Typhlomyrmex lavra

Data on the natural history of this species is based on information from labels and reports of collectors. The species is usually found in the leaf litter of Atlantic Forest regions. Two of the specimens examined were collected in coffee plantations in Minas Gerais, but there is no information on whether the plantations were conventional or agroforestry. The latter is common in the area where the specimens were collected and would provide a more sheltered environment than conventional production. Two records were recently made for the species, one in a Winkler extraction of a layer of five centimeters deep bare soil, also in Minas Gerais, and in a sample from a rotten tree trunk on the forest ground (Júlio Chaul, personal communication). Another collection in the same region revealed individuals of the species in hypogaeic pitfall traps, 25 cm deep (Rodrigo Jesus, personal communication). These records and the small eyes suggest a partially hypogaeic habit. Gnamptogenys lavra was also recorded by one of the authors (RMF) in submontane forests in Rio Grande do Sul during a cold snap, suggesting these ants can tolerate lower temperatures. (Camacho et al., 2020)

Identification
Lattke (2002) - Mandíbulas triangulares con superficie dorsal lisa y pulida, ojos compuestos con apenas un omatidio; en vista lateral espiráculo propodeal separado del declive por un diámetro; dorso de metacoxa sin diente o lóbulo; en vista lateral nudo peciolar más alto que largo.

A primera vista parece una especie emparentada con el grupo striatula que ha retenido más plesiomorfías que las demás especies del grupo. La gran mayoría de las especies de Gnamptogenys tienen un lóbulo o dentículo sobre la cara dorsal de la metacoxa. Sin embargo, en varias especies ubicadas en diferentes agrupaciones la metacoxa es inerme, como en el caso de Gnamptogenys reichenspergeri del grupo relicta.

Esta especie se asemeja mucho a las especies del grupo striatula (Lattke, 1995) pero en una perspectiva lateral todas estas especies tienen el espiráculo propodeal situado justo en el margen posterior del propodeo, colindante con la cara declinante, mientras que en Gnamptogenys lavra, éste está separado del margen posterior. Una serie de características la ubican cerca del grupo de especies emparentadas con Gnamptogenys relicta, como los ojos reducidos, tendencia a nudo peciolar disciforme, proceso ventral peciolar semi-cuadrado con una superficie ventral plana y cuneiforme. Por el otro lado carece de una sutura mesopleural bien definida y el proceso subpeciolar con el margen posterior hendido en vista ventral.

Camacho et al. (2020) - Comparatively small size (TL 3.16−3.44). Dorsal face of mandible smooth and shiny. Eye with a single ommatidium. Scape not reaching vertex margin. Dorsal face of mesosoma flat in lateral view, without metanotal impression. Propodeum with lobes on the angle between the dorsal and declivitous faces. Propodeal spiracle separate from the side of the propodeum declivity by three times the width of the opening. Superior third of declivous face of propodeum with longitudinal costulae gradually becoming transverse on the inferior portion. Metacoxal spine absent. Segments I and II of gaster covered by small ridges extending from the base of the hairs; anterior face of gaster shiny, with inconspicuous rugulae.

This species is morphologically related to Gnamptogenys reichenspergeri and can be differentiated by the abundant and conspicuous sculpture on the mesosoma, without smooth and shiny areas, and also by the smooth and shiny mandible surface. Additionally, the frontal sculpture of the head is more uniform than in G. reichenspergeri, with parallel costulae.

Gnamptogenys lenis has similar features, but differs from Gnamptogenys lavra by the gaster being completely smooth and shiny and the scape surpassing the vertex margin.

Lattke (2002) - Esta especie se asemeja mucho a las especies del grupo “striatula” (Lattke, 1995) pero en una perspectiva lateral todas estas especies tienen el espiráculo propodeal situado justo en el margen posterior del propodeo, colindante con la cara declinante, mientras que en Gnamptogenys lavra, éste está separado del margen posterior. Una serie de características la ubican cerca del grupo de especies emparentadas con Gnamptogenys relicta (Mann, 1916), como los ojos reducidos, tendencia a nudo peciolar disciforme, proceso ventral peciolar semi-cuadrado con una superficie ventral plana y cuneiforme. Por el otro lado carece de una sutura mesopleural bien definida y el proceso subpeciolar con el margen posterior hendido en vista ventral.

