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The Common Spiders of the United States. J. H. Emerton
Читать онлайн.Название The Common Spiders of the United States
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isbn 4064066218614
Автор произведения J. H. Emerton
Жанр Языкознание
Издательство Bookwire
Anyphæna incerta.—About a fifth of an inch long, light yellow, with gray markings. The cephalothorax is three-quarters as wide as long, rounded at the sides and highest in the middle. The front of the head is very low, so that the eyes nearly touch the mandibles. The front row of eyes is nearly straight. The upper row is longer and more curved, with the middle eyes highest and farthest apart (fig. 39). The abdomen is large in the female, widest behind the middle, and a little pointed behind. The labium is not longer than wide, and the maxillæ are straight, with the sides parallel. The sternum is oval, not so short and wide as in pratensis. The opening of the air-tubes is halfway between the epigynum and spinnerets (fig. 38), instead of just in front of the spinnerets, as it is in most spiders. The spinnerets are two-jointed. The legs are slender and tapering, the fourth longest in females and the first in males. The cephalothorax has two longitudinal broken gray bands. The abdomen has a double row of spots in the middle and oblique rows of smaller spots each side. The oblique lines of spots extend under the abdomen halfway to the middle.
Anyphæna calcarata.—The same size and color as A. incerta, with longer legs. The markings are the same in both species. The plainest difference between the females is in the epigynum, the hard and dark parts of which are larger and longer in incerta. Another slight difference is in the shape of the sternum, which in calcarata extends farther between the hind legs (fig. 42). In incerta it is more pointed at the hinder end and shorter (fig. 38). The difference between the length of the legs in the two species, which is slight in the females, is greater in the males, the legs of calcarata being the longer. The palpi of the males differ considerably. In incerta (fig.37) the tibia of the palpus has a large process on the outer side close to the tarsus and extending along its edge a third of its length. In calcarata (fig. 43) the corresponding process is small and does not lap over the tarsus. The coxæ of the third and fourth legs of the male calcarata have little processes on the under side (fig. 42), one on the fourth and two on the third. These do not occur in incerta. It lives on plants like saltabunda (p. 14).
Anyphæna rubra.—Larger than the other species, with the legs shorter. The female is about a third of an inch long, with the abdomen longer and narrower than in incerta or saltabunda. The opening of the air-tubes (fig. 45) is farther forward than usual, twice as far from the spinnerets as from the epigynum. The legs are comparatively short, the longest, the fourth, being about as long as the body. The maxillæ are a little widened at the end. The sternum is widest at the second legs and narrows to a point behind. The head is a little wider than usual, and the whole appearance more like Clubiona than the other species. The color is the usual pale yellow, a little brownish on the head and legs, and with two longitudinal stripes on the cephalothorax. The abdomen is nearly white, with two stripes made up of gray spots, and scattered spots at the sides. The spots turn red in alcohol.
Anyphæna saltabunda.—A pale short spider, with long and slender legs (fig. 46). The body is an eighth to a sixth of an inch long. The abdomen is oval, two-thirds as wide as long, and nearly as high as it is wide. The cephalothorax is three-fourths as wide as long, widest across the dorsal groove and narrowing gradually to half as wide in front. The eyes of the upper row are twice as large as those of the front row. The first legs are longest in both sexes, measuring in the female over twice the length of the body and in the males three times. The spines are very long on the legs and palpi but only a little darker in color. The general color is pale yellow or white, with two broken gray stripes on the cephalothorax and two middle and several lateral rows of light gray spots on the abdomen. The spinnerets are slender and two-jointed. The opening of the air-tubes is halfway between the spinnerets and the epigynum. The palpi of the male (fig. 47) are long and slender, and the tibia is slightly curved and has a large thin process on the outer side.
THE GENUS CLUBIONA
These spiders are all pale and most of them without markings. The eyes are close to the front edge of the head and cover more than half its width (figs. 50, 54, 56). The upper row is longer and the eyes larger and the middle pair farthest apart. The distance between this pair varies according to the species. In crassipalpis and canadensis it is little more than that between the middle and lateral eyes, while in rubra it is nearly twice as great. The mandibles of the females are swelled at the base in front, and this swelling is greatest in canadensis (fig. 55). The mandibles of the males are longer and are shaped in a variety of ways according to the species. The shape of the epigynum is indistinct and variable, and females of different species are difficult to distinguish. The females of ornata and excepta are known by their markings and those of rubra by their size and resemblance to the male. The females of crassipalpis and tibialis are doubtful. The palpal organs and male palpi are of great variety and distinguish the males of all species without much difficulty.
The Clubionas live in flat tubes of silk on leaves of low plants in summer and under bark and stones at all seasons.
Clubiona crassipalpis.—A quarter of an inch long and pale, without markings. The head is sometimes a little darker than the rest of the body, and the mandibles and ends of the male palpi are always darker. The eyes of the upper row are almost equidistant, the middle pair only a little farther apart than they are from the lateral eyes. The mandibles of the male (figs. 49,