Chorismagrion risi, Morton, 1914

Morton, Kenneth J., 1914, A remarkable new genus and new species of Odonata, of the legion Podagrion, Selys, from north Queensland, Transactions Entomological Society London 1914, pp. 169-172 : 170-172

Chorismagrion risi , n. sp.

♂. The whole of the head behind the antennae dull black; vertex frons nasus rhinarium and labrum brilliant metallic green with violet reflections; genae, base of the mandibles and basal joints of the antennae yellowish, last joint of antennae black. Underside of mouth parts mostly yellowish.

Pronotum mostly orange broadly black at the sides. Mesepisterna orange, slightly infuscated, dorsal carina black; mcsepimera, mesinfraepistcrna, metepisterna and a small triangle of metepimera near the bases of hind-wings blackish with traces of yellow near the wing-bases. Underside of thorax and the legs, pale yellowish.

Abdomen very dark green or blackish probably becoming bronzed, first and second segments with the dorsum broadly yellowish, the same colour apparently continued narrowly along the dorsum of 3rd segment; 9th segment yellowish or orange above, probably 10th segment partly marked with the same colour. Proximal ends of segments 4, 5 and 6 above and 3, 4, 5, 6 and 7 beneath marked or ringed with whitish.

Superior appendages longer than 10 and rather shorter than 9. Viewed from above they are broadest at the base at first slightly divergent then rather abruptly they converge becoming flatter or somewhat concave after the geniculation. About half-way between the head and the rounded apex, above, an interruption simulating a joint. Seen from the side these appendages are nearly straight and void of striking character save the indication of the false joint. '

Inferior appendages about 1/3 as long as the superior. Viewed in profile, they are somewhat triangular with a conspicuous process; seen from beneath they are closely approximate for about twothirds of their length, each terminating in a divergent curved process; between these processes there appear to be blades with spinulose edge.

Wings hyaline very faintly tinged with brownish, especially between costa and radius. Pterostigma short and broad, dark brown or blackish with a large orange spot which touches the costa.

♀. unknown.

Length of abdomen, 34 mm. hind-wings, 22 mm.

I have pleasure in dedicating this interesting species to Dr. Fr. Ris, Rhemau, the distinguished Monographer of the Libelluninae, in recognition of many kmdnesses received at his hands during a friendship of over twenty years.

Of Australian genera, Chorismagrion is perhaps most closely related to Synlestes , although differing therefrom in several important respects in addition to the absence of the basal side of the quadrilateral in the fore-wings. In Synlestes the anterior side of the quadrilateral is about one-half the length of the posterior side M3 separates from M 1 + 2 proximal to the sub-nodus Rs at the subnodus Cu1 and Cu2 more closely approximate at their origin, Cu1 more strongly arched. Supplementary sectors present.

To the South African genus Chlorolestes , the relation of Chorismagrion is also rather close. In this genus, M3 separates from M 1 + 2 at the sub-nodus Rs at Pnq 2 Cu1 less strongly arched than in Synlestes supplementary sectors present.

Prof. Calvert m his recent Paper * “ The Fossil Odonate Phenacolestes , with a discussion of the venation 0f the legion Podagrion, Selys , gıves a synopsis of the venatıonal characters of this legıon. The new genus would fall under-

AA.—M3 separating from M 1+2 at the sub-nodus, only two antenodals, Rs beginning distad to the sub-nodus.

VV.—Area posterior to Cu“ with one row of cells, one cubitoanal cross-vein.

For Chorismagrion a new rubric preceding Chlorolestes is required, based on the absence of the basal side of the quadrilateral and the absence of supplementary sectors. In regard to these latter it may be well to call attention to the minute rudiment at the edge of the wing between M2 and Rs ln the new genus.

The opportunity is suitable for giving a good wing photograph of Hemiphlebia , which Dr. Ris has also kindly supplied, as none of the existing figures seems to glve a direct photographic representation of the wing. In sending this photograph he points out the existence of a minute cross-vein between A* detached from the anal margin and this margin, Just at the Cuq. This detail, which Dr. Ris says is not known to him in any other Agrionid, is so minute in the photograph that it may be lost in reproduction. In one of my specimens it is more distinct, but it does not appear to be constantly present, and Tillyard’s figure truly represents in this respect the condition of another example 1n my collection.