Distribution
Atlantic Forests, Southern Brazil.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Nomenclature

 *  lavra. Gnamptogenys lavra Lattke, 2002: 141, fig. 6 (w.) BRAZIL.

Worker
[Holotipo] LC 0,80; AC 0,67; LM 0,38; LE 0,50; DO 0,04; LW 1,01 mm. IC 0,83; IE 0,76; IM 0,57; IO 0,05.

Cabeza en vista frontal alargada, más ancha anterior- que posteriormente; margen lateral convexo; margen posterior cóncavo; margen anterior con pequeño lóbulo posterior a inserción mandibular; clípeo antero-medialmente prominente; lámina del clípeo poco desarrollada, margen anterior convexo, formando ángulo obtuso con lados rectos. Escapo no alcanza margen posterior, dorsalmente liso y pulido con punteaduras pilíferas finas; lóbulos frontales convexos, levantados dorso-oblicuamente; lóbulo dorsal del tórulo separado del lóbulo frontal, sobresaliendo más cerca del cóndilo antenal que del borde lateral del lóbulo frontal. Frente cefálico con costillaje paralelo longitudinal, costillas con finas impresiones transversales otorgando aspecto granuloso, costillaje sobre clípeo más fino y sin granulosidad; occipucio liso, lado ventral cefálico con costillaje longitudinal. Mandíbula triangular, dorsalmente lisa y pulida con punteaduras finas, margen masticador denticulado; sección transversal cuneiforme. Ojo con un omatidio. Vértice plano, formando ángulo relativamente recto con frente. Palpo maxilar unisegmentado; palpo labial bisegmentado.

Dorso mesosomal y declividad propodeal con costillaje paralelo longitudinal granuloso; cara anterior pronotal con costillaje transversal; sutura promesonotal bien impresa, interrumpiendo costillaje; surco metanotal ausente; declividad propodeal con ángulo lateral-anterior. Lado mesosomal con costillaje longitudinal, sutura mesopleural y anepisterno indistinguibles; sutura mesometapleural impresa; espiráculo propodeal dirigido posterolateralmente, separado de margen declinante por un diámetro. Mesosoma en vista lateral con promesonoto formando convexidad y metanoto-propodeo formando otra convexidad, margen declinante propodeal ligeramente cóncavo, separado de margen dorsal por ángulo casi recto.

Pecíolo erguido con margen anterior ligeramente cóncavo, nudo sin carena transversal anterior; cara dorsal con costillaje transversal, pasando a oblicuo en cara lateral, costillaje formando arcos concéntricos en cara posterior. Proceso ventral en vista lateral semi-cuadrado, en vista ventral cuneiforme con superficie ventral plana y margen posterior recto, no hendido. Gáster en vista lateral con margen dorsal separado de margen anterior por ángulo fuerte; cara anterior lisa y pulida, dorso pospeciolar finamente rugoso, más esculpido anteriormente que posteriormente que tiende a liso y pulido; lados con fina rugosidad longitudinal a oblicua, cara ventral rugosa; proceso antero-ventral cóncavo. Cuarto tergo abdominal con mayor área lisa y pulida que tergo anterior y con arrugas más finas, esterno con rugosidad fina.

Cuerpo píceo, antenas ferruginosas, patas y mandíbulas marrón con tendencia más clara hacia ápice. Procoxa con costillaje transversal; base del protarso opuesto al espolón con una sola seta gruesa; segundo segmento protarsal con cuatro setas gruesas en ápice antero-ventral; dorso metacoxal sin diente o lóbulo.

Camacho et al. (2020) - Worker: HL 0.74−0.79; HW 0.65−0.70; ML 0.38−0.44; SL 0.50−0.55; EL 0.04−0.05; WL 0.81−1.01; PL 0.25−0.28; GL 0.94−1.00; TL 3.16−3.44; CI 85.71−90.32; SI 75.93−79.63; OI 5.77−7.41 (n=8).

Body brown-copper to reddish-brown to black, with slightly lighter appendages, coppery-brown to coppery. Body predominantly covered by medium length, medium thickness and erect hairs. Scape covered by many short suberect hairs.

