Species Paraphyly and Social Parasitism: Phylogenomics, Morphology, and Geography Clarify the Evolution of the Pseudomyrmex elongatulus Group (Hymenoptera: Author Ward, Philip S. Department of Entomology and Nematology, University of California, Davis, CA 95616, USA, Author Branstetter, Michael G. U. S. Department of Agriculture, text Insect Systematics and Diversity 2022 2022-01-25 6 1 1 31 http://dx.doi.org/10.1093/isd/ixab025 journal article 10.1093/isd/ixab025 2399-3421 Pseudomyrmex ereptor sp. nov. Figs. 12 and 24 Zoobank LSID: urn:lsid:zoobank.org:act: 3F4584C3-EB0C-4C74- B067-01CBEDC8F4EB Holotype alate queen, MEXICO Veracruz : Los Tuxtlas , 10 km NNW Sontecomapan , 500 m , 18° 35 ′ N , 95° 05 ′ W , 21 Mar 1985 , ex dead twig of liana [in nest of P. elongatulus ], rainforest, P. S. Ward PSW07360A ( UNAM ) ( CASENT0863524 ). Other material examined. Known only from the holotype . Queen measurements ( n = 1). HW 0.98, HL 1.25, MFC 0.058, LHT 0.76, CI 0.78, FCI 0.059, REL 0.44, REL2 0.56, FI 0.46, PLI 0.61, PWI 0.75, MSC 11. Queen Diagnosis. Small species (see HW, HL, and LHT measurements), with moderately elongate head (CI 0.78); upper surface of mandible smooth and shiny, with scattered punctures; eyes of moderate length (REL 0.44, REL2 0.56); frontal carinae separated by basal scape width; petiole relatively short (PLI 0.61, PL/HL 0.52) and broad (PWI 0.75, DPW/LHT 0.64), with stout, recurved anteroventral tooth; in profile, petiole with convex anterodorsal face ascending gradually to summit in posterior quarter of node, then rounding into steep posterior face; postpetiole very broad, ovorectangular in dorsal view (PPW/LHT 1.01); profemur robust (FI 0.46); hind leg short (LHT/HL 0.61). Head sublucid, densely but finely punctulate, the punctures separated by one to several diameters, the interspaces smooth and shiny, or (towards vertex) finely coriarious. Standing pilosity scattered on head, mesosoma (MSC 11), and gaster, short and sparse on petiole, postpetiole, and fourth abdominal (first gastric) tergite. Uniformly light orange-brown. Comments. The small size (HL 1.25, LHT 0.76), smooth and shiny mandibles, and very broad (ovorectangular) postpetiole (PPW/LHT 1.01) are distinctive features of P. ereptor that set it apart from the queen of its apparent host species, P. elongatulus , and from other species in the P. elongatulus group. Queens of P. elongatulus are larger (HL 1.37–1.42, LHT 0.90–0.94), with striate mandibles, and a slender, pyriform postpetiole as seen in dorsal view (PPW/LHT 0.78–0.83). Our UCE phylogeny shows that P. ereptor is sister to the entire assemblage of P. elongatulus samples (Fig. 1). It is well separated from an alate queen of P. elongatulus (D1985) collected in the same nest, thus confirming its status as a different species. Distribution and Biology. The only known specimen of P. ereptor — an alate queen—was collected in a nest of P. elongatulus in a dead twig attached to a liana, on Vereda Cima, Estación de Biología ‘Los Tuxtlas’, Veracruz . The nest (collection code PSW07360) contained numerous workers, alate queens, males, and brood of P. elongatulus . Pseudomyrmex ereptor apparently represents a workerless, inquiline parasite of P. elongatulus . The fact that only a single alate queen of P. ereptor was found in the nest suggests that she was a recent arrival. The absence of a dealate queen of P. elongatulus should not be over-interpreted; it could simply indicate that this was part of a larger polydomous colony. Pseudomyrmex colonies are often comprised of disjunct nests occupying several dead twigs on a plant.