Lithosoma novaezealandiae McKnight, 1973

Mah, Christopher L., 2011, Taxonomy of high-latitude Goniasteridae (Subantarctic & Antarctic): one new genus, and three new species with an overview and key to taxa, Zootaxa 2759, pp. 1-48 : 30-31

Lithosoma novaezealandiae McKnight, 1973

( Figure 12 A–D)

McKnight, 1973: 189, fig. 9; A.M. Clark, 1993: 260; H.E.S. Clark in Clark & McKnight, 2001: 63.

Distribution. New Zealand and surrounding areas. 120–1190 m.

Material examined. South Pacific. USNM 1100882 Campbell Plateau, New Zealand. 49°01’60’S, 168°53’30’E, 733 m. Coll. National Institute of Water and Atmosphere. (1 dry spec. R=5.2, r=1.9); USNM 1100883 South Island, New Zealand 41°58, 170 °28’E, 480 m. Coll. National Institute of Water and Atmosphere (1 dry spec. R=5.5, r=1.7); USNM 1120469 South of New Zealand. 53˚29’S, 169˚48’E, 389– 594 m. Coll. Univ. Southern California (1 dry spec. R=2.3, r=0.9).

Description. Body strongly stellate in shape, R/r=2.5–2.8, flattened, stout with acutely tapering triangular arms with weakly curved interradial arcs ( Fig. 12 A).

Abactinal surface flat, planar ( Fig. 12 A). Individual plates in well-ordered arrangement, hexagonal to round in outline. Fasciolar rows, shallow, present between plates. Primary circlet is evident with larger primary plates present on each interradius of center disk. Carinal plate series strongly hexagonal, angular becoming more rounded interradially. Abactinal plates restricted to disk, but absent from arms. Largest individual plates at disk center becoming more irregularly shaped and smaller closer to contact with superomarginal plate series with which it is flush. Abactinal plate surface is bare, smooth with no additional accessory surficial features (i.e., no granules, etc.). However, embossed, glassy granules embedded in abactinal plate surface present, 15–150 per plate ( Fig. 12 B). These embossed granules are absent in abactinal plates at distal edge adjacent to contact with superomarginal plates which leaves these plates bare of any decoration. Granules, evently spaced, small, bead-like to quadrate, 15– 50 form periphery around each plate. Madreporite pentagonal, with well-developed suclii, bordered by six abactinal plates. Papulae present only on radial regions, including carinal and two lateral rows on each side.

Marginal plate series 40–48 per interradius with superomarginal and inferomarginal plates with mostly 1:1 correspondence becoming more offset distally, forming jagged contact between the two plate series towards the arm ( Fig. 12 C). Both marginal plate series wide (W>L), largest interadially becoming smaller distally. Marginal plate surface bare, smooth, absent of all accessory features (i.e., no granules, etc.), weakly swollen. Peripheral granules, elongate to rounded, approximately 40–70 per plate, arranged closely. Superomarginals, approximately 20–22 abut over midline on arms with primarily 1:1 correspondence with some arms having slightly offset articulation, forming jagged offset between superomarginals. Basalmost superomarginals on arm only in contact along one side. Inferomarginals similarly bare with comparable numbers of peripheral granules present.

Actinal surface weakly inset relative to periphery formed by inferomarginal plate series. Actinal plates forming 5 chevrons, becoming more weakly defined closer to the contact with inferomarginal plate series (fig. 12D). Individual actinal plates bare, smooth, flat, weakly convex, quadrate to rounded in outline. Embossed, glassy granules similar to those on the abactinal surface observed on actinal plates of some individuals but not all. Peripheral granules evenly distributed, 20–40 per plate, round and bead-like. Furrow spines 6–7, each flattened, triangular to rounded quadrate in cross-section arranged in a convex pattern on plate. Region immediately behind furrow spines is bare. Pointed to round granules 12–15, in irregular rows on adambulacral plate adjacent to bare spot, similar to granules present on actinal plate surface. These granules forming discrete rows adjacent to the actinal plate region. Oral plates with 6 furrow spines and 1 spine projecting into mouth at plate apex. These furrow spines similar in form to furrow spines, triangular to quadrate in cross-section. Oral plate surface with large blunt, pointed granules to spines, very thickened and quadrate to triangular in cross-section. These oral spines are elongate becoming shorter until they approach oral granule height similar to those on actinal plates.

Pedicellariae not observed.

Figures

FIGURE 12. Lithosoma novaezelandiae. USNM 1100883. A. Abactinal surface. B. Close up of abactinal plates and madreporite. C. Lateral view of marginal plate series. D. Actinal surface. Scale Bar = 0.5 cm.