SYSTEMATICS
Class FRAGILARIOPHYCEAE Round
Order licmophorales Round emend Cox
Family Licmophoraceae Kützing
Genus Licmophora C.A.Agardh
Licmophora repanda, n. sp. Macatugal, Tharngan &
Lobban
(
Figs. 1 and
2)
Diagnosis
Colonies on long, single-stranded mucilage stalks. Valve length 190–215 μm, width 12–18 μm, without inflated basal pole; 1–2 axial waves mid-valve. Striae 25–30 in 10 μm. Apical rimoportulae on both valves, on edge of mantle beyond sternum. Multiscissura with 23–26 slits. Valvocopula with advalvar striae throughout. The 4th pleura an apical cap plus narrow band.
Type material
Holotype: valve located at 13.6 mm E and 9.4 mm S of the reference mark on slide 2459, GU44BV-1 deposited at ANSP Diatom Herbarium, accession # 20082. Sample collected by C. Lobban and M. Schefter, 28 Oct. 2017, GabGab reef, Apra Harbor, Guam, 13° 26′ 33.63“ N, 144° 38’ 34.25” E, Halimeda with fringe of diatoms from 10 m depth (not in farmer-fish territory). Fig. 1c–e.
Etymology
Latin, repanda = having a slightly uneven and waved margin.
Additional materials examined
Observed frequently, especially as a fringe on green calcified seaweeds in the genus Halimeda at 10–15 m along the GabGab fore-reef. Samples: GU44AL-2A (black sponge with diatom fringe, 20 Nov 2011), GU44AR-3 (Halimeda fringe, 12 Aug. 2012), GU44AS-1 and − 3 (Halimeda fringe, 27 Aug. 2012), GU44BN-3 (Plectroglyphidodon farmer-fish territory, 8 Sep. 2015), GU76A-2 (Vecky’s Reef, Apra Harbor; Halimeda in Plectroglyphidodon territory, 27 July 2017), GU68C-5 (Western Shoals, Apra Harbor, Halimeda in Plectroglyphidodon territory, 29 May 2017), and others.
Morphology
Samples were available from several collection times from GabGab and several different locations in and near Apra Harbor. Characteristics of valves and girdle bands from different samples were alike. Frustules were attached by long, single-stranded stalks. Plastids were elongated discs (Fig. 1b).
Valves (Fig. 1) were 190–215 μm long, 17 μm wide at apex gradually tapering from apex to base, basal pole not inflated (Fig. 1a, d–f, h, i). Multiscissura with 23–26 slits (Fig. 1h, i). Striae 25–30 in 10 μm, areolae 12–14 in 10 μm, fairly uniform (Fig. 1c, j). Three rimoportulae, all ca. 0.8 μm across inside (Fig. 1i, k), the two apical ones at the end of the sternum on the edge of the valve face, oriented along one of the radiating striae; external opening hard to distinguish (Fig. 1j). Basal pole width increased from 4.8 μm at end of multiscissura to 5.2 μm 10 μm from base, and continued gradually increasing towards apex. One to two waves were usually present (Fig. 1a, e–g), but we observed two populations (GU44AL-2A and GU44AR-3) that were straight but proved to be otherwise indistinguishable from L. repanda.
Valvocopula (Fig. 2a–e) with a narrow septum (0.9–1.3 μm wide) (Fig. 2a), open ends tapering abruptly and symmetrically (Fig. 2e), closed end with broad ligule on abvalvar side (shown as unnamed species in Lobban et al. 2018, Fig. 2). Copular striae 36–37 in 10 μm, apparently rimate on both sides of the midrib all the way to the open ends, where rimae becomes shorter. Midrib straight, asymmetrical, transition gradual: close to abvalvar margin near the apex but starting to move toward advalvar margin within 10 μm, completed ca. one third along the band.
4th pleura (Figs. 1l and 2f–h) comprised a shallow apical cap and a narrow band with one or two rows of pores and no midrib (see also apical view of whole mount of this species, then unnamed, in Lobban et al. 2018, Fig. 2).
