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Mallomonas spinosa Gusev 2012, sp. nov.
No full text<i>Mallomonas spinosa</i> Gusev, <i>sp. nov.</i> (Figs 2–11) <p>Cells ellipsoidal, approximately 20 × 11 µm, covered by scales with spines (Fig. 2). Apical scales lack spines (Fig. 4). Body scales oval, 4.5–5.6 × 2.7–3.6 µm. Shield with densely and regularly spaced papillae (Figs. 6–11). V-rib conspicuous, acute to slightly rounded. Distal ends of arms of V-rib curve and become continuous with anterior submarginal ribs. Anterior submarginal rib forms a prominent asymmetrically placed stout spine with four edges (Fig. 7). Anterior flange with a row of papillae (Fig. 8). Posterior flange smooth with depression containing pores on the base plate (Figs. 5–11). Posterior rim wide and smooth in SEM view. Bristles unknown. Cysts not observed.</p> <p> <b>Type:</b> — VIETNAM. Dong Nai Province: unnamed temporary forest pool in Cat Tien National Park, 11°24’26” N, 107°24’48” E, 23 November 2010, <i>E.S. Gusev s.n.</i> SEM stub CT40/2010 (holotype IBIW!, see Fig. 2), sample CT40 23.11.2010, in collection E.S. Gusev.</p> <p> <b>Distribution and habitat:—</b> This species was found in the type locality and two other water bodies in Khanh Hoa province in Vietnam.</p> <p> <b>Etymology:—</b> The epithet “spinosa” refers to the whole cell being covered by scales with stout spines.</p>Published as part of <i>Gusev, Evgeniy S., 2012, A new species of the genus Mallomonas (Synurophyceae), Mallomonas spinosa sp. nov., from Vietnam, pp. 1-5 in Phytotaxa 66 (1)</i> on pages 2-3, DOI: 10.11646/phytotaxa.66.1.1, <a href="http://zenodo.org/record/5065820">http://zenodo.org/record/5065820</a>
Mallomonas acidophila Gusev & Shkurina & Huan 2023
No full text<i>Mallomonas acidophila</i> Gusev & Shkurina (Figures 2–22) <p>Cell dimensions unknown. Scales are tripartite, oval, 4.3–5.6 × 2.4–3.5 μm, with a dome, a V-rib, anterior submarginal ribs, a shield, anterior and posterior flanges, and a posterior rim. The base plate is devoid of pores. The dome is recessed from the distal margin, shallow, elongated or narrowly elliptical, sometimes curved. The dome can be placed perpendicular to the longitudinal axis of the scale or at an angle to this axis. It is covered with papillae. The shield is ornamented with numerous unevenly distributed papillae. The V-rib is rounded, with a broad and U-shaped base, slightly hooded, with arms that are continuous with the anterior submarginal ribs. The anterior submarginal ribs are of equal length if the dome is perpendicular to the longitudinal axis or unequal if the dome is located at an angle to the longitudinal axis. The anterior flanges are narrow. The posterior rim is narrow and encircles one-third to one-half of the scale perimeter. The posterior flange is wide and smooth. It lacks a secondary siliceous layer in a narrow area along the posterior rim and is strongly thickened in the area adjacent to the V-rib. Bristles are 2.4–7.2 μm long, straight, with a hook-shaped flattened foot, turned at an angle of approximately 45 degrees or less relative to the shaft, gutter-shaped bristle shaft, and a flattened and bifurcated apical tip with a wide, rounded middle part. Cysts are unknown.</p> <p> <b>Holotype (</b> designated here <b>)</b>:— Portion of a single gathering of cells on SEM stub number TTH55 deposited at the Herbarium of the Papanin Institute for Biology of Inland Waters RAS, Borok (IBIW). Material from unnamed reservoir in Thua Thien Hue Province, Vietnam. Sample collected 28 October 2022 by E. Gusev. Figure 3 is a representative scale from the type specimen.