Vaucheria edaphica Muralidhar, Novis & Broady, 2014

Muralidhar, Abishek, Broady, Paul A., Macintyre, Duncan P., Wilcox, Michael D., Garrill, Ashley & Novis, Phil M., 2014, Morphological and phylogenetic characterization of seven species of Vaucheria (Xanthophyceae), including two new species, from contrasting habitats in New Zealand, Phytotaxa 186 (3), pp. 117-136 : 131

Vaucheria edaphica Muralidhar, Novis & Broady , sp. nov.

Siphons 25–40 µm diameter; branches frequent.Alga monoecious; antheridia lateral to 1–2 oogonia borne on a gametophore; gametophores frequent ( Fig. 8 ). Antheridia circinate, 70–90 µm long × 20–35 µm diameter. Oogonia 1–2, reniform, pendent, 75–100 µm long × 25–35 µm diameter, mostly sessile, rarely with short pedicels (always <10 µm long); distal prominence towards peduncle; wall thin. Oospores same size as oogonia, no oogonial cavity left behind by mature oospores.

Type:— NEW ZEALAND:. Canterbury: Christchurch (43.554800° S, 172.628833° E), P. A. Broady, 7 August 2012, UCVT1 ( CHR 631520 ) .

Section:— Racemosae.

Etymology:— named after the edaphic nature of the type strain which, was sourced from garden soil.

Molecular data:— In terms of p-distance, our V. edaphica strain was closest to a V. walzii Rothert (1896: 82) strain from Botanical Garden, University of Düsseldorf, Germany (p-distance = 0.063).

Notes:— Although V. edaphica shared some common traits with other species in sect. Racemosae, it was difficult to place it unequivocally under any of these species. It most closely resembled V. prona as recorded by Entwisle (1988a, b) but his strains often showed more than two oogonia on each gametophore which were in different orientations and had pedicels always> 10 µm long. He suggested referring to all these populations with one or more oogonia and with no distal oogonial cavity left behind by mature oospores as V. prona ( Entwisle 1988a, b). Our strain was distinct as it never had more than two oogonia which were mostly sessile and rarely possessed very short pedicels always <10 µm. The oogonia of this strain were always laterally oriented towards the antheridium. The number and orientation of oogonia and length of the oogonial pedicels have been used as delineating characters in this section and we based our decision to erect this strain as a new species based on these characters. We suggest that populations with one to two oogonia, laterally oriented towards the antheridium, mostly sessile or sometimes with a short oogonial pedicel (<10 µm) and with no oogonial cavity left behind by the mature oospore, should be referred to as Vaucheria edaphica . A comparison of characters of some closely related morphospecies in the sect. Racemosae is given in Table 5.

While we erected the species solely based on the morphological differences mentioned above, our strain was found to be genetically distinct from all other species in sect. Racemosae including all V. prona sequences in Genbank.

This strain grew as light green mats on moist soil surfaces. Field material was fertile.

Figures

FIGURE 8. Light micrographs and illustrations of Vaucheria edaphica reproductive structures (UCVT1).A, C, G, I. Gametophore bearing pendent, mostly sessile oogonia with distal prominence and a circinate antheridium, note oospores covering entire portion of oogonium. B, D. Single reniform oogonium with circinate antheridium. E, F. Developing oogonia; note green colouration. J, K, L. Variations of gametophore arrangement. Scale bars = 20 µm.