Nanofrustulum sp. 2

Li, Chun L., Witkowski, Andrzej, Ashworth, Matt P., Dąbek, Przemysław, Sato, Shinya, Zgłobicka, Izabela, Witak, Malgorzata, Khim, Jong Seong & Kwon, Chun-Jung, 2018, The morphology and molecular phylogenetics of some marine diatom taxa within the Fragilariaceae, including twenty undescribed species and their relationship to Nanofrustulum, Opephora and Pseudostaurosira, Phytotaxa 355 (1), pp. 448-450 : 448-450

Nanofrustulum sp. 2 (SZCZP178) (SEM: Figs 318–323 )

Valves circular to oval ( Figs 318–321 ). Sternum narrow-linear. Transapical striae radiate. Length: 2.5–4.0 µm, width: 2.5–4.0 µm and estimated stria density: 27–34 /10 µm (n = 10). Striae uniseriate, composed of two to three areolae on valve face and one on mantle ( Figs 318–323 ). Areolae round or slightly elongate towards valve mantle, occluded by complex volae, projecting from transapical or apical side of areolae ( Figs 318, 321 ). Sometimes branched projections detected above external areolar opening on valve face ( Fig. 318 ). Apical pores present at both apices, each consisting of one round pore ( Fig. 321 ). Marginal spines cuneate, positioned within striae, with lateral projections associated with base of spines ( Figs 322–323 ). Copulae plain ( Fig. 323 ). No rimoportulae ( Figs 320–321 ).

Distribution: Lurio, Mozambique coast of the Indian Ocean.

Observations: This clone resembles Nanofrustulum sp. 1 , but it differs from the latter by the presence of open copulae, as opposed to the numerous segmented copulae seen in Nanofrustulum sp. 1 . As above, due to the lack of a morphological distinction from N. shiloi , we did not formally describe this strain at this time.

Opephora Petit (sensu stricto)

Opephora pacifica (Grunow) Petit 1888: 131 (LM: Figs 21 , 99–104 , SEM: Figs 324–329 )

Basionym: Fragilaria pacifica Grunow (1862: 373) .

NANOFRUSTULUM , OPEPHORA AND PSEUDOSTAUROSIRA

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NANOFRUSTULUM , OPEPHORA AND PSEUDOSTAUROSIRA

Phytotaxa 355 (1) © 2018 Magnolia Press • 55 Chloroplast one, plate-like ( Fig. 21 ). Frustules rectangular in girdle view ( Fig. 104 ). Valves heteropolar, clavate with broadly rounded head pole and cuneate foot pole, becoming elliptical in smaller cells ( Figs 99–103 ). Sternum narrow-linear. Striae alternate, becoming radiate towards apices ( Figs 99–103 ). Length: 4.5–10.5 µm, width: 2.5–3.0 µm and estimated stria density: 11–14 /10 µm (n = 11).

Transapical striae uniseriate, each composed of one transapically-elongate areola, extending from valve face to mantle continuously and gradually ( Figs 324–325 ). Areolae occluded by complex inwardly-bent vela, with rods projecting from transapical sides of areolae ( Figs 324–325 ). Apical pore field on foot pole composed of four to five observed vertical rows of small round pores, positioned on valve mantle ( Figs 324–327 ). Apical pore field on head pole located on valve mantle, consisting of few small pores covered externally by granules ( Fig. 324 ). Marginal spines absent. Cingulum composed of numerous open and plain copulae ( Fig. 329 ). Valvocopula much wider than other girdle elements ( Fig. 328 ). Rimoportulae not observed ( Figs 326–327 ).

Distribution: Collected by plankton net over the sand at Ward Island, Corpus Christi Bay, Texas, USA (27°42'18" N 97°17'20.4"W) by M. Ashworth, March 2009.

Observations: As discussed in Round et al. (1990), the combined characters of stria constituted by one

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transapically elongate areola extending from valve face to mantle continuously and absence of marginal spines are the typical features for Opephora sensu stricto. Based on these features, only O. pacifica and O. marina (W. Gregory) Petit (1888: 131) can be regarded as Opephora . O. pacifica differs from O. marina by the shape of valve and sternum, which is narrowly-linear in O. pacifica and broadly lanceolate in O. marina ( Andrén 1997, Round et al. 1999). In terms of valve shape, in O. pacifica , the valve apices are broadly rounded to cuneate, whereas O. marina has a broadly-rounded head pole and tapering towards the foot pole. The valve shape and type of sternum in our strain conformed with O. pacifica , which was described as having larger valves (e.g. the specimens from Westerschelde estuary in Sabbe & Vyverman (1995) with length: 13.0–48.5 µm, width: 4.0–7.5 µm and coarse transapical striae, 6–9 /10 µm; while our strain shows valves that are smaller in length (4.5–10.5 µm), width (2.0–3.0 µm) and higher stria density (11–14/10 µm). The slight difference of the size and stria density could be an effect of the decrease in size during the life cycle. We tentatively identified our strain as O. pacifica .

