Plagiostriata baltica Chunlian Li, Witkowski & Witak, 2018

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

Plagiostriata Sato & Medlin 2008

Plagiostriata baltica Chunlian Li, Witkowski & Witak , sp. nov. (LM: Figs 22–27 , 105–107 , SEM: Figs 330–340 )

Chloroplast one, big plate-like. Cells solitary ( Figs 22–27 ). Frustules rectangular in girdle view ( Fig. 107 ). Valves linear with obtusely rounded apices ( Figs 105–106 ) or elliptical in smaller cells ( Figs 26–27 ). Sternum and striae both inconspicuous, barely recognizable in LM ( Figs 105–106 ). Length: 14.0–27.0 µm, width: 2.0–3.0 µm and stria density: 29–30 /10 µm (n = 26).

Valve face flat ( Fig. 340 ). Striae uniseriate, weakly alternate and radiate at apices ( Fig. 330 ). Sternum indistinct ( Figs 330–333 ). Areolae small, round, occluded by simple volae ( Figs 334–335 ). Rimoportulae present in middle of valve. External opening of rimoportula observed as narrow, slit-like opening ( Fig. 339 ). Internally, rimoportulae situated close to indistinct sternum and parallel to striae ( Figs 331, 333, 337 ) and simple, losing tube structure present in many araphid pennate diatoms with rimoportula and only retaining elongate slit on internal valve surface, with grooves alongside ( Fig. 337 ). Valves lacking rimoportulae observed, but rare ( Figs 332, 338 ). Apical pore field poorly developed, composed of one or two pores, located on valve mantle ( Figs 334–336 ). Cingulum broad, composed of numerous, plain copulae, fringe present ( Fig. 340 ).

Etymology: This name is referred from sampling site where it was collected: the Baltic Sea.

Holotype: BM 101909 , in the Natural History Museum, London, UK, collected by M. Witak, March 2016.

Isotype: Slide SZCZCH1550 , deposited in Palaeoceanology Unit , Faculty of Geosciences, University of Szczecin .

Type habitat: Fine sand from a water depth of 5 m in Sopot, the Gulf of Gdańsk, the Baltic Sea.

Distribution: So far known only from the type locality, sediments of the Baltic Sea (Gulf of Gdańsk, Sopot), Poland.

Observations: Plagiostriata baltica shares many morphological similarities with Plagiostriata goreensis , having the same type of rimoportulae, similar apical pore fields and absence of marginal spines. However, P. baltica differs from P. goreensis by its indistinct sternum, linear valves, round areolae and lower stria density which are parallel (not oblique as in P. goreensis ).

Pseudostaurosira elliptica (Schumann) Edlund, Morales & Spaulding (LM: Figs 108–113 , SEM: Figs 341–348 )

Basionym: Fragilaria elliptica Schumann (1867: 52 , pl. I: fig. 5).

Synonym: Staurosira elliptica (Schumann) Williams & Round (1987: 272, figs 19–20).

Frustules rectangular in girdle view ( Fig. 109 ). Valves lanceolate in bigger cells and lanceolate-rhombic in smaller cells ( Figs 108, 110–113 ). Transapical striae marginal, with widely lanceolate sternum. Length: 6.0–14.5 µm, width: 2.5–4.5 µm, and stria density: 15.0–18.0 /10 µm (n = 28).

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Valve face flat ( Fig. 345 ). Striae uniseriate, composed of one areola on valve face and one or two areolae on mantle ( Figs 341 , 345–348 ). Areolae round to slightly elliptical, occluded by branched volae ( Figs 342 , 346 ). Apical pore fields small, present at both apices, composed of few pores, positioned on valve margin and sunken into circular depression internally ( Figs 341–342 ). Marginal spines branched, and situated within striae ( Figs 343–345, 347–348 ). Lateral projections observed close to base of marginal spines, oriented towards mantle, in combination with smaller projections at edge of mantle areolae, occluding areolae beneath marginal spines ( Figs 343–344 , 347–348 ,). Copulae numerous, plain ( Fig. 344 ). Fringed and ligulae copulae observed ( Fig. 345 ). Valvocopula wider than other copulae ( Figs 344 , 347 ). No rimoportulae ( Figs 342 , 346 ). Mantle plaques present ( Fig. 344 ).

Distribution: In our study, this species was observed in Resko Lake, located at the Polish Baltic Sea coast and beach channel in Miedzyzdroje, Baltic Sea, Poland.

Observations: Our specimens are brackish water forms and their morphology fit very well with Pseudostaurosira elliptica as illustrated by Edlund et al. (2006). The size dimensions of our populations overlap with those illustrated and described in Edlund et al. (2006), which has length: 6–14 µm, width: 3–3.5 µm and stria density: 14–16 /10 µm.

Pseudostaurosira madagascariensis Chunlian Li, Witkowski & Ashworth , sp. nov. (LM: Figs 28 , 114–119 , SEM: Figs 349–359 )

Chloroplasts one or two ( Fig. 28 ). Frustules rectangular in girdle view ( Fig. 119 ), forming chain-like colonies at valve face by interlocking spines ( Fig. 28 ). Valves oblong, elliptical or oval with broadly rounded apices (Figs

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Phytotaxa 355 (1) © 2018 Magnolia Press • 59 114–118). Sternum widely-lanceolate. Transapical striae alternate, marginal. Length: 3.0–6.5 µm, width: 2.0–3.5 µm, and estimated stria density: 18–22 in 10 µm (n = 19).

Striae uniseriate, each composed of one areola on both valve face and mantle ( Figs 349–355 ). Areola round or transapically elongate, occluded by complex volae, projecting from transapical sides or apical sides of areolae ( Figs 351–354 ). Areolar rim projections, oval and leaf-like with serrated margin observed above external opening of areolae on valve face, originating from region close to central sternum ( Fig. 354 ). Apical pores present at both apices, each composed of single round pore ( Figs 351, 353 ). Marginal spines spatulate with serrated margins located within striae. Large lateral projections associated with base of marginal spines detected, sometimes occluding external opening of mantle areolae entirely ( Figs 356–357 ). Six copulae observed, plain and segmented—composed of at least two fragments ( Fig. 358 , see black arrows) and with fringed structure at margin of copulae ( Figs 358–359 , see white arrow). Rimoportulae not observed ( Fig. 355 ). Mantle plaques present ( Fig. 356 ).

Etymology: This species is named for the location where the sample was collected, Madagascar.

Holotype: BM 101910 , in the Natural History Museum, London, UK, Collected by Dr. J. Bemiasa, October 2014.

Isotype: Slide SZCZCH741 , deposited in Palaeoceanology Unit , Faculty of Geosciences, University of Szczecin .

