The embryology of Lytta viridana Le Conte (Coleoptera: Meloidae). VII. Eighty-eight to 132 h: the appendages, the cephalic apodemes, and head segmentation
This study deals with segmentation and the segmental appendages in Lytta viridana from 88 to 132 h. The emphasis is on head segmentation. The first part of the paper describes the development of the appendages at 88, 120, and 132 h. The main changes involve the rotation of the mandibles through 120° in a posteromedian direction, which begins shortly before 88 h and is complete at 132 h, the fusion of the labial appendages at 120 h, and the movement of the labium forward in front of the maxillae at 132 h. Blastokinesis, which in this species is limited to the formation of a prominent secondary dorsal organ, occurs at 120 h. The second part describes the cephalic apodemes and tentorium at 88, 120, and 132 h. Cephalic apodemes appear in the labral, antennal, intercalary, mandibular, maxillary, and labial segments. Since the labrum arises from two appendage-like rudiments, possesses mesoderm that arises in situ and is provided with coelomic sacs, and has a pair of apodemes, it is considered to be appendicular. Hence the head is believed to consist of an acron and six metameres.