Ueber die pygidialdruese von enhydrus sulcatus (Wied., 1821) (Coleoptera, Gyrinidae)

The structure of the defence glands in the Dytiscidae, Noteridae, Haliplidae and Gyrinidae (Coleoptera)

“…(Bordas, 1905). Colombini (1935) made a similar study of the pygidial glands of Cybister roeselii F., as did Barth (1960) of the pygidial glands of the Gyrinid Enhydrus suIcatus Wiedemann. He considered that the secretion from the first site was by unicellular dermal glands but gave no explanation for that of the second nor for the function of the secretion apart from that of lubrication of the integument.…”

“…The secretory lobe is about 1.4 mm. The illustration by Barth (1960) of Enhydrus shows that the collecting canal enters the duct proximal to the valve and that ducts from a discrete group of secretory cells enter the reservoir distal to the valve. It is mediodorsal to the reservoir, lying between it and the hind gut.…”

“…was described by Bordas (1899), but he did not mention the opening valve or its relationship to the entry of the collecting canal. Dierckx (1899a) described the secretory cells of Gyrinus natator, and Barth (1960) described the glands of Enhydrus sulcatus. Hatch (1925) considered Enhydrus to be the most primitive of living Gyrinids.…”

“…Such an arrangement is only functional if the valve is proximal to the entry of the collecting canal, as in all the previous species. The illustration by Barth (1960) of Enhydrus shows that the collecting canal enters the duct proximal to the valve and that ducts from a discrete group of secretory cells enter the reservoir distal to the valve.…”

“…Blunk (1917) noted the presence of a pair of glands which open on the prothorax in two species of Dytiscus, and Casper (1 9 13) and Korschelt (1924) described the structure of both the thoracic and the pygidial glands of D. marginalis in detail. Colombini (1935) made a similar study of the pygidial glands of Cybister roeselii F., as did Barth (1960) of the pygidial glands of the Gyrinid Enhydrus suIcatus Wiedemann.…”