1,722,845 research outputs found
Monoportula P. A. Sims & D. M. Williams, nov. gen.
No full text<i>Monoportula</i> P.A.Sims & D.M.Williams nov. gen. <p> <b>Registration</b>: http://phycobank.org/103661</p> <p> Type species:— <i>Monoportula uralensis</i> (Strelnikova) P.A.Sims & D.M.Williams nov. comb.</p> <p>Frustules cylindrical, valve face circular, flat. Valve face bordered by expanded marginal ridge separating it from vertical mantle. Areolae poroid, on valve face arranged in interrupted radial and sub-radial rows extending from off-centre hyaline area from which a stout spine extends. Scattered spinules cover valve face disturbing areolar arrangement. Mantle areolae in vertical rows situated between hyaline marginal ridge and hyaline valve margin. Mantle areolae covered by network of anastomosing costae. Internally areolae sunk in rows between hyaline ribs, areolae becoming more numerous towards valve margin. One (1) rimoportula present, its external opening through stout tube expanded at its summit, internally as slit between raised lips.</p>Published as part of <i>Williams, David M., Sims, Pat A. & Witkowski, Jakub, 2023, Notes on the rare Cretaceous species Syndetocystis uralensis Strelnikova leading to the description of a new monotypic genus Monoportula P. A. Sims et D. M. Williams nov. gen., pp. 219-224 in Phytotaxa 595 (2)</i> on page 220, DOI: 10.11646/phytotaxa.595.2.8, <a href="http://zenodo.org/record/7905940">http://zenodo.org/record/7905940</a>
Juvenile unemployment programmes in England and Wales 1909-1979 A study of continuity and change in social policy
No full textSIGLEAvailable from British Library Document Supply Centre- DSC:D44299/83 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Stictodiscus manilensis D. M. Williams, P. A. Sims, & J. Witkowski 2021, sp. nov.
No full text<i>Stictodiscus manilensis</i> D.M.Williams, P.A.Sims, & J.Witkowski, <i>sp. nov.</i> <p> <b>Type:—</b> Philippines: Manila (‘ Manilla’), (holotype BM Adams F 1148 = Fig. 1, one specimen); BM 5473 (Deby, one specimen), BM 7431 (Deby, one specimen), BM 8865 (Deby, ‘ Manilla’ = Fig. 3, one specimen), BM 10652 (Deby, L.H. 826, two specimens), BM 45641 (Sturt, A578, three specimens), BM 45863 (Sturt A800, one specimen). Singapore: BM 10435 (Deby, L.H. 547, one specimen).</p> <p>Valves circular with flat valve face; mantle distinctive. Valve with small central annulus, radiating network of ‘siliceous bars’ leading to areolae, mostly biseriate. Raised siliceous thickenings surround series of radiating inner areolae, becoming more conspicuous towards valve mantle. No other surface structures.</p>Published as part of <i>Williams, David M., Sims, Pat A. & Witkowski, Jakub, 2021, Notes on the diatom collection of the Natural History Museum, London (BM) V: (a) ' Stictodiscus manillensis' nom. nud., (b) Stictodiscus pantocsekii and ' Stictodiscus pantocsekii var. minor', (c) a note on the name ' Stictodiscella'; and (d) some comments on Jósef Pantocsek's Beiträge zur Kenntnis der Fossilen Bacillarien, pp. 167-174 in Phytotaxa 507 (2)</i> on page 169, DOI: 10.11646/phytotaxa.507.2.4, <a href="http://zenodo.org/record/5425611">http://zenodo.org/record/5425611</a>
Optimal foraging strategies: Lévy walks balance searching and patch exploitation under a very broad range of conditions
No full textWhile evidence for optimal random search patterns, known as Lévy walks, in empirical movement data is mounting for a growing list of taxa spanning motile cells to humans, there is still much debate concerning the theoretical generality of Lévy walk optimisation. Here, using a new and robust simulation environment, we investigate in the most detailed study to date (24×106 simulations) the foraging and search efficiencies of 2-D Lévy walks with a range of exponents, target resource distributions and several competing models. We find strong and comprehensive support for the predictions of the Lévy flight foraging hypothesis and in particular for the optimality of inverse square distributions of move step-lengths across a much broader range of resource densities and distributions than previously realised. Further support for the evolutionary advantage of Lévy walk movement patterns is provided by an investigation into the ‘feast and famine’ effect, with Lévy foragers in heterogeneous environments experiencing fewer long ‘famines’ than other types of searchers. Therefore overall, optimal Lévy foraging results in more predictable resources in unpredictable environments
Kittonia kempii P. A. Sims & D. M. Williams 2022, sp. nov.
