Pseudomyrmex comitator Ward &amp; Branstetter 2022, sp. nov.
Creators: name: Ward, Philip S.
name: Branstetter, Michael G.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Formicidae
Pseudomyrmex
Pseudomyrmex comitator

description: <i>Pseudomyrmex comitator</i> sp. nov. Figs. 9 and 24 LSID: urn:lsid:zoobank.org:act: 4BAA462E-31A4-4799-BEF6- D7BC23B346F0 <i>P. championi</i> nr; Chomicki et al. 2015: 4. Placement in molecular phylogeny. Holotype dealate queen, MEXICO Chiapas: 29 km E La Trinitaria, 1,520 m, 16° 06 <i>′</i> N 91° 46 <i>′</i> W, 21 Jul 2007, ex nest of <i>P. cognatus</i> in dead stick, pine oak scrubby forest, J. Longino JTL6094 (UNAM) (JTLC000010310). Paratype dealate queen, MEXICO Chiapas: Lagos de Montebello, 1,520 m, 16° 08 <i>′</i> N 91° 44 <i>′</i> W, 21 Jul 2007, on ground, pine oak <i>Liquidambar</i> forest, J. Longino JTL6093-s (UCDC) (JTLC 000010349). Other material examined. Known only from the type material. Queen measurements (<i>n</i> = 2, with holotype measurement given first). HW 0.81, 0.77; HL 1.01, 1.00; MFC 0.038, 0.046; LHT 0.70, 0.69; CI 0.80, 0.77; FCI 0.047, 0.060; REL 0.40, 0.42; REL2 0.51, 0.54; FI 0.40, 0.43; PLI 0.67, 0.83; PWI 0.56, 0.80; MSC 4, 7. <i>Queen Diagnosis.</i> Small species (see HW, HL, and LHT measurements), with elongate head (CI 0.77–0.80); upper surface of mandible finely reticulate with scattered punctures, lacking striae; eyes relatively short (REL 0.40–0.42, REL2 0.51–0.54); frontal carinae separated by slightly less than basal scape width; petiole stout and short, the height and width of petiole about 0.8× the length (less so in the paratype); in profile, petiole with flat to convex anterodorsal face, ascending to summit in posterior quarter of node, then rounding into more steeply descending posterior face; profemur slender; hind leg relatively short (LHT /HL 0.69). Head sublucid, densely punctulate-coriarious. Standing pilosity sparse and short on most of body (MSC 4–7). Dark brown to brownish-black, head and gaster darker than rest of body. <i>Comments.</i> This species, known only from two dealate queens, bears some resemblance to <i>P. cognatus</i>, but differs in ways that suggest it represents a workerless inquiline (see also notes on Distribution and Biology below). The <i>P. comitator</i> queens are notably smaller than those of <i>P. cognatus</i> (HW 0.77–0.81, HL 1.00–1.01, vs HW 0.99– 1.11, HL 1.28–1.42 in queens of <i>P. cognatus</i>), lack striae on the mandibles, have reduced mesosomal pilosity (MSC 4–7 vs 15–22 in <i>P. cognatus</i> queens), and possess an oddly swollen and foreshortened petiole (PLI 0.67–0.83, vs 0.45–0.53 in <i>P. cognatus</i> queens) (Figs. 8 and 9). The two specimens of <i>P. comitator</i> do not show the same degree of modification of the petiole (compare PLI and PWI values), with the holotype being more extreme, indicating some instability in the expression of this character. Both individuals of <i>P. comitator</i> were sequenced; they are sister taxa in our UCE tree and embedded phylogenetically within the putative host species (Fig. 1). They are more closely related to <i>P. cognatus</i> populations from Honduras and Nicaragua, however, than to samples from Chiapas. <i>Distribution and Biology. Pseudomyrmex comitator</i> is an apparent workerless social parasite of <i>P. cognatus</i>, and is currently known only from two adjacent sites in high-elevation forest (1,520 m) of Chiapas, Mexico. The holotype was collected by Jack Longino in a nest of <i>P. cognatus</i> that contained workers, alate males, alate queens, and brood (larvae, prepupae) of the presumed host. Only a single dealate queen of <i>P. comitator</i> was found in the nest. The paratype queen was encountered as a stray on the ground, in a nearby locality.
description: Published as part of <i>Ward, Philip S. &amp; Branstetter, Michael G., 2022, Species Paraphyly and Social Parasitism: Phylogenomics, Morphology, and Geography Clarify the Evolution of the Pseudomyrmex elongatulus Group (Hymenoptera:, pp. 1-31 in Insect Systematics and Diversity 6 (1)</i> on pages 21-22, DOI: 10.1093/isd/ixab025
description: {"references": ["Chomicki, G., P. S. Ward, and S. Renner. 2015. Macroevolutionary assembly of ant / plant symbioses: Pseudomyrmex ants and their ant-housing plants in the Neotropics. Proc. R. Soc. B. 282: 20152200."]}