Type habitat: Coral sand from shallow water at Toliara, SW Madagascar, 13°29'4.8"S 48°14'13.2"E

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Observations: Under LM, this species can be confused with other taxa with extremely shortened striae, like small specimens of Pseudostaurosira brevistriata (Grunow) Williams & Round ( Morales et al. 2015, fig. 127), Pseudostaurosira sajamaensis Morales & Ector ( Morales et al. 2012, figs 15–18) and Staurosirella mutabilis ( Morales et al. 2015: figs 33–36). All the aforementioned species have elliptical valves with rounded apices, marginal striae, a wide sternum and overlapping size dimensions. However, P. madagascariensis can be distinguished by its higher stria density. In the SEM, P. madagascariensis , as well as Pseudostaurosira sajamaensis Morales & Ector (2012: 45) , Pseudostaurosira brevistriata , and species of Pseudostaurosiropsis Morales (2001: 116) , possess areolar rim projections above external opening of valve face areolae, but the number, shape and originated places of areolar rim projections are different. In P. madagascariensis , there is only one rim projection, oval-leaf shaped with serrated margin, originating from the region close to central sternum, far away from the region near the base of marginal spines. In Pseudostaurosira sajamaensis , there is a single lobed or branched projection, originating from the region close to the base of linking spines ( Morales et al. 2012, fig. 45). In Pseudostaurosira brevistriata , there are two (rarely one) opposing plate-like projections, originating from transapical sides of areolae, which sometimes meet in the middle and give the impression of a single round plate covering the entire areolar external opening ( Morales et al. 2015, figs 136, 138). As for Pseudostaurosiropsis

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Morales (2001: 116, 2002: 105), there are disc-like projections, originating from vimines or near the base of linking spines. The specimens named as Fragilaria sp. 3 in Montgomery 1978 (figs F-H) should be included in P. madagascariensis .

Serratifera Ashworth, Chunlian Li & Witkowski (amended)

Frustules rectangular in girdle view, forming radiate colonies attached by apical pore fields, rarely forming ribbon-like colonies by valve faces. Cells heteropolar, rarely isopolar, clavate, rhombic, elliptical or oval. Sternum narrow-linear and rarely widely-lanceolate. Striae alternate, uniseriate, composed of one (very rarely two) areolae on valve face and one (very rarely two or absent) on mantle. Areolae rarely round or elliptical, usually large, transapically-elongated, occluded with complex volae, with rods projecting from transapical sides of areolae. APFs heteropolar (rarely isopolar). Foot APFs often composed by few (two to five) vertical rows of pores and head APFs consisted of few pores, ornamented with granules externally. Marginal spines often present, simple, branched or spatulate, located within striae. Copulae plain. Valvocopula broader than remaining elements. Rimoportulae absent. Marine.

Comment: When observed with LM, the most common shared characters within this genus are the clavate valves and distinctly narrowly-linear sternum. When examined with SEM, the most dominant characters found within the taxa are: striae often composed of a single areola on both valve face and mantle, and areolae occluded by complex volae, with rods projecting from transapical sides of areolae. However, these characters also can be observed in other araphid diatoms, like Pseudostaurosira , Pseudostaurosiropsis Morales (2001: 116) and Nanofrustulum . At this time, we have been unable to find a synapomorphic character to define this genus. Nonetheless, a combination of characters did exist to help distinguish Serratifera from the above genera, such as the combination of striae composed of a single areola on both valve face and mantle and distinctly narrowly-linear sternum ( Table 4). For instance, Pseudostaurosira decipiens Morales, Chávez & Ector (2012: 44) , Pseudostaurosira sajamaensis , Pseudostaurosira brevistriata , Pseudostaurosira clavatum , Pseudostaurosiropsis connecticutensis Morales (2001: 116) , Pseudostaurosiropsis geocollegarum (Witkowski) Morales (2002: 104) and Nanofrustulum Wachnickianum , likewise possess one areola on both valve face and mantle, their areolae are relatively small and marginal, leaving a very broad lanceolate central sternum. Additionally, N. wachnickianum possesses warts on the valve face, and Pseudostaurosiropsis spp. always have lateral projections above external opening of the areolae but those characters are not observed within Serratifera .

Serratifera andersonii Chunlian Li, Dąbek & Wachnicka , sp. nov. (LM: Figs 29 , 120–129 , SEM: Figs 360–373 ).

Morphological descriptions based on young, old cultures and wild materials.

Chloroplast two ( Fig. 29 ). Frustules rectangular in girdle view ( Fig. 122 ) and aggregated colonies observed ( Fig. 29 ). Valves heteropolar, clavate in larger specimens and lanceolate to elliptical in smaller cells ( Figs 120–121, 123–129 ). Striae alternate, becoming radiate at apices. Sternum narrow-linear. Length: 3.5–21.0 µm, width: 2.0–5.0 µm, and stria density: 14–17 /10 µm (n = 45).

Striae uniseriate, each composed of single large areola on both valve face and mantle ( Figs 360–363 , 368–370 ). Areolae transapically-elongate, extending from valve margin to central sternum or mantle, occluded with complex volae, with multiple rods originating from transapical sides of areolae ( Fig. 360 ) and areolae more extensively-elongated in smaller cells ( Figs 368, 369, 370 ). Foot pole APFs composed of three to four observed vertical rows of small circular pores ornamented with projections, positioned on mantle, while head pole APF consisting of few scattered pores, ornamented with small granules ( Figs 360–363 , 368 ). Marginal spines spatulate in young cultures and wild materials ( Figs 360–363, 366 ), becoming slit-like in older cultures ( Figs 368–369, 370 ) located at valve face/mantle junction, positioned within striae. Copulae numerous, plain and valvocopula wider than other girdle elements ( Figs 366 , 372 ). Fringed structure at edge of copula observed ( Figs 367 , 373 ). No rimoportulae ( Figs 364–365 , 371 ).

Etymology: This species is dedicated Professor Robert Anderson – a distinguished South African phycologist.

Holotype: BM 101898 , in the Natural History Museum, London, UK, collected by P. Dąbek, May 2015.

Isotype: Slide SZCZCH1126 , deposited in Palaeoceanology Unit , Faculty of Geosciences, University of Szczecin .

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Type habitat: Muddy rock pools from Kraalbaai, South Africa, 33°08'16.4"S 18°01'34.6"E .

Distribution: The type strain and clone SZCZP695 were collected from muddy rock pools from Kraalbaai,

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Phytotaxa 355 (1) © 2018 Magnolia Press • 65 which is a part of the large Langebaan Lagoon in South Africa; Clone SZCZP1059 from a Klein Oesterwal tidal flats rock scrape, Langebaan Lagoon, South Africa; Clone SZCZP1183 from a small embayment in Key West, Florida. This taxon was also observed in the wild material from Sandwich Harbor, Namibia.

