Luticola permuticopsis Kopalová & Van de Vijver

Kohler, Tyler J., Kopalová, Kateřina, Vijver, Bart Van De & Kociolek, J. Patrick, 2015, The genus Luticola D. G. Mann (Bacillariophyta) from the McMurdo Sound Region, Antarctica, with the description of four new species, Phytotaxa 208 (2), pp. 103-134 : 118-120

Luticola permuticopsis Kopalová & Van de Vijver in Kopalová et al. (2011: 53 , figs. 51 – 72) ( Figs. 75–83 )

LM observations:— ( Figs. 75 – 82 ) Valves linear-elliptical with two convex margins. Apices broadly rounded, capitate throughout the size series. Valve dimensions (n=11): length 19.7–28.9 μm, width 7.6–9.4 μm. Axial area linear, widening toward central area. An isolated pore present in the central area, halfway between the valve center and valve margin. Central area bow-tie shaped and asymmetric, sometimes wider opposite isolated pore, with shortened striae present on both sides. Raphe branches straight, both proximal and distal ending deflecting away from isolated pore. Transapical striae radiate throughout, 16–22 in 10 μm.

SEM observation s: — ( Fig. 83 ) Striae composed of 3–5 areolae, 2–4 at apices. Areolae rounded, elongated toward valve margin, extending to distal raphe endings. Isolated pore small, rounded. Central area bordered by 1–2 rows of three rounded to elongated areolae on isolated pore side, and a single row of four rounded areolae on opposite side. Proximal raphe endings resolve into drop-like pores, deflect away from isolated pore. Distal raphe endings resolve into smaller, slit-like pores on valve face. Clear separation between valve face areolae and valve margins. A single row of rounded areolae is present along valve margin.

Habitat, ecology and distribution:— Luticola permuticopsis was described recently from the lakes of James Ross Island, Maritime Antarctica ( Kopalová et al. 2011), and until now has not been documented from elsewhere. This diatom occurs throughout the MDVs, but has been identified as Navicula muticopsis f. capitata . Therefore, we can confirm its distribution as widespread throughout the Wright, Taylor, and Miers Valleys from the McMurdo Sound Region, though rare or absent on Cape Royds ( Sakaeva 2014).

INSTAAR herbarium:— Aiken Creek 900–902, 2224–2228; Von Guerard Stream 905–908, 911–913, 916–919, 923–926; Harnish Creek 928; Bowles Creek 933–935, 938–940; Commonwealth Stream 945–948, 951, 954; Priscu Stream 960–961; Bohner Stream 963–966; Wharton Creek 980, 982; Delta Stream 983–984, 986–987, 990–992; Onyx River 995–996; Canada Stream 1002, 1004, 2257; Green Creek 1018, 1021–1022, 1025–1027; Lawson Creek 1030– 1031, 1038, 1041; Adams Stream 1051, 1053–1057, 1064; Relict Channel 1066–1068, 1070–1071, 1077–1081, 1084, 1087; Wales Stream 1580; Lyons Stream tributary 2349; Many Glaciers Pond 2492; Parera Pond 2493; Spaulding Pond 2494–2496; Clear Lake 2501; McMurdo Hut Ridge 2664–2665; Picture Pond 2667; Nussbaum Regal Pond (unofficial name) 2671; Upland Pond 2678.

Observations:— The MCMLTER has historically identified this diatom as N. muticopsis f. capitata ( Esposito et al. 2008, Stanish et al. 2011, 2012). Peragallo (1921: 17, pl. 1, fig. 40) described what is perhaps a similar species, Navicula muticopsis var. capitata , though the type material of both taxa is wanting (as discussed in Kopalová et al. 2011), and as a result the identities of these species are not verifiable. Levkov et al. (2013) only briefly mention N. muticopsis f. capitata and N. muticopsis var. capitata at the end of their book volume as probably also belonging to the genus Luticola , without descriptions or images. Since the existing description of L. permuticopsis fits our McMurdo populations well, we suggest that this taxon name be used rather than the former two, and further suggest that the range of L. permuticopsis from the Maritime Antarctic extends to the Antarctic continent. In the case that one of the former names should be demonstrated to be conspecific with L. permuticopsis , then the name should be replaced by the first published, accepted one.

Luticola permuticopsis is most similar to L. muticopsis in valve outline, but L. muticopsis has one straight and one convex margin. This is in contrast to L. permuticopsis , which always has two convex margins and is generally narrower than L. muticopsis . The apices in L. muticopsis are always flattened and more rostrate, contrary to L. permuticopsis , which are more rounded ( Kopalová et al. 2011). Furthermore, striae in L. permuticopsis can be composed of 3–6 areolae, whereas only 3–5 have been observed for L. muticopsis . Finally, the proximal and distal raphe endings in L. permuticopsis are weakly deflected and terminate into small pores, whereas raphe endings are deflected at strong 45-degree angles in L. muticopsis and resolve into slits. Luticola permuticopsis is also similar in morphology to L. austroatlantica , although L. austroatlantica is more narrow (4.4–8.7 vs. 7.3–9.2) and has fewer areolae per stria (2–3 vs. 3–6) ( Esposito et al. 2008). Apices in L. permuticopsis are typically broader than in L. austroatlantica , and margins in L. austroatlantica are generally more elongated. Luticola gaussii also resembles L. permuticopsis , with both having broadly rounded apices with convex margins. However, the body of L. gaussii is typically more rounded than in L. permuticopsis , which has a more elongated mid-section. Futhermore, L. gaussii has striae that are only comprised of up to 3–4 areolae, whereas L. permuticopsis has 3–6. Lastly, a deep depression is visible around the margin of L. gaussii that is not present in L. permuticopsis .

Figures

FIGURES 75–83. Luticola permuticopsis Kopalová & Van de Vijver. Light (LM) and scanning electron micrographs (SEM). 75–82. Specimens from Canada Stream, Taylor Valley, LM. 83. External valve view of specimens from Canada Stream, SEM. LM scale bar = 10 μm. SEM scale bar = 5 μm.