广东淡水鱼类弓背青鳉分类形态性状再描述

Characteristic Re-description of Ricefish Oryzias curvinotus from Guangdong,China

食蚊鱼Gambusia affinis的入侵导致弓背青鳉Oryzias curvinotus种群严重下降而趋于濒危。其模式标本产地种群(海南岛那大)已经灭绝,野外种群已多年未见报道。过去,研究者对正模标本的描述存在严重错误且难于复检,现亟需对其分类性状进行再描述及模式标本重建。本文对近期采自广州南沙岛的弓背青鳉孑遗种群进行了分类形态性状再描述,补充了活体及浸制标本彩色照片,并对其雌雄间的形态差异进行了统计分析。结果显示,弓背青鳉区别于其他青鳉鱼类的主要分类检索性状是臀鳍条数目为19.60±0.80(19~22)、体侧纵列鳞数目为28.51±0.67(27~30),定种的关键特征是背鳍-吻端/体长:雄鱼为(80.9±1.3)%、雌鱼为(82.2±1.0)%、全部为(81.6±1.3)%;同时,通过单因素方差分析、主成分分析及判别分析等多元统计方法证实了其种内存在的雌雄异形现象,文中回顾并澄清了有关弓背青鳉的分类形态性状问题。当前亟待加强弓背青鳉保护生物学研究并应采取有力的保护措施尽早对现存种群进行有效保护。

The population of ricefish（ Oryzias curvinotus） had been significantly declined since the invasive species mosquitofish（ Gambusia affinis） widely introduced to China during the recent few decades. As a result,the population of this species in type locality had been extinct. Unfortunately,the researcher had made some big mistake in the description of its holotype,and thus brought big confusions to the researchers during their identification to the Oryzias species in China. In order to rebuild the holotype,relocate the type locality and amend the characteristics descriptions of this Oryzias species,in this paper,we conducted a characteristic re-description of O. curvinotus which were collected from the Huangshanlu National Forest Park and its adjoin zone（ Guangzhou city,China）,and replenished the chromophotograph of this species. The result showed that the principal identification characteristics of O. curvinotus from other Oryzias species should be as following：anal-fin rays are 19. 60 ± 0. 80（ 19-22）,scales in a lateral series are 28. 51 ± 0. 67（ 27-30） and the ratio of pre-dorsal length/standard length is（ 81. 6 ± 1. 3） % in total. Meanwhile,the sexual dimorphism of this species also was determined by one way analysis of variance,principal component analysis and discriminant analysis. As the O. curvinotus was greatly threatened by the invasion of mosquitofish,and the invader had also been found in the sites where O. curvinotus populations still remained,we strongly suggest that effective measures are urgently needed to protect the relict populations of this species.