Observations: In LM, all these strains resemble to some extent Pseudostaurosira perminuta (Grunow) Sabbe & Vyverman (1995: 237 , figs 1–12). The two taxa differ, however, in terms of the width of the sternum, which is narrowly to broadly lanceolate in P. perminuta and strictly narrow in S. andersonii . In SEM the major difference is the stria structure, being composed of few small areolae in P. perminuta and of a single areola in S. andersonii .

Serratifera sp. ( S. cf. andersonii ) (LM: Figs 30 , 130–137 , SEM: Figs 374–384 )

Morphological descriptions based on young and old cultures.

Frustules rectangular in girdle view ( Fig. 137 ), forming radiate colonies by apical pore fields ( Fig. 30 ). Valves heteropolar, clavate or even oval in case of smallest cells ( Figs 130–136 , 376 ). Striae alternate, becoming radiate near apices. Sternum narrowly-linear. Length: 3.0–11.0 µm, width: 2.5–4.5 µm and estimated stria density: 14–18 / 10 µm (n = 31).

Striae uniseriate, each composed of one (rarely two) transapically-elongate areolae on both valve face and mantle ( Figs 374–377 , 381–384 ). Areolae occluded by complex volae, with rods originating from transapical sides of areolae ( Figs 374–377 , 381–384 ). Apical pore fields on foot pole composed by four observed vertical rows of pores, located on mantle ( Figs 374–375 ). Apical pore fields on head pole covered by few granules. Marginal spines stick-like, positioned within striae ( Figs 378 , 382, 384 ). Copulae open and plain ( Figs 378–379 ) and fringed structure at edge of copula observed ( Fig. 380 ). Valvocopula wider than remaining girdle elements ( Figs 378–379 ). Rimoportulae not observed ( Figs 377 , 383 ).

Distribution: Specimens were collected from Sea of Marmara, Turkey, and from a small embayment at San Sebastian Beach in La Gomera, Canary Islands and Lokrum Beach, Croatia.

Observations: Although two smaller areolae on both valve face and mantle were observed, this could be the effect of culturing. This taxon has many similarities with S. andersonii under both LM and SEM, and it was hard to separate them. Moreover, the size dimensions and stria density of this taxa overlap with that of S. andersonii . Although DNA sequence data show that they position in different clades, we cannot find a character to distinguish them. Therefore, we designated this taxon as Serratifera sp. ( S. cf. andersonii )

Serratifera brevis Chunlian Li & Ashworth , sp. nov. (LM: Figs 31 , 138–142 , SEM: Figs 385–392 )

Morphological description based on young culture and one wild specimen.

Chloroplast two, each compressed to both valve faces ( Fig. 31 ). Frustules rectangular in girdle view ( Fig. 142 ), forming chain-like colonies by valve faces ( Fig. 31 ). Cells heteropolar, lanceolate-clavate. Sternum narrow-linear ( Figs 138–141 ). Striae alternate, becoming slightly radiate at apices. Length: 5.5–14.5 µm, width: 2.0–3.0 µm and stria density: 16–19 /10 µm (n = 35).

Striae uniseriate, each composed of a single areola on both valve face and mantle ( Figs 385–390 ). Areolae roundish near apices and transapically-elliptical in center ( Figs 385–386, 388–389 ) and more elongated in smaller cells ( Fig. 387 ). Areolae occluded by complex volae, with rods projecting from transapical sides of areolae ( Figs 385, 387–388 ). Apical pore field at foot pole composed of three observed vertical rows of small round pores ( Figs 385, 389 ). Head pole apical pore fields obscured by granules ( Fig. 385 ). Marginal spines flattened, with bifurcated tips, positioned within striae ( Figs 386–387 ). Tiny granules around base of marginal spines observed ( Fig. 391 ). Girdle composed of several (six observed) plain and open copulae. Valvocopula wider than remaining girdle elements ( Fig. 390 ) and fringed structure at edge of copula observed ( Fig. 392 ). No rimoportulae ( Fig. 389 ). Mantle plaques present ( Fig. 390 ).

Etymology: The species name is inferred from the very narrow valves, Latin brevis = narrow.

Holotype: BM 101900 , in the Natural History Museum, London, UK, collected by N. Leclear, January 2012.

Isotype: Slide HK 446, in the E. Theriot Lab collection at University of Texas , Austin .

Type habitat: Unspecified benthic environment on the island of Hawaii, Hawaii, USA.

Distribution: This species was also observed in wild material from the coast of Nosy Be Island, Madagascar.

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Observations: This species looks similar with S. parkii due to its narrow, lanceolate-clavate valve and acutely cuneate foot pole under LM, but differs in the presence of small tiny granules around base of marginal spines and wider valves (2.0–3.0 µm). While in S. parkii , small granules have never been observed associated with the base of spines and its width is narrower (1.5–2.0 µm). Furthermore, S. brevis lacks the swollen base of marginal spines seen in S. parkii .

Serratifera clavata Chunlian Li, Tomczak & Witkowski , sp. nov. (LM: Figs 32 , 143–147 , SEM: Figs 393–398 )

Chloroplasts one or two, compressed to valve face ( Fig. 32 ). Frustules rectangular in girdle view ( Fig. 147 ), forming radiate colonies by apical pore fields ( Fig. 32 ). Cells heteropolar, clavate. Sternum narrow-linear ( Figs 143–146 ). Striae alternate, slightly radiate at apices. Length: 9.5–14.0 µm, width: 2.5–4.5 µm and stria density: 15–17 /10 µm (n = 49).

Striae uniseriate, each composed of single areola (rarely two smaller areolae) on both valve face and mantle ( Figs 393, 396, 398 ). Areolae round near apices and transapically-elongate in center, occluded by complex volae, with rods originating from transapical sides of areolae ( Fig. 397 ). Apical pore fields at foot pole composed of five vertical rows of small pores, ornamented with projections along the vertical margin of areolae externally, situated on mantle ( Figs 395–396 ). Head pole apical pore field positioned on mantle, consisting of few pores covered by numerous granules externally ( Figs 394, 396 ). Marginal spines columnar sometimes with bifurcated tips on top, positioned within striae ( Fig. 394 ). Cingulum not clearly presented but relatively narrow ( Fig. 398 ). No rimoportulae ( Fig. 396 ).

Etymology: The species name is derived from the valves purely clavate outline.

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Phytotaxa 355 (1) © 2018 Magnolia Press • 69 Holotype: BM 101901 , in the Natural History Museum, London, UK, collected by M. Tomczak, October 2014. Isotype: Slide SZCZCH752 , deposited in Palaeoceanology Unit , Faculty of Geosciences, University of

Szczecin.

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Type habitat: Sand in shallow water site of the Persian Gulf in Abu Dhabi, 24°28'53.4"N 54°20'43.2"E .

