4 8 



SCIENCE- GOSSIP. 



BRITISH FRESHWATER MITES. 



By Charles D. Soar, F.K.M.S. 



I ( '/>/// iiiitril from page 19.) 



GENUS PI ON A. 



nn HE characteristics of this genus are : body sof t- 

 -*- skinned ; claws to all feet ; fourth pair of 

 legs much modified in the male ; three discs let 

 into each plate on each side of the genital fissure, 

 and a small peg on the fourth segment of the palpi 

 partly projecting over the fifth. This peg is on the 

 inner edge of each palpus. The females of some 

 species of this genus appear to be fairly common, 

 but the males are very rare. I have myself taken 

 a number of females whilst collecting, but have 

 never met with any males. Piersig describes five 

 species for Germany, but at present I shall only be 

 able to give two for Britain. I believe I have the 

 females of two others, but until the males are found 

 they must go unrecorded. 



1. Piona ornata Koch. 



Body. — Female oval in shape, length about 

 1.40 mm., breadth about 1.14 mm. Colour a bright 

 red, with dark brown markings ; a yellow or some- 

 times pale-red patch occurs in the centre of the 

 dorsal surface. 



Fig. 1. Piona ornata. Genital area of female. 



Legs. — First rjair about 1.40 mm. Fourth pair 

 about 2.40 mm., with claws to all feet. The claws 

 on the fourth pair are smaller than the others. The 

 legs are like those we find on the females in the 

 genus Curvipes. In colour a pale blue, becoming- 

 yellow towards the feet. 



Epimera.-— In four groups, the last pair being 

 much pointed posteriorly (fig. 1). Colour a pale 



Fig. 2. P. ornata. Peg on palpi. 



slaty-blue, as are all the chitinous parts of this 

 mite. 



Palpi. — About 0.48 mm. in length, with a peg- 

 on the inner edge on the fourth joint (fig. 2). 



Genital Area. — Composed of two plates, with 

 three discs on each plate (fig. 1). 



Male. — Smaller than female, being about 0.88 

 mm. long and 0.66 mm. in breadth. The epimera 

 in three groups (fig. 3), not in four like the female, 



Fig. 3. P. ornata. Epimera of male. 



covering a great part of the body. The third pair 

 of legs are the shortest, and have modified tarsi. 

 The best point of difference between the sexes, and 

 the best point for the recognition of species, is the 

 fourth leg (fig. 4), which is very peculiar with its 

 fourth thick seement. 



Fig. 4. P. ornata. Fourth leg of male. . 



Localities. — Not very common. The first female 

 found in Britain was in Lincolnshire, and sent to 

 me by Dr. George in May 1895, since which I have 

 myself found about six females in different places, 

 at Sunningdale and in Suffolk. The male of this 

 sxoecies was only found in the spring of 1900 in 

 this country, a single specimen having been sent 

 to me in May of this year by Dr. George, through 

 whose courtesy I now record it for the first time in 

 Britain. 



2. Piona latipes Miiller. 



Body. — Female very like the female of the pre- 

 ceding mite. About 1 mm. in length and about 

 0.80 in breadth. It is of a bright red colour, with 

 dark markings, slightly lighter in tone on the 

 front and posterior margins. There is a very light 

 T-shaped patch in the centre. The whole colour is 

 red, including legs and all chitinous parts as well 

 as the softer parts. Male. — This is also of a bright 