No full textKittonia kempii P.A.Sims & D.M.Williams sp. nov. (Figs 1–7) Type:— New Zealand, DSDP 275 1-2, 64- 5 cm, “Southeast Campbell Plateau, Position: 50°26.34’S; 176°18.99’E […] Late Cretaceous”, New Zealand; see Shipboard Scientific Party (1975) (holotype BM 101972!, one specimen = Figs 1, 2) Etymology:— Named for the late Klaus Kemp (1937–2022) who found and mounted the holotype specimen. Registration: http://phycobank.org/103337 Valve outline broadly oval with crenulated margin, two specimens found (Figs 1, 2, the holotype specimen, BM 101972; Figs 3–7, SEM miCrographs): 36 x 127μm (Figs 1, 2), 45 x 150μm (Figs 3–7). Valve faCe gently Convex with depressed central area, small hyaline valve centre lying within (Figs 5, 6). Well-developed marginal ridge separating valve from Crenulated mantle and margin, Ca. 7μm deep (Figs 4–6, arrows in Figs 5, 6). On valve faCe, towards pole, large hyaline area, stout tubular process with flattened summit at centre, angled towards valve margin, but not beyond it (second process presumed missing due to break in valve, Figs 1, 4). Ocellus-like structure on surface of subtriangular summit, Ca. 7.5μm wide with radial rows of five poroids surrounding hyaline margin (Figs 1–5, 7). Areolae poroid arranged in rows radiating from valve Centre, Ca. 7 areolae in 10μm, 7 rows in 10μm (Figs 1, 3–6). Areolae on valve face with raised rims and occluded by elaborate cribra (Figs 1, 3–6). Mantle areolae in mostly vertical rows, cribra lying flush with valve surface (Figs 5, 6). Only two specimens have been found, both lack a significant part of the central area where the rimoportulae would normally have been situated.Published as part of Sims, Pat A. & Williams, David M., 2022, Description of the new species Kittonia kempii (Biddulphiales: Kittoniaceae) with comments on Kittonia hannai P. Lefébure & Chenevière and Kittonia gigantea (Greville) De Toni, pp. 275-285 in Phytotaxa 573 (2) on page 276, DOI: 10.11646/phytotaxa.573.2.7, http://zenodo.org/record/734998
FIGURES 9–15 in Notes on the diatom collection of the Natural History Museum, London (BM) VII: An account of some original specimens of Pyrgodiscus (Bacillariophyta) with notes on Stephanogonia (Bacillariophyta)
No full textFIGURES 9–15. Pyrgodiscus armatus Kitton ex Cleve LM. 9, 10. BM 7333, d= 78 µm; cd = 26 µm; sp = 29 µm. 11, 12. BM 7334, d= 72 µm; sp = 30 µm. 13–15. BM 7334, d= 73 µm; cd = 28 µm; sp = 32 µm. Scale bars = 10 µm (Figs 9–12), 20 µm (Figs 13–15).Published as part of Williams, David M. & Sims, Pat A., 2023, Notes on the diatom collection of the Natural History Museum, London (BM) VII: An account of some original specimens of Pyrgodiscus (Bacillariophyta) with notes on Stephanogonia (Bacillariophyta), pp. 213-229 in Phytotaxa 589 (3) on page 219, DOI: 10.11646/phytotaxa.589.3.1, http://zenodo.org/record/777694
FIGURES 34, 5. Pyrgodiscus kinkeri Pantocsek. 34. Reproduced from Pantocsek 1905 in Notes on the diatom collection of the Natural History Museum, London (BM) VII: An account of some original specimens of Pyrgodiscus (Bacillariophyta) with notes on Stephanogonia (Bacillariophyta)
No full textFIGURES 34, 5. Pyrgodiscus kinkeri Pantocsek. 34. Reproduced from Pantocsek 1905: pl. 34, fig. 486. 35. Specimen from BM Adams L22, "F̧r Jutland", d = 50 µm. Scale bar = 10 µm (Fig. 35).Published as part of Williams, David M. & Sims, Pat A., 2023, Notes on the diatom collection of the Natural History Museum, London (BM) VII: An account of some original specimens of Pyrgodiscus (Bacillariophyta) with notes on Stephanogonia (Bacillariophyta), pp. 213-229 in Phytotaxa 589 (3) on page 222, DOI: 10.11646/phytotaxa.589.3.1, http://zenodo.org/record/777694
FIGURES 16–23 in Notes on the diatom collection of the Natural History Museum, London (BM) VII: An account of some original specimens of Pyrgodiscus (Bacillariophyta) with notes on Stephanogonia (Bacillariophyta)
