Noonilla

A mysterious genus that is known from males of the monotypic species Noonilla copiosa.

Identification
Petersen (1968) - This new genus is readily differentiated from all other ant genera, in fact from all other Hymenoptera, by the highly unusual shape of the genitalia including the supporting structure in connection with sternum 8. The absence of a distinct gonobase and the strongly reduced gonocoxites recall the condition in some Chalcidoidea (Snodgrass, 1941). Other unique and distinctive characters of Noonilla are the shape of the coxae with prolongations beyond the trochanters and probably the shape of the petiole with the spiracles placed on prominences.

The wing venation of Noonilla is also extraordinary, but not unique as almost exactly the same pattern exists in the genus Scyphodon. The wing venation of Scyphodon is just a little more reduced and the marginalis longer and narrower, and this type of venation is no doubt transitional between Noonilla and the condition found in Phaulomyrma and Leptanilla. On account of the type of venation and the peculiar shortened shape of the proximal part of the forewing it is apparent that Noonilla is closely related to these Leptanillinae with which Noonilla shares several other features which are mainly apomorphic, e. g. the one-segmented maxillary and labial palpi, the shape of the pronotum, the strong and crooked fore femora, the absence of meta pleural glands, the reduction of the terminal abdominal segments, the absence of a true gonobase, and the absence of volsellar cuspital lobes.

On the other hand it is apparent that Noonilla occupies a rather isolated position within the Leptanillinae, not because of the unique and specialised features of the fore coxae, the petiole, and the genitalia, but because the genus has retained some plesiomorphic features which are apomorphic in all other known leptanilline males, viz., the vertical head and the normal, rather short, uncompressed thorax which give Noonilla a quite different general appearance to other leptanillines which have a horizontal head and an elongated, laterally compressed thorax. This clear gap between two groups of leptanilline males may give rise to phylogenetic speculations, but in the present state of knowledge of the subfamily and without knowing workers and queens, these seem premature.

Nomenclature

 *  NOONILLA [Leptanillinae]
 * Noonilla Petersen, 1968: 582. Type-species: Noonilla copiosa, by original designation.
 * Noonilla incertae sedis in Formicidae: Ogata, Terayama & Masuko, 1995: 33.
 * Noonilla in Leptanillinae: Boudinot, 2015: 32.

Description
Male. Head vertical; frontoclypeal region not differentiated by sutures or carinae (fig. 7). Antennae fifiform, 13-jointed. Mandibles vestigial, cylindrical, bluntly rounded apically, setaceous. Maxillary and labial palpi one-segmented.

Thorax not compressed and not elongated (as in other leptanillines). Dorsal part of pro no tum neck-like, lateral parts long, posterolateral borders extend onto the ventral surface; propleuron undivided; prosternum small, triangular (fig. 8). Mesoscutum lacking notauli and parapsidal lines; scutellum simple, strongly convex; mesopleuron large, strongly bulging ventrally, oblique pleural line weak. Metanotum narrow, central area prominent; metapleuron undivided, invisibly fused to pcropodeum; metapleural glands lacking.

Legs long and slender; fore femora, however, strong and curved; fore coxae flattened, with apical prolongations beyond insertion of trochanters (fig. 8). Tibial spur formula 1:2:2. Claws simple.

Wings as shown in fig. 6. Venation of fore wing strongly reduced with only three cells, the costal cell and two basal cells hardly separated by the weak median vein; main stem of venation consists of subcosta, marginal vein replacing pterostigma which is not truly developed, a short submarginalis and a very long radialis; perpendicularly to sub costa upper and lower basal veins extend to meet an almost complete analis. Costa indicated proximally. Hind wing short, veinless; anal lobe lacking.

Abdomen curved as shown in fig. 6. Terga and sterna separate in all segments. Abdominal segment 2 (petiole) simple, anteriorly flattened with the spiracles on lateral prominences, posteriorly cylindrical without a node. Tergum 8 elongated dorsally, attenuated, apex rounded. Tergum 9 (+10) membraneous, short, covered by tergum 8; pygostyli lacking. Sternum 8 strongly reduced, its lateral portions still plate-like but ventrally it is a narrow, strongly sclerotized bar. This bar supports the two arms of a reversed v-shaped, strongly sclerotized structure in firm connection with the genitalia, probably a true gonocondyle; the structure bears a short anteromedian process. Sternum 9 not recognizable as a normal sclerite; it might have been strongly modified into the structure mentioned above, or it might have fused with the ventral bar of sternum 8.

Genitalia(terminology of Michener (1956) used throughout the paper) very large, non-retractile (figs. 9, 10). Gonobase lacking; basal shaft of genital organ consists presumably of fused strongly reduced gonocoxites, dorsally, and medially fused volsellar plates, ventrally; gonostyli lacking; volsellar digiti strongly sclerotized, bluntly hooked at apices; penis valves proximally united constituting a cylindrical tube, distally and ventrally separated from tip of dorsal, oval phallotreme to well anterior to the unusual trigger-like ventral structure which is also divided into two symmetrical parts.