Myrmecina harrisoni

Two specimens were collected from different rotten logs in wet mountain forest dominated by oaks at 1070 m altitude.

Identification
Sculpture of head and alitrunk coarser than in Myrmecina americana, costulae thicker, and the spaces between the costulae relatively narrower and with nearly smooth, shining bottoms.

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico.

Biology
Found in rotten logs in wet mountain forest dominated by oaks, Liquidambar, and Podocarpus at about 1070 m altitude, Rancho del Cielo, Sierra Guatemala, above the village of Gomez Farias in southern Tamaulipas, Mexico.

Castes
Known only from the worker caste.

Nomenclature

 *  harrisoni. Myrmecina harrisoni Brown, 1967c: 237, fig. 3 (w.) MEXICO.

Description
Holotype worker: TL 3.4, HL 0.77, HW (without eyes) 0.75 (CI 97), ML (adjusted because mandibles are partly open) 0.21, WL 0.90, antennal scape L (chord, from basal collar) 0.61mm.

Sculpture of head and alitrunk coarser than in Myrmecina americana, costulae thicker, and with nearly smooth, shining bottoms. Promesonotal disc with costulae strongly diverging anteriad, forming an irregular triangle with three transverse anterior elements.

Other characters within the range of variation of eastern Myrmecina americana; median lobe of clypeus squarely truncate, with lateral and median tubercles present and about equally developed, not very prominent. Scapes not notably flattened at base. Propodeal teeth prominent, diverging, but also straight. Integument of gastric dorsum shining, with "Scotch-grain" shagreening or microreticulation distinct on basal segment.

Color black, shading to castaneous on mouthparts, coxae, and lower petiole and postpetiole; antennae and legs dull yellowish. Holotype and paratype deposited in the Musuem of Comparative Zoology, Harvard University.

Paratype worker: TL 3.5, HL 0.80, HW 0.76 (CI 95), ML 0.22, WL 0.90, scape L 0.65 mm. Similar to the holotype but a trifle larger. Median clypeal lobe with a more concave anterior border, the 3 tubercles somewhat better developed than in holotype. Details of sculpture, color and pilosity almost exactly as in holotype.

Etymology
This species is dedicated to the memory of Mr. Francis Harrison, proprietor of Rancho del Cielo, naturalist, and frequent host to itinerant naturalists. Months after the collection of this new species, Mr. Harrison was cruelly and senselessly murdered. Let us hope that his attempts to save some part of the northernmost true wet tropical forest in the Western Hemisphere will not have been in vain (Brown, 1967c).

References based on Global Ant Biodiversity Informatics

 * Coronado-Blanco J. M., D. A. Dubovikoff, E. Ruiz-Cancino, M. Vasquez-Bolanos, K. Y. Flores-Maldonado, and J. V. Horta-Vega. 2013. Formicidae (Hymenoptera) del estado de Tamaulipas, Mexico. CienciaUat 25(1): 12-17.
 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Fernandes, P.R. XXXX. Los hormigas del suelo en Mexico: Diversidad, distribucion e importancia (Hymenoptera: Formicidae).
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133