Hobaniella longicruris (Greville) P.A. Sims & D.M. Williams, 2018

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 : 38-41

Hobaniella longicruris (Greville) P.A. Sims & D.M. Williams , nov. comb. ( Figs 144–147 )

Basionym:— Biddulphia longicruris Greville (1859: 163 , pl.8, fig.10)

Synonym:— Odontella longicruris (Greville) Hoban (1979: 87) , nom. invalid. Denticella longicruris (Greville) De Toni (1894: 886) Odontella longicruris (Greville) Hoban (1983: 283)

Type:— Californian guano; J. T. Norman ( Greville 1859; Williams 1988:19, pl. 23, figs 7–9; BM.1773, lectotype!)

Valve face oval with an elevation at each pole ( Fig. 144 ), valves 20–100m in length. Valve face convex with a strongly raised valve centre lying between almost vertical long, narrow elevations ( Fig. 146 ), ocellus on each summit ( Fig. 145 ). Valve mantle steep merging at base into expanded hyaline valve margin. Areolae poroid, in rows radiating from valve centre extending length of narrow elevations. Areolae occluded by a simple velum ( Figs 145. 147 ). Rimportulae 2, arising beneath the summit of central area inclined towards opposite poles, each opening through long narrow spine forked at its summit. Specialised pore probably present; valves exhibit a number of smaller, simple pores with elevated rims ( Fig. 147 , arrow).

Observations:— With respect to the rimoportulae, Hoban (1979) notes between 1–3, with 2 being most common and Lavigne et al. notes a number of permutations, where “most specimens have one rimoportula per valve […] some have two [...] others have one on one valve and two on the other”, Lavigne et al. 2016: 309).

The combination Odontella longicruris was first made by Hoban in his PhD thesis ( Hoban 1979: 87, figs 70–88) but this is not a valid place of publication— Hoban’s 1983 paper is the valid source of the combination ( Hoban 1983: 283). This latter paper, however, lacks any images. Some eventually appeared in Hoban (2008: figs 1–8; these are the same images that can be found in Hoban 1979: figs 70–88).

Lavigne et al. (2016: 308–312) provide further images of living cells which have “numerous, small discoid chloroplasts” ( Lavigne et al. 2016: figs 2–5) and a handful of SEM images ( Lavigne et al. 2016: figs 6–23). Of note are the numerous external, domed cribra with a knob ( Lavigne et al. 2016: fig. 16).

The description above is based on specimens from Malibu and California USA (living) and from the culture ECT 25 V 112–1, Hunting Island, South Carolina, USA.

Figures

FIGURES 144–147. Hobaniella longicruris (Greville) P.A. Sims & D.M. Williams (Culture ECT 25v 112–11A, Hunting Island, South Carolina, USA. ex Matt Ashworth). Fig. 144. Circular valve exterior with opposing marginal elevations, two long hollow spines, the openings of rimoportulae lying off the raised valve centre, directed outwards midway between elevations; scale bar = 10 μm. Fig. 145. Detail rimmed ocellus at summit of long elevation, poroid areolae occluded by raised vela with central spinule; scale bar = 4 μm. Fig. 146. Mantle view with long central spine with forked opening, two substantial elevations and broad hyaline valve margin with raised border; note interior with uninterrupted radial rows of poroid areolae; scale bar = 10 μm. Fig. 147. Segment of elevation with occluded poroid areolae and opening from specialised pore (?) (arrow); scale bar = 2 μm.