Ardissoneopsis fulgicans Lobban & Ashworth, 2022

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

Ardissoneopsis fulgicans Lobban & Ashworth sp. nov.

Fig. 14

Ardissonea fulgens (Greville) Grunow sensu Lobban et al. 2012, p. 259, pl. 16, figs 3-5. Synonym.

Diagnosis.

Differing from congeners in the straight outline, only weakly inflated at the center.

Description.

Valves 205-320 µm long, 9-15 µm wide, usually slightly widened in the middle and bluntly rounded at poles (Fig. 14A-F ); 17-19 parallel striae in 10 µm. Cells attached by one pole to sturdy mucilage stalks (not shown). Annulus along valve-margin junction and not visible in LM, underlain by longitudinal costae (Fig. 14C, D, F, G ); sternum absent but striae often out of alignment at the midline (Fig. 14B, H ); often spines on poles (Fig. 14D, I ). Valve rims straight (i.e., lacking a pseudoseptum) and valvocopula simple, therefore no apical groove (Fig. 14E, F ); transverse costae on the mantle thinning toward the margin (Fig. 14G ; contrast Fig. 13J ). Transverse costae on most vimenes but absent from a relatively large area at the poles (compared to Synedrosphenia recta , Fig. 13H ) (Fig. 14F, H ). Three girdle bands were present (Fig. 14E, I, J ). Valvocopula (Fig. 14E, H, J ) with generally two rows of pores on pars exterior; pars interior with a single row along outer edge and a fimbriate inner edge. Copula (Fig. 14D, E, I ) with multiple rows of pores forming a decussate pattern, and a fimbriate advalvar margin. Pleura barely visible as a narrow cap at each end, possibly connected, apparently fimbriate at the poles (Fig. 14E, I ).

Holotype

(designated here). Slide 449, multiple specimens present. Slide deposited at ANSP, accession # ANSP-GC20111. Representative specimen published in Lobban et al. 2012, Micronesica 43: pl. 16, figs 4, 5.

Registration.

Phycobank http://phycobank.org/103241.

Type locality.

Guam: Apra Harbor, GabGab reef. 13.443°N, 144.643°E, sparse filamentous algal turf in farmer fish territory ( Plectroglyphidodon lacrymans ), depth ca. 5 m., collection number GU44Y-13, 10 May 2009. C. Lobban, M. Schefter leg.

Additional materials examined.

Guam: GU7R!, GU44Z-15!, GU44L!, GU44N-A!, GU44AC-3!, GU44BJ-4! (inter alia); Federated States of Micronesia: Chuuk: TK28!; Marshall Islands: Jaluit J5!.

Etymology.

Adjective (Latin), Plectroglyphidodon fulgens (shiny) + - icans ("indicates... resemblance sometimes so close as to be almost identical" - Stearn 1973: 309).

Taxonomic comments.

In our region, this species is hard to positively identify in LM from the new species Synedrosphenia recta described above, and some other species so far only glimpsed but differs in (1) having simple apical structure unlike Synedrosphenia spp.; (2) the presence of two or more rows of pores on the valvocopula exterior. Lobban et al. (2012) previously identified this species as Ardissonea fulgens on the basis of literature but Kanjer et al.'s (2021) surprising finding about the type material (see above) forced the reevaluation.

Figures

Figure 13. Synedrosphenia recta sp. nov. Chuuk TK 28 except as noted A, C holotype and details of pole at two focal planes, showing valve face and valvocopula B, D-F specimen in SEM with details of pole at 0 ° tilt (D), arrows showing position of annulus, and 60 ° tilted views of central portion (E) showing copula and opposite pole (F) showing copula and valvocopula with apical notch (arrow) G, H internal view of a pole with valve and valvocopula at 60 ° tilt, showing apical notch (arrow), and at 0 ° tilt, showing apical area without transapical costae; arrows show inferred position of annulus as in D and absence of longitudinal costae I polar view of valve with valvocopula, showing apical notch J broken valve showing continuous transverse costae (arrow) and pores on pars interior of valvocopula (arrowheads) K specimen from Guam (GU 76 B- 4), showing fragments of very narrow pleura (pl, arrows) L specimen from Jaluit (J 5), pole of valve without valvocopula, showing continuous rim and absence of longitudinal costae; two-way arrow marks position of annulus, as in D, H. Scale bars: 50 µm (A, B); 10 µm (C); 5 µm (D-L).

Figures 14. Ardissoneopsis fulgicans sp. nov. A, B valve in LM showing shape and striation (TK 28) C pole of frustule from acid cleaned material in SEM, showing annulus (double-headed arrow) (J 5) D, E poles of frustules in whole mounts, attached at opposite ends, showing girdle bands and apical spines (GU 7 R) F, G internal views of valve pole and central portion, showing the absence of pseudoseptum at pole and presence of longitudinal costae (arrows) (GU 44 N-A) H pole of valve with valvocopula, showing start of transverse costae (arrow) (contrast with pole of Synedrosphenia recta Fig. 13 H); arrowhead indicates edge of fimbriate copula (J 5) I, J poles of frustules showing fimbriae on copula and valvocopula, respectively (J 5). Scale bars: 25 µm (A); 10 µm (D); 5 µm (B, C, E-J).