Psammodiscus calceatus Tsuy.Watanabe, Nagumo & Ji. Tanaka, 2013

Watanabe, Tsuyoshi, Nagumo, Tamotsu, Sun, Zhongmin, Hasegawa, Kazukiyo, Miyagawa, Tomofumi, Kumada, Misato & Tanaka, Jiro, 2013, Morphology and taxonomy of Psammodiscus Round & Mann (Bacillariophyceae: Rhaphoneidales) with a description of the new species Psammodiscus calceatus, Phytotaxa 124 (1), pp. 1-12 : 5-6

publication ID	https://doi.org/ 10.11646/phytotaxa.124.1.1
persistent identifier	https://treatment.plazi.org/id/543D878B-3707-A90A-7DC7-FC86B1846656
treatment provided by	Felipe
scientific name	Psammodiscus calceatus Tsuy.Watanabe, Nagumo & Ji. Tanaka
status	sp. nov.

Treatment

Psammodiscus calceatus Tsuy.Watanabe, Nagumo & Ji. Tanaka , sp. nov. ( Figs 19–52 View FIGURES 19–22 View FIGURES 23–31 View FIGURES 32–36 View FIGURES 37–51 View FIGURES 52 )

TYPE:— JAPAN: Honshū Island, Fukui Prefecture, Tsuruga-shi, Kutsu , sandy beach 35°45’24”N, 136°01’25”E, epipsammic GoogleMaps ( BM 101648!, illustrated in Fig. 20 View FIGURES 19–22 , holotype designated here as marked specimen on slide; MTUF-AL- 43009, marked specimen, isotype) .

Size and shape: Cells discoid. Valves circular to elliptic, 25.5–28.5 µm in diameter, striae ca. 8 in 10 µm, areolae 4–5 in 10 µm ( Figs 19–22 View FIGURES 19–22 ). Single small rimoportula occasionally present, situated near valve centre. Apical pore fields and central pores absent.

Fine structure of valve: Striae radiating from centre to mantle ( Fig. 23 View FIGURES 23–31 ). Areolae much smaller in mantle than valve face ( Fig. 24 View FIGURES 23–31 ). Areolae circular to elliptical, occluded by plated rotae with 5–9 spokes ( Fig. 24 View FIGURES 23–31 ). Spokes connect rotae to external valve surface ( Fig. 32 View FIGURES 32–36 ), connecting part of rota, concave at margin ( Fig. 33 View FIGURES 32–36 ). Ring structure surrounding inside bases of areolae ( Fig. 34 View FIGURES 32–36 ). Spokes of areolae not evident internally ( Fig. 35 View FIGURES 32–36 ). Rotae with seven to eight pairs of fin-like projections ( Figs 35, 36 View FIGURES 32–36 ). Spokes connecting to rotae between finlike projections ( Fig. 36 View FIGURES 32–36 ). Spoke located behind ring structure and fin-like projections ( Figs 35, 36 View FIGURES 32–36 ).

Rimoportula: Number of rimoportula 0–1 ( Figs 23, 26 View FIGURES 23–31 ) per valve. When present, rimoportula always central and always one per valve. External opening of rimoportula either present ( Fig. 25 View FIGURES 23–31 ) or absent ( Figs 26, 27 View FIGURES 23–31 ). From internal view, valve surface flat ( Fig. 28 View FIGURES 23–31 ) and spokes of rotae not evident ( Figs 29, 30 View FIGURES 23–31 ). Small sessile rimoportula present near valve centre, with simple slit ( Figs 28, 31 View FIGURES 23–31 ). Rimoportula not located in internal view.

Small pore: Central and additional small pores always absent ( Figs 23–30 View FIGURES 23–31 ).

Cingulum: Epicingulum consists of four open bands: the valvocopula ( VC), second (2B), third (3B) and fourth (4B) band ( Figs 37, 38, 39 View FIGURES 37–51 ). VC and 3B open on same side of frustule whereas ( Figs 42, 43 View FIGURES 37–51 ); 2B and 4B open on opposite sides ( Figs 38, 39 View FIGURES 37–51 ). Position of band openings shift slightly, offsetting each other ( Figs 38, 39 View FIGURES 37–51 ). Ends of VC have rounded corners ( Fig. 40 View FIGURES 37–51 ). Pars interior of VC almost equal in size to pars exterior ( Fig. 40 View FIGURES 37–51 ). VC with two rows of small pores ( Fig. 41 View FIGURES 37–51 ) occluded by rotae with 1 or 2 spokes ( Fig. 42 View FIGURES 37–51 ). VC highly visible, other bands less so ( Fig. 41 View FIGURES 37–51 ). Internally, bands form a line in sequence from 4B to VC ( Fig. 43 View FIGURES 37–51 ). Pars interior of VC slightly undulate to fit valve ( Fig. 43 View FIGURES 37–51 ). Single row of elongated grooves advalvar to pores in VC ( Figs 43, 44 View FIGURES 37–51 , marked G). Tongue-like ligula of second band occludes opening of VC ( Fig. 45 View FIGURES 37–51 ). Opening of 2B evident in external view ( Fig. 38 View FIGURES 37–51 ). Single row of pores present on pars interior of second band ( Fig. 46 View FIGURES 37–51 ); pores occluded by rotae with either 1 or 2 spokes ( Fig. 47 View FIGURES 37–51 ). 3B with small trapezoid ligula ( Fig. 48 View FIGURES 37–51 ). Single row of pores lacking rotae present on pars interior ( Figs 48, 49 View FIGURES 37–51 ). 4B with very small trapezoid ligula ( Fig. 50 View FIGURES 37–51 ). 4B opens as narrow slit ( Fig. 51 View FIGURES 37–51 ). Pars interior with single row of triangular areolae lacking rota ( Figs 50, 51 View FIGURES 37–51 ; Fig. 52 View FIGURES 52 = schematic drawing of epitheca).