Dorsal sclerite of labrum chestnut brown, with minute spinules; anterior- 

 margin processes reddish; setae 5 and 6 brownish; seta 3 grayish; the other 

 setae light; arrangement and form of the setae as in B. be Hi cos a. 



Mandibles reddish apically in some specimens, thinner than in 

 B. bellicosa, yellowish at the margin, black basally ; brush of chaetoids 

 light, setae situated basally, dorsal seta short, brown; ventral light, small. 



Pronotum whitish; spinules lighter than in B. b e 1 1 i c o s a, brown, larger 

 near the anterior margin, which is narrow, chestnut brown; lateral margin 

 slightly wider, with smaller spinules; surface with brownish dots, one dot 

 in the middle lateral to the median suture, 2 dots further posteriorly; large 

 dots on small, brown area in each half near the posterior margin, small 

 dots anteriorly on light background in the same group, 4 large dots anteriorly 

 and laterally; posterior margin wide, separated by a chestnut brown stripe 

 from the other surface, its middle brownish, with minute spinules, with black 

 stripe posteriorly, light laterally and with larger spinules; posterior-angle 

 process of posterior margin small, reddish brown, with a few, small, dark 

 spinules, and divided from the rest of the margin by narrow black stripe, 

 base of process with large, reddish black spot. Anterior-angle and 

 medioanal seta moderately long, pinkish brown, other setae lighter, their 

 arrangement and size as in B. b e 1 1 i c o s a. 



Number and arrangement of gills of B. 



thamastoides 



Segment 



Dorsal 



Ventral 



2 



1 

 1 



1 



3 



1 



1 



4 



1 (0) 



1 (0) 



Mesonotum without curved posterior process, in contrast to B. belli- 

 cosa; median suture very thin posteriorly; anterior margin with wide 

 pinkish brown stripe lateral to median suture; spinules covering the whole 

 tergite; greater part of surface chestnut brown, light brown posteriorly; 

 a large whitish area in the middle, sides with white stripe without spinules; 

 dots brown or light brown; spot at posterior angle large, blackish, with 

 reddish brown outline; small, oblique, narrow, dark band; anterior -angle 

 seta situated more posteriorly, this and the medioanal seta pinkish brown, 

 longer than the others. 



Metanotum with 5 — 6 brown setae, 3 of them moderately long, on the 

 site of each anterior median sclerite; 3 setae on the site of each posterior 

 median sclerite; medioanal seta long, brown, second seta moderately long, 

 third seta small; a small brown sclerite at the base of the setae. Lateral 

 sclerites slightly sclerotized posteriorly, light brown, with a large brownish 

 dot and an indistinct posterior border; a transverse band of dark streaks and 

 groups of chestnut brown dots; anterior area with 10—11 chestnut brown 

 setae, 3 of them, including the primary seta, moderately long. 



129 



