Hormoscilla irregularis Novis & Visnovsky, 2011

Novis, Phil M. & Visnovsky, Gabriel, 2011, Novel alpine algae from New Zealand: Cyanobacteria, Phytotaxa 22 (1), pp. 1-24 : 18

Hormoscilla irregularis Novis & Visnovsky , sp. nov. ( Figs 7A–F )

Trichomata isopolaria uniseriata, cellulis doliiformibus, 4–7 µm latis, 1–3 µm longis, semper brevioribus quam latioribus, materia contenta grandulari, ad parietes transversales constricta. Non motiles. Trichomata ex fascibus vel segmentis composita, quoque segmento plerumque longitudine cellularum 2 vel 4, positione laterali irregulari vel titubanter irregulari. Trichomata saepe brevia (longitudine cellularum usque ad 20) sed interdum longiora (tum ad fragorem apta). Cellulae terminales rotundatae, raro conicae. Vagina tenuis , pellucida vel pallide brunnea. Ramificatio nulla. Regeneratio trichomatum per fragorem, plerumque in longitudines cellularum quadruplicium, saepissime 4–12 propter structuram trichomatis segmentatam atque generationem hormogonii per cellulas necridicas.

Type:— NEW ZEALAND. Westland : Mt Philistine, 1400 m, preserved cultured specimen from sample collected 30 November 2007, CHR610794 .

Trichomes isopolar and uniseriate, cells doliiform, 4–7 µm wide, 1–3 µm long, always shorter than wide, contents granular, constricted at transverse walls ( Figs 7A–B ). Non-motile. Trichomes composed of cell packets or segments, each segment usually 2 or 4 cells long, with irregular or staggered lateral positioning ( Fig. 7B ). Trichomes often short (up to 20 cells long) but sometimes longer (and then prone to fragmentation). Terminal cells rounded, rarely conical. Sheath thin and translucent to light brown. Branching absent. Trichome reproduction through fragmentation, usually into multiples of 4 cells long, most commonly 4–12, as a consequence of the segmented trichome structure, and by hormogone generation via necridic cells ( Figs 7D, F ).

Habitat:— Alpine herbfield soil, 1640 m, associated with scattered Chionochloa sp.

Distribution:— Mt Philistine, Arthur’s Pass National Park, New Zealand.

Etymology:— Referring to the irregular arrangement of segments.

Observations:— Potential designations for this material include the freshwater species Hormoscilla pringsheimii ( Anagnostidis & Komárek 1988) , but the sheaths of this and other freshwater speices lack pigmentation and the cells are more regularly arranged ( Anagnostidis & Komárek 1988, Komárek & Anagnostidis 2005). Hormoscilla irregularis appears to be the first freshwater species reported that has brown pigmentation (marine species have red trichomes; Komárek & Anagnostidis 2005). At present molecular data are unavailable for this strain.

Culture:— LCR-OSC2.

Figures

FIGURE 7. A–F. Hormoscilla irregularis Novis & Visnovsky (photographed from culture LCR-OSC2; light micrographs). A. Long trichome showing short cells with constrictions between them. B. Typical morphology with arrangement of trichomes into segments of cells, with irregular lateral position. C. Trichomes become truncated by fragmentation and dissolving of the sheath. D. False branching through trichome fragmentation (during which necridic cells occur, as indicated by arrow). E. False branching by trichome overlap. F. Release of hormogonia. G–M. Phormidium arthurensis Novis & Visnovsky (photographed from culture LCR-OSC4, G–K light micrographs, L–M transmission electron micrographs). G. Mature trichome with rounded end cell, and arrangement into cell segments (arrows between the segments). H. Trichome with fragmented end, in which the sheath is visible (arrow). I. Prior to fragmentation, the cell segments become pronounced. J. A hormogone released from this fragmentation. K. Development of the new trichome (arrow) is isopolar. L, M. Cells in transverse section showing sheath (s) and thylakoid membranes (tm), which are peripheral and tightly packed, and may be somewhat curved (M). Scales: 10 µm in F (use in A–K), 1 µm in L (use in L–M).