Neidium beatyi, Hamilton & Savoie & Sayre & Skibbe & Zimmermann & Bull, 2019

Hamilton, Paul B., Savoie, Amanda M., Sayre, Cynthia M., Skibbe, Oliver, Zimmermann, Jonas & Bull, Roger D., 2019, Novel Neidium Pfitzer species from western Canada based upon morphology and plastid DNA sequences, Phytotaxa 419 (1), pp. 39-62 : 46

Neidium beatyi sp. nov. Figs 2–18

Individuals examined for morphological analyses: n = 48, no molecular material recovered.

Frustules rectangular. Valves linear elliptic to lanceolate with weak sagittate to cuneate apices ( Figs 2–5 ). Valve length 126–201 μm, width 18.0–27.0 μm. Areolae round to elliptical, striae oblique to weakly radiate at apices, 15–18 in 10 μm. Areolae 14–18 in 10 μm. Voigt faults distinct on secondary side of valve. Central area small round to transapically expanded, covering 1/3 to 1/2 the valve width. Axial area linear-elliptical from mid-valve to apex. In LM, raphe filiform and linear-elliptical. Three or more longitudinal canals present along each margin. Central raphe ends small deflected hooks, terminal ends forming bifurcate lacinia. Small terminal hyaline area present at apex. In girdle view, areolae form lineal apical and transapical rows ( Fig. 3 ).

In SEM external view, raphe linear with thickened ridges along each side ( Figs 6–8 ). Ridges terminate prior to apex ( Fig. 11 ). Proximal ends form distinct small hooks in opposite directions on small central mound. Distal raphe ends form lacinia ( Figs 6, 11 ). Lacinia narrow arrowhead shaped with curved expansion at mantle base ( Fig. 11 ). Axial area scattered with surface depressions. Areolae adjacent to axial area orientated towards axial area and not directly up from valve face ( Fig. 8 ). Areolae around central area larger and more linear elliptic randomly scattered. Areolae depressions on external valve face with recessed finger-forming silicate cribra ( Figs 7, 9 ). Areolae chambered with transapical interconnections ( Fig. 12 ). Areolae around central area sometimes larger than valve face areolae. Three to five longitudinal canals present along each valve margin ( Figs 8–11 ). Longitudinal canal flat with valve face ( Figs 8, 9 ). At apex, narrow linear slit-like areolae may open from a longitudinal canal ( Figs 10, 11 ). Internal valve: central area elevated with ghost striae. Helictoglossae linear and interconnected ( Fig. 13 ). Terminal helictoglossae vertical and curl back from terminal nodule ( Fig. 14 ). Longitudinal canals centrally, forming small bulge along valve margin; towards apex one canal extends to hyaline terminal nodule at apex ( Figs 14, 15, 17 ). Longitudinal canals form apical and transapical network of interconnections ( Fig. 18 ). Internally, areolae covered by fine poroid hymenes ( Figs 15–17 ). Renilimbia (2–6) around areolae along axial area, and longitudinal canals ( Fig. 16 ). Renilimbia randomly scattered around areolae on valve face.

Holotype:— CANADA. British Columbia: Vancouver, VanDusen Botanical Garden, J. Holmes, December 28, 2016. Small stream at the end of Livingstone Lake (pond) ( CANA! 126257-2, fig. 2 holotype specimen circled on slide. Isotype ANSP GC65328 (circled specimen on slide). Genbank# No DNA results).

Etymology:—The specific epithet ( beatyi ), is linked to the generosity of the Beaty Foundation in supporting the Beaty Botanical Museum, the VanDusen Botanical Garden and the Canadian Museum of Nature.

