Odontella aurita (Lyngbye) C. Agardh (1832: 56)

Sims, Pat A., Williams, David M. & Ashworth, Matt, 2018, Examination of type specimens for the genera Odontella and Zygoceros (Bacillariophyceae) with evidence for the new family Odontellaceae and a description of three new genera, Phytotaxa 382 (1), pp. 1-56 : 17-20

Odontella aurita (Lyngbye) C. Agardh (1832: 56) ( Figs 56–64 )

Basionym:— Diatoma auritum Lyngbye (1819: 182 , pl. 62, fig. D)

Synonyms:— Biddulphia aurita (Lyngbye) Brébisson (1838: 12) Denticella aurita (Lyngbye) Ehrenberg (1838: 210) Candollella aurita (Lyngbye) Gaillon 1833a: 34 ( Gaillon 1833b: 56)

Type:— Hofmansgave [Otterup, Denmark] ( Lyngbye 1819: 182)

In girdle view frustules square-rectangular ( Figs 56 , 60 ), apical axis 25–62μm, transapical axis 20–45μm with central set of open girdle bands. Valves with mantles sloping inwards (waisted) well within width of girdle bands ( Fig. 58 ), at its base extending outwards forming a flat mantle flange ( Fig. 61 ) into which valvocopula inserts ( Fig. 62 ). Apical axis each with elevation inflated at base, its height extending to width of girdle complex and ocellus with hyaline margin at each summit ( Figs 56 , 60, 61 ). Between elevations valve weakly inflated.

Valve outline broadly elliptical ( Figs 61, 64 ), length 25–62μm, breadth 20–45μm, valve margin with hyaline rim extending beyond width of valve face ( Fig. 61 ). Valve semi-cylindrical in transverse section with central circular elevation and elevation at each pole. Areolae poroid, c. 10 in 10μm, arranged in rows radiating from valve centre ( Fig. 61 ). Areolae occluded by two types of vela ( Figs 59 , 63 ), mostly cribra positioned slightly beneath valve surface with occasional specialised pores, in the form of a circle of open pores, scattered at intervals ( Figs 59 , 63 , arrows). Valve surface covered with solid spines of varying heights ( Fig. 60 ) postioned between vela ( Fig. 63 ). Lying centrally at summit of central area are openings of two transapically aligned rimportulae ( Fig. 56 ). Exterior opening through long hollow spine, with slightly fluted opening, internally through radially aligned slit across papillus ( Fig. 64 ).

Numerous girdle bands present, all half bands with open valvocopula inserted beneath valve margin. Each band with hyaline margins and vertical rows of poroid areolae ( Fig. 62 ), 9–17 rows in 10μm.

Observations:— The description above is based on material from Hofmansgave, Denmark (after Lyngbye 1819: 182) and Breskens Creek, Netherlands.

Figures

FIGURES 56–59. Odontella aurita (Lyngbye) C.A. Agardh (Hofmansgave, Denmark). Fig. 56. Fractured frustule with full set of girdle bands; lower valve with indented valve mantle, broad short elevations at apices, raised valve centre with opposing long spines positioned near summit; scale bar = 20 μm. Fig. 57. Reproduction of plate 62, fig. D for Diatoma auritum from Lyngbye (1819) (not to scale). Fig. 58. Fractured valve with expanded hyaline valve margin with raised border, interior with indented hyaline area between mantle and margin, fracture across poroid areolae and rimmed ocellus at summit of elevation; scale bar = 10 μm. Fig. 59. Poroid areolae with two types of occlusions, mostly cribra with an occasional specialised pore (a circle of pores surrounding a hyaline centre, arrow); scale bar = 1 μm.

FIGURES 60–64. Odontella aurita (Lyngbye) C.A. Agardh, (Breskens Creek, Netherlands). Fig. 60. Frustule with broad triangular elevations with ocelli at apices, raised valve centre and indented valve mantle; scale bar = 10 μm. Fig. 61. Valve face merging into rounded mantle indented at base meeting expanded hyaline valve margin with raised border; valve centre raised with 2 (1 fractured) transapically aligned spines, the openings of rimoportulae, on slopes of central area; scale bar = 10 μm. Fig. 62. Open girdle bands with hyaline abvalvar margins and vertical rows of poroid areolae; scale bar = 5 μm. Fig. 63. Detail of poroid areolae, mostly occluded by cribra with occasional specialised pore (arrow); scale bar = 2 μm. Fig. 64. Valve interior with radial rows of poroid areolae and internal openings of two rimoportulae; scale bar = 10 μm.