Climacosphenia elongata J.W. Bailey, 1854

Lobban, Christopher S., Ashworth, Matt P., Camacho, Terance, Lam, Daryl W. & Theriot, Edward C., 2022, Revision of Ardissoneaceae (Bacillariophyta, Mediophyceae) from Micronesian populations, with descriptions of two new genera, Ardissoneopsis and Grunowago, and new species in Ardissonea, Synedrosphenia and Climacosphenia, PhytoKeys 208, pp. 103-184 : 103

Climacosphenia elongata J.W. Bailey, 1854

Fig. 25

References.

Bailey 1854, p. 353, pl. 1, figs 10, 11; Peragallo and Peragallo 1897-1908, p. 352, pl. 86, figs 2-4; Hustedt 1914, pl. 307, figs 1-4; Ricard 1977, figs 669-677; Montgomery 1978, pl. 114, fig. E-H; Round 1982, figs 1-38 (in part); Round et al. 1990, p. 442.

Description from literature.

C. elongata has been described (e.g., by Peragallo and Peragallo 1897-1908 and Hustedt 1931-1959) as identical to C. moniligera Ehrenberg, 1843 except for the valve tapering more abruptly to a stem with parallel sides. Yet Bailey (1854) had specifically distinguished his species from C. moniligera by the finer stria density (without giving numbers) and described a species 330 µm long, with very wide craticular bars (as shown also in Peragallo and Peragallo 1897-1908, pl. 86, fig. 5; Hustedt 1914, pl. 307, figs 1-4; and Round 1982, fig. 3) (Table 5 ). Peragallo and Peragallo (1897-1908) gave stria densities of 18-21 near the basal pole, 27->30 near the apical pole for C. elongata versus 16-17 in 10 µm basal and 19-20 in 10 µm apical for C. moniligera but expressed the opinion that there was intergradation between the two species. Hustedt (1931-1959) said that Peragallo and Peragallo had confused their European specimens of C. elongata with C. moniligera and he attempted to resolve the confusion with an original drawing of a cell with a very long, very narrow stem. The drawing (his fig. 626) was based on Samoan specimens he had published in “Schmidt’s Atlas" ( Hustedt 1914). Round (1982) attempted to clarify the difference between the two species, not considering the variation within C. elongata , but his drawings of C. elongata show specimens no more than 320 µm long. In recent literature, Álvarez Blanco and Blanco (2014), show short cells similar those in Peragallo and Peragallo (1897-1908), while Navarro and Lobban (2009) reported cells 750-1200 µm long from a Guam sample, similar in shape to those in Hustedt (1931-1959), a range that otherwise occurs only in Hustedt’s report (table in Álvarez Blanco and Blanco 2014: 103). Ultrastructural characters: Apical spines present; costae generally present; frustules have only two girdle bands, both with fimbriate inner margins ( Ricard 1987, fig. 677; Montgomery 1978, pl. 114, fig. G; Round 1982).

Materials examined.

Guam: GU44Y-13!, GU44U-1B!, GU44BM-4!, GU44BM-7!, GU52X-1!. Federated States of Micronesia: Chuuk, TK4!

Observations.

Valve clavate, apical part gradually tapering to a narrow stem nearly half the total length of 278-516 µm (Fig. 25A, B ); maximum width 30-33 at apical pole, 7-8 µm across stem and expanding slightly to 9 µm across basal pole (Table 5 ); annulus closed at both poles, gradually tapering from maximum width of 16-17 µm near apical pole (Fig. 25B arrows, D, E). Stria densities 28 in 10 µm near apical pole (Fig. 25E ), 22 in 10 µm near basal pole outside the annulus; sparser and more loosely organized inside annulus at basal pole (Fig. 25D, G ). Apical spines present (Fig. 25E ), pseudoseptum absent (Fig. 25G ). Costae present except at basal pole, where they start at margin and extend centripetally, eventually thickening the virgae inside the annulus (Fig. 25G ). Valvocopula stria density 19 in 10 µm (Fig. 25E, F ), pars interior with comb of long, unbranched fimbriae (Fig. 25C ). Craticular bars consistently narrow (1 µm) (Fig. 25B, D, G, H ), though sometimes doubled (Fig. 25A ), the spaces between them rectangular with rounded corners; connections complex in most of the stem, becoming simple where the valve widened (Fig. 25C, D, G vs Fig. 25B, H ). There was a wider space between two of the bars in the middle of the wide part (Fig. 25B , thick arrow); based on our observations on C. elegantissima (below), this is probably the location of the nucleus. Copula with 24 striae in 10 µm (Fig. 25F ), pars interior not observed.

Taxonomic comments.

The shape and morphometrics accord adequately with the literature on C. elongata , the narrow craticular bars, especially in the stem, differing from the sturdy bars and oval spaces of C. moniligera , and from the very long-stemmed specimens depicted by Hustedt (1931-1959, p. 89, fig. 626). Based on the available evidence, we accept the hypothesis that the specimens shown in Fig. 25 are Bailey’s species.

Figures

Figure 25. Climacosphenia elongata, GU 44 BM- 7, except as noted A valve with valvocopula in LM, showing consistently narrow craticular bars, some double (arrowheads) (GU 44 X- 2) B apical part of a valve with valvocopula in SEM, showing the progressive narrowing of the annular ring (series of small arrows) and the wider space between craticular bars where the nucleus resides (thick arrow) C narrow portion of valve with valvocopula showing the fibmbriae D basal pole of valve with valvocopula, showing the scattered pattern of areolae inside the annulus gradually becoming regular striae, development of costae (arrow), and complex unions in the craticular bars E external view of apical pole showing annulus (double-headed arrow) and spines F frustule in girdle view showing the two girdle bands G, H valvocopula near basal pole and in tapering part at top of " stem, " respectively, showing complex versus simple unions in the craticular bars (TK 4). Scale bars: 100 µm (A); 50 µm (B); 10 µm (C-H).