We report a series of sponge-like hydrogels prepared by polymerizing an aqueous solution of methacrylic acid (MAAc) in the presence of N,N,N′,N′-tetramethylethylenediamine (TMEDA), which results in hydrogen bond complexation, microphase separation, and formation of a unique colloidal network. The microstructure of the gels is determined by the coupling of microphase separation and gelation, which are influenced by the feeding concentrations of MAAc and TMEDA. Colloidal gels are only obtained at a relatively low concentration of MAAc in the presence of a certain amount of TMEDA. The structural evolution during the polymerization and the formation mechanism for the colloidal network are revealed by a combination of dynamic light scattering measurements and optical microscopy. It reveals that hydrogen bond complexes are formed between poly(methacrylic acid) (PMAAc) and TMEDA, leading to the formation of colloidal particles that assemble into clusters and then the interconnected colloidal network. The physical hydrogels with a colloidal network are stable in water and possess high stretchability and good selfrecovery ability due to the robustness of colloidal particles joined by adhesive PMAAc chains. These sponge-like hydrogels are applied to remove dye molecules for water purification and devised into a solar vapor generation device to produce clean water. The strategy by harnessing reaction-induced phase separation should be applicable for other systems to engineering the microstructure and properties of functional materials toward specific applications.
This study reports five species of Pareuchiloglanis in the Lancangjiang drainage of China, including descriptions of two new species: P. abbreviatus sp. nov., P. gracilicaudata, P. kamengensis, P. myzostoma and P. prolixdorsalis sp. nov. The two new species are distinguished from P. feae, P. poilanei, P. sichuanensis and P. tianquanensis by a shorter adipose-fin base and the adipose-fin base being separated from the caudal fin, differ from P. sinensis, P. macrotrema, P. longicauda and P. rhabdurus by a more restricted gill opening (not reaching the base of the first pectoral-fin element ventrally), and differ from P. songmaensis by an anal-fin ray count of ii-3-4 (vs. ii-8). Pareuchiloglanis abbreviatus is distinguished from congeners by the tip of the dorsal fin reaching the origin of the adipose fin when depressed. Pareuchiloglanis prolixdorsalis is distinguished from P. gongshanensis, P. macropterus and P. kamengensis by lacking a sulcus between the lower lip and the base of the maxillary barbel, and differs from P. anteanalis by the shorter pectoral fin, the pectoral fin not reaching to the origin of pelvic fin. It differs from P. gracilicaudata, P. myzostoma, P. nebulifer and P. robusta by a caudal-fin ray count of 6+7 (vs. 7+8), and differs from P. abbreviatus by the tip of dorsal fin not reaching to the origin of the adipose fin when depressed (vs. reaching). It differs from P. songdaensis by the distance between the origin of the pelvic fin to the base of the anal fin being longer than that to the mouth (vs. equal).
We describe three new species of Pareuchiloglanis. Based on a comparison of 17 valid species of Pareuchiloglanis, the genus can be divided into two groups contingent on their gill opening size and the anus position. One group, which we call the large gill opening group, has a large gill opening extending to the base of the first pectoral‐fin element; the anus is obviously closer to pelvic‐fin insertion than the anal‐fin origin; this group includes five species distributed in the Red and Pearl Rivers, China. The other group has a small gill opening extending only to the middle base of the pectoral‐fin elements; the anus is usually located at the midpoint of the pelvic‐fin insertion to the anal‐fin origin or slightly behind. This group includes the other 12 species, which are distributed in the Mekong and Yangtze Rivers. The large‐gill‐opening group can be divided into two sub‐groups based on the length of the caudal peduncle. One sub‐group has a long caudal‐peduncle and the distance from the anal‐fin origin to caudal‐fin base is greater than distance from the pelvic‐fin insertion. This sub‐group is only distributed in the Pearl River drainage. Another sub‐group has a short caudal peduncle and the distance from the anal‐fin origin to the caudal‐fin base is typically smaller than the distance from the pelvic‐fin insertion. This sub‐group is only distributed in the Red River basin of China and Vietnam. The former will be called the large‐gill‐opening group with long caudal peduncle in the text and only includes one species P. longicauda. During our ongoing taxonomic work of specimens collected from Nanpan‐jiang and Beipan‐jiang (upper Pearl River drainage in Yunnan, China), some Pareuchiloglanis specimens that had the characters of the large‐gill‐opening group with long caudal peduncle represent three undescribed species.
