Taxonomy of the Crematogaster degeeri-species-assemblage in the Malagasy region (Hymenoptera: Formicidae)

We revise the species-level taxonomy of the Crematogaster (Crematogaster) degeerispecies-assemblage, a group of related ants occuring in Madagascar and the wider Malagasy region, and further provide an identification key to all species-groups of the genus Crematogaster in this region. Within the C. degeeri-assemblage, we recognize twelve species based upon morphological data from worker, queen and male ants, as well as genetic data from the barcode region of cytochrome oxidase I. Seven new species are described: Crematogaster alafara Blaimer sp. nov., C. bara Blaimer sp. nov., C. mafybe Blaimer sp. nov., C.maina Blaimer sp. nov., C. malahelo Blaimer sp. nov., C. masokely Blaimer sp. nov., C. ramamy Blaimer sp. nov. Crematogaster tricolor Gerstäcker, 1859 (stat. rev.) and C. dentata Dalla Torre, 1893 (stat. nov.) are raised to species level, and the following new synonymies are proposed: Crematogaster degeeri lunaris Santschi, 1928 as a synonym of C. degeeri Forel, 1886; Crematogaster sewelli improba Forel, 1907 and C. sewelli mauritiana Forel, 1907 as synonyms of C. dentata Dalla Torre, 1893, and C. pacifi ca Santschi, 1919 as a synonym of C. lobata Emery, 1895. Species descriptions, images, and distribution maps and identification keys based on worker ants, as well as on queen ants where available, are presented for all twelve species. In addition, we present a molecular gene tree for cytochrome oxidase I and summarize levels of sequence divergence within and between species of the C. degeeri-species-assemblage. Our findings are discussed in the light of previous work on Malagasy Crematogaster ants

The Chalcidoidea bush of life: evolutionary history of a massive radiation of minute wasps.

Chalcidoidea are mostly parasitoid wasps that include as many as 500 000 estimated species. Capturing phylogenetic signal from such a massive radiation can be daunting. Chalcidoidea is an excellent example of a hyperdiverse group that has remained recalcitrant to phylogenetic resolution. We combined 1007 exons obtained with Anchored Hybrid Enrichment with 1048 ultra-conserved elements (UCEs) for 433 taxa including all extant families, >95% of all subfamilies, and 356 genera chosen to represent the vast diversity of the superfamily. Going back and forth between the molecular results and our collective knowledge of morphology and biology, we detected bias in the analyses that was driven by the saturation of nucleotide data. Our final results are based on a concatenated analysis of the least saturated exons and UCE datasets (2054 loci, 284 106 sites). Our analyses support an expected sister relationship with Mymarommatoidea. Seven previously recognized families were not monophyletic, so support for a new classification is discussed. Natural history in some cases would appear to be more informative than morphology, as illustrated by the elucidation of a clade of plant gall associates and a clade of taxa with planidial first-instar larvae. The phylogeny suggests a transition from smaller soft-bodied wasps to larger and more heavily sclerotized wasps, with egg parasitism as potentially ancestral for the entire superfamily. Deep divergences in Chalcidoidea coincide with an increase in insect families in the fossil record, and an early shift to phytophagy corresponds with the beginning of the "Angiosperm Terrestrial Revolution". Our dating analyses suggest a middle Jurassic origin of 174 Ma (167.3-180.5 Ma) and a crown age of 162.2 Ma (153.9-169.8 Ma) for Chalcidoidea. During the Cretaceous, Chalcidoidea may have undergone a rapid radiation in southern Gondwana with subsequent dispersals to the Northern Hemisphere. This scenario is discussed with regard to knowledge about the host taxa of chalcid wasps, their fossil record and Earth's palaeogeographic history

Figures 31–36 in Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera)

Figures 31–36. Crematogaster workers, showing lateral view of body (A), full-face view of head (B) and dorsal view of body (C). 31, C. cerasi lectotype (USNMENT00529078); 32, C. vermiculata (CASENT0914534); 33, C. rifelna holotype (LACMENT164556); 34, C. ashmeadi (CASENT0922720); 35, C. pinicola (CASENT0172943); 36, C. pilosa (CASENT0914530). Images courtesy of AntWeb (www.antweb.org); photographers Michele Esposito (31, 33), Zach (Ziv) Lieberman (32, 36), Wade Lee (34), April Nobile (35).Published as part of <i>Ward, Philip S. & Blaimer, Bonnie B., 2022, Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera), pp. 893-937 in Zoological Journal of the Linnean Society 194</i> on page 921, DOI: 10.1093/zoolinnean/zlab047, <a href="http://zenodo.org/record/10115063">http://zenodo.org/record/10115063</a&gt

Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera)

Ward, Philip S., Blaimer, Bonnie B. (2022): Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera). Zoological Journal of the Linnean Society 194: 893-937, DOI: 10.1093/zoolinnean/zlab04

Figure 2 in Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera)

