Portia

Small horse spiders . The length of females is from 5 to 10 mm, males from 5 to 7 mm. The main coloration is dark brown with light and dark marks ^[2] . These spiders feed mainly on other spiders. Touching the web, they can simulate the movement of a wind blow to go unnoticed. Thanks to good vision, they can approach the victim, go unnoticed, and quickly attack ^[3] .

Africa , Madagascar , Australia , South and Southeast Asia (China, Malaysia, Myanmar, India, Nepal, Sri Lanka, Philippines, Vietnam) ^[1] .

Apparently their favorite prey are Orbiting Spiders, which are 10-200% larger than their own size. Spiders of the genus Portia are similar to leaf detritus stuck in a web, such a disguise is enough to deceive orbiting spiders that have poor eyesight ^[3] .

Hunting orbiting spiders, Portia creates various types of web vibrations that imitate insect attempts to get out or courtship signals, repeating any actions that prompt the intended victim to move to a spider of the genus Portia ^[4] . It was observed how Portia fimbriata performed vibrational signals for three days, until the victim decided to approach her ^[5] . Often they begin their invasion of someone else's web with the approach of a light breeze to hide the vibration that gives out their presence; they retreat if the intended victim begins to respond aggressively. The remaining horse spiders make short walks around the victim without interrupting eye contact, but Portia makes long walks with no eye contact ^[4] .

Laboratory studies have shown that the spiders of the genus Portia are very quickly trained in hunting techniques for orbiting spiders, which neither she nor her ancestors met in the wild. Accurate visual recognition of potential prey is an important part of her hunting tactics. For example, in the Philippines, spiders of this genus attack from the rear hunting very dangerous spider-spiders , who themselves prey on horse-spiders. This is instinctive behavior. On the other hand, they will attack spithead spiders that carry eggs in the forehead. However, as a result of experiments in which spiders of the genus Portia were poisoned by “living” spiders with different but consistent patterns of natural behavior, it was shown that instinctive tactics are only the starting point of the trial and error method, thanks to which these spiders learn very quickly ^[4] .

Compared to other horse spiders, which also have excellent eyesight, Portia can mimic leaf detritus. When Portia is close to its attack range, it begins to use different hunting tactics for various spiders. On the other hand, attacking simple prey, such as flies, they simply chase and rush at it ^[6] , and they also capture prey with a sticky web ^[4] .

Like its mimicry hunting method, Portia also relies heavily on traffic signals to find prey. In this particular strategy, non-directional jumps take place in the immediate vicinity of their victim to send visual signals. As a result of such actions, the victim will respond to this visual signal, give a reverse visual signal to the predator and after that Portia will quickly attack its victim ^[7] .

Portia can also eat the corpses of arthropods that they found ^[8] , as well as consume nectar ^[9] .

Some representatives of the species Portia africana were observed living together, and at the same time they shared the prey ^[10] .

If a mature male meets an immature female, he will try to coexist with her ^{[8] : 467} .

Females of Portia labiata can recognize a web of familiar and unfamiliar individuals of their species ^[11] , as well as distinguish their own web from someone else’s ^[12] .

Portia spiders have 8 eyes that support exceptional space sharpness ^{[13] [14]} . Three pairs of eyes located on the sides of the cephalothorax (the so-called secondary eyes) have a common field of view of almost 360 ° and serve mainly as motion detectors. A pair of forward middle eyes (called the primary eyes) is adapted for color vision and high spatial sharpness ^[15] .

The main eyes precisely focus on the subject at a distance of about 2 centimeters to infinity ^{[16] [17]} , and in practice can see up to 75 centimeters. ^{[16] : 53} . Like all horse spiders, Portia can perceive only a small field of view at the same time ^[18] , since the sharpest part of the main eye can see the whole circle up to 12 millimeters wide at a distance of 20 centimeters or up to 18 millimeters wide at a distance of 30 centimeters ^[19] . The main eyes of jumping spiders can see from the red to the ultraviolet parts of the spectrum ^[20] .

Portia eye receptor angles can be as little as 2.4 minutes in an arc, which is only six times worse than humans, but six times better than the sharpest insect eye ^[21] . It is also better in daylight than a cat’s vision ^[3] .

In determining the prey types, spiders of the P. africana species rely on visual features of the general morphology and color (or relative brightness) ^[22] . The hunting of P. schultzi is stimulated only by sight, and if the victim is nearby, but hidden, then it does not cause a spider reaction ^[16] . P. fimbriata uses visual cues to distinguish members of its species from other members of the Salticidae family ^[23] .

