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|Valkyria pukapuka O'Connor n. sp.|
Plate 2. figures 15,16; plate 3, figures 12; plate 7, figures 11,12; plate 8, figures 1, 2
Description: Cephalis truncate spheroidal, generally smooth surfaced. Pores very small, circular to subcircular, irregularly arranged. Two horns present (both arc external expressions of internal elements - see below); apical horn bladed, shorter than cephalis; vertical horn bladed, generally shorter than apical horn. Collar stricture externally visible as change in shell contour.
Thorax truncate conical, slightly rough-surfaced due to small nodes at pore bar junctions, thicker walled than cephalis. Pores circular to subcircular, roughly hexagonally arranged and framed, larger than those on cephalis. generally increasing slightly in size distally to widest part of thorax then decreasing in size, or remaining same size. Aperture slightly constricted, surrounded by basal ring. Lumbar stricture generally externally visible as weak constriction.
Abdomen truncate pyramidal, triangular in cross-section, relatively smooth-surfaced. Pores circular to subelliptical, larger than those of thorax, irregular in distribution and size. Aperture constricted on more complete specimens, but termination undifferentiated. Abdomen extends from basal ring of thorax.
Three long, distally diverging, straight to slightly inwardly curving ribs extend from cephalis through thoracic wall and along edges of abdomen. They are extensions of internal cephalic elements D, LI and Lr (sec below) which are not expressed
externally until the distal thorax, about 1-2 pore rows up from basal ring (although pore bars align longitudinally on the thorax where ribs would be). Once externally visible, ribs fenestrated proximally, thicken distally and extend below abdomen
as three short, pointed, bladed feet.
Internal skeleton consists of bars A, V, M, D, LI, Lr, arches ALl, A-Lr, D-Ll, D-Lr, V-Ll, V-Lr and spine Ax (text-fig. 7; pl. 7, fig. 12). A incorporated in cephalic wall, extends outside as apical horn (see above). V extends outside cephalis as small horn (see above). D incorporated in thoracic wall. LI and Lr extend to arches then extend downward to thoracic wall. D. LI and Lr become externally visible as ribs in distal thorax and abdomen (see above). Ax reduced to a node. Arches A - L l and A - L r
extend from uppermost part of A, incorporated in cephalic wall, generally indistinct. Rest of arches form indistinct ring at base of cephalis.
Dimensions: Holotype (Range of 20 specimens): length of apical horn: 15pm (8-30): length of cephalis: 20pm (15-20); width of cephalis: 27pm (21-30); length of vertical horn: 15pm (5-15); length of thorax: 40pm (35-50): width of thorax: 60pm (59-63); length of abdomen: 75pm (55-80); maximum width of abdomen excluding ribs: 80pm (55-89); length of ribs including feet: 100pm (60-100); number of pores in vertical row on thorax: 9 (6-8); number of pores across half equator of thorax: 9 (8-11): number of pores on length of abdomen: 6 (4-7); number of pores across one side of abdomen: 6 (5-7).
Etymology: Pukapuka is the Maori name for the type locality of this species and is used as a noun in apposition.
Holotype: R177 (Plate 2, figures 15, 16).
Type Locality: Pukapuka Quarry, R09/60I224.
Discussion: Valkyria pukapuka differs from V. annikae (Nishimura 1992, p. 356, pl. 7, figs. 4, 5, 6a-b) by having bladed apical and vertical horns, bladed feet, and by being about half the size; from V. procera (Nishimura 1992, p. 348, pl. 7, figs. I- 3, pl. 13, fig. 3) by having shorter and bladed vertical and apical horns, a longer abdomen, shorter feet, and smaller dimensions; from V. gigas (Nishimura 1992, p. 348, pl. 7, figs. 9. 10, pl. 13, fig. 7) by having smaller and bladed vertical and apical horns, bladed and much shorter feet, abdominal pores that are larger than those on the thorax, and smaller dimensions. All three of Nishimura's (1992) species are restricted to the late Paleocene.
Range: Valkyria pukapuka has been observed from the Cryptocarpium
ornatum Zone to the Cyrtocapsa tetrapera Zone (early Oligocene to early Miocene (late Runangan/early Whaingaroan to Waitakian)).