| 摘要 | 自由生活线虫是海洋环境中物种多样性高且数量占优势的底栖生物类群，其物种多样性对于海洋底栖生态系统运转具有重要意义。因其个体较小、分选困难且专业技术人才匮乏等原因，对于线虫的系统分类研究十分薄弱，大量种类仍然未知。南海是我国海洋生物多样性最高的海域，但也是海洋线虫分类研究最为欠缺的区域，对于深海的线虫更是鲜有报道，缺乏对于南海线虫物种多样性本底的认知。此外，基于传统分类学确立的许多阶元的系统地位仍然存疑，很多类群的系统发育关系仍十分混乱，亟待通过分子技术的引入获得新认知。
本论文基于自南海潮间带至深海的39个站位获得的沉积物样品(涵盖南海潮间带 7 个采样点以及南海陆架区和深海海盆 32 个采样站位，水深跨度为 0–4000m)，通过经典分类学手段，研究了南海线虫的基本分类组成，发现并描述新物种；在准确分类学基础上，结合 18S rDNA 测序分析，对线虫单宫目内主要类群的系统地位和系统发育关系进行了研究，以期为中国海洋线虫编目和物种多样性研究提供翔实可靠的基础资料，清理单宫目内主要类群的系统发育关系。
对南海陆架区和深海海盆 32 个站位沉积物的定量与定性研究结果表明，南海线虫平均丰度为 192.1±38.7 inds/10 cm 2 ，是小型底栖生物数量上占绝对优势类群，占总数的 85.5%，平均生物量为 76.8±15.5 µg dwt/10 cm 2 。本研究共鉴定出线虫 366 种(或分类实体)，隶属 8 目 39 科 187 属，整理出南海线虫优势属有Acantholaimus, Cervonema, Chromadorina, Dorylaimopsis 和 Halalaimus。物种多样性最高的属有 Acantholaimus, Cervonema, Daptonema, Diplopeltoides, Halalaimus,Leptolaimus 和 Sabatieria, 以上每个属中都发现了 10 种以上。通过与我国其他海域的线虫比较分析发现，南海和东海有 128 个共有属，与黄海有 46 个共有属，三个海域共有的属有 19 个；仅在南海发现的种有 65 个。
本研究共发现并描述南海线虫新种 32 种、新记录 12 种。其中新种 4 种发现自潮间带，15 种自陆架海域，13 种发现自深海。本研究已发表新种 5 种，待发表新种 27 种，分别是：长刺长颈线虫 Cervonema longispicula Huang, Jia & Huang,2018; 锥尾双盾线虫 Diplopeltoides conoicaudatus Sun, Huang & Huang, 2021; 尖头多旋线虫 Minolaimus multisupplementus Sun, Huang & Huang, 2020; 小毛萨巴线 虫 Setosabatieria minor Huang, Xu & Huang, 2019; 丝尾萨拉光皮线虫Thalassironus filiformis Huang, Huang & Xu, 2019; 丝尾头感线虫 Anticoma filiformis sp. nov.; 长化感器轴线虫 Axonolaimus longiamphidatus sp. nov.; 南海深咽线虫 Bathylaimus nanhaiensis sp. nov.; 中华长颈线虫 Cervonema sinica sp. nov.;细刺大链环线虫 Desmodorella filiformis sp. nov.; 长刺项链线虫 Desmoscolex longispiculatus sp. nov.; 小化感器双盾线虫 Diplopeltoides microamphidatus sp.nov.; 长刚毛龙线虫 Draconema longiseta sp. nov.; 毛头咽线虫 Gomphionema setiforme sp. nov.; 辅器线荚线虫 Linhystera hamatus sp. nov.; 长刺线荚线虫Linhystera longispicula sp. nov.; 小体线荚线虫 Linhystera minor sp. nov.; 南海线荚 线 虫 Linhystera nanhaiensis sp. nov.; 锥 尾 宽 口 齿 线 虫 Nannolaimoides conicaudatus sp nov.; 长刺拟联体线虫 Paracomesoma longissimum sp. nov.; 小拟囊咽线虫 Parasphaerolaimus minor sp. nov.; 南海光皮线虫 Phanodermopsis nanhaiensis sp. nov.; 长体前单宫线虫 Promonhystera longicorporis sp. nov.; 弯刺前单宫线虫 Promonhystera curvispicula sp. nov.; 毛刺前单宫线虫 Promonhystera seta sp. nov.; 长刺覆瓦线虫 Pselionema longispicula sp. nov.; 长体圆链环线虫Robbea praelonga sp. nov.; 尖头管咽弯线虫 Solenolaimus stenocephatus sp. nov.;长尾圆双盾线虫 Southerniella longicauda sp. nov.; 长尾前咽球线虫 Stylotheristus longicaudatus sp. nov.; 大化感器微口线虫 Terschellingia macramphida sp. nov.; 短尾韦氏线虫 Wieseria brevicaudata sp. nov.。12 种新记录分别是：卡通毛覆瓦线虫
Ceramonema carinatum Wieser, 1959; 澳洲方唇线虫 Corononema parvum Warwick,1995; 长化感器细环线虫 Cricohalalaimus vagabundus Bussau, 1993; 美式项链线虫 Desmoscolex americanus Chitwood, 1936; 小双盾线虫 Diplopeltoides pumilus Holovachov, & Boström, 2017; 安达曼龙线虫 Draconema andamanense Kito & Chatterjee, 2012; 小头细咽线虫 Manganonema microcephalum Bussau, 1933; 螺旋玛丽亚线虫 Marylynnia dentikulata Kim, Tchesunov & Lee, 2015; 齿拟杯咽线虫Paracyatholaimus intermedius De Man, 1880; 巴 布 拉 拟 双 单 宫 线 虫Paramphimonhystrella barbula Leduc, 2014; 微笑覆瓦线虫 Pselionema dissimile Vitiello, 1974; 毛刺方体线虫 Quadricoma scanica Filipjev, 1922。本文对上述新物种和新记录种进行了细致的形态学描述，就新物种建立做了讨论，对新记录种与相近种做了比较分析。