</p> <p>Type locality:— Vietnam: unnamed swamp water body in Thua Thien Hue Province, Phong Điễn District, Latitude / Longitude: N16°39.777’ E107°21.905’.</p> <p> <b>Etymology</b>:—The epithet “acidophila” refers to the fact that this species is found at low pH values.</p> <p> <b>Distribution:</b> —To date, <i>M</i>. <i>acidophila</i> has been observed in two neighbouring localities in Vietnam. In addition to the type locality, it has been found in another unnamed water body (Latitude/Longitude: N16°39.694’ E107°21.746’).</p> <p> <b>Observations:</b> — <i>Mallomonas acidophila</i> was found in acidic conditions (pH 5.0–5.2), with low specific conductance values ranged from 17 to 18 μS cm-1, temperature 26 ºC, total phosphorus concentrations 68–133 μL-1, Kjeldahl nitrogen concentrations 406–508 μL-1.</p>Published as part of <i>Gusev, Evgeniy, Shkurina, Nataliya & Huan, Phan Trong, 2023, Mallomonas acidophila sp. nov. (Synurales, Chrysophyceae) - a new species from the tropics with morphological features of fossil taxa, pp. 157-166 in Phytotaxa 620 (2)</i> on page 159, DOI: 10.11646/phytotaxa.620.2.3, <a href="http://zenodo.org/record/10022374">http://zenodo.org/record/10022374</a>
3D Structure of the Gusev Crater region
No full textGusev Crater lies within the Aeolis Quadrangle of Mars at the boundary between the northern lowlands and southern highlands. The ancient valley Ma'adim Vallis dissects the highlands south of Gusev Crater and is thought to have fed the crater with sediments.High Resolution Stereo Camera data and Digital Elevation Models were used to construct a geologic-geomorphic map (173.5-178.5° E, 10-18° S) and cross-sections, complemented by data from Mars Orbiter Camera, Mars Orbiter Laser Altimeter and Thermal Emission Imaging System.Three geologic domains are recognised: the highlands in the south, Gusev Crater and lowlands in the north. Twelve units are mapped, with thicknesses ranging from hundred meters to several kilometres. Thicknesses of units, and their bedding attitude, are estimated combining the geologic map and topographic information. Relative ages are determined from crater counts, ranging from Early Noachian for highland units to Middle Amazonian for units in Gusev Crater and in lowlands. Episodes of intense geologic activity (deposition, volcanism, deformation) occur at around 4.0. Ga, 3.7. Ga, and 3.5. Ga. Comparing the geometry of the Gusev Crater with similar sized, filled and un-filled, Martian craters, suggests that the Columbia Hills are relics of the original central peak of Gusev Crater. © 2010 Elsevier B.V
Mallomonas loricata Gusev, Shkurina & Kulikovskiy 2021, sp. nov.
No full text<i>Mallomonas loricata</i> Gusev, Shkurina & Kulikovskiy <i>sp. nov.</i> <p>(figs 2–13)</p> <p>Scales are obovate, 5.7–6.8 × 3.8–4.4 μm in size. A wide posterior rim encircles one-half to two-thirds of the scale perimeter (figs 2–4). Evenly spaced small base-plate pores cover the scale surface and are often more widely spaced across the distal part (figs 5–6). One large, rimmed pore is situated in the posterior region and is surrounded by a cluster of minute pores. A thick secondary siliceous layer with internal reticulation covers almost the entire surface of the scales, excluding a small, rounded area surrounding the large, rimmed pore (figs 2–4 and 8–10). Bristles are 12–14 μm long, smooth, slightly curved, and possess a serrated distal tip; the bristle shaft is tubular, with a longitudinal slit (figs 7, 12–13). Cysts unknown.