68 



MORPHOLOGY AND TAXONOMY OF ADULT MALES 



primitive : (i) the absence of the preocular ridges ; (2) the presence of a pair of 

 prosternal apophyses ; and (3) the less pronounced sclerite degeneration of the 

 abdominal segments. 



According to Hambleton (1946), the genera Rhizoecus, Riper siella, Geococcus and 

 Pseudorthizoecus appear to be elements of a natural group within the mealybugs, to 

 which he also added 4 new genera : Radicoccus (Radiococcus, misspelling), Brevi- 

 coccus, Morrisonella and Neorthizoecus. This group was erected on the basis of 

 certain female characters (geniculate antennae and nature of the anal ring) and 

 on the fact that all these genera include ground-inhabiting species. Apart from 

 Rhizoecus, no information about the males of this group is available, and it would 

 be interesting if Hambleton's conception of this natural group could be confirmed 

 on the basis of male characters also. 



Relationships between the groups of Pseudococcidae 



The relationships between the groups of genera is illustrated in table IV which 

 shows : (1) the number of characters shared by any pair of groups ; (2) the number 

 of characters exclusive to each of these pairs ; and (3) the number of characters 

 by which the pairs of groups differ from each other. These affinities are based on 

 the total number of shared characters, since the specialized or primitive condition 

 of most of these could not be determined with great certainty. 



Table IV 

 Relationships between the groups of genera 



Number of Characters. 



Pairs of groups 



Planococcus — Pseudococcus 

 Planococcus — Saccharicoccus 

 Planococcus — Octococcus 

 Planococcus — Ceroputo 

 Planococcus — Nairobia 

 Pseudococcus — Saccharicoccus 

 Pseudococcus — Octococcus 

 Pseudococcus — Ceroputo 

 Pseudococcus — Nairobia 

 Saccharicoccus — Octococcus 

 Saccharicoccus — Ceroputo 

 Saccharicoccus — Nairobia 

 Octococcus — Ceroputo 

 Octococcus — Nairobia 

 Ceroputo — Nairobia 



Examination of this table suggests that : 



(a) The Planococcus and Pseudococcus groups are the closest relatives, sharing 

 the largest number of characters (44) and differentiated by the smallest (4). 



(A) 



(B) 



(C) 



Shared 



of which 

 exclusive 



Differentiating 



44 







4 



38 







10 



37 







11 



25 







22 



26 







22 



42 







14 



36 







21 



22 







35 



24 







33 



3i 







27 



18 







39 



20 







38 



32 



4 



25 



28 







30 



34 



8 



24 



