Contrasting patch choice behaviour by immature ambush predators, a spider (Misumena vatia) and an insect (Phymata americana)

1. Spiderlings of the crab spider Misumena vatia and nymphs of the ambush bug Phymata americana normally ambush prey in flowers, as do the adults. The immatures of M. vatia are more mobile, by ballooning, than the ambulatory but largely sedentary adult female spiders, but the apterous immatures of P. americana are less mobile than the alate adults. The aim of the work reported here was to investigate how immatures, as compared with adults, select sites from which to ambush their prey. 2. Individual immatures of both species were released in experimental arenas with variously manipulated natural stems: normal, with and without leaves, and with and without flowers of three species of plants. 3. The spiderlings and nymphs showed discriminatory behaviour but not in accordance with optimal foraging in either case. The spiderlings chose more leafy stems than any other kind of stem. For the nymphs, the importance of leaves was less marked, food apparently being more important than shelter. 4. Neither of the predators discriminated among flowering stems of Solidago canadensis, Daucus carota, and Cirsium arvense. 5. In other experiments, in which flowered and deflowered stems were located in two separated groups in the arena and the individual was released in a bare area between the two groups, the spiderlings chose either group as predicted by chance but the nymphs showed a slight preference for the flowered sector. Nevertheless, once in either of the groups, the predators showed similar behaviour in choosing leafy stems more often than other stems. 6. Nymphs of P. americana are much more selective than adults but spiderlings of M. vatia are less selective than adult females. These results appear to accord with the time and energy costs of changing hunting sites, walking being slower than flying or ballooning. 7. The results indicate the need to include other parameters, such as enemy‐free space and time spent in not being able to forage, in the analysis of foraging behaviour.     

中国蟹蛛科蜘蛛4新种记述（蜘蛛目）

记述蟹蛛科蜘蛛4新种:勐腊峭腹蛛Tmarus menglae sp.nov.、滇微蟹蛛Lysilelesdiamicus sp.nov.、昆明微蟹蛛Lysileles kunming ensis sp.nov.和湖北花蛛Misumenops hubeiensis sp.nov.     

Animal camouflage: compromise or specialize in a 2 patch-type environment?

Many animals possess camouflage markings that reduce the riskof detection by visually hunting predators. A key aspect ofcamouflage involves mimicking the background against which theanimal is viewed. However, most animals experience a wide varietyof backgrounds and cannot change their external appearance tomatch each selectively. We investigate whether such animalsshould adopt camouflage specialized with respect to one backgroundor adopt a compromise between the attributes of multiple backgrounds.We do this using a model consisting of predators that hunt preyin patches of 2 different types, where prey adopt the camouflagethat minimizes individual risk of predation. We show that theoptimal strategy of the prey is affected by a number of factors,including the relative frequencies of the patch types, the traveltime of predators between patches, the mean prey number in eachpatch type, and the trade-off function between the levels ofcrypsis in the patch types. We find evidence that both specialistand compromise strategies of prey camouflage are favored underdifferent model parameters, indicating that optimal concealmentmay not be as straightforward as previously thought.     

海南3种蟹蛛记述

记述海南尖峰岭3种蟹蛛:海南泥蟹蛛Borboropaclus hainanus Song(雌蛛新发现),大东斜蟹蛛Lox obales dailoensis Ono(中国新纪录)和海南花蟹蛛Xysticus hainanus sp.nov.(新种)。同时对各种的分类地位作简短的讨论。     

中国瘤蟹蛛属1新纪录种(蜘蛛目:蟹蛛科)

记述我国瘤蟹蛛属1新纪录种,加藤瘤蟹蛛（Phrynarachne katoi Tkiuni,1955)。     

我国2种微蟹蛛记述（蜘蛛目：蟹蛛科）

提出对前报道的蟹蛛科微蟹蛛属２种的修订：西安微蟹蛛ＬｙｓｔｉｅｌｅｓｘｉａｎｅｎｓｉｓＳｏｎｇｅｔＷａｎｇ,１９９１应为小微蟹蛛Ｌｙｓｔｅｌｅｓｍｉｎｉｕｍｕｓ（Ｓｃｈｅｎｋｅｌ１９５３）的异名,唐迎秋等（１９９５）报道的小微蟹蛛雌蛛,改订为１个新种－文微蟹蛛Ｌｙｓｔｅｌｅｓｗｅｎｅｎｓｉｓｓｐ．ｎｏｖ。     

