Lithosoma Fisher 1911

Mah, Christopher L., 2018, New genera, species and occurrence records of Goniasteridae (Asteroidea; Echinodermata) from the Indian Ocean, Zootaxa 4539 (1), pp. 1-116 : 51

Lithosoma Fisher 1911

Fisher 1911: 422; 1919: 298; Macan 1938: 398; McKnight 1973: 189; H.E.S. Clark & McKnight 2001: 62.

Diagnosis. Body stellate to strongly stellate, arms elongate, triangular in shape, tapering distally ( Fig. 19A ). Disk broad. Abactinal surface smooth, bare with no surficial accessories. Crystalline bosses embedded on plate surface. Individual plates abutted, polygonal in outline. Superomarginal plates abutted over midline along the arm ( Figs 19A, B ). Marginal and actinal plates smooth, bare with no surficial accessories.

Comments. Lithosoma comprises a widespread species complex known only from deep-water settings in the Pacific and Indian Ocean regions, extending from New Zealand to southern Japan, New Caledonia, and west to the eastern coast of Africa and the northern Indian Ocean.

Lithosoma species show relatively few discrete character differences, varying primarily based on continuous characters (e.g. number of furrow spines, number of plates abutted over midradius) and/or those characters which vary by differing degrees of expression (e.g. superomarginal plates thickened, interradial arcs curved versus angular). As a consequence, species boundaries with Lithosoma have not always been clearly delineated with some species showing character overlap. Further revision of this group is needed.

Figures

FIGURE 19. Lithosoma pentaphylla brevipes USNM E51276. R=3.3, r=1.3 cm. A. Abactinal surface. Scale bar=1.0 cm. B. Closeup of arm and superomarginal plates. Scale bar=0.5 cm. C. Actinal surface. Scale bar=1.0 cm. D. Closeup of oral region. Scale bar=0.3 cm. E. Furrow spines and adjacent adambulacral spination. Scale bar=0.3 cm.