Observations: Under the LM, this species looks similar to S. andersonii , S. sp. ( S. cf. andersonii ) and S. takanoi ; Size and stria density of S. clavata overlap with that of the former two taxa, but it differs from that of S. takanoi , which possess shorter and narrower valves (length: 6.0–9.0, width: 2.0–2.5) and relatively higher stria density (17–18 /10 µm). Additionally, it can be distinguished from those aforementioned species by the narrower cingulum, concave striae, thickened and elevated virgae, while the striae and virgae are flat for S. andersonii , S. sp. ( S. cf. andersonii ) and S. takanoi .

Serratifera corallina Chunlian Li, Górecka & Kwon , sp. nov. (LM: Figs 148–151 , SEM: Figs 399–404 )

Valves elliptical-rhombic or slightly heteropolar with rounded apices ( Figs 148–151 ). Striae alternate, slightly radiate at apices. Sternum narrow-linear ( Figs 148–151 ). Length: 5.0–7.0 µm, width: 2.0–3.0 µm and stria density 18–23 /10 µm (n = 34).

Striae uniseriate, consisting of single areola on both valve face and mantle ( Figs 399–402 ). Areolae transapically-elongate, occluded by branched volae, with rods originating from transapical sides of areolae ( Fig. 399 ). Apical pore fields small, positioned on valve mantle, and composed of several pores, ornamented with few granules ( Figs 399–400 ). Marginal spines spatulate, with lateral projection originating from one side and downwards to valve mantle, positioned within striae ( Figs 401, 403 ). Copulae open and plain ( Fig. 404 ). No rimoportulae ( Fig. 402 ).

Etymology: This species name refers to the coral reef habitat where the type sample was collected by C. J. Kwon in December 2015.

Holotype: BM 101897 , in the Natural History Museum, London, UK, collected by Dr. Kwon from the National Marine Biodiversity Institute of Korea.

Isotype: Slide SZCZE1544 , deposited in Palaeoceanology Unit , Faculty of Geosciences, University of Szczecin .

Type habitat: Submarine rock cliff, water depth of 50 m, MoalBoal , Cebu Island Philippines, 09°56'57.7"N 123°21'55.4"E .

Observations: This species could be confused with S. nosybeana (see below) due to the overlap in size dimensions and stria density. Lateral projections associated with the marginal spines are seen in S. corallina as well observed in S. nosybeana . However, the lateral projections in the former are originating from one side of spines and extending downwards to mantle. In S. nosybeana , the lateral projections are observed in the surroundings of the spines and then extending towards to mantle. Additionally, this two species differ in valve outline, which is elliptical–rhombic or slightly-clavate in S. corallina and clavate or clavate-elliptical in S. nosybeana .

Serratifera namibica Chunlian Li & Witkowski , sp. nov. (LM: Figs 152–156 , SEM: Figs 405–412 )

The morphological description based on young, old cultures and wild material.

Valves heteropolar, clavate in larger cells and oval in smaller cells ( Figs 152–156 ). Striae alternate, slightly radiate at apices. Sternum narrow-linear ( Figs 152–156 ). Length: 3.0–16.0 µm, width: 2.0–4.5 µm and stria density: 14–16 /10 µm if length> 10 µm, for length <10 µm, stria density: 15.5–22 /10 µm (n = 32).

Striae uniseriate, each consisting of single areola on both valve face and mantle ( Figs 405–411 ). Areolae transapically-elongate, occluded by complex volae, with rods originating from transapical sides of areolae. Apical pore field on foot pole composed of three observed vertical rows of pores, positioned on valve mantle ( Figs 406–411 ). Apical pore fields on head pole, located on mantle, obscured by few small granules ( Figs 405, 407, 411 ). Marginal spines absent ( Figs 405–409 ). Copulae plain with fringed structures observed at margin ( Fig. 412 ). Rimoportulae not observed ( Fig. 410 )

Etymology: The species name is derived from the country of the type habitat location, Namibia.

Holotype: BM 101902 , in the Natural History Museum, London, UK, collected by A. Witkowski and P. Dąbek, April 2013.

Isotype: Slide SZCZP88 , deposited in Palaeoceanology Unit , Faculty of Geosciences, University of Szczecin .

Type habitat: A short sediment core retrieved from Sandwich Harbor lagoon in Namibia.

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Observations: Under LM, the small specimens of S. namibica could be confused with small specimens of Gedaniella flavovirens or Gedaniella boltonii but can be differentiated from them and other taxa of Serratifera by the absence of marginal spines observed under SEM.

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Serratifera nosybeana Chunlian Li, Witkowski & Riaux-Gobin , sp. nov. (LM: Figs 157–160 , SEM: Figs 413–419 )

Morphological description based on old cultures and one wild specimen.

Frustule rectangular in girdle view ( Fig. 160 ). Cells slightly heteropolar, clavate or clavate-elliptical ( Figs 157–159 ). Sternum narrow-linear. Striae alternate, becoming radiate at apices ( Figs 157–159 ). Length: 4.5–6.5 µm, width: 2.0–3.0 µm and estimated stria density 20–24 /10µm (n = 34).

Striae uniseriate, each consists of single (sometimes two) areolae on valve face and one areola on mantle ( Figs 413–415, 418 ). For wild specimen, valve with one areola on both valve face and mantle ( Fig. 416 ). Areolae transapically-elongated, occluded by branched volae, with rods projecting from transapical sides of areolae ( Figs 413–416 ). Apical pore field at foot pole composed of three observed vertical rows of small round pores ornamented with marginal rims externally, located on mantle ( Figs 413, 415, 418 ). Head pole apical pore fields obscured by few granules ( Figs 413–416 ). Marginal spines when present columnar with lateral projections around base and extending towards valve mantle ( Figs 413–417 ). Copulae plain and open ( Fig. 419 ). No rimoportulae ( Fig. 418 ).

Etymology: This species name is derived from the name of the type habitat, Nosy Be Island in NW Madagascar.

Holotype: BM 101903 , in the Natural History Museum, London, UK, collected by A. Witkowski and C. Riaux-Gobin in July 2014.

Isotype: Slide SZCZCH992 , deposited in Palaeoceanology Unit , Faculty of Geosciences, University of Szczecin .

Type habitat: A rock surface at the coast of Nosy Be Island in NW Madagascar, 13°29'4.8"S 48°14'13.2"E .

Observations: The size dimensions and stria density of this species overlap with that of S. corallina . Additionally, both possess lateral projections associated with the base of marginal spines, however, in this species, these lateral projections occur in the surrounding of marginal spines and then extending to mantle ( Fig. 417 ). In S. corallina , there are no lateral projections observed in the surrounding area of spines but only lateral projections originating from one side of marginal spines, extending to valve mantle ( Fig. 403 ). Additionally, this species often has clavate valves (sometimes clavate-elliptical in smaller cells, and clavate-lanceolate in wild specimens), while valves of S. corallina are usually rhombic to elliptical.

