Table 1 in A reappraisal of the taxonomy and biodiversity of the extant coccolithophore genus Palusphaera (Rhabdosphaeraceae, Prymnesiophyceae)

Table 1. Description and diagnostic morphologies of all currently known extant Palusphaera species vs other spine-bearing taxa of the family Rhabdosphaeraceae. SEM images are not to the same scale. Extant taxon in RhabdosphaeraceaeGenusSpeciesCoccosphereCoccolithSpineDiagnostic featuresPalusphaera Coccosphere monomorphic and monothecate, spherical in shape. Body coccoliths are spine-bearing planoliths. Coccolith central area is well developed with a lamellar cycle but no radial cycle. Lamellar cycle elements show dextrogyral curvature in distal view and laevogyral curvature in proximal view. Spines with no collar.Palusphaera vandeliiBody coccoliths that are circular in outline. Spine is styliform, long and tapering with spirally arranged crystal segments near its base.Palusphaera probertiiBody coccoliths that are broadly elliptical in shape. Spine is styliform and tapering with crystallites parallel oriented to its axis.Palusphaera crosiaeBody coccoliths that are nearly circular. Spine is styliform and markedly thicker at one-third to one-quarter height from the base of the spine.Palusphaera bowniiBody coccoliths that are circular in shape. Spine is salpingiform and short.Extant taxon inRhabdosphaeraceaeGenusSpeciesCoccosphereCoccolithSpineDiagnostic featuresRhabdosphaera Coccosphere dimorphic and monothecate, spherical in shape. Body coccoliths with a well-developed central area that does not possess a radial cycle; body coccoliths distinguished into (1) spine-bearing planoliths (inner layer) and (2) non-spine-bearing planoliths (outer layer). Lamellar cycle elements show leavogyral curvature in distal view and dextrogyral curvature in proximal view. Spines with or without collar.Rhabdosphaera clavigera var. clavigeraSpine-bearing and non-spine-bearing coccoliths of elliptical to broadly elliptical outline. Claviform, long, robust spines with pentameral structure.Rhabdosphaera clavigera var. styliferaSpine-bearing and non-spine-bearing coccoliths of elliptical outline. Parallel-sided, long, narrow spines with pentameral structure.Rhabdosphaera xiphosSpine-bearing and non-spine-bearing coccoliths of elliptical to broadly elliptical outline. Parallel-sided, long, narrow spines with pointed tips, collar near the base but without pentameral structure.Discosphaera Coccosphere monomorphic and monothecate, spherical in shape. Body coccoliths are planoliths bearing trumpet-shaped spines without a collar. Planolith central area with both lamellar and radial cycles.Discosphaera tubiferaBody coccoliths of circular shape bearing trumpet-shaped spines. Trumpet width greater than basal width.