</p> <p> <b>Holotype</b>:—Portion of a single gathering of cells on SEM stub no. BD25 (holotype designated here in fig. 2) deposited at the Herbarium, Papanin Institute for Biology of Inland Waters RAS, Borok (IBIW). Material from My Binh Reservoir, Binh Dinh Province, VIETNAM, collected by E.S. Gusev on the 23 d of May, 2018. Figure 2 illustrates a representative scale from the specimen.</p> <p> <b>Type locality:</b> — VIETNAM: Binh Dinh Province, My Binh Reservoir, Latitude / Longitude: 14°33.869’ N, 108°59.427’ E.</p> <p> <b>Epithet</b>:—The epithet refers to the thick scales, forming armor, surrounding the cell.</p> <p> <b>Distribution</b>:—In addition to the type locality, this species has been observed from the other regions of Vietnam: Binh Dinh, Binh Thuan, Dak Lak, Khanh Hoa, Phu Yen, Quang Tri, and Thua Thien Hue provinces, and in Hanoi (Table 1). Also, scales of this species were reported from Singapore and Malaysia under the name <i>M. matvienkoae</i> (Neustupa & Řezáčová 2007: 225, fig 7). <i>Mallomonas loricata</i> was found in a wide range of environmental parameters including pH (6.1–8.3), specific conductance (32–287 µS cm-1) and temperature (28–36 ºC) (Table 1).</p>Published as part of <i>Gusev, Evgeniy, Shkurina, Nataliya & Kulikovskiy, Maxim, 2021, Mallomonas loricata sp. nov. (Synurales, Chrysophyceae), a new tropical species from section Planae, pp. 225-233 in Phytotaxa 500 (3)</i> on page 229, DOI: 10.11646/phytotaxa.500.3.6, <a href="http://zenodo.org/record/5424594">http://zenodo.org/record/5424594</a>
Non-uniqueness and prescribed energy for the continuity equation
Get PDFIn this note, we provide new non-uniqueness examples for the continuity equation by constructing infinitely many weak solutions with prescribed energy
Size and duration of the high-frequency radiator in the source of the 2004 December 26 Sumatra earthquake
No full textWe recover the gross space–time characteristics of high-frequency (HF) radiator of the great Sumatra-Andaman islands earthquake of 2004 December 26 (M w = 9.1–9.3) using the time histories of the power of radiated HF P waves. To determine these time histories we process teleseismic P waves at 36 BB stations, using, in sequence: (1) bandpass filtering (four bands: 0.4–1.2, 1.2–2, 2–3 and 3–4 Hz); (2) squaring wave amplitudes, making ‘power signals’ for each band and (3) stripping the propagation-related distortion (P coda, etc.) from the power signal and thus recovering source time function for HF power. In step (3) we employ an inverse filter constructed from an empirical Green’s function, which is estimated as the power signal from an aftershock. For each ray we thus obtain signals with relatively well-defined end and no coda. From these signals we extract: total duration (joint estimate for all four bands) and temporal centroid of signal power for each band. Through linear inversion, the set of duration values for a set of rays delivers estimates of the rupture stopping point and stopping time. Similarly, the set of temporal centroids can be inverted to obtain the position of the space– time centroid of HF energy radiator. The quality of inversion for centroid is acceptable for lower-frequency bands but deteriorates for higher-frequency bands where only a fraction of stations provide useful data. For the source length and duration the following joint estimates were obtained: 1241 ± 224 km, 550 ± 10 s. The estimated stopping point position corresponds to the northern extremity of the aftershock zone. Spatial HF radiation centroids are located at distances 350–700 km from the epicentre, in a systematic way: the higher is the frequency, the farther is the centroid from the epicentre. Average rupture propagation velocity is estimated as 2.25 km s–1
Mallomonas pseudocorymbosa Gusev, Martynenko & Shkurina 2023, sp. nov.