本研究还获取了 11 种单宫目线虫的 16 条 18S rDNA 序列，结合 GenBank 的64 条序列分析，建立了 ML 和 BI 系统进化树，对单宫目条线虫科(Linhomoeidae Filipjev, 1922)、球咽线虫科(Sphaerolaimidae Filipjev, 1918)、希阿利线虫科(Xyalidae Chitwood, 1951)及单宫线虫科(Monhysteridae De Man, 1876)及科内类群进行了系统发育分析。结果显示，Daptonema, Terschellingia 和 Geomonhystera 属均未与相近类群聚为一支；结合分类学研究，将 Daptonema longiapophisis Huang & Zhang, 2010 转移至 Theristus Bastian, 1865 属，将 Terschellingia de Man, 1888属继续归属于条线虫科(Linhomoeidae)，将 Geomonhystera Andrássy, 1981 属由单宫线虫科转移至希阿利线虫科(Xyalidae)。 |
| 其他摘要 | Free-living nematodes are the dominant benthic groups with high species diversity in marine benthic environment. Due to their smaller size, the difficulty in taxonomy and the lack of qualified taxonomists, the taxonomy and systematics of nematodes are relatively scant and a large number of species remains unknown. The South China Sea
has the highest marine biodiversity in the sea areas of China, but it is also an area where the taxonomy of marine nematodes is very deficient. The species composition and diversity of nematodes in the South China Sea, particularly those in the deep-sea area, are not well understood. In addition, the systematic positions and phylogenetic relationships of many nematode taxa, which were established on the basis of classic taxonomy, are still in doubt or in confusion. Thus, there is a need to acquire new
understanding through the introduction of molecular techniques.
The present study investigated the taxonomy and phylogeny of nematodes based on a total of 39 sediment samples collected from intertidal zone through continental shelf to deep-sea basin in the South China Sea. The sampling areas comprised the intertidal zone (7 stations) in Hainan and Guangdong provinces, the contiental shelf in the northeast South China Sea and the central deep-sea basin (32 stations), with water
depths up to 4000 m. Through morphological taxonomy, the basic species composition of nematodes in the South China Sea was examined and new species were described herein. Moreover, the molecular phylogenetic relationships of some groups within the order Monhystera were revealed on the basis of 18S rDNA sequencing. The aim of this study is to provide reliable data for the cataloging and the understanding of species diversity of nematodes in the sea areas of China, and to clear the phylogenetic
relationships within the order Monhystera.
The results of quantitative and qualitative analyses on sediments from 32 stations in the continentlal shelf and deep-sea basin in the South China Sea showed that the average abundance of nematodes was 192.1±38.7 inds /10 cm 2 , occupying about 85.5% of the total meiofaunal abundance. The average biomass was 76.8±15.5 µg dwt/10 cm 2 .
