Cymbopleura huohuaensis sp. nov. (Cymbellaceae; Bacillariophyceae), a new species from Sichuan Province, China

Cymbopleura huohuaensis sp. nov. is identified as a new species and described from stone surfaces in Huohua Lake, Sichuan Province, China. A detailed morphological description of the new species is presented, based on light and scanning electron microscopy. Cymbopleura huohuaensis sp. nov. has the features that assign it to the genus Cymbopleura, including the raphe with dorsally deflected terminal fissures and ventrally curved central raphe ends, punctate-lineate striae, and the absence of apical pore fields and stigmata. There are five features that easily distinguish the new species from the other similar taxa within the genus: 1) linear-lanceolate central area, 2) mostly slit-like, partly T-shaped, V-shaped or irregularly-shaped areolae, 3) strongly reverse-lateral raphe, 4) slightly truncate to obtusely rounded ends and 5) the highest density of areolae (30–50 in 10 μm). Among the currently described species of Cymbopleura, the new species is in general most similar to C. subaequalis var. pertruncata in valve shape and possessing a reverse-lateral raphe, but is easily distinguished from that taxon by the size and shape of valve, shape of central area, and the degree of asymmetry about the apical axis and its notable lack of an intermissio. This species might be better placed in the C. austriaca group due to its lack of an intermissio. These findings increase our understanding the morphology and distribution of the genus Cymbopleura in China.

Cryo-EM structure of the NLRP3 decamer bound to the cytokine release inhibitory drug CRID3

NLRP3 is an intracellular sensor protein whose activation by a broad spectrum of exogenous and endogenous stimuli leads to inflammasome formation and pyroptosis. The mechanisms leading to NLRP3 activation and the way how antagonistic small molecules function remain poorly understood. Here we report the cryo-electron microscopy structures of full-length NLRP3 in its native form and complexed with the inhibitor CRID3 (also named MCC950). Inactive, ADP-bound NLRP3 is a decamer composed of homodimers of intertwined LRR domains that assemble back-to-back as pentamers with the NACHT domain located at the apical axis of this spherical structure. Molecular contacts between the concave sites of two opposing LRRs are mediated by an acidic loop extending from an LRR transition segment. Binding of CRID3 significantly stabilizes the NACHT and LRR domains relative to each other, allowing structural resolution of 3.9-4.2 Ang. CRID3 binds into a cleft, connecting four subdomains of the NACHT with the transition LRR. Its central sulfonylurea group interacts with the Walker A motif of the NLRP3 nucleotide-binding domain and is sandwiched between two arginines from opposing sites, explaining the specificity of NLRP3 for this chemical entity. With the determination of the binding site of this lead therapeutic, specific targeting of NLRP3 for the treatment of autoinflammatory and autoimmune diseases and rational drug optimization are within reach.

Oricymba gongshanensis sp. nov. (Cymbellaceae; Bacillariophyceae), a new species from southwest China

Oricymba gongshanensis sp. nov. is identified as a new cymbelloid species, and described from a rock wall in Gongshan County, Yunnan Province, China. A detailed morphological description of the new species is presented, based on light and scanning electron microscopy. O. gongshanensis sp. nov. has the features that assign it to the genus Oricymba, including a thickened ridge positioned around the margin of the valve, presence of pore fields at the apices, a stigma with a single opening externally and two openings internally together with external distal raphe ends deflected dorsally. There are three features that easily distinguish the new species from all others in the genus. They include: 1) valves that are weakly asymmetrical about the apical axis, 2) presence of mostly biseriate striae and 3) areolae that are round to elliptical in shape. Among the currently described species of Oricymba, the new species is most similar to O. tianmuensis in valve shape, but is easily distinguished by the degree of asymmetry about the apical axis and presence of biseriate striae. These findings increase our understanding the morphology and distribution of the genus Oricymba in China.

Four new species of monoraphid diatoms from Western Sichuan Plateau in China

Four new monoraphid diatoms are examined and described from a high-altitude (> 3000 m) region of western Sichuan, China. The descriptions are based on light and scanning electron microscopy observations, and the four new species are compared with similar taxa worldwide. Achnanthidium sichuanense sp. nov. has small, lanceolate-elliptical valves, with rounded apices. The outline and central area differentiate it from similar species. The unique characteristic of Eucocconeis undulatum sp. nov. is that it has valves that are undulate along the apical axis, forming an “H”-shaped area on both raphe and rapheless valves as seen in light microscope (LM). Platessa mugecuonesis sp. nov. and Platessa lanceolata sp. nov. are two small species, whose valve outlines and central areas make them different from other species in this genus. A. sichuanense sp. nov. and E. undulatum sp. nov. are discussed in terms of the relationship between “Achnanthidium & Psammothidium” and “Eucocconeis & Psammothidium”, as these genera are difficult to separate according to morphological characteristics.

Gomphonema qingyiensis sp. nov., a new freshwater species (Bacillariophyceae) from Qingyi River, China

In this study, a new Gomphonema species from Qingyi River, Anhui Province, China, was identified and named Gomphonema qingyiensis sp. nov. We detailed its morphology using light microscopy (LM) and scanning electron microscopy (SEM). The LM and SEM photographs illustrate the size ranges and particular ultrastructure of the new species. The valves of G. qingyiensis are clavate and symmetrical to the apical axis. The headpole is broadly rounded and the footpole is narrowly rounded. The axial area is narrow, linear to linear-lanceolate. The central area is small and rectangular in shape. One stigma is evident. Striae are slightly radiate at the center. Biseriate striae and areolae are clearly evident in the LM images. The new species was compared with G. irroratum, G. zairense, G. dirangense, G. doonensis, G. latistigmata, G stoermeri, G marvanii, G cholnokyi, and G. clavatulum and was found to differ from these species in terms of the valve shape, size, striae density and row number, and central area.

