Matching dimorphic sexes and immature stages with adults: resolving the systematics of the Bekilya group of Malagasy assassin bugs (Hemiptera: Reduviidae: Peiratinae)

The Madagascar endemic assassin bugs Bekilya Villiers and Hovacoris Villiers were described from macropterous male specimens with striking colour patterns, and are currently monotypic. Mutillocoris Villiers, with two species from Madagascar, was based on brachypterous female specimens that resemble female mutillid wasps. To investigate the validity of the three genera, recently collected specimens from Madagascar were studied with both morphological and molecular techniques. Morphology alone appeared to be of limited value for associating males with females, and immature stages with adults, because of drastic differences between the sexes and the life stages. However, the use of morphology in conjunction with molecular data resolved these associations and showed that species of Mutillocoris represent females of Bekilya and Hovacoris, which we transfer accordingly to these two genera and refer to them as the Bekilya group. The type species of Mutillocoris belongs in Bekilya, resulting in the synonymy of these two genera (Mutillocoris syn.n. ). The Bekilya group is diagnosed and several new species are described: Bekilya mahafalya sp.n. , Bekilya tenebra sp.n. , Bekilya tuleara sp.n. , Hovacoris bicolornotum sp.n. , Hovacoris melanoceps sp.n. and Hovacoris rufiventris sp.n. A total of ten species are recognized within the Bekilya group. The monophyly of Bekilya, Hovacoris and the Bekilya group is confirmed by morphological and molecular phylogenetic analyses.     

Phytogenic biosynthesis and emission of methyl acetate

Acetylation of plant metabolites fundamentally changes their volatility, solubility and activity as semiochemicals. Here we present a new technique termed dynamic ¹³C‐pulse chasing to track the fate of C_1–3 carbon atoms of pyruvate into the biosynthesis and emission of methyl acetate (MA) and CO₂. ¹³C‐labelling of MA and CO₂ branch emissions respond within minutes to changes in ¹³C‐positionally labelled pyruvate solutions fed through the transpiration stream. Strong ¹³C‐labelling of MA emissions occurred only under pyruvate‐2‐¹³C and pyruvate‐2,3‐¹³C feeding, but not pyruvate‐1‐¹³C feeding. In contrast, strong ¹³CO₂ emissions were only observed under pyruvate‐1‐¹³C feeding. These results demonstrate that MA (and other volatile and non‐volatile metabolites) derive from the C_2,3 atoms of pyruvate while the C₁ atom undergoes decarboxylation. The latter is a non‐mitochondrial source of CO₂ in the light generally not considered in studies of CO₂ sources and sinks. Within a tropical rainforest mesocosm, we also observed atmospheric concentrations of MA up to 0.6 ppbv that tracked light and temperature conditions. Moreover, signals partially attributed to MA were observed in ambient air within and above a tropical rainforest in the Amazon. Our study highlights the potential importance of acetyl coenzyme A (CoA) biosynthesis as a source of acetate esters and CO₂ to the atmosphere.     

The ‘paradox’ of polyembryony: A review of the cases and a hypothesis for its evolution

Animal polyembryony appears to be paradoxical because it clones an unproven genotype at the expense of genetic diversity in a clutch. However, it is employed by at least 18 taxa in six phyla (excluding instances of occasional twinning). Most polyembryony occurs in parasitic stages or in other environments whose quality is not predictable by the mother; in some instances, it compensates for a constraint on zygote number. We predict that polyembryony is likely to evolve when the offspring has more information regarding optimal clutch size than the parents.