Brachymyrmex giardi

The collector of the type material, Prof. Giard, noted an association between B. giardi and the coccid Margadores vitium. De Zolessi et al. (1978: 39) provided details of an excavated nest (of the synonymized Brachymyrmex melensis): subterranean, with several chambers between 15 and 50 cm deep, each chamber being about 3 cm high and 3 to 5 cm long and wide. Some repletes were found hanging from the roof together with normal workers as is observed in Mymecocystus hortideorum.

Identification
Ortiz-Sepulveda et al. (2019) - Brachymyrmex giardi resembles Brachymyrmex depilis and Brachymyrmex heeri as these species have a mesonotum that bulges dorsally above the pronotum in lateral view, and a gaster with dense pubescence. Additionally, B. giardi and B. depilis have bodies without erect hairs; they can be distinguished because B. giardi has dense decumbent pubescence on the head and mesosoma, usually a dark brownish body, and it is geographically restricted to Chile and Uruguay. Furthermore, B. giardi differs from B. heeri by having short scapes, and no erect hairs on the pronotum or mesonotum.

Emery, 1895: L'ouvriere normale se distingue de Brachymyrmex patagonicus Mayr et Brachymyrmex heeri Forel par la suture pro-mesonotale formant encoche sur le profil et I'absence de poils dresses sur le thorax et sur l'abdomen. (The normal worker differs from Brachymyrmex patagonicus and Brachymyrmex heeri by the pro-mesonotal suture forming a notch on the profile and the absence of erect hairs on the thorax and abdomen.)

Distribution based on Regional Taxon Lists
Neotropical Region: Chile, Uruguay.

Biology
Emery 1895: Cette espece m'a ete envoyee par M. le professeur Giard, qui pupliera prochainement des observations sur ses moeurs et sur ses rapports avec le Cocci de Margarodes vitium. Elle est surtout remarquable par l'existence des exemplaires a gros ventre, qui rappellent les ouvrieres melligeres de certains Myrmecocystus et de Melophorus. La dissection d'un exemplaire m'a montre que l'abdomen est a demirempli par le jabot plein de miel, le reste etant occupe par le corps graisseux fort abundant. Les ovaires sont plus develop pes que chez les ouvrieres normales et composes chucun de 5-6 tubes, avec un ou deux gros oeufs. Ces exemplaires participent done de l'ouvriere et de la femelle et sont probablement en meme temps pots a miel et reproducteurs. Toutefois, a en juger par la condition anatomique, la premiere fonction predomine sur l'autre, qui doit etre fort peu active.

Nomenclature

 * . Brachymyrmex giardi Emery, 1895d: 215 (w.q.) CHILE.
 * Emery, 1906c: 178 (m.); Ortiz-Sepúlveda, et al. 2019: 502 (w.-q. intercaste).
 * Status as species: Emery, 1895i: 16; Emery, 1906c: 178; Santschi, 1923b: 663; Emery, 1925b: 42; Goetsch, 1933: 29; Goetsch & Menozzi, 1935: 100; Menozzi, 1935c: 324; Kempf, 1970a: 31; Kempf, 1972a: 39; Snelling, R.R. & Hunt, 1976: 114; Brandão, 1991: 332; Bolton, 1995b: 82; Ortiz-Sepúlveda, et al. 2019: 501 (redescription).
 * Senior synonym of melensis: Ortiz-Sepúlveda, et al. 2019: 501.
 * melensis. Brachymyrmex melensis Zolessi, Abenante & Gonzalez, 1978: 26, figs. 3-22 (w.q.l.) URUGUAY.
 * Status as species: Zolessi, et al. 1988: 6; Brandão, 1991: 331; Bolton, 1995b: 82.
 * Junior synonym of giardi: Ortiz-Sepúlveda, et al. 2019: 501.