Hantzschia subandina Frenguelli (Bacillariophyceae): Morphology, status and typification, as well as the description of a new species of Nitzschia

Backgrounds and aims: Hantzschia Grunow is a genus characterized by having valves asymmetric to the apical axis, markedly dorsiventral, with an eccentric raphe on the ventral side supported by fibulae and ‘hantzschioid’ symmetry of the frustules. In 1942 J. Frenguelli published the flora of diatoms of Neuquén province (Argentina), work in which he erected Hantzschia subandina as a new species for science. This work investigates the identity and taxonomic status of this taxon. M&M: Original material of Hantzschia subandina of the Frenguelli Collection was analysed with light and scanning electron microscopy. Results: Observations on the material suggested two different species were included in the concept of this species assigned originally to the genus Hantzschia. Furthermore, neither of the two species present are assignable to the genus Hantzschia. Nitzschia subandina (Frenguelli) comb. nov. has a large central nodule and a slight asymmetry about the apical axis; it also produces frustules with nitzschioid and hantzschioid symmetry. We designate a lectotype for this taxon. In addition, another diatom in the same material with slight asymmetry about the apical axis has distinctive ornamentation on the mantle of the valve and produces nitzschioid and hantzschioid frustules. For this taxon we tentatively assign it to the non-monophyletic genus Nitzschia, describing it as N. araucana sp. nov. We discuss the possible phylogenetic position of this new taxon, and suggest that the genus Nitzschia is “the next Navicula” ready to be further subdivided into distinct genera.

A New Aerophilic Neidium Pfister (Neidiaceae, Bacillariophyta) species from Guangxi Zhuang Autonomous Region, China

A new Neidium species was observed from a wet-wall in Shiwan Mountains National Forest Park, Guangxi Zhuang Autonomous Region, in the Southwest of China. This region of China has not had much previous attention focused on the biodiversity of freshwater algae. The new species, Neidium convolutum Y.Liu & Kociolek, is very distinctive compared with other known Neidium species, having torsion of the valves along the apical axis, large linear valves with wedge-shaped apices, oblique striae and volate occlusions in the areolae. We present a formal description of this species based on both light and scanning electron microscopic observations, and compare it with other, morphologically-similar species.

Gomphonema wuyiensis sp. nov., a new freshwater species (Bacillariophyceae) from Wuyi Mountains, China

During a survey of freshwater diatoms from Xingjiang River in the north region of the Wuyi Mountains, Jiangxi Province, China, a new Gomphonema species, Gomphonema wuyiensis sp. nov., was recorded. A detailed morphological description of G. wuyiensis is herein presented, based on light and scanning electron microscopy. LM and SEM micrographs show the size ranges and ultrastructural details of the new species. Gomphonema wuyiensis sp. nov. is characterized by valve outline asymmetrical to the apical axis. In addition, the valve outline on the primary side strongly tapers from the middle part to the footpole, and less strongly on the secondary side. In addition, distinctive morphological features and ecology of the taxon are discussed.

Entomoneis tenera sp. nov., a new marine planktonic diatom (Entomoneidaceae, Bacillariophyta) from the Adriatic Sea

The genus Entomoneis Ehrenberg includes diatoms with structurally complex frustules having a bilobate keel elevated above the valve surface and numerous girdle bands. We describe here a new member of the genus, Entomoneis tenera sp. nov., a minute species found in the plankton of the south-eastern Adriatic Sea. The description and proposed taxonomic affiliation are based on both morphological observations and molecular analyses obtained from three cultivated strains. The cultures were established from plankton net samples taken during BIOTA (Bio-tracing Adriatic Water Masses) cruise conducted in February–March 2015. In addition to characteristic Entomoneis features such as panduriform cells, often twisted around the apical axis and a raphe with simple endings positioned on the sigmoid keel, morphological characteristics of E. tenera are: (1) very small cells, 16–21 μm long and 5–20 μm wide (2) very lightly silicified, delicate frustules without valve striation discernible in light microscopy, (3) broad lanceolate valves with scalpeliform apices (4) a straight to slightly arcuate junction line. Phylogenetic analyses using SSU, rbcL and psbC supported the position of E. tenera within the Entomoneis genus with a clear separation from the other described species.

Gomphonema shanghaiensis sp. nov., a new diatom species (Bacillariophyta) from a river in Shanghai, China

This paper describes the new species Gomphonema shanghaiensis sp. nov. from Shujiawan River, Shanghai City, in the lower reaches of Yangtze River, China. The description is based on data derived from light and scanning electron microscopy. Valves of Gomphonema shanghaiensis are narrowly lanceolate to rhombic-lanceolate, slightly asymmetrical to the apical axis, with a gibbous central region. The footpole is broadly rounded and the headpole is slightly rostrate to narrowly rounded. The axial area is narrow and linear. Central area is small, and irregularly rectangular in shape. 1–5 rounded external stigmal openings are evident, and internally 1–2 of these are positioned on the central nodule. Striae are slightly radiate at the center, radiate towards the poles. The new species was compared with G. hasta, G. archaevibrio, G. spiculoides, G. stagnorum, G. guaraniarum, G. tumens and G. disgracile, all of which resemble Gomphonema shanghaiensis but differ from the new species in specific details of size, striae density, valve shape and stigmal openings number. This species occurs in relatively clean water in Shanghai.