Odontella rostrata (Hustedt) Simonsen (1987: 251)

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 : 32

Odontella rostrata (Hustedt) Simonsen (1987: 251) ( Figs 111–116 )

Basionym: Biddulphia rostrata Hustedt (1939: 591 , figs 5–7, see Simonsen 1987: 250, pl. 373, figs 1–11).

Type:— Germany: “Memmert. 12341. Sandplate” [Memmert, Linke Nr. 12341 Sandplate, Sandwatt, 2.9.1938, from online web catalogue], BRM 391/54 = lectotype (see Simonsen 1987: 250).

Valves broadly lanceolate with rostrate apices ( Fig. 111 ), length 12–25μm, breadth 10–20μm. Valve face gently convex with raised transapically aligned area at valve centre ( Fig. 115 ). Mantle linked to well-developed hyaline mantle flange with upturned margin ( Figs 111, 116 ). Outwardly directed narrow elevation at each pole, ocellus at summit. Valve structure poroid, areolae arranged in rows radiating from valve centre, c. 20 areolae in 10μm. Most areolae occluded by cribra with occasional specialised pores present ( Fig. 112 , arrow). Raised valve centre covered in long solid spines some buttressed from valve centre to valve face and foot of elevations ( Fig. 112 ). Rimoportulae 2, subcentral in transapical position, extending externally through long substantial spines with slightly flared ends ( Figs 111, 112 ) and internally through a slit between raised lips ( Figs 113, 114 ).

Observations:— Further details can be found in Lavigne et al. (2016: 315–318); some relevant images are: Odontella aurita sensu Hoban (1979 : figs 58, 62, 66, Hoban 2008: figs 20–22, 24, 25, 28); Sar (1989: 187, figs 1–7).

This description is based on specimens from Redfish Bay, Aransas County, Texas, USA ( ECT 3828 TX).

Figures

FIGURES 111–116. Odontella rostrata (Hustedt) Simonsen (Redfish Bay, Aransas County, Texas, USA, ECT 3828 TX). Fig. 111. Valve exterior flat with elevations at apices, a rimmed ocellus on summit; valve face with raised circular valve centre and two opposing transapically aligned hollow spines off centre; spinules covering valve, some linking valve centre to foot of elevations and mantle; a broad hyaline expanded valve margin with a raised border surrounds the valve face; scale bar = 2 μm. Fig. 112. Valve with radial rows of poroid areolae mostly occluded by raised cribra with occasional specialised pores (arrow); scale bar = 1 μm. Fig. 113. Valve interior with broad hyaline valve margin; scale bar = 1 μm. Fig. 114. Detail of valve interior with openings from two rimoportulae; scale bar = 1 μm. Fig. 115. Mantle view of valve with attached girdle bands showing indented valve mantle and an outwardly directed elevation at each pole; scale bar = 2 μm. Fig. 116. Valve tilted with two long hollow spines off valve centre, the exterior openings of rimoportulae; scale bar = 1 μm.