Grunowago pacifica 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

Grunowago pacifica Lobban & Ashworth sp. nov.

Figs 20 , 21

References.

Lobban et al. 2012, pp. 256-257, pl. 13, figs 1, 2 [as Synedra bacillaris (Grunow) Hustedt].

Diagnosis.

Differing from Grunowago (Synedra) bacillaris in width and lanceolate outline of valve.

Description.

Valves lanceolate, often slightly rostrate, 194-341 µm long, 11-16 µm wide, striae 9-10 in 10 µm (Fig. 20A-D ), the striae comprising large oval pores; poles with smaller, circular pores, but not organized into polar pore fields (Figs 20E , 21A ). Isopolar but wider in the middle in girdle view (Fig. 18F-H ). Two small spines usually present on each pole (Figs 20G-I , 21B ). Rim present on the valve border but not extended into a pseudoseptum (Fig. 21A ). Valve single-walled (Figs 20J , 21A ), internally costate with a distinctive central costa the entire length of valve and thickened vimines (Figs 20J , 21A ), no annulus detected either as a break in the striae, or any other longitudinal costae (Fig. 21A ). Three girdle bands were present (Fig. 20F-H ). Valvocopula (Figs 20I, J , 21A, C ) without extended lip but having groove on pars interior that fits rim of valve. A single row of pores on advalvar side of pars exterior, circular except elongated near poles (Figs 20G, H , 21A, C ), a short line of pores around poles on pars interior (Figs 20I , 21C ). Copula has a row of pores on outer edge of pars interior (Fig. 21A, B, D ), often hidden under valvocopula and a well-developed fringe on the pars interior; up to 5 rows of pores on pars exterior (Figs 20G, H , 21B, D ). Pleura a very thin fimbriate band, continuous along cell length (Figs 20G, H , 21B, D ).

Holotype

(designated here). Specimen at 18.3 mm E and 6.4 mm S of the mark on slide 146, deposited at ANSP accession # ANSP-GC20085. Fig. 20D, E .

Registration.

Phycobank http://phycobank.org/103245.

Type locality.

GabGab reef, Apra Harbor, Guam, 13.443°N, 144.643°E, ca. 1 m depth, collection number GU44Z-15, 20 June 2009. C.S. Lobban and M. Schefter leg. Additional slides from this sample have previously been deposited at California Academy of Sciences (CAS) for other species holotypes, but specimens of G. pacifica are not marked. Slides include CAS accession/slide numbers: 627386/223007 ( Perideraion spp.), 627383/223005 ( Gato hyalinus ); 627409/223023 ( Astrosyne radiata ); and 627396/223010 ( Hanicella moenia ).

Additional materials examined.

Guam: GU44L-C!, GU44AI-5! (in culture), GU44AP-8!, GU44BH-5!.

Etymology.

Adjective (Latin) with reference to its presence in the Western Pacific Ocean.

Taxonomic comments.

Specimens that we ( Lobban et al. 2012) referred to Synedra bacillaris were 180-400 µm long, 14 µm wide, with 9-14 striae in 10 µm. This range of stria density is suspiciously large for Ardissoneaceae and suggests that two or more species are being confounded. Some specimens in GU44BJ-4 population were nearly linear but most likely represent an extreme within G. pacifica rather than an occasional G. bacillaris . Both Hustedt (1931-1959) and Sullivan and Wear (1995) remarked on the ease of identifying this species by the strong central costa, compared to other Ardissonea spp., but as with other taxa where a strong identifying character has masked species diversity (e.g., Cyclophora tenuis - Ashworth et al. 2012, Bleakeleya notata - Lobban and Perez 2016), we suspect that there is hidden diversity within " Synedra bacillaris ". The genetic branches are long between lanceolate samples from Guam (GU44AI-5) and Florida (HK291) (see, below, Fig. 33 ). For now, we can only describe Grunowago pacifica and deal with the generic placement of that species cluster.

Figures

Figure 18. Ardissoneopsis gracilis sp. nov. (GU 44 BJ- 4, except B TK 28) A-C three specimens to scale in LM to show size range: valves from Guam (A) and Chuuk (B), frustule from Guam in girdle view (C) showing heteropolarity D frustule in SEM tilted 60 °, showing both valve and girdle faces E, F pole and mid-section of holotype G-K external views of valve in SEM with other species adjacent for comparison (GU 44 BJ- 4): index image (G) with locations of details marked, apical pole (H) (shown by depth of mantle), compare stria density with Ardissoneopsis appressata (A. g.); top half of center (I), offset areolae in striae within the oval suggest location of annulus; narrow portion below center (J), compare with scattered areolae in adjacent Toxarium undulatum (T. u.); basal pole (K), note spines on both poles L, M internal aspect near middle and at the apical pole, showing lack of costae N, O girdle view of frustule apical and basal poles, showing taper in mantle and girdle bands P possible piece of pleura (pl?) with fimbriae Q, R fimbriate edges of valvocopula and copula, respectively. Scale bars: 50 µm (A-D, G); 10 µm (E, F, H-K); 5 µm (L-R).

Figure 20. Grunowago pacifica sp. nov. A-D LM of specimens from GU 44 BJ- 4 (A-C) and GU 44 Z- 15 (D) D, E holotype specimen F-H frustule in girdle view, showing isopolar frustule wider in the middle and three girdle bands (GU 44 BJ- 4) I external view of pole and advalvar surface of valvocopula, the latter showing a short row of small pores on the apical part of the pars interior (arrowhead) and the crenulated edge of the pars interior (arrow) J internal view of pole and abvalvar surface of valvocopula. Scale bars: 50 µm (A-D, F); 10 µm (E, G-J).

Figure 21. Grunowago pacifica sp. nov., cont., all GU 44 BJ- 4, except A = SPN 2022 - 1 - 4 A valve apex showing continuous rim, broken away at lower right, not expanded into a pseudoseptum B frustule at 40 ° tilt, showing fimbriate inner margin of copula on the hypotheca (top) and line of pores on pars interior (arrow) C valvocopula, showing internal and external aspects, the pars exterior pores (arrow) separated by ridges on the pars interior, and the presence of pores on the pars interior at the pole (arrowhead) D frustule in girdle view with fimbriate pars interior of pleura exposed (arrow) E frustule in polar view tilted 60 °, showing girdle bands. Scale bars: 10 µm (A-D); 5 µm (E).

Figure 33. Phylogenetic trees resulting from three analytical methods of the 3 - gene DNA sequence dataset assembled for this manuscript. Only the Ardissoneaceae and their sister group in the molecular phylogeny, Lampriscus, is shown here-the complete trees can be found in Suppl. materials 5 - 7: Figs S 3 - S 5 A Maximum Likelihood phylogeny resolved by RAxML, where values at nodes are bootstrap support values B Maximum Likelihood phylogeny resolved by IQTREE, where values at nodes are bootstrap support values C Bayesian Inference phylogeny resolved by ExaBayes, where values at nodes are posterior probability values. Strain taxonomy (name followed by DNA voucher ID or strain ID) follows currently accepted classification, with proposed genera based on morphology shown to the right of strain ID.