No full textFIGURES 16–23. Pyrgodiscus armatus Kitton ex Cleve. 16–18. BM 57612, Wynne Baxter 2985, Kitton, d= 70 µm; cd = 33 µm. 19, 20. BM Adams J3765, Alfredo Truan, Sep [18]86), d= 78 µm; sp = 19 µm. 21–23. BM 46164, Sturt A1101, Kitton, d= 70 µm; cd = 28 µm; sp = 29 µm. Scale bars = 5 µm (Figs 16–18), 10 µm (Figs 19–23).Published as part of Williams, David M. & Sims, Pat A., 2023, Notes on the diatom collection of the Natural History Museum, London (BM) VII: An account of some original specimens of Pyrgodiscus (Bacillariophyta) with notes on Stephanogonia (Bacillariophyta), pp. 213-229 in Phytotaxa 589 (3) on page 220, DOI: 10.11646/phytotaxa.589.3.1, http://zenodo.org/record/777694
FIGURES 24–33. Pyrgodiscus simplex Witt. 24. Reproduced from Witt 1885 in Notes on the diatom collection of the Natural History Museum, London (BM) VII: An account of some original specimens of Pyrgodiscus (Bacillariophyta) with notes on Stephanogonia (Bacillariophyta)
No full textFIGURES 24–33. Pyrgodiscus simplex Witt. 24. Reproduced from Witt 1885: 30, pl. VI, fig. 6. 25. Reproduced from Schmidt 1886: pl. 100, fig. 13. 26–29. BM 64641 eX Barker 185, d = 54 μm, cdw = 34 μm; 30–33. BM 65879 eX FergUsOn, d = 44 μm, cdw = 31 μm. Scale bars = 5 µm (Figs 26–29), 10 µm (Figs 27–33).Published as part of Williams, David M. & Sims, Pat A., 2023, Notes on the diatom collection of the Natural History Museum, London (BM) VII: An account of some original specimens of Pyrgodiscus (Bacillariophyta) with notes on Stephanogonia (Bacillariophyta), pp. 213-229 in Phytotaxa 589 (3) on page 221, DOI: 10.11646/phytotaxa.589.3.1, http://zenodo.org/record/777694
Longinata fueloepi D. M. Williams & P. A. Sims 2023, comb. nov.
No full text<i>Longinata fueloepi</i> (Hajós) D.M.Williams & P.A.Sims <i>comb. nov.</i> <p> <b>Registration</b>: http://phycobank.org/103525</p> <p> Basionym:— <i>Eunotogramma fueloepi</i> Hajós in Hajós & Stradner 1975: 936, pl. 13, fig. 19.</p> <p>Holotype:— NEW ZEALAND, Campbell Plateau, South Pacific (Hajós & Stradner 1975: fig. 1), “ DSDP Leg 29, Sample 275-1-2, 130- 132 cm […] Upper Cretaceous” (Hajós & Stradner 1975: 935); there 5 slides in BP, of which only one is marked as ‘/1’ and is hence the holotype, BP 2800/1! = Hajós & Stradner 1975: pl. 13, fig. 19 = reproduced as our Figure 7, additional specimen in Figure 6)</p> <p> Illustrations:— Chambers 1997:291, pl.13, fig. 35 (as ‘ <i>Longinata acuta</i> ’ recorded from ‘1-23, 24, 2-21, DSDP 275’, illustrated from ‘275-2-5-115/117, Slide 1-23 A’ = BM s.n.!); Harwood 1988: [pl.] 10, fig. 19 (as 19, ‘ <i>Eunotogramma producta</i> var. <i>recta,</i> J.A.Long, Fuge & James Smith, SI-19’, a wider specimen with no evidence of any ‘pegs’ or bars, questionable, but not <i>Eunotogramma producta</i> var. <i>recta</i>).</p> <p>The description given by Hajós is brief but sufficient without having further specimens (apart from Figure 6): “Elongate valves with two asymmetrically bent ends. The longer central part is round and separated from the shorter, pointed ends by transverse costae. Surface sparsely dotted. Length, 75μ; width, 7μ in the middle, 4μ at the ends” (Hajós & Stradner 1975: 936). This can be slightly emended as follows:</p> <p>Elongate valves with two asymmetrically poles bent in same direction (Figs 6, 7). Valve centre gently swollen, tapering to shorter, pointed poles with faint transverse costae (Fig. 7). Surface punctate, no sternum visible, valve length, 75μm, width 7μm at centre, 4μm at poles.</p> <p>The recorded stratigraphic range indicated is summarised in Table 2.</p> <p> <i>Longinata fueloepi</i> appears to have one, maybe two, cross-members, but the published images in both Hajós & Stradner and Chambers are not that clear. The valve depicted in Hajós & Stradner has a kink in the valve at either end towards each pole, one third of the way down. <i>Longinata fueloepi</i> is retained as a separate species for the time being and assumed, unsatisfactorily, on its general appearance rather than any specific character, to be a species of <i>Longinata</i>.</p> <p> <i>Longinata acuta</i> is recorded from DSDP 275, 2-1; 130-132, which may be specimens of <i>Longinata fueloepi</i>.</p>Published as part of <i>Williams, David M. & Sims, Pat A., 2023, The diatom genus Longinata Hajós (Bacillariophyta): structure, relationships and distribution, pp. 209-219 in Phytotaxa 591 (3)</i> on pages 213-215, DOI: 10.11646/phytotaxa.591.3.3, <a href="http://zenodo.org/record/7800839">http://zenodo.org/record/7800839</a>
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