Figure 2. Biogeography and nesting preference of the Crematogaster scutellaris group. Time-calibrated phylogeny estimated with mcmctree and codeml in PAMLv.4.9. The analysis is based on the 90% completeness matrix after application of spruceup trimming with a cut-off of 0.98 (90%-0.98-spruceup), and the best maximum likelihood tree resulting from SWSC-EN partitioning of this matrix. This matrix and tree was pruned to a reduced dataset of 34 taxa for dating analysis. Node numbers refer to Table 1, where median ages and 95% highest posterior densities (HPD) are given. Biogeographic range reconstructions with BioGeoBEARS v.1.1.2 are mapped on this chronogram as E = eastern US and north-east Mexico (orange), W = western US and north-west Mexico (dark blue), C = the Caribbean (grey), M = southern Mexico to Honduras (red), EW = combined E and W distributions (light blue), EM = combined E and M distributions (purple), EC = combined E and C distributions (dark green), WM = combined W and M distributions (peach). Respective probabilities for ancestral ranges are given in Table 1. Ancestral states for nesting preference, estimated with the R package corHMM v.2.5, are further mapped on the phylogeny; pie colours are: light green = arboreal; brown = ground-dwelling.Published as part of <i>Ward, Philip S. & Blaimer, Bonnie B., 2022, Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera), pp. 893-937 in Zoological Journal of the Linnean Society 194</i> on page 901, DOI: 10.1093/zoolinnean/zlab047, <a href="http://zenodo.org/record/10115063">http://zenodo.org/record/10115063</a&gt

Figures 3–12. Crematogaster worker features useful for identification. 3 in Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera)

Figures 3–12. Crematogaster worker features useful for identification. 3, petiole shape, dorsal view, C. lineolata (CASENT0863235) (3A) and C. torosa (CASENT0795540) (3B); 4, sculpture on declivitous face of propodeum, C. dentinodis (CASENT0863070) (4A) and C. depilis (CASENT0863478) (4B); 5, mesosomal pilosity, C. punctulata (CASENT0863277) (5A) and C. emeryana (CASENT0863099) (5B); 6, position and shape of propodeal spines, dorsal view, C. isolata (CASENT0863072) (6A) and C. pinicola (CASENT0882129) (6B); 7, petiole shape, dorsal view, C. mutans (CASENT0862488); 8, subpetiolar tooth, lateral view, C. mutans (CASENT0862488); 9, promesonotal sculpture, C. californica (CASENT0221085) (9A) and C. coarctata (CASENT0221962) (9B); 10, postpetiolar seta, C. browni (CASENT0863144) (10A) and C. cerasi (CASENT0795541) (10B); 11, cephalic pilosity, C. torosa (CASENT0795540) (11A) and C. missouriensis (CASENT0221041) (11B); 12, mesosomal profile, C. crinosa (CASENT0795543) (12A) and C. torosa (CASENT0863226) (12B).Published as part of <i>Ward, Philip S. & Blaimer, Bonnie B., 2022, Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera), pp. 893-937 in Zoological Journal of the Linnean Society 194</i> on page 908, DOI: 10.1093/zoolinnean/zlab047, <a href="http://zenodo.org/record/10115063">http://zenodo.org/record/10115063</a&gt

Figure 1 in Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera)

Figure 1. Phylogeny of the North American Crematogaster scutellaris group. Maximum likelihood phylogenetic tree estimated from the 90% taxon completeness matrix after application of spruceup trimming with a 0.98 cut-off (90%-0.98-spruceup), using a combined best tree and ultrafast bootstrap (N = 1000) search in IQ-TREE v.1.6.12 and implementing 746 partitions. The analysis was rooted using the most distantly related outgroup taxon C. cf. rogenhoferi; the long branch leading to this taxon has been shortened for space-saving purposes. All nodes have bootstrap support = 100% unless labelled otherwise. Species images courtesy of AntWeb (www.antweb.org).Published as part of <i>Ward, Philip S. & Blaimer, Bonnie B., 2022, Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera), pp. 893-937 in Zoological Journal of the Linnean Society 194</i> on page 898, DOI: 10.1093/zoolinnean/zlab047, <a href="http://zenodo.org/record/10115063">http://zenodo.org/record/10115063</a&gt

Figures 19–24 in Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera)

Figures 19–24. Crematogaster workers, showing lateral view of body (A), full-face view of head (B) and dorsal view of body (C). 19, C. mutans worker (CASENT0922736); 20, C. colei (CASENT0922726); 21, C. detecta holotype (CASENT0863461); 22, C. larreae paratype (CASENT0005943); 23, C. depilis (CASENT0005668); 24, C. californica lectotype (CASENT0923319). Images courtesy of AntWeb (www.antweb.org); photographers Wade Lee (19, 20), Zachary Griebenow (21), April Nobile (22, 23), Michele Esposito (24).Published as part of <i>Ward, Philip S. & Blaimer, Bonnie B., 2022, Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera), pp. 893-937 in Zoological Journal of the Linnean Society 194</i> on page 913, DOI: 10.1093/zoolinnean/zlab047, <a href="http://zenodo.org/record/10115063">http://zenodo.org/record/10115063</a&gt

Figures 13–18 in Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera)

Figures 13–18. Crematogaster workers, showing lateral view of body (A), full-face view of head (B) and dorsal view of body (C). 13, C. dentinodis (CASENT0102830); 14. C. vetusta holotype (CASENT0863254); 15, C. navajoa worker (CASENT0064826); 16, C. punctulata lectotype (CASENT0923318); 17, C. isolata (CASENT0922731); 18, C. sp. cf. opaca (MCZENT00589113). Images courtesy of AntWeb (www.antweb.org); photographers Jen Fogarty (13), Michele Esposito (14, 16), April Nobile (15), Wade Lee (17), Zachary Griebenow (18).Published as part of <i>Ward, Philip S. & Blaimer, Bonnie B., 2022, Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera), pp. 893-937 in Zoological Journal of the Linnean Society 194</i> on page 910, DOI: 10.1093/zoolinnean/zlab047, <a href="http://zenodo.org/record/10115063">http://zenodo.org/record/10115063</a&gt