CYDNIDAE OF THE WESTERN HEMISPHERE — FROESCHNER 411 



Mesopleuron (figs. 100, 101): Flat, with a strong, oblique, riigo- 

 pimctate groove anterior to evaporatorium; latter extensive, reaching 

 to posterolateral angle; posterior margin creniilate; mesosternum 

 prominent and subcarinate along midline, with numerous hairs on 

 apical half. 



Metapleuron (figs. 100, 101): Nearly flat, evaporatorium occupying 

 mesal two-thirds of segment; lateral polished area punctate near 

 evaporatorium; osteolar peritreme extending less than half wa}^ across 

 segment; anterior part of peritreme curved posteriorly around osteolar 

 opening which is visible ventraliy (figs. 100, 101), posterior apex 

 narrowly polished. 



Legs: Long, slender; anterior tibia (fig. 126) only moderately 

 widened, 8 to 9 stout, sharp spines dorsally, apex not prolonged beyond 

 tarsal insertion; middle and hind tibiae slender, latter (fig. 145) about 

 half as long as body, slightly curved in apical half, margins uniformly 

 spined. 



Sternites: Strongly convex; each segment with a broad, lateral area 

 of shallow punctures; segment VI sometimes modified medially on 

 posterior margin in females (see "discussion" below). 



Terminalia: Male genital capsule very broadly, shallowly emargi- 

 nate; ventral plates of female convex, flat or convex, sternite VI 

 variously or not modified (figs. 182, 183). 



Three fifth-instar nymphs were available for stud}^ These showed 

 the sparse lateral setigerous punctures of the head and body and the 

 long, terete, posterior tibia of the adult. They differed from adults 

 in possessing a weak, su]:)marginal primary setigerous puncture anterior 

 to the eye. In color they wore quite striking. The head, thorax and 

 appendages were the usual brownish black color, but the abdomen 

 was very bright red with the dorsal and lateral plates black. The 

 eyes, also, were brilliant red. 



Type of genus. — Cydnus holomelas Burmeister (1835), monobasic. 



Distribution.— The general range of Ectinopus extends from 

 Mexico south to Bolivia and BraziL 



Discussion. — The three species of this genus are structurally very 

 similar, allowing most of the physical features to be incorporated into 

 the generic description. One structural feature, however, merits 

 additional comment — the modification of the sixth sternite which 

 occurs in the females. This modification of the middle of the pos- 

 terior margin of the segment forms a progressive series from no modifi- 

 cation in the new species muticus, through a polished, flattened, 

 transverse area in rugoscutum (fig. 183) to a deep excavation between 

 a pair of prominent, blunt tubercles in holomelas (fig. 182). 



