Ctenophora saxonica (Kütz.) D.M.Williams & Van de Vijver 2023

Williams, David M. & Vijver, Bart Van De, 2023, The diatom genus Ctenophora: A discussion on its morphology, relationships, and some species, Phytotaxa 632 (1), pp. 1-26 : 9-13

Ctenophora saxonica (Kütz.) D.M.Williams & Van de Vijver , comb. nov. ( Figs 32–52 )

Basionym: Synedra saxonica Kütz. 1844 , Die kieselschaligen Bacillarien oder Diatomeen: 68, pl. 15, fig. XIV (see Figs 32–34 )

Synonym: Synedra pulchella var. saxonica (Kütz.) Grunow in Van Heurck 1881, pl. 41, fig. 3 (see Figs 39, 40 )

Ctenophora pulchella var. saxonica (Kütz.) H.Schönf. 1907: 104 , 248, invalid

Registration: http://phycobank.org/104111 (name); http://phycobank.org/104119 (type)

TYPE:— GERMANY, “[…] in süssen und salzigen Gewässern an Conferven […]” ( Kützing 1833: 561, 1834a: 33) ; “In lacu salso ad Confervam flavescentenem [ Cladophora flavescens ] prope Rollsdorf, fl. Halens” ( Kützing 1834b [ 1833], Dec. VIII, no. 74), see https://data. nhm.ac.uk/object/44e566fe-37b5-45b6-8e47-9da9a9e79d08 ; “An C. flavescens im Salzsee bei Rollsdorf” (in Flora 17(45): 716, 1834) ; “Im salzigen See [Salzsee] bei Eisleben an Cladophora flavescens ! im Flensburger Meerbusen an Ectocarpus : Binder!” ( Kützing 1844: 68), BM 18344 !, https://data.nhm.ac.uk/object/44e566fe-37b5-45b6-8e47-9da9a9e79d08, “Salzsee” (‘Kützing 166’, see Fig. 34 , specimens Figs 35–8 ) , “Salzee | Kützing”, see https://data.nhm.ac.uk/object/ 24051470 -3546-4bb4-b01d-c5262e934f85, lectotype designated here .

Valves lanceolate, gradually tapering towards sub-capitate poles; length ca. 51–97μm, width ca. 4–6μm ( Figs 35–38 , 41 , measurements based on type specimens only). Sternum narrow, but linear, regular, slightly narrowing towards poles ( Figs 35–38 , 41–44 ). Meeting square to broadly circular-oblong shaped ‘central area’, not buttressed, simply series of infilled virgae and vimines, not extending on mantle ( Figs 42 , 47 , arrows on Fig. 47 ); ‘ghost striae’ present, faint ( Fig. 42 ). Sternum meeting and integrated with virgae, both same size; vimines reduced in size relative to virgae ( Figs 45 , 47, 49 ), appearing as mesh-work with ca. 6–8 strutted closing plate, circular with smaller pores at centre ( Figs 45 , 47, 49 ). Striae (= virgae+vimines) 13–14 (?) in 10μm, areolae ca. 20 (?) in 10μm, regularly spaced, parallel, extending onto mantle, in ca. 4 ‘rows’ ( Figs 45 , 47, 49 ). Apical pore field as ocellulimbus (sunken pore field), composed of 5 x 7 rows/ columns of pores, situated entirely on valve mantle ( Figs 45 , 47, 49 ). Spines absent. Rimoportulae simple, composed of (internally) paired lips situated on or adjacent to virga, externally occur between virgae, one at each pole, externally centred ( Figs 43–6 , arrow in Fig. 45 ). Girdle composed of two (?) open bands, VC plus one C ( Fig. 49 ); VC plain, pi with crenulated edge to fit virgae, central smooth area to fit ‘central area’; pe separated with ridge, ca. four times larger than pi ( Fig. 49 , arrows). Open portions of VC meet at pole, aligned horizontally ( Fig. 49 ).

In the protologue for Synedra saxonica, Kützing (1844: 68) refers to specimens he had previously named Exilaria fasciculata ( Kützing 1833: 561, taf. 15, fig. 40, Kützing 1834a: 33, taf. III, fig. 40; Kützing 1834b [ 1833]: Dec. VIII, no. 74, see Figs 50–52 ). In this earlier account, Kützing attributed the name Exilaria fasciculata to Greville and provided a list of synonyms ( Kützing 1833: 561, and Kützing 1834a: 32; in Kützing 1834b [ 1833]: no. 74, he cites just the two Greville publications; all of these synonyms are summarised in Table 4 ). In addition, he offered an additional sub-taxon (with no specified rank) with the name “β Frustulis longioribus ” itself with two synonyms ( Table 4 ). Inspection of all the specimens related to these names is beyond the scope of this paper but potential synonym to one side, the name Synedra saxonica can be interpreted as the given valid name for Exilaria fasciculata sensu Kützing (1834b [ 1833]: Dec. VIII, no. 74). The locality details given for Synedra saxonica in Kützing (1844) and Exilaria fasciculata sensu Kützing are (almost) identical and one might conclude they are based on the same material.

