588 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.51. 



T. ununguis Jacobs, both of Europe, and T. yothersi McGregor, of 

 America. The present species also bears some likeness to Tragardh's 

 genus ScTiizotetranychus in the presence of two main divisions of the 

 tarsal claw. 



TETRANYCHINA MACDONOUGHI, new species. 



Color, bright ferruginous to orange red. Dorsal cuticular appen- 

 dages, 26, arising from very prominent tubercles, arranged as follows: 

 Two frontals, 2 subfrontals, 5 on each side along the lateral margins of 

 the abdomen, 8 grouped on the hind region of abdomen, and 4 near 

 the center of abdomen. Each appendage is rather filiform, appressed 

 plumose, slightly thicker at tip than at base, tinged with red. Body 

 elliptical, widest equatorially; cephalo thorax truncate in front; 

 abdomen rounded behind. Mandibular plate with sides arching to a 

 narrow, unemarginated tip. Palpi stout, bearing in all eight spines; 

 "Thumb" of palpus three times as long as thick, bearing two spines 

 at tip, two dorsally and one ventrally; claw of penultimate joint 

 reaching two-thirds distance to tip of "thumb." Legs I of female 

 almost two and a half times the length of body; tibia I a trifle over 

 one- third the length of entire leg; tarsi I slightly swollen immediately 

 behind tip; tarsus on its tip bears a single claw, which is nearly 

 straight for two-thirds its length and is then bent to form a short 

 hook; the claw is plumose, bearing 11 pairs of capitate spines. Aris- 

 ing from the onychium by the sides of the claw base (much as in the 

 case of Tetranychus) are the four tenent hairs, the two on each side 

 imited at base into a swollen pedicel. Comparative length of seg- 

 ments of leg I of female as follows: trochanter, 4; femur, 35; patella, 

 5; tibia, 36; tarsus, 16. Leg I of male three times the length of body. 



Type.— C&t. No. 20168, U.S.N.M. 



The type material was collected by Mr. F. L. McDonough at 

 Quincy, Florida, June 5, 1915, on the underside of leaves of Oxalis 

 stricta. The species is probably closest to TetranycJiina (NeopJiil- 

 lohius) harti of Ewing, but is easily separable from the latter as 

 follows: 



T. macdonoughi: Body, 0.43 mm. by 0.35 mm.; dorsal bristles 

 enlarged toward end; differently distributed (from that of T. harti): 

 tarsi I somewhat swollen at end; palpus bears eight bristles. 



T. harti: Body, 0.64 mm. by 0.44 mm.; dorsal bristles accuminate 

 to tip; none of leg joints swollen; palpus bears six bristles. 



Mr. McDonough says that the species is gregarious, living in small 

 colonies, just as is the case with red spiders, and that the effect on 

 the leaves is exactly similar to the work of red spiders. 