Creteuchiloglanis, new genus, is established for three species previously placed in Pareuchiloglanis (P. gongshanensis, P. kamengensis, and P. macropterus) and two new species described herein. Creteuchiloglanis is distributed in the upper Mekong River (Lancang-Jiang) basin west to the Brahmaputra River basin and is distinguished from Pareuchiloglanis by a unique combination of characteristics involving the form of the connection of the lower lip to the maxillary barbel, premaxillary tooth patches, and the morphology of the dilator, operculi, sternohyoideus, and adductor pelvicalis superficialis muscles. Creteuchiloglanis brachypterus, new species, from the upper Irrawaddy River basin in China, is diagnosed by a unique combination of characteristics involving pectoral-and pelvic-fin length, caudal-peduncle length and depth, pelvic-fin position, caudal-fin length, eye size, body and head depth, and coloration. Creteuchiloglanis longipectoralis, new species, from the upper Mekong River (Lancang-Jiang) basin, is diagnosed by a unique combination of characteristics involving pectoral-and pelvic-fin length, caudal-peduncle length and depth, pelvic-fin position, body and head depth, post-adipose fin distance, number of dorsal-fin rays, and coloration. New diagnoses are provided for previously described congeners C. gongshanensis from the upper Salween River (Nu-Jiang) basin, C. kamengensis from the Brahmaputra basin, and C. macropterus from the upper Irrawaddy River and upper Salween (Nu-Jiang) basins. C HU (1981) resurrected the catfish genus Pareuchiloglanis Pellegrin 1936 for species in the genus Euchiloglanis that lack a posterolateral extension of each premaxillary tooth patch (vs. posterolateral extension present in Euchiloglanis). Seven species and two subspecies were placed in Pareuchiloglanis, including P. poilanei (type species), P. feae feae, P. feae myzostoma, P. kamengensis, P. gracilicaudata, P. gongshanensis, P. macrotrema, and P. sinensis. A morphology-based phylogenetic analysis of glyptosternine catfishes found Pareuchiloglanis to be nonmonophyletic (He, 1995(He, , 1996. Therein, specimens identified as P. feae from Yunnan and P. kamengensis were found to be more closely related to the genera Pseudexostoma and Oreoglanis than to a clade composed of Pareuchiloglanis macrotrema, P. longicauda, and P. myzostoma.A study using mitochondrial cytochrome b and 16S rRNA gene sequences (Guo et al., 2005), and another using mitochondrial genes (cytochrome b and ND4) and one nuclear gene (rag2; Peng et al., 2006), found specimens identified as Pareuchiloglanis kamengensis to be more closely related to species of other genera of glyptosternines than to the other examined species of Pareuchiloglanis. These molecular results corroborate the non-monophyly of Pareuchiloglanis discovered by He's (1995He's ( , 1996 morphological analysis.Nevertheless, recent studies continued to recognize Pareuchiloglanis as defined by Chu (1981) and new species continue to be described in this genus. Thomson and Page (2006) recognized ...
The genus Pareuchiloglanis, distributed in the Salween, Mekong, Red, Pearl and Yangtze River basins in China, Laos, Myanmar and Vietnam, consists of 20 valid species and 5 uncertain species. This study provided a taxonomic revision to Pareuchiloglanis occurring in the Yangtze River. According to the results of a morphological comparison, the type locality of Pareuchiloglanis sinensis was updated to the Nanpan‐jiang (the upper Pearl River) basin; five species were identified in Pareuchiloglanis from the Yangtze River basin. Specimens formerly identified as Pareuchiloglanis sinensis from this basin were described as a new species, Pareuchiloglanis chui sp. nov. Moreover, Pareuchiloglanis tianquanensis was synonymized with Pareuchiloglanis sichuanensis. This study provided a key to these two species and three others (Pareuchiloglanis anteanalis, Pareuchiloglanis hupingshanensis and Pareuchiloglanis robusta) from the Yangtze River basin, including information about their geographical distribution. These findings provide an insight into the evolution, distribution and taxonomy of this genus for future studies.
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