No full text<i>Mallomonas pseudocorymbosa</i> Gusev, Martynenko & Shkurina <i>sp. nov.</i> (Figure 2). <p> <b>Diagnosis:</b> Scales are oval, tripartite, 4.8–5.9 × 3.3–4.3 µm in size, with or without a dome. The dome is large, rounded, oval or asymmetrical. The V-rib is acute, slightly hooded and its arms continuous with the anterior submarginal ribs. Anterior submarginal ribs are well developed. The anterior flange is wide, especially on the domeless scales, with a row of base plate pores at each side. The posterior flange is wide, with numerous base plate pores distributed on the surface. The shield and posterior flange have a secondary siliceous layer forming circular or elongated oval meshes unevenly distributed on the surface often with areas without development of the secondary layer. Numerous pores are placed on the basal plate. The posterior upturned rim is narrow, with inner struts visible only on TEM images, encircles less than a half of the scale perimeter. Bristles are 13–25 μm long, curved and serrated at the distal half. Shorter bristles have a bifurcated tip with a long terminal spine, and longer bristles have a prolonged thread-like terminal part. Cysts unknown.</p> <p> <i>Holotype (here designated):</i> Portion of a single gathering of cells on SEM stub No. CD8 deposited at the Herbarium, Papanin Institute for Biology of Inland Waters RAS, Borok (IBIW). Material from Ahn Hai Lake, Côn SƠn Island, Bà Rịa-Vũng Tàu Province, Vietnam. Figure 2C illustrates a representative scale from the holotype specimen.</p> <p> <i>Type Locality:</i> Ahn Hai Lake, Côn SƠn Island, Bà Rịa-Vũng Tàu Province, Vietnam. Latitude / Longitude: 8° 40.645’ N 106° 35.867’ E. At the time of collection, the pH was 6.5, temperature 30 °C, and specific conductance 201 µS cm-1. Material was collected by E.S. Gusev and Nguyen-Ngoc Lam on 3 May 2015.</p> <p> <i>Etymology:</i> The species name is derived from the fact that its scales resemble, and could be confused with, those of <i>Mallomonas corymbosa</i>.</p> <p> <i>Distribution:</i> This species has been observed in 17 localities in 13 provinces of Vietnam (Table 1). Scales of this species were also observed in Bangladesh (Takahashi & Hayakawa 1979), China (Wei &Yuan 2001, 2013; Wei <i>et al</i>. 2014), Brazil (Franceschini & Couté 1991)and South Africa (Janse van Vuuren <i>et al</i>. 2022). <i>Mallomonas pseudocorymbosa</i> was found at wide ranges of environmental parameters: pH from 6.1 to 8.6, specific conductance from 62 to 2370 µS cm-1, chlorophyll <i>a</i> values from 5 to 76 µg l –1, and temperature 17–39 ºC (Table 1).</p>Published as part of <i>Gusev, Evgeniy, Martynenko, Nikita, Shkurina, Nataliya & Dien, Tran Duc, 2023, Description of a new species of the genus Mallomonas from section Mallomonas (Synurales, Chrysophyceae) in the tropics, pp. 59-68 in Phytotaxa 618 (1)</i> on page 62, DOI: 10.11646/phytotaxa.618.1.5, <a href="http://zenodo.org/record/8389917">http://zenodo.org/record/8389917</a>
Mineralogy at Gusev crater from the Mössbauer spectrometer on the Spirit rover
No full textMössbauer spectra measured on Mars by the Spirit rover during the primary mission are characterized by two ferrous iron doublets (olivine and probably pyroxene) and a ferric iron doublet (tentatively associated to nanophase ferric iron oxide). Two sextets resulting from nonstoichiometric magnetite are also present, except for a coating on the rockMazatzal, where a hematite-like sextet is present. Greater proportions of ferric-bearing phases are associated with undisturbed soils and rock surfaces as compared to fresh rocksurfaces exposed by grinding. The ubiquitous presence of olivine in soil suggests that physical rather than chemical weathering processes currently dominate at Gusev crater
Crater gradation in Gusev crater and Meridiani Planum, Mars
