Isoetes candelariensis is a new species of Isoetaceae from Misiones, Argentina. This species is ephemeral, and grows on basaltic bedrock outcrop pools, in Urutau Reserve from Candelaria Department. This taxon differs from other aquatic Isoetes in this region by the unique combination of characters of its leaves, ligule, labium and megaspore ornamentation.
Key words
Isoetes; new species; lycophyte; Argentina
| I. candelariensis | I. ekmanii | I. pedersenii | |
|---|---|---|---|
| Site/ habitat | Ephemeral bedrock outcrop pool at low elevation (<150 m s. n. m.) | Emergent or aquatic by permanent water body at low elevation (<100 m s. n. m.) | Low generally flooded land (<100 m s. n. m.) |
| Labium | Inconspicuous to absent | Yellowish-white, membranous, 1.6 mm wide and 0.92 mm high. | Conspicuous, 3.0 mm high and 1-1.5mm wide. |
| Ligule | Deltate to widely ovate, delicate, ephemeral, 1-1.5 mm high, 0.5 mm wide. | Triangular, slightly elongated, delicate, 2 mm high, 1 mm wide. | Deltoid, auriculate at base, 1.3 mm high, 1.85-2 mm wide. |
| Microspores size | 28 [30] µm long | 28 [32] μm long | 30 [35] μm long |
| Microspores ornamentation | echinate with broad-based, occasionally hollow spines | obscurely echinate | echinate |
| Megaspores size | 342 [387.75] µm | 400 [500] μm | 395 [410] μm |
| Megaspore ornamentation | Laevigate to low rugulate (sometimes in distal face). Microsculpture: velutinuous (low-matted) | Low-reticulate | Verrucate |
| Equatorial band (girdle) | Absent | Echinate | Absent |
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