Registration: http//phycobank.org/102929

Observations:— Neidium beatyi was found from a regional locality (multiple samples) collected from VanDusen Botanical Garden, British Columbia, Canada. The species is identified by its size, 3–6 longitudinal canals and shape of valve including apices. Neidium beatyi has a large size range (length, 126–207 μm) and is similar to Neidium subampliatum (Grunow) Flower (2005: 54) . Flower (2005) elevated the taxon Navicula firma var. subampliata Grunow. ( Schmidt 1877, 49: 19) [note: as a typing mistake Neidium firma var. subampliatum ] to the rank of species within the genus Neidium . For N. subampliatum he chose a neotype, since a holotype specimen was not available. Neidium subampliatum (specimens) presented by Flower (2005, p. 64, 51–55) are significantly smaller than N. beatyi , with one longitudinal canal and the shape form is different (Supplement A). However, the valve morphology of N. subampliatum sensu Flower does not represent the original line drawing of Navicula firma var. subampliata , which is larger relative to other taxa on Schmidt’s original plate. Further, Kobayashi (1968) illustrated a specimen he identified as Neidium iridis var. subampliatum (Grun.) Kobayshi (1968: 102) from the vicinity of Tokyo that is similar to our specimens and the line drawing of Schmidt for N. firma var. subampliata .

Neidium reimeri John (1981: 571–572) and N. zoigeaeum Liu et al. (2017: 17) are similar, but are smaller in size (both taxa <115 μm) and the apices of these taxa are weakly cuneate to round, not notably drawn out, cuneate to sagittate. In addition, the formation of the proximal helictoglossae seems to differ (connected together in N. beatyi ). It is possible that N. reimerii and N. zoigeaeum are simply smaller populations of N. beatyi with some loss of valve form with smaller sizes. Both genetic and more thorough morphological studies of these taxa are required.

Neidium iridis is similar in valve shape and was also found at the same locality, although rare. Neidium reimeri is distinguished by size ( N. iridis 184–237 μm long, 32–25 μm wide), number of longitudinal canals (3–5 versus 1 canal in N. iridis ), higher stria count and the presence of an elevated ridge adjacent to the raphe. Neidium iridis sensu auct. ( Metzeltin & Lange-Bertalot 2007) is similar in valve shape form, with multiple longitudinal canals, but this South American form is much larger (ca. 300 μm long) and requires more study. Neidium cuneatum Krammer & Metzeltin (= N. iridis ; Metzeltin & Lange-Bertalot, 1998: 146, pl. 124: 6) also has a similar valve outline, but is larger (>196 μm long), only one longitudinal canal and has fewer striae. See Hamilton et al. (2019) for a more complete discussion of N. iridis including N. maximum ( Cleve 1894: 69) Meister (1912: 109) . The large size of N. beatyi and valve shape can also be compared with N. obliquestriatum ( Schmidt 1877: figs 49: 41, 42) Cleve (1894: 69), but distinguished by shape, number and size of longitudinal canals (1 for N. obliquestriatum ), size and formation of the proximal raphe ends, round to transapically elongated central area ( N. beatyi ) and shape of the apices. Also comparable is N. krasskei Metzeltin & Lange-Bertalot (2007: 174–175) which is <103 μm long. Neidium beatyi is larger, apices are not as cuneate and central raphe ends smaller. No SEM images of N. krasskei are available for comparison.

Figures

FIGURES 1–5. Neidium iridis (Fig. 1) and Neidium beatyi sp. nov. (Figs 2 (holotype), 3–5). Scale bar = 50 μm.

FIGURES 6–12. Neidium beatyi sp. nov. SEM, external view. Fig. 6. Whole valve. Fig. 7. Central area raphe with silica ridges along each side. Figs 8, 10. Valve margin and mantle with multiple longitudinal canals. Copulae 2 rows of poroids. Fig 9, 12. Recessed areolae chambered and interconnected with finger-like cribra. Fig. 11. Apex showing arrow-like bifurcate lacinia. Copulae (3 evident) open bands with no evident poroids. Scale bars = 20 μm: Fig. 6; 10 μm: Fig. 11; 5 μm: Figs 7–10; 2 μm: Fig 12.

FIGURES 13–18. Neidium beatyi sp. nov. SEM internal view. Fig. 13. Central area with linear forming interconnected helictoglossae. Fig. 14. Apex with a curved forming helictoglossa at the edge of the terminal nodule.A single prominent longitudinal canal extends to the nodule. Figs 15, 17. Multiple longitudinal canals; at center canal similar (Fig. 15), towards apex one becomes more prominent (Fig. 17, arrow). Fig. 16. Renilimbia surround hymenae covered areolae (arrow). Fig. 18. Open chambered formation (apically and transapically) of the longitudinal canal. Scale bars = 10 μm: Fig. 14; 5 μm: Figs 13, 17; 2 μm: Fig. 15: 500 nm: Figs 16, 18.