Get PDFThe Mars Exploration Rovers investigated numerous craters in Gusev crater and Meridiani Planum during the first ∼400 sols of their missions. Craters vary in size and preservation state but are mostly due to secondary impacts at Gusev and primary impacts at Meridiani. Craters at both locations are modified primarily by eolian erosion and infilling and lack evidence for modification by aqueous processes. Effects of gradation on crater form are dependent on size, local lithology, slopes, and availability of mobile sediments. At Gusev, impacts into basaltic rubble create shallow craters and ejecta composed of resistant rocks. Ejecta initially experience eolian stripping, which becomes weathering-limited as lags develop on ejecta surfaces and sediments are trapped within craters. Subsequent eolian gradation depends on the slow production of fines by weathering and impacts and is accompanied by minor mass wasting. At Meridiani the sulfate-rich bedrock is more susceptible to eolian erosion, and exposed crater rims, walls, and ejecta are eroded, while lower interiors and low-relief surfaces are increasingly infilled and buried by mostly basaltic sediments. Eolian processes outpace early mass wasting, often produce meters of erosion, and mantle some surfaces. Some small craters were likely completely eroded/buried. Craters \u3e100 m in diameter on the Hesperian-aged floor of Gusev are generally more pristine than on the Amazonian-aged Meridiani plains. This conclusion contradicts interpretations from orbital views, which do not readily distinguish crater gradation state at Meridiani and reveal apparently subdued crater forms at Gusev that may suggest more gradation than has occurred
Geissleria baicalosimilis Kulikovskiy, Gusev, Andreeva & Annenkova 2014, sp. nov.
No full textGeissleria baicalosimilis Kulikovskiy, Gusev, Andreeva & Annenkova sp. nov. Figs 2–19 LM, live cells (12–14): One large chloroplast with two lobes. LM (Figs 2–11): Valves elliptic, ends protracted and capitate. Length 14.0–15.6 µm, breadth 5–6 µm. Raphe filiform, axial area narrow, central area small and irregularly bordered. One isolated pore near the middle of central nodule, on primary part of valve. Striae weakly radiate, 16–17 in 10 µm. SEM, external view (Figs 15, 16, 18): The raphe slit is straight without visible sternum. One isolated pore near central nodule. Central raphe ends straight. Terminal raphe ends deflected towards the secondary side of valve and continue onto mantle. Striae uniseriate throughout. Areolae present as short slits, 65–70 in 10 µm of stria. Annulus presents as two rows of larger then in stria areolae, apically elongated. In every row from 3 to 4 apically elongated areolae are present. SEM, internal view (Figs 17, 19): Raphe slit lying in internal sternum.Central raphe endings straight, terminal ends terminate in small helictoglossae. Elongated subpolar areolae (annulus) with warty outgrowths. Internally no hymens or occlusions are observed on the areolae. Type:— RUSSIA: Lake Baikal, pool near Bay, fouling on tree submerged in water, at 8 km from Enkhaluk village, N 52027.042 E 106053.215, 14.07.2011, leg. M. Kulikovskiy (IBIW slide no. 18589/B088, holotype designated here (= Fig. 3)), COLO slide 18589/B088p is isotype. Etymology: —Epithet refers to the similarity with Geissleria similis (Krasske) Lange-Bertalot & Metzeltin (1996: 68) and the type locality. Observations: This species is very similar to G. similis. However it is easy distinguish this species by both quantitative and qualitative features. G. baicalosimilis sp. nov. has finer striae in 10 µm (16–17, not 15) and more finer areolae in 10 µm of stria (65–70, not 60) than in G. similis. Striae in the central area of G. similis are long and almost reach central nodule. Additionally, only two elongate pores (one in each stria) at the end of valve present in G. similis. G. baicalosimilis sp. nov. possesses six or more elongated pores.Published as part of Kulikovskiy, Maxim, Gusev, Evgeniy, Andreeva, Svetlana & Annenkova, Natalia, 2014, Phylogenetic position of the diatom genus Geissleria Lange-Bertalot & Metzeltin and description of two new species from Siberian mountain lakes, pp. 249-260 in Phytotaxa 177 (5) on page 252, DOI: 10.11646/phytotaxa.177.5.1, http://zenodo.org/record/514488
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