670 



PROCEEDINGS OF THE NATIOXAL MUSEUM. 



VOL. 56. 



PARATETRANYCHUS MODESTUS (Banks). 



Tetranychus inodeshis Baxks, 1900, U. S. Dcpt. Agi-ic, Div. Entom., Tech. Ser. 

 No. 8, p. 73. 



It is necessary to revise radically Banks's (9) original description 

 of this species. He writes that the tarsus "ends in a long 

 simple claw," and that the palpal "thumb" is not as long as 

 claw, with three nearly equal fingers on tiie tip. A critical study 

 of the type material reveals the fact that the tarsal claw is not simple 

 but possesses a series of six appendiculate spurs, 

 while the palpal "thumb" actually considerably 

 exceeds tiie claw, and only the one usual terminal 

 "finger" occurs on the "thumb," as well as the 

 customary two digituli. A revision of the original 

 description based on a careful study of the type 

 material is as follows: 



Head, palpi, and legs are brownish: the body 

 yellowisli, with quite large blackish irregular spots 

 across middle of thorax; a large lateral spot in region 

 of last pair of legs; and a broad irregular border 

 around end of body. Body rather more elongate 

 than usual ; bristles in tlie usual arrangement. Legs 

 sliort; femur I fully twice as long as broad: tibia I 

 only a trifle longer than patellal; tarsus short, ends 

 in a large, uniformly curved, acuminate claw, which 

 is uncleft to its tip; arising ventrally from this claw, 

 at a point one-quarter its length from the base, are 

 six closely clustered appendicidate spurs which are 

 two-thirds the length of tiie main claw and fused for about half their 

 length. The usual series of four tenent hairs arise by the sides of 

 the base of tlie claw from the tip of the onychium. Mandibular 

 plate of moderate length, not much narrowed toward tip, which is 

 broadly rounded. Palpi sliort, "thmnb" a trifle wider than long, 

 bearing at its tip a slender "finger" three times as long as thick 

 whose base is less than half as wide as tip of "thumb." On its upper 

 distal corner are two digituli one-lialf again as long as the terminal 

 ' 'finger,' ' on upper side barelj^ halfway to the base is a smaller 'finger' ' 

 a trifle over iialf the thickness of the terminal "finger," and between 

 this and base are two short hairs. Another similar hair arises latero- 

 ventrally near the center of "thumb." On each side of the anal 

 opening there is a pair of fine hairs. 



Found in August at Washington, District of Columbia, causing' a 

 rustlike appearance on the blades of corn. 



Fl<; . 8.— I'AKA'iHTItA- 

 NYCHUS MODESTUS 

 JiANKS. 1, TARSAL 

 APPKNT)AGES; 2, 

 MANDIBULAR PLATE; 

 3, PALPAL "THUMIi" 

 AND ITS APPENDAGKS 

 (ORIGINAL). 



