Fragilariforma Hajósiae (Pant.) D.M. Williams and Buczkó, 2016

Williams, David M. & Buczkó, Krisztina, 2016, Fragilariforma Hajósiae: re-description and revision of Pantocsek’s species Diatoma fossile (Bacillariophyta), Phytotaxa 244 (2), pp. 181-190 : 185

Fragilariforma Hajósiae (Pant.) D.M. Williams and Buczkó , nom. nov. et comb. nov.

Basionym: Diatoma (‘fossile’) fossilis Pantocsek (1892 : Tab. 2, fig. 27, 1905: 46)

Synonym: Fragilaria fossilis (Pant.) Lange-Bertalot in Lange-Bertalot, Rumrich & Hofmann (1991: 121) non Fragilaria fossilis Hajós (1973a: 375 , pl. 3, figs 52, 53), nom. nud. = Fragilaria fossilis Hajós (1974: 504) , nom. nud.

Type:— SLOVAKIA. Deménd (Demandice), “In stratis tertiariis aquae dulcis ad Deménd in Hungarica” ( Pantocsek 1892: 47), BP Krenner 951 (see also Krenner 1981) (lectotype designated here: Fig. 3 , specimen from BP Krenner 951; further specimens from the type material are Figs 9–13 ).

Description:— In girdle view, frustule box-like, tapering towards poles, cingulum clearly identifiable ( Figs 11, 13 ). Valves linear, gently tapering towards the poles, 20–35 μm length, 5–7 μm width ( Figs 3 , 18 ), tapering more sharply in some specimens, to rostrate/capitate apices ( Figs 5–8 , 12 , all specimens illustrated from type material). Striae uniseriate, 10–12 in 10 μm, virgae considerably wider than vimines ( Figs 14–16, 18 ); in places virgae appear fused ( Figs 15 , smaller arrow to the right of specimen). Spines situated at valve/mantle border, most extending from directly from a virga ( Figs 14–16 ), occasionally from a vimine ( Fig. 16 , smaller arrow). In places spines are fractured ( Fig. 15 , near smaller arrow), when whole, spines branch at tips and interlink with those from adjacent valve ( Fig. 14 , arrow). Sternum present but faint ( Fig. 15 ). Apical pore fields at each pole, on mantle, but tilt with valve towards its adjacent valve in colony ( Figs 14–16 , arrow in Fig. 15 ). Abvalvar edge of mantle with numerous plaques ( Fig. 16 , arrow). Girdle composed of at least six simple bands ( Fig. 14 , double headed arrow, Fig. 17 ), all open, each with a single row of poroids when in situ orient just below surface of adjacent band ( Fig. 17 ); each band becoming progressively smaller when situated away from mantle ( Figs 14–17 ). No internal view available.

Etymology: — Fragilariforma Hajósiae is named for the late Márta Hajós.

Figures

FIGURES 1–8. 1. Reproduction of Pantocsek’s figure of Diatoma anceps var. fossilis Pantocsek (1892: pl. 8, fig. 141), specimen from Sentenaï, Japan. 2. Reproduction of Pantocsek’s figure of Diatoma fossilis Pantocsek (1892: pl. 2, fig. 27), specimens from Deménd (Demandice Slovakia). 3. Diatoma fossilis Pantocsek = Fragilariforma Hajósiae, specimen from BP Krenner 951, lectotype. 4. Reproduction of Hajós figures of Fragilaria fossilis Hajós (1973a: pl. 3, figs 52, 53). 5–8. Diatoma fossilis Pantocsek = Fragilariforma Hajósiae, specimens from BP 2246, specimens from Deménd (Demandice Slovakia). Scale bar = 10μm.

FIGURES 9–13. Diatoma fossilis Pantocsek = Fragilariforma Hajósiae, specimens from BP Krenner 951, lectotype material, specimens from Deménd (Demandice Slovakia). Scale bar = 10μm.

FIGURES 14–18. Fragilariforma Hajósiae, specimens from Deménd (Demandice Slovakia).14. Girdle view showing valve and cingulum (marked with arrowed line in upper part of figure), linking spines from a virga (large arrow) and from a vimine (thin arrow), scale bar = 20 μm. 15. Part of the valve face and part of the mantle with some girdle bands, pore fields (large arrow) and fused striae (virgae) (thin arrow), scale bar = 10 μm. 16. Girdle view of two adjacent linked valves, pore fields at each pole and plaques along mantle edge (arrow), scale bar = 20 μm. 17. View towards the polar frustules showing the girdle band formation, scale bar = 10 μm. 18. Valve view for striae (virgae and vimines) and sternum, scale bar = 10 μm.