Ardissonea crystallina (C. Agardh) Grunow, 1880
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https://dx.doi.org/10.3897/phytokeys.208.89913 |
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https://treatment.plazi.org/id/C5D5D4CD-3C67-581E-9EE1-CA5FDA9603D2 |
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Ardissonea crystallina (C. Agardh) Grunow, 1880 |
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Ardissonea crystallina (C. Agardh) Grunow, 1880
Fig. 3 View Figure 3
References.
Peragallo and Peragallo 1897-1908, p. 310, pl. 79, fig. 1; Hustedt 1931-1959, p. 232, fig. 719; Navarro 1982, p. 260, figs 59, 60; Poulin et al. 1986, figs 28-30; Poulin et al. 1987, p. 2689, figs 1-11; Pickett-Heaps et al. 1991, figs 9-19; Lobban et al. 2012, p. 259, pl. 15, figs 1-3; Davidovich et al. 2017, figs 1, 2.
Description from literature.
Valves 200-700 µm long, 8-20 µm wide, linear but slightly wider at the middle and poles; 11 striae in 10 µm but much closer in "transitional forms such as var. Ardissonea formosa dalmatica " ( Hustedt 1931-1959). Internally with prominent costae developed on every virga except at poles, and with two longitudinal costae corresponding to location of annular ring; spines completely absent. Edge of valve recurved into a pseudoseptum; an interpretive diagram in Pickett-Heaps et al. (1991) shows the relationship between the valve, valvocopula, copula and a small, plain pleura at the pole. Valvocopula and copula have interior comb-like fringe, exterior part with four or more rows of pores arranged decussately; an apical groove between the pseudoseptum and a fold in the valvocopula provides an exit for attachment mucilage ( Poulin et al. 1987; Pickett Heaps et al. 1991) but Pickett-Heaps et al. (1991) argued that this groove was a very different structure from the apical pore in A. formosa as shown by Round et al. (1990). Shorenko et al. (2016) obtained auxospores of this species and determined a maximum length of 678 µm.
Materials examined.
Guam: GU44Y-13!, GU44AV-8!, GU44BJ-4!, GU56A-2!. Federated States of Micronesia: Chuuk: TK4, TK28. Marshall Islands: M1!
Observations.
Specimens from Guam and Chuuk 220-350 µm long, 11-16 µm wide, isopolar in both valve and girdle views, striae 16-19 in 10 µm, slightly offset on internal and external sides of annulus (Fig. 3A, B View Figure 3 ). Annulus well separated from valve-margin junction and clearly visible in LM and SEM, including around the poles (Fig. 3A, B View Figure 3 ). Pseudoseptum at poles (Fig. 3B View Figure 3 ) and rim along entire valve (Fig. 3C View Figure 3 ), facing pars interior of the valvocopula. Apical spines not observed (Fig. 3A, D, H View Figure 3 ). Costae well developed (Fig. 3B, C View Figure 3 ). Three girdle bands present (Fig. 3D View Figure 3 ): valvocopula fimbriate (Fig. 3D, F-H View Figure 3 ), forming a slot on one side of the pole and a sharper notch on the other (Fig. 3D View Figure 3 arrows, Fig. 3H View Figure 3 ); pores on pars interior passing across back of flange, elongated into slits at pole, clearly closed at inner margin (Fig. 3G View Figure 3 arrow) and pars interior expanded and recurved at pole (Fig. 3F View Figure 3 ). Pores on pars exterior discontinuous around pole in front of the groove (Fig. 3F-H View Figure 3 ). Copula (Fig. 3D, I, J View Figure 3 ) broader and flat, even at pole, with up to 10 rows of circular pores in a decussate pattern; pars interior fimbriate with free fimbriae highly developed at pole, where they overlap the valvocopula, elsewhere shorter fimbriae arising from fused base (arrows, Fig. 3I, J View Figure 3 ). Small difference in shape, number of rows of pores and length of fimbriae between Fig. 3I and J View Figure 3 may be due to origin of material (Fig. 3D View Figure 3 and 3I View Figure 3 are from Chuuk wild samples, Fig. 3J View Figure 3 from Guam culture) but copulae from wild material from Guam (not shown) also had>6 rows of pores. Pleura (Fig. 3D View Figure 3 ) fimbriate, an apical cap extending along the valve as a very narrow ribbon.
Taxonomic comments.
Ardissonea crystallina cannot remain in Ardissonea sensu stricto and will be transferred in the Taxonomic Revisions section at the end of the paper. Álvarez-Blanco and Blanco (2014) show Mediterranean specimens of Ardissonea dalmatica ( Kützing) De Toni, restored to species status without comment, but the length ranges only up to 151 µm. There was a row of papillae/spines around the pole, not present in our material and the length range in the literature is 100-151 µm, but the stria density matches our specimens more closely. We leave our identification at A. crystallina pending broader study. Although Hustedt (1931-1959) noted A. crystallina as distributed on coasts of warmer waters, Poulin et al. (1987) reported it as the only Ardissonea on the coast of Québec, an area that is far from tropical. Likewise, Shorenko et al. (2016) and Davidovich et al. (2017) collected it from the Black Sea. We do not agree with Pickett-Heaps et al. (1991) that there is a fundamental difference in the architecture at the pole of the valvocopulae of A. formosa and A. crystallina as both involve irregularities in the surface of the flange of the valvocopula where it lies below the pseudoseptum.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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