Encyonema jordaniforme Krammer (1997: 191)

Harper, Margaret A., Vijver, Bart Van De, Kaulfuss, Uwe & Lee, Daphne E., 2019, Resolving the confusion between two fossil freshwater diatoms from Otago, New Zealand: Encyonema jordanii and Encyonema jordaniforme (Cymbellaceae, Bacillariophyta), Phytotaxa 394 (4), pp. 231-243 : 239-240

Encyonema jordaniforme Krammer (1997: 191) ( Figs 66–89 )

Basionym: — Encyonema jordaniforme Krammer (1997) , Bibliotheca Diatomologica 37: 66, pl. 201, figs 9–15

Synonyms: — Cymbella jordanii Grunow sensu Foged 1979, p. 39 , Fig. 48 : 9–15

Original description: —“Valvae valde dorsiventrales, lanceolatae, margine dorsali et ventrali convexiore, ad centrum tumidis, apicibus protractis et rotundatis, 18–38 μm longae, 8–12 μm latae. Area axialis angustasma, area centralis nulla vel vix formata. Raphe filiformis, terminis proximalibus ad latus dorsale inclinatis, fissuris distalibus in latus ventrale deflexis. Striae in latere dorsali radiantes, 15–20 in 10 μm.” [“angustasma” is an unusual abbreviation of “angustissima”].

Type: —Slide 508/ 1966 in Coll. Foged, N.

Type locality: —The original type locality is given as “Locus typicus: Nova Zealandia, Diatomit, Te Anau regio, leg. Foged 1966” (1966 is when Foged collected samples in New Zealand). His published New Zealand flora ( Foged 1979 p. 39) says “Recorded from a river rich in fast running water (No.472/1966) and from diatomite in the Te Anau District, the South Island”. Foged also lists on this page the dimensions and sample numbers for the specimens in his photographs. Six photographs are listed as from No. 508/1966 and one as from No. 472/1966. However the label on sample phial 508/1966 ( Fig. 17 ) says ‘Middlemarch district’, which is about 180 km distant from Te Anau. This locality must refer to Foulden Maar, the freshwater lacustrine diatomite which is dominated by this diatom species ( Lee et al. 2016).

The type locality is herein corrected to: —Foulden Hills Diatomite, Foulden Maar, on private land near the township of Middlemarch about 50 km west of Dunedin. The site is registered as I43/f 8503 in the New Zealand Fossil Record File administered by the Geoscience Society of New Zealand and GNS Science ( New Zealand 45.5271° S, 170.2218° E).

Light microscopy ( Figs 66–84 ): —Valves clearly dorsiventral, weakly bent along the apical axis to almost straight, with a distinctly convex dorsal margin and a convex, weakly tumid ventral side. Valve apices not protracted nor enlarged, usually acutely rounded. Valve dimensions (n=30): length 18–45 μm, width 7–11 μm. Axial area very narrow, linear. Central area very small to almost not discernible, rounded to elliptical. Raphe filiform, weakly curved to straight. Proximal raphe endings slightly dorsally deflected, short, weakly expanded to simple. Terminal raphe fissures long, dorsally deflected. Central dorsal striae (weakly) radiate, becoming parallel to convergent near the apices, 19–21 in 10 μm. Ventral striae radiate becoming convergent near the apices, 20–21 in 10 μm. Short dorsal striae occasionally inserted in the regular striation pattern (see for instance Figs 67, 70, 79 ). Central striae very rarely more widely spaced than the others. Areolae discernible in LM, 30–35 in 10 μm.

Scanning electron microscopy ( Figs 85–89 ): —Striae uniseriate, composed of small, rounded areolae ( Figs 85, 86 ). External raphe branches almost straight ( Fig. 85 ). Proximal external raphe endings indistinct, straight to very weakly dorsally deflected ( Fig. 86 ). Terminal raphe fissures elongated, ventrally bent ( Fig. 87 ). Internally, distal raphe endings terminating onto small helictoglossae ( Fig. 88 ). Proximal raphe endings clearly dorsally bent to weakly hooked ( Figs 88, 89 ) with a clear intermissio.

Figures

FIGURES 66–84. Light micrographs of E. jordaniforme from Foulden Maar (sample 7 U. K.). Scale bar represents 10 μm.

FIGURES 85–89. Scanning electron micrographs of E. jordaniforme from Foulden Maar. 85. External view of an entire valve. 86. External view of the central area showing small rounded areolae and almost straight proximal raphe endings. 87. External view of a valve apex showing the terminal raphe fissure. 88. Internal view of an entire valve. 89. Internal view of the central area showing the deflected proximal raphe endings with a broad intermissio. Scale bar represent 10 μm for figs 85, 88 and 1 μm for figs 86, 87, 89.

FIGURES 25–61. E. jordanii. 25–43. Light micrographs from sample AT82 (Encyonema jordani, Otago, New Zealand, Weissflog Collection, Jordan, 4/1882) present in the Hustedt Collection in Bremerhaven (Germany). 44–61. Light micrographs from sample Slide VIII-2-B1 (Van Heurck Collection, Botanic Garden Meise, Belgium). Scale bar represents 10 μm.

FIGURES 1–24. 1–2. P. T. Cleve’s original figures of Encyonema jordanii. 3–10. E. jordanii from Hustedt in A.Schmidt Atlas plate 379. 11–16. E. jordanii sensu Foged 1979, Krammer’s type for E. jordaniforme. 17. Foged’s sample phial 508 photographed by Nina Lindholm. 18–24. Raeside’s figures of Cymbella jordanii. Scale bars represent 10 μm.