Gnamptogenys lavra Lattke, 1863

Camacho, Gabriela P., Franco, Weslly & Feitosa, Rodrigo M., 2020, Additions to the taxonomy of Gnamptogenys Roger (Hymenoptera: Formicidae Ectatomminae) with an updated key to the New World species, Zootaxa 4747 (3), pp. 450-476 : 467-470

Gnamptogenys lavra Lattke

( Figures 19 and 20 )

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

Holotype: BRAZIL: Minas Gerais: Lavras , 30-iii-1975, W.D. Fronk. Berlese funnel (1 worker) [MCZC] [examined].

Diagnosis: 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 ( Fig. 19A and 20A, D ). 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 ( Fig. 19B and 20B, E ). 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 ( Fig. 19B, C and 20C, F ).

Redescription

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-cop- per 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 (first description): 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.

Dealate queen (first description): 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.

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

Distribution: This species was recorded in the South of Brazil ( Fig. 17 ), usually collected in rainforests.

Natural history: 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.

Comments: This species is morphologically related to G. reichenspergeri (Santschi) 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 , described here, has similar features, but differs from G. lavra by the gaster being completely smooth and shiny and the scape surpassing the vertex margin.

Examined material: BRAZIL: Minas Gerais: Viçosa, i.1988, M.V.B. Queiroz col. (2 workers) [MZSP]; Viçosa, 20° 46’ 36.70”S, 42° 50’ 32.95”W, 20.iv.2013, J. Chaul col., n. P7 (1 queen /1 intercaste) (UFV-LABECOL- 005812/005813) [DZUP] ; Machado , 21º40’54.56”S 46º0’56.91”W (1 worker) (UFV-LABECOL-005814) [DZUP] .

Rio Grande do Sul: Itati , 29°27’54’’S, 50°09’49’’W, 24-30. viii.2009, R.R. Silva & R. M. Feitosa col. (1 worker) [MZSP] . Santa Catarina: Palhoça , 27°44’28’’S, 48°41’50’’W, 02-10.vi.2003, R.R. Silva, B.H. Dietz & A. Tavares col., n. 25 (2 workers) [MZSP] . São Paulo: Ubatuba , 23°19’S, 44°49’W, 18.i.2006, Scott-Santos, C.P. & Santos, E.F. col., n. 9 (1 worker) [CPDC] .

Figures

FIGURE 17. Distribution records of the new and revived species of Gnamptogenys.

FIGURE 19. Worker of Gnamptogenys lavra (UFV-LABECOL-005814) in A) frontal view; B) dorsal view; and C) lateral view.

FIGURE 20. Intercaste specimen of Gnamptogenys lavra (UFV-LABECOL-005813) in A) frontal view; B) dorsal view; C) lateral view; and queen of Gnamptogenys lavra (UFV-LABECOL-005812) in D) frontal view; E) dorsal view; F) lateral view.