The 1st–3rd pleurae did not have features that were useful in distinguishing among the species described here and in Lobban et al. (2018). However, the taxonomically useful pleura characters have not yet been established for the genus, so they may be useful in comparison with other species. We thus include brief descriptions here and have put the three associated plates in Additional files 1, 2 and 3.
1st pleura (Additional file 1A–D). Band bluntly rounded to tapered at open ends and closed end narrow with two rows of pores around the basal pole. Striae rimate; midrib symmetrical except tending toward abvalvar at open tips, wider in the middle and lower portions (ca. 800 vs 400 nm), then narrowing as band narrows toward basal pole (closed end).
2nd pleura (Additional file 1E–H): Band with broad ligules on both sides at the apex the advalvar ligule more clearly defined and raised into a narrow ligule with an apparently wider margin, though in apical view of whole mount there appears to be a narrow ligule on both margins. Striae rimate except around the apex, abvalvar ends of striae uneven across the ligule. Midrib symmetrical except strongly deflected toward the advalvar side around apex (Fig. 1k). Midrib narrow around apex, broadest about half-way along the band.
3rd pleura (Additional file 1I–M): Band with broad, blunt open tips. Asymmetrical, midrib toward the advalvar side. Abvalvar striae porate to nearly half the distance from the open end, then rimate; advalvar striae rimate throughout.
Licmophora undulata, n. sp. Macatugal, Tharngan & Lobban
(
Figs. 3,
4 and
5)
Diagnosis
Cells on mucilage pads. Valve length 150–200 μm, width 10–15 μm, inflated basal pole. Striae 30–35 in 10 μm. Areolae significantly elongated along sternum, about twice as long as those away from sternum. Apical rimoportula only on front valve, at end of sternum on edge of mantle. Multiscissura with 20–24 slits. Valvocopula with advalvar striae ending halfway along band. The 4th pleura an apical cap with narrow band.
Type material
Holotype: valve located at 16.4 mm E and 7.5 mm S of the reference point on GU44O-F slide 507, deposited at ANSP Diatom Herbarium, accession # 20083. Sample collected by C. Lobban and M. Schefter, 3 Aug. 2008, GabGab reef, Apra Harbor, Guam, 13° 26′ 33.63“ N, 144° 38’ 34.25” E, coarse red algal turf on submerged scrap metal in Stegastes nigricans farmer-fish territory in the Navy swimming pool, ca. 3 m deep; sample noted as being heavily dominated by the large centric diatom Stictocyclus stictodiscus. Fig. 4c-e.
Etymology
Latin, undulata = wavy.
Additional materials examined
GU44P-B (S. nigricans turf on shallow rock, 1 Sep. 2008), GU44P-E (Halimeda with fringe of diatoms, 1 Sep. 2008).
Morphology
Cells attached individually or in small groups by mucilage pads with oval plastids (Fig. 4b). Valve length ranged from 150 to 200 μm and 10–15 μm wide at the apex, gradually tapered from apex to base with an inflated basal pole (Figs. 3 and 4a, c, g, f, j, k). Multiscissura with 20–24 slits (Fig. 4j, k). Striae 30–35 in 10 μm; areolae markedly long along the sternum (Fig. 4h), ca. 7x longer than wide (where wide is in apical direction). Areolae 10–12 in 10 μm. Apical rimoportula at end of sternum on the edge of the valve face, small, apically oriented. Basal rimoportula further from pole (2 striae) than in L. repanda (Fig. 4j). Basal pole width at apex of multiscissura ca. 4.2 μm, but 10 μm from base ca. 2.5, whereas in L. repanda, width of pole was slightly wider and got continually wider. In L. undulata, there was a ± parallel section until the first wave, then gradually wider.
Valvocopula (Fig. 5a–e) with narrow septum (ca. 1.25 μm) (Fig. 5a), advalvar striae ended halfway along the band (Fig. 5c), leaving a wide margin and midrib on advalvar side, alongside the abvalvar row of slits. Midrib asymmetrical throughout, deflected toward the abvalvar side around the apex (Fig. 5b). The midrib did not get wider but became continuous with the abvalvar margin.
