Vol. 33, pp. 101-102 December 30, 1920 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



A NEW DIPLOPOD OF THE GENUS ATOPETHOLUS. 



BY RALPH V. CHAMBERLIN. 





A series of specimens recently sent for identification from 

 the National Museum prove to represent an undescribed 

 species of the Spiroboloid genus Atopetholus, proposed by the 

 writer in these Proceedings for Dec, 1918 (Vol. 31, p. 167), 

 the present one making the fourth known species. The types 

 of the new species were collected by Gordon Grant on Dec. 

 30-31 at Los Angeles in Edendale suburb (Silver Lake) and 

 on Bishop's Road. 



Atopetholus angelus, sp. nov. 



Clearly distinct from the previously known species in the structure of 

 the gonopods of the male. As compared with those of the genotype, 

 A. calif ornicus, the caudal or reflexed limb of the median plate of the 

 anterior gonopods is narrower; ventral end of plate either evenly rounded 

 or weakly indented. Posterior apophysis of telopodite of anterior gono- 

 pods in ventral view longer and more slender, not expanded distally; 

 the distomesial angle of telopodite more prominent, often meeting its 

 mate in the middle line. Telopodite of posterior gonopods distally more 

 strongly uncate than in californicus or fraternus; a small point or mucron 

 from bentral side of base of hook. General color typically shining black 

 with a narrow, typically ferruginous but sometimes nearly white, pale 

 line along caudal border of each segment, the collum having an anterior 

 ferruginous border as well. Legs from dark brown to fuscous or black. 

 Sulcus of head widely interrupted in the upper frontal region, elsewhere 

 deep, especially in clypeal region. Clypeal foveolae 5 + 5, the most ectal 

 one on each side separated by a wider space than the others. Collum 

 narrow on each side below as usual, extending freely below level of second 

 tergite farther than in the other species; tip on each side bent slightly 

 caudad so that the caudal margin just above the end appears weakly con- 

 cave ; anterior margin incurved opposite cardo, forming a prominent obtuse 



22 — Proc. Biol. Soc. Wash., Vol. 33, 1920. (101) 



