The systematics and biology of the south African gall-inducing scale insect, Calycicoccus merwei brain (Hemiptera : Coccoidea : Eriococcidae)

The scale insect genus Calycicoccus Brain has a single described species, C. merwei Brain, which is endemic to southeastern South Africa. Females of C. merwei induce small, mostly conical galls on the foliage of their host tree, Apodytes dimidiata E. Meyer ex Arn. (Icacinaceae), which has a wider, mostly coastal distribution, than that currently known for the scale insect. Calycicoccus has been placed in the family Eriococcidae and may be related to the South American genus Aculeococcus Lepage. No other native eriococcid species have been described so far in South Africa, although the family is diverse in other Gondwanan regions. This paper summarizes the biology of C. merwei, redescribes the adult female, describes the adult male, the second-instar female and the first-instar nymphs for the first time, and reconsiders the phylogenetic relationships of the genus. The adult female is shown to have unusual abdominal segmentation, in that segment I is present both dorsally and ventrally, but a segment is absent ventrally on the middle abdomen. First-instar nymphs are sexually dimorphic; males have a larger and relatively narrower body, larger mouthparts, longer antennae and legs, and more thoracic dorsal setae compared with females. Molecular data from nuclear small-subunit ribosomal DNA (18S) and elongation factor 1 alpha (EF-1a) show C. merwei to have no close relatives among the Eriococcidae sampled to date. Instead, the Calycicoccus lineage is part of a polytomy near the base of the Eriococcidae. Molecular dating of the node suggests that the Calycicoccus lineage diverged from other eriococcids more than 100 Mya. These data support the placement of Calycicoccus as the only genus in the subfamily Calycicoccinae Brain.

Aryliminopropadienone-C-amidoketenimine-amidinoketene-2-aminoquinolone cascades and the ynamine-isocyanate reaction

Imidoylketenes 11 and oxoketenimines 12 are generated by flash vacuum thermolysis of Meldrum's acid derivatives 9, pyrrolediones 17 and 18, and triazole 19 and are observed by IR spectroscopy. Ketenimine-3-carboxylic acid esters 12a are isolable at room temperature. Ketenes 11 and ketenimines 12 undergo rapid interconversion in the gas phase, and the ketenes cyclize to 4-quinolones 13. When using an amine leaving group in Meldrum's acid derivatives 9c, the major reaction products are aryliminopropadienones, ArN=C=C=C=O (15). The latter react with 1 equiv of nucleophile to produce ketenimines 12 and with 2 equiv to afford maIonic acid imide derivatives 16. N-Arylketenimine-C-carboxamides 12c cyclize to quinolones 13c via the transient amidinoketenes 11c at temperatures of 25-40 degrees C. This implies rapid interconversion of ketenes and ketenimines by a 1,3-shift of the dimethylamino group, even at room temperature. This interconversion explains previously poorly understood outcomes of the ynamine-isocyanate reaction. The solvent dependence of the tautomerism of 4-quinolones/4-quinolinols is discussed. Rotational barriers of NMe2 groups in amidoketenimines 12c and malonioc amides and amidines 16 (24) are reported.