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Notes: Summary The entire rhabdom of the ommatidia in dorsal and ventral eyes (“superposition eyes”) ofGyrinus proceeds from the base of the crystal cone to the vicinity of the basal membranewithout any interruption. However, a differentiation of three distinguishable sections can be recognized. The electronmicroscopic results presented in this paper show that the distal section of the ommatidial retinulae contain the rhabdomere of cell 1 only. The proximal section is occupied by the basal rhabdom of cells 2–7, further proximal by the much smaller rhabdomere of cell 8. Concerning a probable ability to use the pattern of polarized skylight for orientation, the alignment of the microvilli as well in one ommatidium as across large areas of the eye is of special interest. In the ventral eye the microvilli-alignment of cells 1–7 shows one direction over large ommatidial areas, respectively. This only partially comes true for the alignment in the dorsal eye, since there also occur twistings. As a consequence microvilli of corresponding cells may point towards different directions. In both eye types the rhabdomeres of neighbouring cells 8 can point towards different directions. Sometimes microvilli of one cell 8 gather in tufts with axises different directions. There are substantial differences in both the ventral and dorsal eye concerning the rhabdomere of cell 1. The relations of alignment of rhabdomeres described in this paper are subject for a discussion on a probable analysis of polarized light byGyrinus.

Notes: Summary The eyes in 55 species of 8 subfamilies of long-horned beetles (Cerambycidae) have been examined ultrastructurally. An eye consists of acone ommatidia of which each is assembled by a bi-convex corneal lens, 4 Semper-cells, 8 retinula cells, 2 primary pigment cells, and of a larger and variable number of secondary pigment cells. The differently arranged rhabdomeres of the — as a rule — open rhabdoms can be summed up to two basic patterns: In the case of the basic pattern 1 the central rhabdomeres R 7/8 are completely isolated from the peripheral rhabdomeres R 1–6. As to the basic pattern 2 the central rhabdomeres R 7/8 are structurally attached to the peripheral rhabdomere arrangement through R 1 and R 4. Due to different directions of the microvilli in R 7 and R 8 there occur several rhabdomeral shapes. Furthermore, within some taxa partially fused rhabdoms are present; in one species the fusion is even complete. Nevertheless, a derivation from an open rhabdom with reference to one of the basic patterns is always possible due to a clear homologous comparison of the anticipating retinula cells. The successfully answered question upon a taxon-specifity of the basic patterns and the rhabdomeral shape allows statements as to the value of these ultrastructural patterns for a phylogenetic argumentation. In Cerambycidae the distinct and not uniform arrangement of these patterns and shapes within lower, closer related taxa represents the occurrence of convergencies (as compared to the extraordinarily similar rhabdoms in Chrysomelidae, Wachmann, 1977, which receive in this paper a further support as to their subfamiliar specification). However, these convergencies are demonstrable through the phylogenetic system only. Thus, patterns of open rhabdoms can only be used as more or less additional indices on a monophyly of groups which already has been proved by means of other characteristics. In spite of an extreme conformity within different taxa rhabdomeral characteristics solely are not appropriate enough in order to separate monophyletic groups. The ultrastructural investigations give a good basis as to the interpretation of the function of the different rhabdoms. However, the question remains not answered whether there exist equal or unequal strategies of circuits within the lamina and medulla.

Notes: Summary Eyes of the Coleoptera previously examined possess fused rhabdoms in all but a few species that have open rhabdoms consisting of 2 central and 6 peripheral rhabdomeres. Recent investigation of more than 70 species from about 20 families (with a total of 150,000 species) led to the conclusion that nearly one-half of all Coleoptera species possess the open-rhabdom type of eye. All of these species belong to the Cucujiformia (composed of the 5 superfamilies Cleroidea, Lymexyloidea, Cucujoidea, Chrysomeloidea and Curculionoidea, sensu Crowson, 1967), and — until now — no species of this group has been found to have fused rhabdom eyes. The open rhabdomic eye is therefore considered a synapomorphous feature (sensu Hennig, 1966) of the Cucujiformia, and this taxon is regarded as a monophyletic. From electronmicroscopic examinations of 41 Chrysomelidae species from 9 subfamilies and of 18 Cerambycidae of 3 subfamilies, the position of the central rhabdomeres (R 7, 8) relative to the peripheral rhabdomeres (R 1–6) and the direction of microvilli in the central rhabdomeres were chosen for comparison. The central rhabdomeres were found to be fused, laterally, to R 1 and R 4 in all of the species from the subfamily Chrysomelinae, but no such fusion was found in any species of the other 8 subfamilies of the Chrysomelidae, nor in any of the Cerambycidae or Bruchidae examined. Microvilli of R 7 and R 8 are parallel in Donaciinae, Criocerinae, Eumolpinae, and many Chrysomelinae, and in Lepturinae, Cerambycinae and Lamiinae (Cerambycidae) and in Bruchidae. Microvilli of both rhabdomeres are aligned in several directions in the Galerucinae, Hispinae, Clytrinae, but only inPhytodecta of the Chrysomelinae, and characteristic differences in the arrangement of microvilli were recognized among these Chrysomelidae. Microvilli were parallel in one of the central rhabdomeres, but aligned in two or more directions in the other, in species of Megalopodinae, Orsodacninae, but only inTimarcha among Chrysomelinae, and again the arrangement of microvilli was characteristic of the subfamilies of these Chrysomelidae (exception: Chrysomelinae). The central rhabdomere systems possessing microvilli of only one direction, but not fused at any level of the ommatidia with peripheral rhabdomeres, are considered symplesiomorphous for this superfamily. This simple arrangement of microvilli in many diverse groups of Chrysomelidae, Cerambycidae and Bruchidae may be regarded as the basic pattern from which the different arrangements in other subfamilies were derived. Similarities in arrangement of the microvilli (among taxa of different families) are considered to be convergences. — The results are also discussed with a view to functional properties of the rhabdomeres.