ИСТИНА

Larvae and pupae of Poecilus (s. str.) versicolor (Sturm, 1824) and P. (s. str.) reflexicollis Gebler, 1830, obtained in the laboratory between 1.06.2015 and 27.08.2015 at 22–24°C and LD 16:8, served us as study material. Stages of prepupal morphogenesis were evaluated based on the shape and position of pigmented eye spots: these latter separated from the eye tubercle and shifted proximad to reach the prothorax border, at which stage a molt ensued. Since the duration of a prepupal stadium differed in both species, it was the position of the pigment spot that comparisons between the stages of morphogenesis were based upon. In the beginning of prepupal morphogenesis, when the pigment spots were located in the postocular furrow area, segments IX and X retained a size and a structure typical of the larva, but the ventral area of segment IX showed genital system anlage. The middle stage of morphogenesis, when the pigment spots were located between the postocular and occipital furrows, was characterized by the appearance of external genitalia on sternite IX, while the ducts of the genital system grew differentiated and considerably elongated. The proportions of the urogomphi and segments IX and X remained almost unchanged. In the final stage of prepupal morphogenesis, when the pigment spots were placed proximal to the occipital furrow, both urogomphi and segment X became considerably shortened, and the genitalia differentiated to show clear distinctions between the sexes. Further on, in the pupal stage, the urogomphi went on shortening, segment X was diminished in size and invaginated inside segment IX, whereas, in contrast, both VII and VIII expanded to attain a structure typical of an imago. The above observations allow for a few conclusions to be drawn: (1) in the course of metamorphosis, segment X is gradually reduced to take no part in the formation of a genital system, this observation contradicting those of Jeannel (1941) and Snodgrass, 1957; (2) external genitalia are derived from sternite IX alone, their relations to pleurites or tergites IX (Verhoeff, 1918; Bils, 1976; Deuve, 1993) being refuted; (3) there is no evidence whatever for the external genitalia being derived from extremities (Singh-Pruthi, 1924a; Dupuis, 1950; Metcalfe, 1932; Matsuda, 1976; Bils, 1976); (4) our data confirm the hypothesis that the male aedeagus in Carabidae is a new formation (Sharp, Muir, 1912; Matsuda, 1976). There is no question that the above information is provisional and requires verification using other species, first of all those which represent basal subgroups of the family.