Worker
Ouvriere normale. Couleur brun fonce, bouche, scape des antennes et premier article du flagellum, pattes et pedicule de l'abdomen testaces. Peu luisante, a cause d'une fine sculpture dans les interstices des points pubigeres. Quelques poils dresses sur le devant de la tete, dos du thorax et de l'abdomen sans poils dresses; tout le corps pourvu assez copieusement d'une pubescence fine, a demi-couchee, partant des points. Tete de forme ordinaire. Thorax a suture pro-mesonotale bien marquee, presque aussi fortement que la suture meso-metanotale; sur le profil, le dos du mesonotum para it convexe et separe des deux segments voisins par une petite en coche; la face basale du metathorax est tres courte et reunie a la face declive par une courbe. Vue de dessus, la face declive a la forme d'un triangle curviligne; elle est assez plane en avant, deprimee au milieu et en arriere et tres luisante. - Long. 1 1/4 mm.

Ouvriere melligere. Je designe sous ce nom des exemplaires beaucoup plus gros, l'abdomen spherique tres distendu. Leur couleur est entierement testace pale, avec les sutures, les genoux et les tarses roussatres, le bord des mandibules brun, le flagellum des antennes et la base de l'abdomen plus ou moins rembrunis. Les yeux sont plus grands et le vertex porte trois ocelles rudimentaires. Le thorax est plus large, plus voute longitudinalement, avec un scutellum tres court et des episternums distincts au mesothorax; d'ailleurs pas trace d'ailes. Ecaille plus haute que chez l'ouvriere normale. Quelques poils dresses au pronotum et a l'abdomen. La taille de ces exemplaires est variable. - Longueur, sans l'abdomen, 1 ¼ - 1 ¾ mm.; avec l'abdomen (dans l'alcool) 3 ½ - 4 ½ mm.

Ortiz-Sepulveda et al. (2019) - Lectotype and paralectotype (n = 8). HL1 0.45–0.68; HL2 0.29–0.42; HL3 0.10–0.32; HW 0.35– 0.68; SL 0.33–0.59; EL 0.10–0.18; WL 0.39–0.89; PnL 0.10– 0.21; PnW 0.25–0.57; ML 0.08–0.35; MW 0.16–0.52; Indices CI 78.26–105.00; SL1 84.85–100.00; SL2 113.33–142.86; OI1 23.53–33.33; OI2 21.74–50.00.

Head. Slightly longer than wide in full face view; posterior cephalic margin is flat. Dorsum of the head has dense appressed hairs. Clypeus with a rounded anterior margin and five long, erect hairs of which a single, usually conspicuous hair is near the anterior margin, two hairs are in mediolateral position, and two more near the toruli; other hairs on the clypeus are clearly shorter and appressed or decumbent. Toruli surpassing the posterior clypeal margin in oblique anterodorsal oblique view. The scapes surpass the posterior cephalic margin by a length smaller than the maximal diameter of the eye and have decumbent hairs. Three ocelli appear to be present. Eyes are positioned on the cephalic midline and have 7–9 ommatidia along their maximal diameter.

Mesosoma. Without erect hairs. The mesonotum is inflated and bulges dorsally above the pronotum in lateral view. Metanotal groove usually absent, or narrower than the diameter of the metathoracic spiracles. Metathoracic spiracles in dorsolateral position, not protruding, and touching the propodeal suture. Dorsum of the propodeum slightly convex and shorter than the posterior propodeal margin. Propodeal spiracles circular, positioned on the posterior propodeal margin slightly posterior of the middle of the propodeal slope. Legs with appressed hairs. Petiole short and inclined forward.

Gaster. With dense pubescence and scattered long erect hairs along the edges of the segments. Some specimens have the same morphology as a regular worker as to the head and mesosoma, but have a gaster that is somewhat expanded, i.e., they are somewhat physogastric.

Color and sculpture. Body smooth and shiny, usually dark brownish with yellowish legs and pubescence.

Intercaste
Ortiz-Sepulveda et al. (2019) - The morphology of the putative worker-queen intercaste differs from that of the worker by its larger size, the eyes that have around nine ommatidia along their maximal diameter, the pronotum that bears several semierect hairs, the enlargened mesonotum that does not bulge dorsally above the pronotum in lateral view, and that does not bear erect but several subdecumbent hairs, the sharper posterior ending of the mesonotum in dorsal view, the deep metanotal groove that is wider than the metathoracic spiracles, the almost laterally positioned metathoracic spiracles, that do not protrude and do not touch any suture, and the uniform yellowish body color (albeit with lighter-colored legs).

