Tapinoma onaele sp. nov. from the Kodagu region of the Western Ghats, India, is described as the fourth species in the Tapinoma lugubre species group. This species is morphologically close to Tapinoma himalaicum Bharti et al., 2013, as both have long scapes and deep and concave anteromedial clypeal margins. However, it differs from T. himalaicum in having a darker and brownish body, contrasting with a darker gaster, longer scapes, and the dorsal surface of the propodeum being convex and rising above the mesonotum. An identification key for workers of the Tapinoma lugubre species group is provided. Tapinoma onaele sp. nov. is crepuscular and nocturnal, ground-nesting, and forages in the leaf litter. The species was observed carrying seeds, insects, and tending scale insects (Hemiptera), suggesting it is generalist like other members of Tapinoma.

A new species of the genus Aenictus Shuckard, 1840 is described from the Western Ghats region, India, under the name A. kodagura Shakur & Bagchi, sp. nov. based on the worker caste. The new species belongs to the Aenictus pachycerus species group and shares affinities with A. sirenicus Yamane & Wang, 2015, in having a smooth head, smooth pronotum and sculptured propodeum, pedunculate petiole and postpetiole. The new species can be differentiated from A. sirenicus by the presence of subpetiolar process, propodeum being slightly convex in profile, petiole and postpetiole being comparable in length, and a uniform pale brown coloration of the body. The holotype was collected from coffee plantations in Kodagu district of Karnataka.

Diversity-function relationships in producers, and how these are influenced by consumers, are well known. However, these are not well known for microbial decomposers in soil. It is also unknown whether and how consumers such as large mammalian herbivores influence soil microbial decomposer diversity-function relationships. We used a 14-year-old herbivore-exclusion experiment in the Trans-Himalayan drylands of northern India to address whether microbial functions vary with microbial diversity (both species richness and composition), and whether herbivores alter the diversity-function relationships. We analyzed soils from n = 10 paired grazed-and-fenced plots three times during the growth season of 2019. Data were from 16S rDNA gene amplicon sequencing of 7.6 million reads covering 1937 operational taxonomic units (OTU) of bacteria across 47 phyla (of which 924 OTUs were identifiable to genus level), and 1800 catabolic profiles across 30 substrates related to carbon metabolism. We found that functional diversity was positively related to microbial community composition, but not to species richness; it was also unaffected by large mammalian herbivore-exclusion to indicate resilience and resistance. This positive relationship between community composition and functional diversity challenges the prevailing notion of functional redundancy in hyper-diverse soil microbial communities since certain combinations of species could outperform others and determine decomposition processes and services. Structural equation models suggested that the strength of this relationship is favoured by availability of soil moisture. Microbial functions varied more strongly with temporal variables (e.g., seasonality) than with spatial variables (e.g., edaphic factors such as soil texture and pH). Although interpretations can be constrained by which and how many functions are investigated, the relationship was generalizable and robust once 16 or more functions were quantified. Decomposition in drylands may be particularly susceptible to how the identity of the microbial species, and not the number of species, responds to rising precipitation variability under ongoing and projected climate change.

Diversity-function relationships are well established for producers and their productivity. They are also evident among consumers. However, these are not well known for microbial decomposers and decomposition processes in soil. Further, it also remains unknown whether and how consumers, such as large mammalian herbivores who are a major feature across more than one-third of the world’s terrestrial realm, influence microbial decomposer diversity-function relationships. We used a14-year old long-term herbivore-exclusion experiment to answer two questions: (a) whether microbial functions vary with microbial diversity (both species richness and composition), and (b) whether herbivores alter the diversity-function relationships among microbial decomposers. We measured functional richness, functional dispersion, and multifunction from the utilization profiles of 30 metabolic substrates. Alongside, we also measured species richness and species composition of soil microbes. Data were from 60 16S rDNA gene amplicon sequences with 7.6 million reads covering 1937 potential species across 47 phyla, and 1800 catabolic profiles. We found microbial functional diversity in soil was positively related (i.e., coupled) to community composition, but not to species richness. This challenges the prevailing paradigm of functional redundancy in hyper-diverse soil microbial communities where changes in species richness is expected to not affect functional diversity. Instead, our results indicate that certain combinations of species can outperform others. Therefore, global change factors that alter microbial communities can also impact decomposition processes and services. This coupling between diversity and functions was unaffected by experimental herbivore-exclusion, indicating resilience and resistance among decomposers. Structural equation models suggested that the strength of this relationship is favoured by availability of soil moisture. These also showed microbial functions varied more strongly with temporal variables (e.g., seasonality) than with spatial variables (e.g., edaphic factors such as soil texture and pH). While ecosystem functions and services derived from microbial decomposers have intrinsic resilience and resistance, they respond strongly to variability in water availability. Decomposition in grazing ecosystems may be particularly susceptible to how soil microbes respond to increased precipitation variability under ongoing and projected climate change. Highlights Diversity-function relationships for microbial decomposers remain uncertain. Microbial diversity is positively related to functions This relationship is robust to grazer-exclusion. Microbial diversity-function relationship can be susceptible to altered precipitation

Grazing by large mammalian herbivores impacts climate as it can favor the size and stability of a large carbon (C) pool in the soils of grazing ecosystems. As native herbivores in the world's grasslands, steppes, and savannas are progressively being displaced by livestock, it is important to ask whether livestock can emulate the functional roles of their native counterparts. While livestock and native herbivores can have remarkable similarity in their traits, they can differ greatly in their impacts on vegetation composition which can affect soil-C. It is uncertain how these similarities and differences impact soil-C via their influence on microbial decomposers. We test competing alternative hypotheses with a replicated, long-term, landscape-level, grazing-exclusion experiment to ask whether livestock in the Trans-Himalayan ecosystem of northern India can match decadal-scale (2005-2016) soil-C stocks under native herbivores. We evaluate multiple lines of evidence from 17 variables that influence soil-C (quantity and quality of C-input from plants, microbial biomass and metabolism, microbial community composition, eDNA, veterinary antibiotics in soil), and assess their inter-relationships. Livestock and native herbivores differed in their effects on several soil microbial processes. Microbial carbon use efficiency (CUE) was 19% lower in soils under livestock. Compared to native herbivores, areas used by livestock contained 1.5 kg C m-2 less soil-C. Structural equation models showed that alongside the effects arising from plants, livestock alter soil microbial communities which is detrimental for CUE, and ultimately also for soil-C. Supporting evidence pointed toward a link between veterinary antibiotics used on livestock, microbial communities, and soil-C. Overcoming the challenges of sequestering antibiotics to minimize their potential impacts on climate, alongside microbial rewilding under livestock, may reconcile the conflicting demands from food-security and ecosystem services. Conservation of native herbivores and alternative management of livestock is crucial for soil-C stewardship to envision and achieve natural climate solutions.