288 



cobb: notes on mononchus and tylenchulus 



Fig. 2. Nearly adult male 

 of Tylenchulus semi-pene- 

 trans, a, mouth pore; b, an- 

 terior part of spear; c, pro- 

 truding-muscle of spear; 

 d, beginning of oesophagus; 

 €, deteriorated median bulb; 

 /, nerve-ring; g, deteriorated 

 posterior bulb; /t, beginning 

 of intestine; i, terminus; 

 j, larger intestinal granule; 

 k, smaller intestinal granule; 

 I, anus; m, left spiculum; 

 n, excretory pore; o, sper- 

 matocyte; p, vas deferens; 

 q, spermatozoon. 



roots, and Circular No. 85 was issued to 

 call the attention of other investigators 

 to the subject. 



The writer has recently examined the 

 nematode mentioned, and finds it a 

 new generic form, for which the name 

 Tylenchulus is most appropriate. 



Tylenchulus has the characters of 

 Tylenchus, except that, (1) there is no 

 functional anus; (2) the excretory pore 

 is near the middle of the body, or even 

 farther back in the adult female; (3) 

 there is no male bursa; (4) the male prac- 

 tically loses the spear at the final moult ; 



(5) the cuticle of the female is much 

 thickened when the posterior portion of 

 the body becomes saccate at maturity; 



(6) the vulva is located in a deep suture. 

 The type species is : 



Tylenchulus semi-penetrans, nov. gen., 

 n. sp. 



U. _^l^ 67.' ' 90. 94 .' 



7.1 2:7 



-M 88. 



2.2 7.1 8.7 20. 

 3.3 16. 29. 



2.7 



.5 mm. 



4 mm. 



2.2 2.7 2.7 3. 



Cuticle naked, traversed by 400-500 plain 

 transverse striae. Neck cylindroid, becom- 

 ing convex-conoid near the continuous head, 

 which is rounded in front. No lips, amphids 

 or eye-spots. Spear and oesophagus typi- 

 cally tylenchoid. Median bulb ellipsoidal, 

 with valve; posterior swelling pyriform to 

 elongated, without valve. Male tail conoid 

 to the somewhat blunt terminus. Posterior 

 part of the adult female saccate, with wide 

 blunt tail bent toward the ventral side. 

 Vulva in the midst of a prominent ventral 

 suture. 



Habitat: Parasitic on citrus roots in Cali- 

 fornia and Florida. 



Fuller publication with illustrations will 

 follow. 



1 Measurement near the middle of the saccate part. 

 * Arbitrary, as there is no anus. 