A total of 366 species (or taxonomic entities) of nematodes belonging to 8 orders, 39 families and 187 genera were identified. The dominant nematode genera in the South China Sea were composed of Acantholaimus, Cervonema, Chromadorina, Dorylaimopsis and Halalaimus. The genera each comprising more than ten species included Acantholaimus, Cervonema, Daptonema, Diplopeltoides, Halalaimus,
Leptolaimus and Sabatieria. There were 128 common nematode genera found in the South China Sea and East China Sea, 46 common genera in the South China Sea and Yellow Sea, and 19 common genera in all the three seas. Sixty-five species were found only in the South China Sea.
In this study, 32 new species of nematodes and 12 first records of China were found and described from the South China Sea, including 7 species from the intertidal zone, 16 species from the continental shelf and 21 species from the deep sea. Of the 32 new species, 4 species were found from the intertidal zone, 15 from the continental shelf area, and 13 from the deep-sea area, including five new species that have been published (Cervonema longispicula Huang, Jia & Huang, 2018; Diplopeltoides conoicaudatus Sun, Huang & Huang, 2021; Minolaimus multisupplementus Sun, Huang & Huang, 2020; Setosabatieria minor Huang, Xu & Huang, 2019; Thalassironus filiformis Huang, Huang & Xu, 2019). The other 27 new species are to be published as follows: Anticoma filiformis sp. nov.; Axonolaimus longiamphidatus sp. nov.; Bathylaimus nanhaiensis sp. nov.; Cervonema sinica sp. nov.; Desmodorella filiformis
sp. nov.; Desmoscolex longispiculatus sp. nov.; Diplopeltoides microamphidatus sp. nov.; Draconema longiseta sp. nov.; Gomphionema setiforme sp. nov.; Linhystera hamatus sp. nov.; Linhystera longispicula sp. nov.; Linhystera minor sp. nov.; Linhystera nanhaiensis sp. nov.; Nannolaimoides conicaudatus sp nov.; Paracomesoma longissimum sp. nov.; Parasphaerolaimus minor sp. nov.; Phanodermopsis nanhaiensis sp. nov.; Promonhystera longicorporis sp. nov.; Promonhystera curvispicula sp. nov.; Promonhystera seta sp. nov.; Pselionema longispicula sp. nov.; Robbea praelonga sp. nov.; Solenolaimus stenocephatus sp. nov.;
Southerniella longicauda sp. nov.; Stylotheristus longicaudatus sp. nov.; Terschellingia macramphida sp. nov.; and Wieseria brevicaudata sp. nov. In addition, 12 are first records in the sea areas of China. These include Ceramonema carinatum Wieser, 1959; Corononema parvum Warwick, 1995; Cricohalalaimus vagabundus Bussau, 1993; Desmoscolex americanus Chitwood, 1936; Diplopeltoides pumilus Holovachov, &
Boström, 2017; Draconema andamanense Kito & Chatterjee, 2012; Manganonema microcephalum Bussau, 1933; Marylynnia dentikulata Kim, Tchesunov & Lee, 2015; Paracyatholaimus intermedius De Man, 1880; Paramphimonhystrella barbula Leduc, 2014; Pselionema dissimile Vitiello, 1974; and Quadricoma scanica Filipjev, 1922. All these new species and first records are described in detail, the establishment of the new species is discussed, and the comparison of the first records with related populations and species are provided. Based on 16 new sequences of 18S rDNA obtained from 11 species of the order Monhystera and 64 related sequences from GenBank, the ML and BI phylogenetic trees were constructed for Monhystera. Phylogenetic analysis was performed on the families Linhomoeidae Filipjev, 1922; Sphaerolaimidae Filipjev, 1918; Xyalidae Chitwood, 1951; and Monhysteridae De Man, 1876. The results showed that Daptonema, Geomonhystera, Terschellingia did not clustered with their related taxa. In combination with morphological taxonomy, Daptonema longiapophisis Huang & Zhang, 2010 was transferred to the genus Theristus Bastian, 1865, the genus Terschellingia de Man, 1888
was suggested to stay in the family Linhomoeidae, and the genus Geomonhystera Andrássy, 1981 was transferred from the family Monhysterae to Xyalidae. |
修改评论