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A new gomphid species, named as Gomphidictinus tongi sp. nov. (Holotype male, Mt. Diaoluoshan, altitude 930m a.s.l., Lingshui County, Hainan Province, China) is described here. It is regarded as the third species of Gomphidictinus based on the presence of the basal spine on median segment of the penis organ. Gomphidia interruptistria Zha, ZhangZheng, 2005 is regarded as a junior synonym of Gomphidictinus perakensis (Laidlaw, 1902), which is recorded from Yunnan, China.

A new gomphid species, named as Gomphidictinus tongi sp. nov. (Holotype male, Mt. Diaoluoshan, altitude 930m a.s.l., Lingshui County, Hainan Province, China) is described here. It is regarded as the third species of Gomphidictinus based on the presence of the basal spine on median segment of the penis organ. Gomphidia interruptistria Zha, Zhang & Zheng, 2005 is regarded as a junior synonym of Gomphidictinus perakensis (Laidlaw, 1902), which is recorded from Yunnan, China.

An investigation was made on the dynamic changes of tannin concentration in Syzygium jambos and Dracontomelon duperreanum leaves over a 105-day period of leaf litter decomposition in a second-order stream in Longdong Reservoir, Guangzhou. The initial tannin concentration in S. jambos leaves (0.191 g x g(-1) DM) was higher than that in D. duperreanum leaves (0.057 g x g(-1) DM). In the first week of leaf litter decomposition, the tannin concentration in D. duperreanum and S. jambos leaves decreased by 45% and 22% respectively. 21 days after, the decline in tannin concentration slowed down, but the decomposition rate increased, with the leaves of D. duperreanum decomposed faster than those of S. jambos (k value was 0.038 d(-1) and 0.013 d(-1), respectively). The average density of benthonic invertebrate colonized on D. duperreanum leaves (287.9 ind x g(-1) leaf mass) was significantly higher than that on S. jambos leaves (26.2 ind x g(-1) leaf mass) (P0.05). A continual increase of benthonic invertebrate's abundance was observed during leaf litter decomposition, which could be attributed to the rapid decrease of leaf tannin concentration. The slower breakdown of S. jambos leaf litter was likely because of the high tannin concentration in S. jambos leaves, which inhibited benthonic invertebrate, especially the shredder's colonization.