Mandible smooth and shiny without rugulae or striae on the dorsal surface. Head dorsum covered by long longitudinal costulae, shallow and subparallel; vertex with rugulae and inconspicuous striae. Pronotal dorsum longitudinally costulae. Dorsal surface of mesonotum, metanotum and propodeum covered by longitudinal and subparallel costulae, without smooth and shiny areas. Superior third of declivous face of propodeum with longitudinal costulae gradually becoming transverse on the inferior portion. Procoxae covered by transverse rugulae; mesocoxa and metacoxa covered by irregular striations and heavily punctuated. Petiole covered by inconspicuous rugulae on dorsal and lateral surfaces, with smooth regions and punctuated regions. Segments I and II of gaster smooth and shiny, covered by rugulae and irregular striations at the base of hairs. Anterior face of the first gastral segment bare, smooth and shiny and with some inconspicuous rugulae.

Mandible triangular. Anterior margin of clypeus strongly projected anteriorly, giving it a triangular appearance in frontal view. Lateral margins of head straight and subparallel, slightly tapered anteriorly. Antennal scape does not reach vertex margin; scape ranging from brown to yellowish-copper from the base to the apex. Eye with a single ommatidium located slightly behind the anterior half of the head in frontal view. Vertex margin slightly concave in its central region, giving vertex corners a slightly angled aspect.

Dorsal profile of mesosoma compact and flat in lateral view, without metanotal impression. Lateral margins of the declivity of propodeum distinguishable by the presence of two subparallel carinae; dorsal surface and declivity of propodeum distinguishable by a weak arcuate carina at the junction between them; propodeal spiracle at the same level of the integument; propodeal spiracle distant from declivity margin by a distance three times larger than its opening; opening of propodeal spiracle very wide and facing sideways. Propodeum armed with denticles. Metacoxal spine absent.

In lateral view, anterior and posterior faces of petiole slightly convergent, giving petiole a slightly triangular shape; petiole not pedunculated. Subpetiolar process predominantly opaque and subquadrate, very large, occupying more than half of the ventral surface of the petiole; subpetiolar process with a translucent fenestration which occupies about 2/3 of its area. Dorsal surface of gaster covered by small striae at the base of each hair, with smooth and shiny areas in between; posterior margin of the first tergite of gaster without leathery sculpture; in dorsal view, the first segment of gaster trapezoidal, anterior angles rounded, but differentiated. Prora prominent.

Intercaste
Camacho et al. (2020) - HL 0.76; HW 0.66; ML 0.38; SL 0.48; EL 0.12; WL 0.96; PL 0.28; GL 1.00; TL 3.38; CI 84.61; SI 72.73; OI 18.18 (n=1). Differing from workers by the presence of three ocelli well-developed and arranged in triangle on the head dorsum; compound eye slightly convex, with about eight ommatidia in its largest diameter; body more robust with the presence of scutum and scutellum

Queen
Camacho et al. (2020) - HL 0.80; HW 0.66; ML 0.40 SL 0,52; EL 0,14; WL 1.04; PL 0.3; GL 1.00; TL 3.54; CI 82.5; SI 78.79; OI 21.21 (n=1).

Color, pilosity and sculpture as the workers. Head dorsum with three ocelli well-developed and arranged in triangle; compound eye slightly convex, with about eight ommatidia in its largest diameter; scape failing to reach the vertex margin. Scutum flat in lateral view; notauli not distinguishable; indistinguishable parapsidal lines through the sculpture; parapsides obsolete; tegulae wide, rounded, yellow and translucent; suture between anepisternum and katepisternum lightly marked and transverse, forming an impression that is not enough to completely stop the sculpture. Very narrow pre-scutellum; axillae laterally rounded; scutumscutellum sulcus poorly marked. Scutellum sculptured, with a smooth and shiny region in the center. Dorsal surface of propodeum slightly convex below the level of the scutellum, covered by transverse costulae.

Type Material
Holotipo. Brasil, Minas Gerais, Lavras, 30-iii-1975, W.D. Fronk. Embudo de Berlese. Una obrera depositada en el. El ejemplar Holotipo está montado en un alfiler con tres triángulos de cartulina, uno tiene una pata delantera, uno el gáster y el tercero sostiene el resto del cuerpo.

Etymology
El epíteto específico “lavra” se deriva del nombre de la localidad tipo, Lavras.

The species name is derived from the name of the type locality, Lavras, Minas Gerais, Brazil.

References based on Global Ant Biodiversity Informatics

 * Lattke, J.E. 2002. Nuevas especies de Gnamptogenys Roger, 1863 de America (Hymenoptera: Formicidae: Ponerinae). Entomotropica 17(2):135-144.