Kampylaster Koehler, 1920: 136–137.— Fisher, 1940: 250–252.— Bernasconi, 1973: 344.—A.M. Clark, 1993: 220.
Diagnosis. Rays 5; body small, frequently arched, abactinally covered by integument and subgranular spinelets; rays 5, short petaloid; abactinal plates thin, not notched, irregular arrangement; actinal plates in oblique series; actinal spines per plate few, subglobose; lacking superambulacral and superactinal plates; abactinal and actinal distal interradial plates lacking contiguous internal projections.
Type species. Kampylaster incurvatus Koehler, 1920 (original designation).
Material examined. K. incurvatus. Syntypes. Antarctica, Adelie Land, AM J 3581 (2, A and B).
Description. Rays 5, petaloid to tapered from wide base; margin incurved and subacute interradially; body variably arched; size small, up to R = 15 mm; lacking pedicellariae; brood-protects under body.
Abactinal plates obscured by integument and close uniform cover of coarse subgranular spinelets; abactinal plates on rays large, thin, imbricating, not notched, irregular arrangement; papulae small, inconspicuous, single, irregular over rays (seen from coelomic side by Fisher, 1940; not seen here); abactinal spinelets subgranular, wide base, narrowed waist, convex and spinous distally; superomaginal plates similar to adjacent abactinal plates, covered with granular spinelets, not aligned with inferomarginals; series of thick rounded projecting inferomarginal plates define margin, covered with granular spinelets.
Actinal interradial areas small, series of plates oblique.
Actinal spines per plate: oral 3; suboral 0; furrow 2–3 proximally, webbed; subambulacral 1–2; actinal 1–3; adradial actinal plates with series of shorter spines; actinal spines short, thick, rounded, subglobose distally.
Lacking superambulacral and superactinal plates; abactinal and actinal distal interradial plates meet at an angle, lacking contiguous internal projections.
Distribution. Antarctica, Enderby Land to Scotia Sea; 93– 750 m.
Remarks. Molecular data are not available for incurvatus, and this review is based on a morphological examination of syntypes and the observations of Fisher (1940). Distinctive diagnostic characters of Kampylaster are the integument and granuliform spinelet cover, irregular arrangement of thin abactinal plates, inconspicuous papulae, absence of a series of superomarginal plates, and absence of superambulacral and superactinal plates.
Koehler (1920) considered Kampylaster to be similar to Tremaster Verrill, 1880 and referrable to the subfamily Tremasterinae. Fisher (1940) rejected the similarity because of the distinctive interradial perforations of Tremaster, and considered Kampylaster to be closer to Stegnaster Sladen, 1889. Additional reasons for rejecting a similarity with Tremaster are the quadriserial arrangement of tube feet and vertical furrow spines on adambulacral plates in Tremaster.