Kützing wrote “Diese Art ist sehr häufig verbreitet, in süssen und salzigen Gewässern an Conferven, auch fand ich sie an Melosira varians und orichalcea und sogar an den Frustulen der Exilaria crystallina in der Soole bei Artern, aus der Ostsee erhielt ich sie von Herrn Lieutenant v. Suhr und Herrn Pastor Frölich” ( Kützing 1833: 561, Kützing 1834a: 33). The reference to Lieutenant v. Suhr (Johannes Nicolaus von Suhr, 1792–1847) implies that Kützing may have been referring to the specimens later named ‘ Exilaria notata’ Suhr (in Kützing 1849: 47, nom. nud.). This name (‘designation’) was invalidly published as it was placed directly into synonymy with Synedra fasciculata (C.Agardh) Kütz. by Kützing (1849: 47, “ Exilaria notata Suhr Herb. ”; In Prep.; Baltic Sea [‘mer Baltique’], BM 18319, ‘Kützing 1166’). The name ‘ Exilaria notata ’ occurs only rarely in synonymy lists and is most likely derived from the entry in de Toni (1892: 662, e.g. Hustedt 1931: 218). It is unlikely anyone has studied Kützing’s “ Exilaria notata Suhr ”: the specimens are actually of a species of Tabularia (Kütz.) D.M.Williams & Round see Williams pers. obs.).

No material has yet been identified as original specimens of ‘ Exilaria fasciculata β Frustulis longioribus ’.

Synedra pulchella var. saxonica (Kütz.) Grunow (in Van Heurck 1881: pl. 41, fig. 3) is based on material from “Salzsee” (‘Kützing 166’).

Figures

FIGURES 32–40: Fig. 32, reproduction of the original drawing of Synedra saxonica (from Kützing 1844: pl. 15, fig. XIV); Fig. 33, reproduction of the original description of Synedra saxonica (from Kützing 1844: 68); Fig. 34, text from catalogue indicated sample 166; Fig. 35. packet for ‘Kützing 166’ (“Salzsee”); Figs 36–38, LM for specimens from BM 18344; Figs 39, 40, reproduction of figure for Synedra pulchella var. saxonica (Kütz.) Grunow in Van Heurck 1881: pl. 41, fig. 3, Fig. 40 the original, Fig. 39, from Van Heurck’s annotated archived copy). Scale bars = 10μm.

FIGURE 41–45: SEM micrographs, Ctenophora saxonica, Fig. 41, internal view of whole valve; Fig. 42, detail of buttressed central area; Figs 43, 44, detail of poles, for rimoportula, virgae and vimines; Fig. 45, external detail of pole with narrow sternum, areolae ornamentation, rimoportula (arrow) and ocellulimbus. Scale bars = 2μm (Figs 42, 43, 45), = 1μm (Fig. 44), = 10μm (Fig. 41).

FIGURE 46–49: SEM micrographs, Ctenophora saxonica, Fig. 46, internal view of pole, with rimoportula, ocellulimbus, and striae; Fig. 47, detail of central area from valve and girdle view (arrows); Fig. 48, whole valve in girdle view; Fig. 49, details of VC and copula at pole, plain arrows indicating open bands and dashed arrows their ornamentation. Scale bars = 1μm (Fig. 46), = 2μm (Figs 47, 49), = 10μm (Fig. 48).

FIGURES 50–52: Fig. 50, Exilaria fasciculata sensu Kütz. (1834b [1833]: Dec. VIII, no. 74) in BR; Fig. 51, reproduction of description for E. fasciculata sensu Kützing (1833: 561); Fig. 52, reproduction of drawing for E. fasciculata Kütz. (1834a: taf. 15, fig. 40). Scale bar = 10μm

Tables

TABLE 4: Synonyms Exilaria fasciculata according to Kützing (1833, 1834a); in Kützing 1834b [1833] only the two Greville publications are noted (marked here with a *).

Exilaria fasciculata	Grev. Kütz.	Scottish cryptogamic flora Algarum aquae dulcis Germanicarum	5, pl. 298, fig. 3a [no.74] Dec.VIII	1827* 1834 b [1833]
Echinella fasciculata	Jürg.	Algae Aquatica …	Dec. XI [p. 3, no. 8]	1822
	Grev.	Scottish cryptogamic flora	1, pl. 16, figs 1—3	1823*
	Hornem.	Icones plantarum sponte nascentium in Regno Daniae (Fl. Dan.)	Tab. 1957, fig. 3?	1810
Diatoma fasciculatum	C.Agardh	Conspectus Criticus Diatomacearum	p. 51	1832
Frustulia parasitica Diatoma parasiticum	C.Agardh C.Agardh	Exilaria fasciculata “β Frustulis longioribus ” Syst. Alg. Algarum aquae dulcis Germanicarum	p. 2 p. 50	1824 1832