Serratifera opephoroides (Takano) Chunlian Li & Witkowski , comb. nov.

Basionym: Fragilaria opephoroides Takano (1988 , Bulletin of the Tokai Regional Fisheries Research Laboratory. p. 36, figs 2–3, 16–26).

Synonym: Opephora naveana Le Cohu 1988

Iconotypus: Membranae negativae conservatae in Colletione Novarum Bacillariophycearum Takanoi No. 33.

Type habitat: Littoral zone of Mikawa Bay , Aichi Prefecture , and Yamaguchi Prefecture, Japan .

Comments: Although we do not have DNA sequence data to support this transfer, we feel the valve morphology (described in Takano 1988) of Fragilaria opephoroides fits the generic description of Serratifera , based on the nature of the striae (with one transapically-elliptical or elongate areola on both valve face and mantle), narrow-linear sternum and complex volae ( Takano 1988, figs 18, 21). Although F. opephoroides has many similarities with other species within Serratifera , e.g. the presence of marginal spines, a heteropolar frustule with clavate outline and small apical pore fields located on valve mantle, F. opephoroides obviously differs from these other species by lower stria density (10–12 /10 µm), as opposed to stria densities higher than 12 /10 µm in other species ( Table 6).

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Serratifera parkii Chunlian Li & Ashworth , sp. nov. (LM: Figs 33 , 161–165 , SEM: Figs 420–424 )

Chloroplast one, cup-shaped ( Fig. 33 ). Frustules rectangular in girdle view ( Fig. 165 ). Ribbon-like colonies linked at valve face ( Fig. 33 ). Cells heteropolar, clavate-lanceolate with acutely cuneate foot apices. Striae alternate. Sternum narrow-linear ( Figs 161–164 ). Length: 9.5–12.0 µm, width: 1.5–2.0 µm, and stria density: 16–18 /10 µm (n = 39).

Striae uniseriate, each composed of one areola on both valve face and mantle ( Figs 420–422 ). Areola small, round to elliptical, occluded by complex volae, with rods projecting from transapical sides of areolae ( Fig. 421 ). Apical pore fields on foot pole composed by three vertical observed rows of small round pores, decorated with wavy projections along vertical margin of pores externally ( Figs 420–421 ). Head poles covered with several granules ( Figs 420, 422 ). Marginal spines columnar with bifurcated tips on top and inflated at base, positioned within striae ( Figs 420, 422 ). Copulae plain ( Fig. 424 ) and fringed structure at end of copula observed ( Fig. 423 ). Rimoportulae not detected ( Fig. 421 ).

Etymology: This species is dedicated Dr. Jinsoon Park, a distinguished Korean diatomologist.

Holotype: BM 101904 , in the Natural History Museum, London, UK, collected by J. Park, October, 2014.

Isotype: Slide HK 507, in the Theriot Lab collection at University of Texas, Austin .

Type habitat: Mud sample from the sand flats from Tongyeong, South Korea, vicinity of the LNG Terminal, 34°56'46.2"N 128°25'46.2"E .

Observations: As discussed previously, this species looks similar to S. brevis due to its lanceolate-clavate outline and overlap of valve lengths and stria density. Nevertheless, it can be differentiated from the latter by narrower valves (1.5–2.0 µm, while the width of S. brevis is 2.0–3.0 µm). Furthermore, S. brevis always possesses small granules near the base of spines, which was never observed in this species.

Serratifera punctata Sato & Chunlian Li , sp. nov. (LM: Figs 34 , 166–168 , SEM: Figs 425–430 )

Chloroplast likely one ( Fig. 34 ). Frustules rectangular in girdle view ( Fig. 168 ), forming radiate colonies by apical pore fields ( Fig. 34 ). Valves heteropolar, clavate with rounded apices. Width of valves decreasing from head pole to foot pole gradually ( Figs 166–167 ). Striae alternate, parallel. Sternum narrow-linear ( Figs 166–167 ). Length: 7.5–8.0 µm, width: 2.0–2.5 µm, and estimated stria density: 16 /10µm (n = 5).

Striae uniseriate, each composed of single areola on both valve face and mantle ( Figs 425–426 ). Areolae slightly transapically-elliptical, occluded with branched volae, one or two rods originating from transapical sides of areolae ( Fig. 429 ). Apical pore field on foot pole constituted by four observed vertical rows of pores, positioned on valve mantle ( Fig. 427 ). Head pole APFs, when present, difficult to resolve, covered by few granules externally ( Fig. 428 ). Marginal spines spatulate with few granules (two to three) aggregated near base, located at valve / mantle face junction and positioned within striae ( Fig. 429 ). Copulae plain and open. Six observed copulae per valve and valvocopula wider than remaining girdle elements ( Fig. 430 ). Rimoportulae not observed ( Fig. 426 ). Mantle plaques present ( Fig. 430 ).

Etymology: Species name referred to punctate areolae, which are visible in LM.

Holotype: BM 101905 , in the Natural History Museum, London, UK, collected by S. Matsumoto, September 2006.

Isotype: Slide s0386, deposited in Sato’s collection in Faculty of Marine Bioscience, Fukui Prefectural University, Fukui, Japan .

Type habitat: Collected from sand inside of main port of Goree Island, Dakar, Senegal.

Observations: Under the LM, this species looks different from other taxa within Serratifera by the gradual decreasing of widths of valve from head to foot poles. Under SEM, S. punctata could be confused with larger specimens of S. sourniae , which also possess a clavate outline and few granules near the base of marginal spines. Nevertheless, the foot pole APFs composed by four vertical rows of pores in S. punctata , and three vertical rows of pores seen in S. sourniae . Additionally, S. punctata possess broadly-round foot apices, which is broadly-cuneate in S. sourniae .

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Serratifera rhombica Sato, Chunlian Li & Witkowski , sp. nov. (LM: Figs 35 , 169–171 , SEM: Figs 431–436 )

Morphological description based on young cultures and wild materials.

Chloroplast one ( Fig. 35 ). Frustules rectangular in girdle view, forming radiate colonies at apical pore fields (Fig.

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35). Cells slightly heteropolar, rhombic. Sternum narrow-linear. Striae broad, alternate, punctate, slightly radiate ( Figs 169–171 ). Length: 7.0–10.5 µm, width: 2.0–2.5 µm and estimated stria density: 13–16 /10 µm (n = 17).

Striae uniseriate, each with one areola on both valve face and mantle ( Figs 431–435 ). Areolae irregular, transapically elongate, occluded by highly branched volae, with rods projecting from transapical (rarely apical) sides of areolae ( Fig. 431 ). Foot pole apical pore field composed of few (three observed) vertical rows of small round pores, positioned on mantle and head pole apical pore field, situated on mantle as well, consisting of few scattered pores, decorated with several granules ( Figs 431, 434–435 ). Marginal spines present, with “accessory”

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spines flanking larger central spines, located on valve face/mantle junction and within striae ( Fig. 436 ). Copulae few, plain and valvocopula much broader ( Fig. 436 ). A film seems covering part of cingulum ( Fig. 436 ). No rimoportulae ( Figs 434–435 ).