甘肃数种蟹蛛（蜘蛛目：蟹蛛科）记述

记述采自甘肃文县和武都县的蟹蛛科蜘蛛５种,其中包括３新种和２种雌蛛新发现。     

中国绿蟹蛛属一新种记述(蜘蛛目,蟹蛛科)

记述了采自中国湖南省石门县壶瓶山国家自然保护区境内的蟹蛛科Thomisidae绿蟹蛛属Oxytate 1新种:微绿蟹蛛Oxytate minuta sp.nov,新种与冲绳绿蟹蛛Oxytatehoshizuna Ono,1978较为近似,但有以下几点不同:1)身体大小、形状差别较大,本种身体微小2.60,而后者一般在7.00以上,2)本种插入器隆起于生殖球之上,而后者并不如此.模式标本保存在湖南师范大学生命科学学院.文中量度单位为mm.词源:本种以其体型微小而命名.     

中国蟹蛛科（蜘蛛目）新种记述

记述我国蟹蛛科花蟹蛛属６新种和蟹蛛属２新种,共计８新种,金林花蟹蛛Ｘｙｓｔｉｃｕｓｊｉｎｌｉｎ,玛纳斯花蟹蛛Ｘ．ｍａｎａｓ,林芝花蟹蛛Ｘ．ｎｙｉｎｇｃｈｉｅｎｓｉｓ,拟斑花蟹蛛Ｘ．ｐａｒａｐｕｎｃｔａｔｕｓ,似旋花蟹蛛Ｘ．ｔｏｒｓｉｖｏｉｄｅｓ,吴氏花蟹蛛Ｘ．ｗｕａｅ,广西蟹蛛Ｔｈｏｍｉｓｕｓｇｕａｎｇｘｉｃｕｓ和胡氏蟹蛛Ｔ．ｈｕｉ。     

陕西蟹蛛科蜘蛛三新种记述──(蜘蛛目)

本文记述陕西秦岭山区蟹蛛科Ｔｈｏｎｄｓｉｄａｅ蜘蛛三新种：高寒花蟹蛛,新种Ｘｙｓｔｉｃｕｓａｌｓｕｓｓｐ．ｎｏｖ,太白峭腹蛛,新种Ｔｍａｒｕｓｔａｉｂａｉｅｎｓｉｓｓｐ．ｎｏｖ．,秦岭峭腹蛛,新种Ｔｍａｒｕｓｑｉｎｌｉｎｇｅｎｓｉｓｓｐ．ｎｏｖ．．     

动物的伪装方式

: 伪装是动物防御性体色最重要的功能之一,能减少被捕食者检测和识别的风险。本文综述了隐蔽、乔装、运动炫和运动伪装等4种伪装方式的研究进展,并指出当前研究中存在的一些问题,以期为动物伪装进化的研究提供参考。     

中国绿蟹蛛属一新种(蜘蛛目:蟹蛛科)

本文记述采自浙江宁波天童森林公司的蟹蛛科绿蟹蛛属一新种,钳绿蟹蛛Ｏｘｙｔａｔｅ ｆｏｒｃｉｐａｔｕｓ ｓｐ．ｎｏｖ。     

Countershading enhances crypsis with some bird species but not others

Although the theory of self-shadow concealing countershadingis over a century old, there are very few direct empirical teststo substantiate the prediction that prey that are dorsally darkenedand ventrally lightened (generally termed countershaded) sufferlower rates of attack than other prey. In this paper, we reportexperiments designed to determine whether artificial, countershadedprey are chosen by predators less often than those that areall light, all dark, or reverse shaded (i.e., dorsally lightenedand ventrally darkened). Artificial prey were presented in gardensand parks to free-living birds, either on white backgroundsor on backgrounds with some degrees of color matching. In oneexperiment, birds were unmarked, and in the other, they wereindividually identifiable. We found that in three experimentaltrials, countershaded baits were attacked at a rate not significantlydifferent from that of uniformly dark baits. In one experimentaltrial, countershaded baits were at some advantage. When we examinedthe data set for this trial more closely, it was apparent thatblackbirds were taking countershaded baits least often, butblue tits and robins conferred no special advantage to countershadedbaits. Hence, the efficacy of countershading may vary with speciesof predator.