OF PSEUDOCOCCIDAE & ERIOCOCCIDAE 13 



11B) at the apex of the head ; posteriorly, the ventral arm disappears before 

 reaching the level of the ventral eyes. In Ceroputo and Nairobia groups, all arms 

 of the midcranial ridge meet at the apex of the head, and a cruciform structure is 

 formed (Text-figs. 33B, 35B, 37B). The lateral arms are usually well developed, 

 but sometimes reduced (N. nipae). The postoccipital ridge (por) is slender and 

 usually distinct although sometimes only marked by a sclerotized stripe (C. pilo- 

 sellae) ; the ridge is U-shaped and medially continuous in almost all the species, 

 but in S. sacchari it is V-shaped and medially interrupted. According to Makel 

 (1942), the postoccipital ridge serves for the attachment of the cephalothoracic 

 muscles. The area bounded posteriorly by this ridge is the dorsomedial part of 

 the epicranium (dmep), which corresponds to the median crest in Diaspididae (Theron, 

 1958 and Ghauri, 1962) ; this area is slightly raised, well sclerotized, without 

 polygonal reticulation. 



The preocular (procr) and postocular (pocr) ridges were described as being fused 

 below the lateral ocellus to form the characteristic Y-shaped structure on each side 

 of the head (Theron, 1958 ; Giliomee, 1961), and this condition was considered by 

 Theron as " a minor specialization " in Pseudococcidea. The present study showed 

 that indeed this condition obtains in most species studied, but certain differences 

 in details in a few of them, as well as the conditions described by Giliomee (1967) 

 in some species of Coccidae, indicate that the interpretation of this " fusion " is 

 rather inaccurate. Giliomee (I.e.) found, in Eriopeltis spp. for example, that the 

 pre- and postocular ridges are connected just below the ocellus by a longitudinal 

 inter ocular ridge (ior), giving support to the preocular ridge and its articulation with 

 the antennae ; he suggested that this condition may be a forerunner of the situation 

 in Pseudococcidae where the two ridges are fused. The present author found that 

 most Pseudococcidae have the connecting interocular ridge well developed, and in 

 some species (e.g. P. citri, Text-fig. 5 and T. newsteadi, Text-fig. 20) a short, though 

 well marked lower part of the preocular ridge extends below the point of junction. 

 It appears, therefore, that the Y-shaped ridge on the side of the head is a complex 

 structure of : (1) the upper part of the preocular ridge, intimately fused with (2) 

 the interocular ridge, which joins (3) the postocular ridge below the ocellus, with 

 simultaneous more or less considerable reduction of the lower part of the preocular 

 ridge. This condition, although reminiscent of that found in some species of 

 Coccidae, is not necessarily evolved from it, but probably developed independently 

 within Pseudococcidae and represents a specialization of this family. It also seems 

 that this Y-shaped fusion of the ocular ridges serves to render support to the weakly- 

 developed preocular ridge and its articulation with the antennae. 



In Ceroputo and Nairobia groups the pre- and postocular ridges are well separated, 

 but a longer (C. pilosellae, Text-fig. 34), or a shorter (N. bifrons, Text-fig. 38) 

 rudiment of the connecting ridge is present, arising from the anterior edge of the 

 postocular ridge just below the ocellus and extending anteriorly towards the 

 preocular ridge. An aberrant condition was found in C. insolitus (Text-fig. 36), 

 where a ridge anteriorly arising from the postocular ridge and directed towards 