Etymology: The species name is derived from the rhombic valve shape.

Holotype: BM 101906 , in the Natural History Museum , London, UK, collected by T. Watanabe, October 2005.

Isotype: Slide s0357, deposited in Sato’s collection in Faculty of Marine Bioscience, Fukui Prefectural University, Fukui, Japan .

Type habitat: The coast of Iriomote Island, Okinawa, Japan, 24°12'36"N 123°25'48"E .

Distribution: This taxa was also examined in wild material from the coast of Nosy Be Island, Madagascar.

Observations: When examined with LM, S. rhombica can be differentiated from other Serratifera taxa by the rhombic valve outline. Furthermore, this species is unique among Serratifera species by the presence of “accessory” spines flanking larger central spines, making the shape of marginal spines look like triangular when observed with SEM.

Serratifera sourniae Chunlian Li, Riaux-Gobin & Witkowski , sp. nov. (LM: Figs 36 , 172–175 , SEM: Figs 437–448 )

Morphological description based on young, old cultures and wild material.

Chloroplast likely one, compressed to mantle ( Fig. 36 ). Frustules forming ribbon-like colonies by valve faces ( Fig. 36 ). Valves heteropolar, clavate in bigger cells and oval in smaller valves ( Figs 172–175 ). Sternum narrow-linear. Striae alternate and radiate throughout ( Figs 172–175 ). Length: 2.0–12.0 µm, width: 2.0–3.5 µm. For length>10 µm, stria density: 16–17 /10 µm, if length <10 µm, estimated stria density: 18–30 /10 µm (n = 33).

Valve face flattened, with each stria composed of one (rarely two) transapically-elongate areola on both valve face and mantle ( Figs 437, 439–448 ). Areolae occluded by complex volae, often with rods originating from transapical sides of areolae ( Figs 437 , 443–446 ). Apical pore field absent or composed of few pores (two observed), located on mantle in smaller cells ( Figs 437, 441 ). In clavate valves, foot apical pore fields with two to four vertical row of pores with projections decorated along vertical margin of pores, while head apical pore fields obscured by few granules ( Figs 443–446, 448 ). Linking spines weakly spatulate with serrated edges and swelling base, positioned at valve margin, within striae ( Figs 437, 440–441 , 443–446 ). Multiple small granules observed at both sides of linking spines ( Figs 437, 440 , 443–446 ). Copulae plain ( Fig. 441 ). Rimoportulae not observed ( Figs 438 , 448 ). Mantle plaques present ( Fig. 440 ).

Etymology: This species is dedicated professor Alain Sournia, distinguished phycologist and pioneer of diatom research in the Mozambique channel and in Madagascar.

Holotype: BM 101907 , in the Natural History Museum, London, UK, collected by A. Witkowski and R. Gobin, July 2014

Isotype: Slide SZCZE517 , deposited in Palaeoceanology Unit , Faculty of Geosciences, University of Szczecin .

Type habitat: Rock surface at the Nosy Be coastal zone in tropical part of Western Indian Ocean, 13°29'4.8"S 48°14'13.2"E .

Distribution: Type strain and clones (SZCZCH583 and SZCZE614) were collected from rock scrape, along the coasts of Nosy Be, a small volcanic island in NW Madagascar, and other two clones were collected from Pueu, French Polynesia (17°44'13.2"S 149°13'34.2"W) from intertidal, coarse sediment (gravel).

Observations: For this taxa, the earliest harvest of morphological data are mixture of larger clavate cells and smaller oval cells. However, due to a problem encountered with the method that was used to prepare clean material, we cannot obtain good quality SEM images ( Figs 439, 442 ). When new morphological data was collected from old cultures, the cells were predominantly oval. Therefore, the presentation of this species included young and old cultures. Oval cells of this species could be confused with other tiny oval araphid taxa under LM, nonetheless, it can be distinguished from them by the presence of small granules near the base of marginal spines when observed with SEM. Clavate cells, to some degree, looks similar to S. punctata , which also possesses small granules near marginal spines, nevertheless, S. punctata differs from S. sourniae by the valve outline, where the width of the valve decreases gradually from head to foot pole and with a round foot apex.

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Serratifera takanoi Sato & Chunlian Li , sp. nov. (LM: Figs 37 , 176 , SEM: Figs 449–454 )

Chloroplast one, plate-like. Frustules rectangular in girdle view, forming radiate colonies by apical pore fields ( Fig. 37 ). Cells heteropolar, clavate with roundly cuneate head apices and cuneate foot poles ( Fig. 176 ). Sternum distinct, narrowly-linear ( Fig. 176 ). Striae alternate. Length: 6.0–9.0 µm, width, 2.0–2.5 µm and estimated stria density: 17–18 /10 µm (n = 9).

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Striae uniseriate and each composed of one areola on both valve face and mantle ( Figs 449–452 ). Areolae transapically-elongate, elliptical or roundish near apices, occluded with branched volae, often projecting from transapical sides (rarely apical sides) of areolae ( Figs 449–450 ). Apical pore fields of foot pole positioned on mantle, and consisting of four to five observed vertical rows of three to four small round pores with granular ornamentation along the vertical margin of pores ( Figs 449–451 ). Head pole apical pore field small, ornamented with few small granules ( Figs 449–450 ). Marginal spines simple, sometimes with bifurcated tip at top, situated within striae ( Figs 452–453 ). Copulae plain and open, five observed per valve and fringed structure at margin of copula detected ( Figs 453–454 ). Valvocopula wider than remaining copulae ( Figs 453–454 ). Rimoportulae not observed ( Fig. 451 ).

Etymology: This species is dedicated to the late Dr. Hideaki Takano a distinguished Japanese diatomologist.

Holotype: BM 101908 , in the Natural History Museum , London, UK, collected by T. Watanabe, October 2005.

Isotype: Slide s0308, deposited in Dr. Sato’s collection in Faculty of Marine Bioscience , Fukui Prefectural University, Fukui, Japan

Type habitat: An unknown habitat of Iriomote Island, Okinawa, Japan. 24°12'36"N 123°25'48"E .

Observations: Although S. takanoi , looks similar to S. clavata under LM, both possess roundly cuneate head poles and narrowly cuneate foot poles; it differs from the latter by narrower valves and relatively a high stria density ( Table 6). Furthermore, the striae and interstriae in S. takanoi are flat while the interstriae in S. clavata are elevated and the striae are concave.

