Kuroshioturris angustatus
Dimensions
GS5216, Puketapu, Hawke's Bay: H (incomplete) 14.8, D 6.3 mm; H 15.6, D 6.2 mm; GS4185, Upper Castlecliff Shellbed, Castlecliff: H 12.8, D 4.6 mm; Castlecliff, early collection: H 16.5, D 5.6 mm; Recent, NMNZ M.112114, Deepwater Cove, Bay of Islands, 55 m: H 13.3, D 4.8 mm; H 13.4, D 4.6 mm; NMNZ M.67615, W of Plate I, Bay of Plenty, 59–64 m: H 15.8, D 5.3 mm; H 13.2, D 5.1 mm.
Shell narrowly fusiform, biconic, with nodulous keeled whorls. Spire same height as aperture plus canal. Whorls 6 ½, including a blunt dome-shaped smooth protoconch of 1 ½ whorls. Spire whorls with a moderately strong nodulous subsutural swelling, a broad shallow concavity followed by a heavy rounded nodulous peripheral keel occupying most of the lower half of each whorl and then narrowly contracted underneath to the lower suture. On the base there are three narrow smooth raised wide-spaced spiral cords followed by ten closer-spaced very weak and indistinct threads fading out at the fasciole. The uppermost of the three basal cords is at the lower suture. The peripheral cord, and the subsutural one to a lesser extent, are ornamented with prominent laterally compressed slightly arcuate smooth nodules. The nodules number 16 on the penultimate. Linear spaced subsidiary spiral threads cover the spire-whorls, even between the peripheral nodules, but they become obsolete on the base. The apertural sinus is deep, with a squarish notch situated on the peripheral keel. Numerous sinuous axial lines of growth cover the whole shell. Aperture narrow, terminating in a moderately long open canal.
Remarks
The generic position of ‘Micantapex’ angustatus has long been in doubt. It differs from species of Bathytoma (=Micantapex) in its small size and much narrower shape, and so resembles several other genera, including Gemmula, at least superficially. Powell (1966) transferred it to Lucerapex Iredale, 1936, but the type species (Pleurotoma casearia Hedley & Petterd, 1906, Recent, deep water off New South Wales) lacks all spiral sculpture other than the peripheral nodulose carina formed by the trace of the sinus apex, and instead has the surface crossed by wavy axial lines (low, thin axial lamellae). Species of Lucerapex recognized in the New Caledonian fauna by the MNHN informal ‘Turridae group’ (P Bouchet, Y Kantor, RN Kilburn, A Sysoev; CD of unpublished colour catalogue examined) are taller and narrower than the species considered here, with either a completely smooth, polished teleoconch surface apart from the peripheral nodule row, or the rest of the teleoconch sculptured with thin, closely spaced axial lamellae. The New Zealand fossil and living species are not congeneric with these.
Dimensions
GS5216, Puketapu, Hawke's Bay: H (incomplete) 14.8, D 6.3 mm; H 15.6, D 6.2 mm
GS4185, Upper Castlecliff Shellbed, Castlecliff: H 12.8, D 4.6 mm
Castlecliff, early collection: H 16.5, D 5.6 mm
Recent, NMNZ M.112114, Deepwater Cove, Bay of Islands, 55 m: H 13.3, D 4.8 mm; H 13.4, D 4.6 mm
NMNZ M.67615, W of Plate I, Bay of Plenty, 59–64 m: H 15.8, D 5.3 mm; H 13.2, D 5.1 mm.