Queen
Femelle normale (aptere). D'un brun roussatre, avec le dessus de la tete plus fonce; les scapes et le bout des antennes plus clairs, les articulations des pattes et les tarses testaces. Sculpture a peu pres comme chez l'ouvriere; scutellum et face declive du metanotum luisants et pas pubescents; abdomen a pubescence plus dense et un peu soyeuse; quelques longs poils au prothorax, tres peu a la base de l'abdomen. - Longueur sans l'abdomen 2 1/2 mm.; avec l'abdomen 5 mm.

Type Material
Ortiz-Sepulveda et al. (2019) - Lectotype worker (: USNMENT00757220) and paralectotype workers, putative worker-queen intercaste, queen, male (MSNG: USNMENT00757218–00757220, MHNG: USNMENT00758105–00758109; here designated): six workers, nine putative worker-queen intercastes, one queen, one male [examined]. CHILE: Santiago de Chile.

The second ant from the top in pin MSNG: USNMENT00757220 is designated here as lectotype, whereas the other specimens are paralectotypes.

Etymology
Named after Professor Giard.

References based on Global Ant Biodiversity Informatics

 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Emery C. 1906. Studi sulle formiche della fauna neotropica. XXVI. Bullettino della Società Entomologica Italiana 37: 107-194.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Goetsch W. and C. Menozzi. 1935. Die Ameisen Chiles. Konowia 14: 94-102
 * Goetsch, W., and C. Menozzi. "Die Ameisen Chiles." Konowia 14 (1935): 94-102.
 * Ipinza-Regla J., L. Castro, R. Eissemann, and M. A. Morales. 2010. Factors Influencing the Distribution of Nests of the Argentine Ant Linepithema humile Mayr (Hymenoptera: Formicidae), in a Foothills Ecosystem of the Central Zone of Chile. Neotropical Entomology 39(5):686-690.
 * Kempf W. W. 1970. Catálogo das formigas do Chile. Papeis Avulsos de Zoologia (São Paulo) 23: 17-43.
 * Medel R. G., and R. A. Vasquez. 1994. Comparative analysis of harvester ant assemblages of Argentinian and Chilean arid zones. Journal of Arid Anvironments 26: 363-371
 * Ortiz-Sepuvelda C. M., B. Van Bocxlaer, A. D. Meneses, and F. Fernandez. 2019. Molecular and morphological recognition of species boundaries in the neglected ant genus Brachymyrmex (Hymenoptera: Formicidae): toward a taxonomic revision. Organisms Diversity & Evolution https://doi.org/10.1007/s13127-019-00406-2
 * Santschi F. 1922. Description de nouvelles fourmis de l'Argentine et pays limitrophes. Anales de la Sociedad Cientifica Argentina. 94: 241-262.
 * Snelling R. R., and J. H. Hunt. 1975. The ants of Chile (Hymenoptera: Formicidae) Revista Chilena de Entomología 9: 63-129.
 * Zolessi L. C. de, Y. P. Abenante, and M. E. de Philippi. 1988. Lista sistematica de las especies de Formicidos del Uruguay. Comun. Zool. Mus. Hist. Nat. Montev. 11: 1-9.
 * Zolessi L. C. de, Y. P. de Abenante, and L. A. González. 1978. Descripción y observaciones bioetológicas sobre una nueva especie de Brachymyrmex (Hymenoptera: Formicidae). Revista de Biología del Uruguay 4: 21-44.
 * de Zolessi, L.C., Y.P. de Abenante and M.E. Phillipi. 1989. Catalago Systematico de las Especies de Formicidos del Uruguay (Hymenoptera: Formicidae). Oficina Regional de Ciencia y Technologia de la Unesco para America Latina y el Caribe- ORCYT. Montevideo, Uruguay