Figures

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 330–340. Scanning electron micrographs ofPlagiostriata baltica (type material SZCZCH1550, culture). Fig. 330. External view, showing linear valve with indistinct central sternum. Figs 331, 333. Internal views, showing the presence of simple rimoportulae (indicated by arrows). Fig. 332. Internal view, showing the absence of rimoportulae. Figs 334–335. Close up of external APFs, composed by one or two pores. Fig. 336. Close up of internal APF, composed by two pores (indicated by arrow). Fig. 337. Close up of middle part of specimen in fig. 333, showing simple rimoportula. Fig. 338. Close up of middle part of a valve, showing the absence of rimoportula. Fig. 339. Close up of centre part of a valve, showing slit-like external opening (indicated by arrow) of a rimoportula. Fig. 340. A tilted frustule, showing numerous and plain copulae.

FIGURES 341–344. Scanning electron micrographs of Pseudostaurosira elliptica (SZCZCH1249, culture,). Fig. 341. External view, showing widely-lanceolate central sternum and a single areola per stria on the valve face. Fig. 342. Internal view, showing the absence of rimoportulae and sunken internally apical pore fields. Fig. 343. Close up of girdle view, showing branched marginal spines with lateral projections (indicated by white arrowhead) associated with the base, and another projection (indicated by black arrowhead) originating from opposite side of areola beneath marginal spines. Fig. 344. Girdle view, showing the presence of mantle plaques (indicated by white arrowhead) and fringed structure (indicated by black arrowhead) observed at the margin of a copula.

FIGURES 345–348. Scanning electron micrographs of Pseudostaurosira elliptica within different populations. Fig. 345. Girdle view, showing fringed structure at margin of copula (indicated by white arrowhead) and ligulae copula (indicated by black arrowhead). Fig. 346. Internal view, showing the absence of rimoportulae and branched volae. Fig. 347. Girdle view, showing the presence of mantle plaques. Fig. 348. Girdle view, showing branched marginal spines with lateral projections associated with the base (indicated by white arrowhead) and another projections (indicated by black arrowhead) originating from opposite side of areolae beneath marginal spines. Figs 345, 348. Clone SZCZCH1248, from Resko Lake, Baltic Sea, Poland. Figs 346–347. Clone s0398, from Międzyzdroje, Baltic Sea, Poland.

FIGURES 349–354. Scanning electron micrographs of Pseudostaurosira madagascariensis (type material SZCZCH741, culture), showing variations of valve shape as the size decreases. Figs 349–350. Oblong external valves, showing wide central sternum, presence of single round areola on both valve face and mantle, and an arising rim areolar projection (indicated by arrowhead) attached to the side of each areola. Fig. 351. Elliptical external valve, showing one pore apical pore fields (indicated by arrowhead). Fig. 352. Ovate external valve. Figs 353–354. Circular valve and oval valve surface, note the presence of lateral projections associated with the base of marginal spines (arrowhead in Fig. 353) and of areolar rim projections (arrow in Fig. 354).

FIGURES 355–359. Scanning electron micrographs of Pseudostaurosira madagascariensis (type material SZCZCH741, culture). Fig. 355. Internal view, showing the absence of rimoportulae and complex volae. Fig. 356. Girdle view, showing presence of mantle plaques (indicated by arrow). Fig. 357. Girdle view, showing spatulate marginal spines associated with lateral projection at the base (indicated by arrow). Figs 358–359. Girdle views of frustules, showing plain and segmented (at least two fragments) (indicated by arrows) copulae and fringed structures (indicated by arrowheads) observed at the margin of copulae.

FIGURES 360–367. Scanning electron micrographs of Serratifera andersonii (type material SZCZCH1126 and wild material). Figs 360–363. External views, showing one transapically-elongated areola on both valve face and mantle and complex volae (indicated by arrowheads) originating from transapical sides of areolae. Figs 364–365. Internal views, showing the absence of rimoportulae. Fig. 366. Girdle view of a whole frustule, showing spatulate marginal spines and plain, open copulae. Fig. 367. Close up of specimen in fig. 366, showing fringed structure (indicated by arrowhead) observed at the margin of copula. Figs 361, 363–364. Wild material from Sandwich Harbor lagoon in Namibia. Fig. 362. Wild material from Kraalbaai, South Africa.

FIGURES 368–373. Scanning electron micrographs of Serratifera andersonii within different populations. Figs 368–370. External views, showing narrowly-linear central sternum, each stria composed by a single extensively transapically-elongate (rarely two smaller) areolae on both valve face and mantle. Fig. 371. Internal views, showing the absence of rimoportulae. Fig. 372. Girdle view, showing cingulum composed by numerous, plain copulae. Fig. 373. Close up of girdle view, showing fringed copulae (indicated by arrow). Figs 368–369, 371, 372–373. Clone SZCZP695, from Langebaan Lagoon, South Africa. Fig. 370. Clone SZCZP1059, from Langebaan Lagoon, South Africa.

FIGURES 130–183. Light micrographs, showing morphology of cleaned valves. Figs 130–137. Serratifera sp. (S. cf. andersonii), showing morphological variations within different populations. Figs 138–142. Serratifera brevis. Figs 143–147. Serratifera clavata. Figs 148–151. Serratifera corallina. Figs 152–156. Serratifera namibica. Figs 157–160. Serratifera nosybeana. Figs 161–165. Serratifera parkii. Figs 166–168. Serratifera punctata. Figs 169–171. Serratifera rhombica. Figs 172–175. Serratifera sourniae. Fig. 176. Serratifera takanoi. Figs 177–178. Serratifera sp. 2. Figs 179–183. Stauroforma rinceana. Figs 130–131. Clone SZCZM910, from Lokrum, Croatia. Figs 132–134. Clone SZCZP693, from Sea of Marmara, Turkey. Figs 135–137. Clone SZCZP696, from San Sebastian Beach, Canary Islands. Scale bar, 10 µm.

FIGURES 374–380. Scanning electron micrographs of Serratifera sp. (S. cf. andersonii) (culture). Figs 374–376. External views, showing narrowly-linear sternum and each stria composed of a single transapically-elongate areola (sometimes two smaller areolae) on both valve face and mantle. Fig. 377. Internal view, showing the absence of rimoportulae. Figs 378–379. Girdle views, showing plain and open copulae. Fig. 380. Close up of specimen in fig. 378, showing fringed structure (indicated by arrowhead) observed at the margin of copula.

FIGURES 381–384. Scanning electron micrographs of Serratifera sp. (S. cf. andersonii) within different populations. Fig. 381. Clone SZCZP696, from San Sebastian Beach in La Gomera, Canary Islands. Figs 382–384. Clone SZCZM910, from Lokrum Beach, Croatia.