Figures

FIGURES 318–323. Scanning electron micrographs of Nanofrustulum sp. 2, Lurio, Mozambique. Figs 318–319. External views, showing narrowly-linear sternum. Fig. 320. Internal and external views, showing branched lateral projection (indicated by arrowhead) on valve face. Fig. 321. Internal view, showing the absence of rimoportulae and APFs composed by one pore (indicated by arrowheads).Figs 322–323. Girdle views, showing plain copulae (indicated by arrow) and lateral projections (indicated by arrowhead) associated with marginal spines.

FIGURES 21–32. Light micrographs, showing colonies and chloroplast information of living diatoms. Fig. 21. Opephora pacifica. Figs 22–27. Plagiostriata baltica. Fig. 28. Pseudostaurosira madagascariensis. Fig. 29. Serratifera andersonii. Fig. 30. Serratifera sp. (S. cf. andersonii). Fig. 31. Serratifera brevis. Fig. 32. Serratifera clavata. Scale bars, 10 µm.

FIGURES 39–129. Light micrographs, showing morphology of cleaned valves. Figs 39–41. Cratericulifera crinigera. Figs 42–59. Gedaniella boltonii, showing morphological variations within different populations. Figs 60–62. Gedaniella alfred-wegeneri. Figs 63–67. Gedaniella arenaria. Figs 68–80. Gedaniella flavovirens, showing morphological variations within different populations. Figs 81–87. Gedaniella mutabilis, showing morphological variations within different populations. Figs 88–89. Gedaniella panicellus. Figs 90–94. Gedaniella paucistriata. Figs 95–96. Nanofrustulum shiloi. Figs 97–98. Nanofrustulum wachnickianum. Figs 99–104. Opephora pacifica. Figs 105–107. Plagiostriata baltica. Figs 108–113. Pseudostaurosira elliptica, showing morphological variations within different populations. Figs 114–119. Pseudostaurosira madagascariensis. Figs 120–129. Serratifera andersonii, showing morphological variations within different populations. Figs 42–46, 58. Clone SZCZCH1528, from Kraalbaai, South Africa. Figs 47–48, 53, 59. Clone SZCZCH751, from Ponta Deldaga, Azores, Portugal. Figs 49–50. Clone SZCZP1101, from Kraalbaai, South Africa. Figs 51–52. Clone SZCZCH760, from Capelas, Azores, Portugal. Figs 54, 57. Clone SZCZP15, from Sandwich Harbour, Namibia. Figs 55–56. Clone SZCZP20, from Nuuk, Greenland. Figs 68–69. Clone SZCZCH1549, from Sopot, Baltic Sea, Poland. Figs 70–72. Clone SZCZCH1268, from Resko Lake, Baltic Sea, Poland. Figs 73–74. Clone SZCZCH1276, from Resko Lake, Baltic Sea, Poland. Figs 75–76. Clone SZCZM1465, from Aegean Sea, Turkey. Figs 77–78. Clone SZCZCH1282, from Dalian, Yellow Sea, China. Figs 79–80. Clone SZCZCH1351, from Dalian, Yellow Sea, China. Figs 81–85. Clone SZCZCH1381, from Resko Lake, Baltic sea, Poland. Figs 86–87. Clone SZCZCH153, from Gdansk, Baltic Sea, Poland. Figs 108–109. Clone SZCZCH1348, from Resko Lake, Baltic Sea, Poland. Figs 110–111. Clone s0398, from Miedzyzdroje, Baltic Sea, Poland. Figs 112–113. Clone SZCZCH1249, from Resko Lake, Baltic Sea, Poland. Figs 120–122. Clone SZCZCH1126, from Kraalbaai, South Africa. Figs 123–124. Clone SZCZP1059, from Langebaan Lagoon, South Africa. Figs 125–127. Clone SZCZP695, from Langebaan Lagoon, South Africa. Figs 128–129. Clone SZCZP1183, from Key West, Florida, USA. Scale bar, 10 µm.

FIGURES 324–329. Scanning electron micrographs of Opephora pacifica (ECT3831, culture). Figs 324–325. External views, showing clavate valves with each stria composed by single elongated areola extending from valve face to mantle continuously and head APFs ornamented with granules (indicated by arrow). Figs 326–327. Internal views, showing the absence of rimoportulae and foot pole APFs composed by up to five observed vertical rows of pores (indicated by arrows). Fig. 328. Girdle view, showing plain and open valvocopulae (indicated by arrow). Fig. 329. Girdle view, showing numerous, open and plain copulae.