig. 1–3.—Kitahara, 2007: 502, 503 (listed).—Kitahara et al., 2009: 228 (listed).

Remarks. This species was fairly well characterized in the original description, which was based on 41 specimens, but most of the specimens reported herein are larger than the largest previously reported, and thus allow for additional morphological observations. The largest specimen (PAT1008DR3) is 22.4 mm in CD (circular) and 26.4 mm in height. It contains 76 septa, or 14 pairs of S5, but still not a full fifth cycle. Kitahara & Cairns (2005:119) reported that “robust horizontal curled trabecular lobes” occurred on the lower axial edges of the S1–3 linking those septa to the columella, but these lobes are better interpreted as slender paliform lobes, and they do not occur on the axial edges of the S3, only the twelve S1–2. These P1–2 are separated from their respective septa (S1–2) by a wide notch, and are lamellar basally, becoming cylindrical (rod-shaped), and blunt-tipped apically. They are indistinguishable from the columellar elements, which are of the same size and shape. This species was one of the most commonly collected species in the study area.

Distribution. The specimens reported herein do not appreciably extend the known geographic range of the species, which consists of the continental shelf (150–460 m) off southernmost Brazil (Rio Grande do Sul and Santa Catarina states) but significantly deeper on the continental slope (721–1620 m) off central Argentina ( Fig. 11).

Material. PAT0108DR1, 47, MNCN; PAT0108DR2, 1, MNCN; PAT0108DR3, 2, MNCN; PAT0108DR7, 46, MNCN; PAT0108DR11, 2, MNCN, and 3, USNM 1192658 and 1192653; PAT1008DR1, 50, MNCN; PAT1008DR3, 3, MNCN, and 1, USNM 1192656; PAT1008DR4, 11, MNCN; PAT1008DR8, 8, MNCN, and 3, USNM 1192652; PAT1008DR9, 13, MNCN; PAT1008DR10, 2, MNCN; PAT1008DR12, 1, MNCN; PAT1008DR13, 3, MNCN; PAT1108DR3, 11, MNCN; PAT1108DR4, 2, MNCN; PAT1108DR9, 4, MNCN, and 1, USNM 1192664; PAT1108DR10, 2, MNCN; PAT1108DR11, 4, MNCN; PAT1208DR4, 1, MNCN; PAT1208DR7, 14, MNCN; PAT1208DR9, 8, MNCN; PAT1208DR11, 1, MNCN; PAT0209DR1, 6, MNCN; PAT0209DR3, 1, MNCN; PAT0209DR5, 2, MNCN; PAT0209DR7, 3, MNCN; PAT0209DR10, MNCN; PAT0209DR11, 1, USNM 1192654; PAT0209DR14, 2, MNCN; PAT0210DR7, 3, MNCN; PAT0210DR11, 1, USNM 1192657; ATL09Lo101,1, USNM 1192757.

Figures

FIGURE 3. A – B, Crispatotrochus cornu, PAT 0209 DR 16, calicular and lateral views of corallum. C – G, Monohedotrochus capitolii: C, PAT 1008 DR 8, calicular view; D, PAT 0209 DR 11, calicular view; E – F, PAT 1008 DR 3, calicular and lateral views of corallum; G, PAT 0108 DR 11, calicular view. H – I, Desmophyllum dianthus: H, PAT 0108 DR 11, lateral view of corallum; I, PAT 1008 DR 4, calicular view of corallum attached to a stylasterid. J, Solenosmilia australis, holotype. K – M, Flabellum curvatum: K – L, ATL 09 Lo 66, lateral and calicular views of corallum; M, ATL 10 Lo 89, lateral view of straight corallum. N – O, F. thouarsii, ATL 10 Lo 89, lateral and calicular views of corallum with tissue.