FIGURES 385–392. Scanning electron micrographs of Serratifera brevis (culture HK446 and wild material). Figs 385, 388. External views, showing narrowly-linear sternum, and each stria consisted of single slightly-elliptical areola on both valve face and mantle. Fig. 386. A whole frustule, showing elongated spatulate marginal spines with bifurcated tips on top. Fig. 387. A smaller external valve, showing extensively transapically elongate areolae on valve face. Fig. 389. Internal view, showing the absence of rimoportulae. Fig. 390. Girdle view, showing open (indicated by white arrowhead) and plain copulae, and the presence of mantle plaques (indicated by black arrowhead). Fig. 391. Close up of marginal spine of a specimen, showing few small granules (indicated by arrowhead) aggregated near the base of spines. Fig. 392. Close up of copulae of a specimen, showing fringed structure (indicated by arrowhead) observed at the margin of copula. Fig. 388. Wild material from the coast of Nosy Be Island, Madagascar.

FIGURES 393–398. Scanning electron micrographs of Serratifera clavata (type material SZCZCH752, culture). Fig. 393. External view, showing narrowly-linear sternum and single row of areola on valve face. Fig. 394. Close up of head APF, ornamented with granules. Fig. 395. Close up of foot APF, consisting of five observed vertical rows of pores ornamented with projections along vertical margin of pores. Fig. 396. Internal view, showing the absence of rimoportulae. Fig. 397. Close up of specimen in fig. 396, showing areolae occluded by complex volae, projecting from transapical sides of areolae. Fig. 398. A tilted frustule, showing few pain copulae and relatively narrow cingulum.

FIGURES 399–404. Scanning electron micrographs of Serratifera corallina (type material SZCZE1544, culture). Figs 399–401. External views, showing distinctly narrow-linear sternum, and each stria composed of a single slightly transapically-elliptical areola on both valve face and mantle. Fig. 402. Internal view, showing the absence of rimoportulae and complex volae projecting from transapical side of areolae. Fig. 403. Close up of a valve, showing the presence of a lateral projection (indicated by arrowhead) associated with marginal spine extending to valve mantle. Fig. 404. Plain and open (indicated by arrowhead) copula.

FIGURES 405–412. Scanning electron micrographs of Serratifera namibica (culture SZCZP88 and wild material). Fig. 405. Girdle view of a frustule, showing one row of areolae located on mantle. Figs 406–409. External views, showing narrowly-linear sternum and striae consisting of single, sometimes double row of areola (fig. 406) on valve face and one areola on mantle. Fig. 410. Internal view, showing the absence of rimoportulae. Fig. 411. External valve of a small specimen, showing areolae occluded by complex volae, projecting from transapical side of areolae. Fig. 412. A frustule, showing plain copulae, and fringed structure (indicated by arrowhead) observed at the margin of copula. Figs 406–409, 412. Wild material from Sandwich Harbour, Namibia.

FIGURES 413–419. Scanning electron micrographs of Serratifera nosybeana (culture SZCZCH992 and wild material). Figs 413–415. External views, showing narrowly-linear sternum and each stria composed by one (sometimes two) areolae on valve face and one areola on mantle. Figs 416–417. Incomplete external valve views, showing lateral projections (indicated by arrowheads) associated with the base of marginal spines and extending towards to mantle. Fig. 418. Internal view, showing the absence of rimoportulae. Fig. 419. Plain and open copulae. Fig. 416. Wild material from the coast of Nosy Be Island, Madagascar.

FIGURES 33–38. Light micrographs, showing colonies and chloroplast information of living diatoms. Fig. 33. Serratifera parkii. Fig. 34. Serratifera punctata. Fig. 35. Serratifera rhombica. Fig. 36. Serratifera sourniae. Fig. 37. Serratifera takanoi. Fig. 38. Stauroforma rinceana. Scale bar in Fig. 35, 20 µm; all other scale bars, 10 µm.

FIGURES 420–424. Scanning electron micrographs of Serratifera parkii (culture HK507). Fig. 420. External view, showing narrowly-linear sternum and each stria constituted by single round areola on both valve face and mantle. Fig. 421. Internal view, showing the absence of rimoportulae. Fig. 422. Oblique valve, showing the swelling (indicated by arrowhead) of the base associated with marginal spines. Fig. 423. A copula, showing fringed structures (indicated by arrowhead) observed at the margin of copula. Fig. 424. Plain and open copulae.

FIGURES 425–430. Scanning electron micrographs of Serratifera punctata (culture s0386). Fig. 425. External view, showing narrowly-linear sternum and each stria composed of a single slightly-elliptical areola on both valve face and mantle. Fig. 426. Internal view, showing the absence of rimoportulae. Fig. 427. Close up of a valve, showing foot APF composed by four observed vertical rows of pores. Fig. 428. Close up of a valve, showing head APF ornamented by few particles. Fig. 429. Close up of central part of a specimen, showing 2–3 granules (indicated by arrow) aggregated around the base of marginal spines and complex volae projecting from transapical side of areolae. Fig. 430. Girdle view, showing plain, open copulae, and the presence of mantle plaques (indicated by arrow).

FIGURES 431–436. Scanning electron micrographs of Serratifera rhombica (culture s0357 and wild material). Figs 431–433. External views, showing narrowly-lanceolate or linear sternum and complex volae, projecting from transapical (sometimes apical) side of areolae. Figs 434–435. Internal views, showing the absence of rimoportulae. Fig. 436. Girdle view, showing plain copulae and much wider valvocopulae. Figs 431–432, 434. Wild material from the coast of Nosy Be Island, Madagascar.

FIGURES 437–442. Scanning electron micrographs of Serratifera sourniae (type material SZCZE517, including old and young cultures). Fig. 437. External view, showing each stria composed of a single transapically-elongated areola on the valve face, and the presence of granules around the base of marginal spines. Fig. 438. Internal view, showing the absence of rimoportulae. Fig. 439. External view of a larger cell of young culture, showing clavate outline and each stria composed by one transapically-elongated on valve face and one smaller areola on mantle. Fig. 440. A tilted valve, showing the presence of mantle plaques. Fig. 441. Girdle view, showing two smaller areola per stria on valve mantle for oval cell of old culture. Fig. 442. Numerous valves, showing the mixture of clavate and oval cells in young culture.

FIGURES 443–448. Scanning electron micrographs of Serratifera sourniae (wild material). Figs 443–447. External views, showing the variations of valve shape as the size decrease, from clavate to elliptical to oval. Fig. 448. Internal view, showing the absence of rimoportulae. Figs 443–448. Wild material from sampling location where the type material collected, Nosy Be coastal zone, Madagascar.

FIGURES 449–454. Scanning electron micrographs of Serratifera takanoi (culture s0308). Figs 449–450. External views, showing narrowly-linear sternum and each stria consisting of a single slightly transapically-elongate areola on both valve face and mantle. Fig. 451. Internal view, showing the absence of rimoportulae. Figs 452–453. Girdle views, showing plain copulae and much wider valvocopulae. Fig. 454. Close up of a girdle view, showing open (indicated by arrowhead) copula.