方花丽斑蛇在湖南省莽山再次发现

正2013年4月20日,在湖南省宜章县莽山国家级自然保护区崖子石片区高山矮林(24°58'603″N,112°58'314″E,海拔1 500 m)林下一处岩石旁采集到1条游蛇科(Colubridae)幼蛇标本。依据形态学特征(赵尔宓2006,李操等2009),该蛇鉴定为方花丽斑蛇(Maculophis bellus),这是该蛇种自1982年在莽山大塘坑首次记录报道(梁启燊等1982)以来第2次在湖南省境内发现,也是在湖南省发现的第2号该蛇标本,该标本现存于莽山自然博物馆。此方花丽斑蛇幼体体重12 g,体全长345 mm,尾长50 mm。头背有镶黑边的黄白色"Y"形斑;体背部紫红色,     

Claw morphology, prey size selection and foraging efficiency in generalist and specialist shell-breaking crabs

Claw morphology, and claw-closing forces of four species of intertidal crabs from San Juan Island, Washington were compared and related these findings were related to prey size selection, shell breaking times and total handling times on their snail prey, Littorina sitkana Philippi. Two functional groups of crabs emerged: generalists and specialists on hard-shelled prey. The generalist, Hemigrapsus nudus (Dana), has an omnivorous diet and possesses weak claws with small, fine denticles and mechanical advantage (MA) of the claw's lever system <0.3, while the specialists, Lophopanopeus bellus (Stimpson), Cancer oregonensis (Dana) and C. productus (Randall), consume hard-shelled prey and possess large, powerful claws with broad, blunt molars and MA>0.3. The claws of the generalist, H. nudus, exhibited weaker claw closing forces (5 N) than those of similar sized specialists (>12 N). When crabs of similar weight were offered four size categories of Littorina sitkana, the generalist, Hemigrapsus nudus, exhibited a consistent preference for the smallest size categories, while the three specialists attacked all size classes offered. Hemigrapsus nudus took significantly longer (134 s) than the specialists (30–52 s) to break open a 4 mm L. sitkana. This difference in shell-breaking time between the generalist and the specialists increased with increasing prey size. The rate of successful attacks on increasingly larger L. sitkana decreased with prey size in the generalist (70% on 4 mm, 37% on 6 mm, and 0% on 8 mm snails), but remained high in the specialists (70–100%). Strength limitation of the claws is the best hypothesis to explain the avoidance of large snails by the generalist, H. nudus.     

四川蛇类一新纪录——方花丽斑蛇

2008年7月,在四川省攀枝花市盐边县野外考察期间采集到一条游蛇科幼蛇.经鉴定,该蛇为方花丽斑蛇(Mactdophis bellus),为四川省蛇类新纪录.