Some authors, such as Cross and Jackson (Cross and Jackson, 2014) suggest that spiders of the P. africana species are able to mentally rotate visual objects held in his memory ^[22] .

Nevertheless, Portia spiders spend a relatively long time to see objects, perhaps because obtaining a good image from such small eyes is a complex process and requires more thorough scanning. This makes Portia vulnerable to much larger predators such as birds , frogs, and mantises , which Portia often cannot identify due to the large size of the predator ^[3] .

When Portia spiders do not hunt for prey or mate, they take a special pose called the "secretive rest pose", stretching their legs close to the body, and curling their tentacles back around the chelicera ("jaws"), which makes the contours of these appendages unclear. When walking, most Portia species have a slow, “intermittent” gait, which preserves their secrecy: they often stop at irregular intervals; continuously waving legs, and their tentacles jerk up and down; moving each appendage independently of the other ^{[24] [25]} ; and constantly changing speed ^[26] .

It is known that if they are disturbed, then some species of Portia spiders jump upwards by about 100-150 mm often from their secretive resting position and often along a wide trajectory. Usually, then the spider either freezes or runs about 100 millimeters, and then freezes ^[8] .

The genus was first identified in 1878 by the German arachnologist Ferdinand Karsch . Type species Portia fimbriata (Doleschall, 1859) ^[1] . Using molecular genetic methods and DNA sequence analysis, it was shown that the genus Portia is a basal member of the clade (that is, it is related to the common ancestor of all other horse spiders), in which Spartaeus , Phaeacius and Holcolaetis can be their closest related taxa ^{[27 ]} .

The genus Portia is divided into two species groups: the schultzi group, in which the males have fixed tibial apophysises; and the kenti group, in which the apophysises of the palps are connected through a joint separated by a membrane ^[2] . The schultzi group includes species P. schultzi , P. africana , P. fimbriata, and P. labiata ^[2] .

At least some Portia species are in a state of reproductive isolation: in the laboratory, the male P. africana mated with the female P. labiata , but the eggs were not laid after this; in all cases, the female P. labiata resisted and lunged in an attempt to bite her partner ^{[8] : 435-466}

More than 17 species are distinguished ^{[2] [28]} .

• Portia africana (Simon, 1886)
• Portia albimana (Simon, 1900)
• Portia assamensis Wanless, 1978
• Portia crassipalpis (Peckham & Peckham, 1907) - Singapore, Borneo
• Portia fimbriata (Doleschall, 1859)
• Portia heteroidea Xie & Yin, 1991 - China ^[29]
• Portia hoggi Zabka, 1985 - Vietnam ^[30]
• Portia jianfeng Song & Zhu, 1998 - China ^[31]
• Portia labiata (Thorell, 1887)
• Portia orientalis Murphy & Murphy, 1983 - China ^[32]
• Portia quei Zabka, 1985 - Vietnam, China ^[30]
• Portia schultzi Karsch, 1878 ^[33]
• Portia songi Tang & Yang, 1997 - China ^[34]
• Portia strandi Caporiacco, 1941 - Ethiopia
• Portia taiwanica Zhang & Li, 2005 - Taiwan ^[35]
• Portia wui Peng & Li, 2002 - China ^[36]
• Portia zhaoi Peng, Li & Chen, 2003 - China ^[37]

The life span of these spiders is about 1.5 years ^[38] .

Portia fimbriata can recover a lost limb within a week after molting ^[39] .

Portia spiders can very easily lose their limbs, this is due to the presence of a protective mechanism. Therefore, spiders of this genus are often found without one or more limbs ^[8] .

• Harland DP, Jackson RR "Eight-legged cats" and how they see - a review of recent research on jumping spiders (Araneae: Salticidae ) // Cimbebasia: Journal. - 2000. - Vol. 16. - P. 231-240. Archived March 18, 2009. pdf
• Harland DP, Jackson RR A knife in the back: use of prey-specific attack tactics by araneophagic jumping spiders (Araneae: Salticidae) (English) // Journal of Zoology : Journal. - Wiley-Blackwell 2006. - April ( vol. 269 , no. 3 ). - P. 285-290 . - DOI : 10.1111 / j.1469-7998.2006.00112.x .

• Portia Date of treatment July 7, 2019.
• Portia Karsch, 1878 World Spider Catalog version 20.0. . Natural History Museum Bern (2019). Date of treatment July 7, 2019.
• Portia Tree of Life Web Project . tolweb.org. Date of treatment July 7, 2019.