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.