Mastogloia cf. pumila (Grunow) Cleve

Lobban, Christopher S., 2015, Benthic marine diatom flora of Guam: new records, redescription of Psammodictyon pustulatum n. comb., n. stat., and three new species (Colliculoamphora gabgabensis, Lauderia excentrica, and Rhoiconeis pagoensis), Micronesica 2015 (2), pp. 1-49 : 8

Mastogloia cf. pumila (Grunow) Cleve Figs 68–72

Section Sulcatae

Ref. illus.: Hustedt 1931 –1959, fig. 983; Witkowski et al. 2000, pl. 83, figs 5, 6; Loir & Novarino 2013, pl. 19c

Sample: GU52P-1, GU52P-9

Dimensions: Length 10–17 µm, width 5.5–6.5 µm; striae 27 in 10 µm, radiate

Diagnostics: Small valves, elliptical-lanceolate with slightly rostrate apices; central area extended into an H-shaped hyaline area. In our small cells, 1–2 large partecta in the middle flanked by 1–2 tapering partecta on each side and the H-shaped hyaline area is not evident externally.

Comments: These small specimens have chambers much like M. sergiana Pennesi & Poulin ( Lobban et al. 2012, pl. 36, figs 7, 8 and pl. 37 figs 1, 2), M. manokwariensis Cholnoky ( Lobban et al. 2012, pl. 32, figs 1–3), M. pusilla var. subcapitata Hustedt ( Hustedt 1931 –1959, fig 1002e, Loir & Novarino 2013, pl. 20b), and M. urveae Witkowski, Lange-Bertalot & Metzeltin ( Witkowski et al. 2000, pl. 84, figs 22, 23, Loir & Novarino 2013, pl. 24a, 27b). However, the elliptical valve outline and the distinct lyrate hyaline area distinguish it from each of these. M. urveae also differs in having parallel striae ( Witkowski et al. 2000). Larger size ranges for M. pumilla were given by Hustedt (1931 –1959) (20–20 x 5–9 µm) and Loir & Novarino (2013) (17.5–25 x 6.5–7.5 µm).

Figures

Figures 51–70. Figs. 51–55. Mastogloia emarginata. Figs 51-54. LM views of two specimens focused on valve face and valvocopula, arrowhead indicates one of the prominent exit pores of the partecta (GU44AR-2) (DIC). Fig. 55. Internal view of valve and valvocopula (GU55B-4) (SEM). Figs 56, 57. Mastogloia ovulum specimen at two focal planes (GU44K-6) (DIC). Figs 58-61. Mastogloia matthaei, two specimens at two focal planes (GU52P-2) (DIC). Figs. 62, 63. Mastogloia obliqua, valve at two focal planes (GU66F-4) (DIC). Figs. 64–67. Mastogloia peracuta (GU44AP-9). Figs 64, 65. Specimen at two focal planes (DIC). Figs 65, 66, External views of two specimens in SEM. Figs 68–71. Mastogloia pumila. Figs 68, 69. Specimen in DIC at two focal planes (GU52P-1; catalog # GUD002950). Fig. 70. Internal aspect of valve and valvocopula (GU52P-9) (SEM). Fig. 71. Frustule showing both internal and external valve faces. Scale bars: Figs 51–69 = 5 µm, Figs 70, 71 = 3 µm.

Figures 72–86. Fig. 72. Mastogloia pumila. Frustule showing two internal valve faces and valvocopulae; notice the variation in number of partecta (GU52P-1) (SEM). Figs 73–79. Mastogloia quinquecostata. Fig. 73. Live cell showing plastids (GU66A-5) (DIC). Figs 74–76. Frustule at three focal planes showing conopeum, areola pattern of valve face, and partecta (GU52Q-10a) (DIC). Figs 77, 78. Specimen at two focal planes showing the join in the conopeum (arrow) (GU44I-1) (DIC). Fig. 79. Oblique external view of valve showing seam along the conopeum (arrow) (GU66F-8) (SEM). Figs 80–82. Mastogloia seychellensis (GU52Q-10a). Figs 80, 81. Specimen at two focal planes, the valvocopula showing diagonal partectal ducts (DIC). Fig. 82. External view of valve (SEM). Figs 83–86. Nitzschia janischii. Fig. 83. Live cell in girdle view, showing nucleus (arrow) and plastids with pyrenoids (GU44AR-2) (DIC). Fig. 84. Portion of valve (GU44Z-15) (DIC). Figs 85, 86. Internal details of apex and central area, respectively, the latter showing the central nodule (arrow) (GU44AR-2) (SEM). Scale bars: Figs 73–78, 80–84 = 10 µm, Figs 72, 79, 85, 86 = 5 µm.