中国淡水根管虫(多毛纲、龙介虫科)一新纪录及其组织结构的观察

A New Genus of Ficopomatus (Polychaeta,Serpulidae) from China and Observation on Its Histological Structure

首次报道了中国淡水固着滤食的多毛类动物根管虫(Ficopomatus cf.macrodon)。标本采自深圳市郊人工淡水河底的石块上(113°46′07.52″E;22°43′41.91″N),石块用自来水浸泡后带有盐味。虫管顶部中线有一纵脊,环纹不明显。虫体长6.4～8.0 mm。鳃冠具16根鳃丝。壳盖呈橄榄形。虫体具7个胸刚节,第一刚节具9～11根领刚毛,呈毛状。胸区齿片腹刚毛具单排9个齿,长47～52μm。腹区背齿片刚毛具11～13齿,齿片宽50～55μm。膝状腹刚毛长506～525μm。组织学观察显示,鳃丝、壳盖和领部表面均由单层柱状上皮细胞构成。鳃丝表面有一层胶质层。壳盖顶部布满微型沙粒。胸区表层有大量钙质分泌细胞。雌雄异体,无真正的生殖腺,成熟个体的腹区每个体节充满成熟的精子或卵子。消化道由口、食道、肠和肛门构成。胸区的背纵肌束发达。刚毛上附有刚毛肌,背血管位于食道背部,两侧膨大,上下较窄。排泄系统呈2个U形肾管,仅分布于前胸区,排泄孔位于鳃丝丛中央。脑位于食道的背上方,横切面呈蝶形,2背角和2腹角具密集胶质细胞,内部为胶原纤维,内有零星的细胞。最后,比较和讨论了中国标本与根管虫属现有物种的形态差异。

This study for the first time reported the sessile filter-feeding Ficopomatus ef. macrodon in freshwater in China. Specimen were collected from the stones of a artificial river in the suburbs of Shenzhen（ 113° 46＇ 07.52＂ E ;22° 43＇ 41.91＂ N）. While dipped the stone in tap water for 20 d, the water tasted brackish. There was a longitudinal ridge on the midline of the tube＇s coping, and the annulatious were not obvious. The length of the polypide was 6.4 - 8.0 mm. The branchia coronal had 16 gill filaments. The operculum was olivary in shape. The polypide had 7 thoracic segments, and the first eapillaceous-like segment had 9 - 11 collar setae. Thoracic uncinus contained 9 teeth in a single row,47 - 52 μm in length. Abdominal uncinus contained 11 - 13 teeth, 50 - 55 μm in width. The length of the ventral ehaetae was 506 - 525 μm. Histology observation showed that the branchia filament, opereulum and the surface of collar were constituted by simple columnar epithelium cells. There was a laver of colloid matter on the surface of branchia filament. Mini-sand bestrewed the operculum＇ s coping. Thoracic surface contained numerous secretory cells. Dioecism, with no real germen, each arthromere of mature individual＇s ventral was filled with dense semen or ovum. The alimentary canal was comprised by mouth, esophagus, intestines and anus, Vertical fascicle on the thoracic dorsal developed well. Chaeto-muscle was carried by the setae, and dorsal blood vessel was on the back of esophagus, big on two sides and narrow on fluctuation. Excretory system had two U-like nephridiums, distributing only in the prothorax, and the excretory pore was in the middle of branchia filament. The brain was above dorsal esophagus, and its transverse section showed a shape of butterfly, with two dorsal horns and two ventral horns filled with dense colloid cells, and inside with some fragmentary collagen. Finally, we eompared and discussed modality differences between Chinese specimen and existing species of F. el. macrodon.