4th Pleura (Fig. 5f–h). Band with shallow apical cap and a band that tapered toward open end. A single row of rimate striae along the band.
1st pleura (Additional file 2A–E): Band semi-blunt rounded to tapered at open ends, closed end narrow with a single row (10–15 pores) around the basal pole (Additional file 2E). Striae rimate throughout. Symmetrical, 1.8 μm wide near the open ends. Midrib widest in the middle.
2nd pleura (Additional file 2F–I): Almost symmetrical band that tapers to open end. Striae rimate throughout. Striae on one side discontinued about 7 μm from the basal pole. The midrib was slightly wider around the apex.
3rd pleura (Additional file 2J–M): asymmetrical with a wide blunt open end, porate on one side of midrib near apex and rimate throughout on the other. Valves not observed in whole mount girdle view, so not known which side was advalvar.
Licmophora joymaciae, n. sp. Macatugal & Lobban
(
Figs. 6 and
7)
Diagnosis
Colonies on long single-stranded mucilage stalks. Valves length 300–400 μm, width 17–20 μm at apical pole. Stria density different toward basal and apical poles, 26–28, 30–35 respectively. Areolae fairly uniform, transapically rectangular, long side 2x short side. Three rimoportulae, the apical rimoportulae on edge of valve face beyond sternum. Multiscissura with ca. 26–29 slits. Valvocopula with advalvar striae ending halfway along band. The 4th pleura a relatively large apical cap with narrow band.
Type material
Holotype: valve located at 19.8 mm E and 9.2 mm S of mark on GU68B-5 slide 2046, deposited at ANSP Diatom Herbarium, accession # 20084. Sample collected by C. Lobban and M. Schefter, 3 Apr. 2016, Western Shoals, Apra Harbor, Guam, 13° 27′ 3.24″ N, 144° 39′ 20.16″ E, dense fringe of Licmophora spp. on Halimeda from S. nigricans territory, ca. 7 m deep.
Etymology
Named for the senior author’s mother, Joy Macatugal, who encouraged the author to pursue this undergraduate research opportunity.
Morphology
Colonies on long single-stranded mucilage stalks; frustules narrowly cuneate in both valve and girdle view. Plastids numerous small oval plates.
Valves (Fig. 6) 300–400 μm long, 17–20 μm wide at apex gradually tapering from apex to base (Fig. 6a, e, f), basal pole not inflated (6d, j, k). Stria density 30–35 in 10 μm at the apex and 26–28 at the base, pattern of areolae uniform (Fig. 6c, h, i). Apical rimoportulae on edge of valve face beyond the sternum, oriented more or less in the apical plane along one of the radiating striae (Fig. 6h, i); Fig. 6j and the relative sizes of internal and external openings suggest the rimoportula is a funnel about 1.5 μm across inside. Basal rimoportula at end of sternum, on the right, also about 1.5 μm wide. Multiscissura with 26–29 slits (Fig. 6j, k).
Valvocopula (Fig. 7a–e) with a narrow, solid septum (2.75 μm wide) (Fig. 7a). Copular striae 41–42 in 10 μm. Midrib gradually moved from abvalavar to advalvar margin (Fig. 7a), eliminating the advalvar striae about halfway along the band (Fig. 7d, e).
4th Pleura (Figs. 6g and 7f–h): Band comprised a relatively large apical cap and a narrow band with initially two rows of rimae, the abaxial one soon ending (Fig. 6g).
1st Pleura (Fig. 6g, Additional file 3A–E): Band sharply rounded to tapered at open ends, closed end narrow with two rows of pores around the basal pole. Midrib symmetrical throughout band, widening towards the closed end.
2nd Pleura (6g, Additional file 3F–K): Symmetrical band. Striae of rimae that end on both sides about 10 μm from open end.
3rd Pleura (6g, Additional file 3L–P): Band with blunt open tips that taper toward basal pole. More or less symmetrical, midrib toward the advalvar side. Striae on both sides porate to about 40 μm from open ends, then rimate throughout rest of band. Midrib wider in the middle part of the band.