Leptogenys unistimulosa Roger, 1863

Tozetto, Leonardo, Chaul, Júlio C. M., Lattke, John E. & Boudinot, Brendon E., 2022, Review of the Leptogenys unistimulosa species group (Hymenoptera: Formicidae) with the description of a new Amazonian species, Revista Brasileira de Entomologia (e 20220045) 66 (3), pp. 1-17 : 12-15

Leptogenys unistimulosa Roger, 1863

( Figures 10 and 11D )

Male diagnosis

Uniquely identified among the unistimulosa species complex by the following conditions: (1) Body size not very large (WL <3.05 mm); (2) ocelli medium-sized, the distance between compound eye and lateral ocellus in full face view about no more than 1.5x ocellus width; (3) ocelli close to or slightly surpassing posterior head margin in full face view; (4) compound eyes large but not grossly enlarged, slightly longer than maximum distance between eyes, facial area may be about twice as wide as eye; (5) scape more than two times pedicel length, and longer than clypeal length; (6) mesoscutum longer than broad; (7) mesoscutum largely smooth, with indistinct sculpture posterad notauli; (8) vein Cu-f2 reduced; (9) 2r-rs longer than Rs-f4; (10) petiolar node without bulge anterad posterodorsal corner; (11) abdominal sternites IV–VIII (gastral II–VI) sparsely pilose, without appearance of dense shaggy pads. Most similar to L. parensis , having a long mesoscutum (6) and neither small nor particularly large eyes and ocelli (2–4); distinguished from L. parensis by its smaller body size (1).

Male measurements

EL 0.69–0.88; OL 0.14–0.19; OES 0.14–0.19; CML 0.39–0.48; ML 0.40–0.49; SL 0.50–0.60; HL 1.18–1.25; HW 1.22–1.43; MeL 1.09–1.25; MeW 1.01–1.17; WL 2.62–3.05; PetW 0.50–0.62; PetH 0.90–1.03; PetL 0.70–0.87; OI 54.8–63.7; MI 31.4–36.3; CI 101.7–116.7; SI 37.6–44.4; DPI 65.2–80.0; LPI 108.0–129.5; (n = 10).

Head in full-face view longer than wide, excluding eyes, usually wider than longer including eyes; cuticular surface punctate.Mandible slightly shorter than antennal scape, rounded apically, edentate, dorsal surface smooth and shining. Clypeus with thin lamella present laterally on anterior margin; weakly rugose laterally. Frontal carinae reduced. Antenna: Scape more than 2x pedicel length and longer than clypeal length; pedicel longer than wide. Compound eye large and bulging; minimum distance between eyes in full-face view as wide as eye, sometimes 1.5–2x wider than the eye.Ocelli equal in size, not noticeably protruding beyond posterior border of head; distance between compound eye and lateral ocellus may vary, but not more than 1.5 x greater than median ocellus maximum diameter.

Mesosoma with dorsal profile broadly convex in lateral view. Pronotum punctate, weakly rugose laterally. Mesoscutum in dorsal view longer than wide; usually punctate, occasionally with weakly impressed striae. Notauli strongly impressed, scrobiculate. Parapsidal lines about half mesoscutal length.Mesoscutellar disc with longitudinal striae. Upper mesopleural area (= anepisternum) punctate with median band of oblique striae. Longitudinal mesopleural sulcus scrobiculate. Lower mesopleural area (= katepisternum) punctate to mostly smooth with sparse punctae. Mesometapleural suture well impressed. Upper metapleuron rugulose to punctate, sculpturing shallower than on lower metapleuron. Propodeum in lateral view with an angle between dorsal and descending margins; dorsally rugulose, declivity shining and with few carinae.Sculpture: Propodeum and metapleuron rugulose, declivity with some carinae.

Wings. Vein pattern as in L. bohlsi but 2r-rs is longer than Rs-f4.

Metasoma. Petiole subtriangular in lateral view, anterior profile broadly convex, summit convex to pointed and highest point posteriorly, posterior margin vertical. Subpetiolar process rounded. Petiolar node trapezoidal in dorsal view, longer than wide; lateral surface mostly rugulose, posterior face with weak striae laterally smooth medially. Cinctus well marked. Gaster mostly smooth with sparse punctulae. Abdominal sternum IX posteriorly rounded.

Setation. Head with erect long hairs and with fined decumbent hairs; clypeus with fine sub-decumbent hairs, anteriad with few long suberect hairs; antenna with stout sub-erect hairs and pubescence, scape with few long hairs. Mesosoma, petiole, and gaster covered with some long erect hairs; pronotum, upper and lower mesopleural areas with short sub-decumbent hairs.

Color. Body black to brown; clypeus, antenna, legs, and gaster ferruginous brownish.

Comments

We inferred these males belong to L. unistimulosa on account of the localities from which they were collected, which match the known distribution of L. unistimulosa and are partially beyond the known range of L.bohlsi . Leptogenys unistimulosa has a distribution that covers most of northern South America with no known records south of 17°S, whilst the distribution of L. bohlsi is mostly in southern South America up to Maranhão, Brazil, with a single record from Manaus, Brazil ( Lattke, 2011). A single male from the Coastal Cordillera of northern Venezuela is without a doubt L. unistimulosa , as many workers have been collected in the same site and in other localities of the Cordillera ( Lattke, 2011).

The large and bulging eyes and the subtriangular petiole make this species recognizable. The convexity of the eye is noticeably greater than that of L. bohlsi and L. parensis with the head in full-face view. L. unistimulosa males also resemble L. elzasoares new species, but the former have the petiole summit rounded to subtriangular, while the latter have a truncate summit (seeL. elzasoares new species comments). L. unistimulosa males have a wide morphological variation, even within the same series. The body size may vary, as the specimens from Peru are slightly larger. The ocelli are smaller in the male from Venezuela compared with Brazilian specimens from Pernambuco, Sergipe, and Amazonas. The distance between lateral ocellus and compound eye is less than medium ocellus width in the Venezuela males, while it is equal or greater in specimens from Brazil. The petiolar node shape varies from rounded in the Amazonas specimen to presenting a blunt posterior angle in the Peru specimens, this variation seems to be widespread throughout this species, as a series of three males from Goiás present the node varying from rounded to pointed.

A specimen from La Paz, Bolivia (DZUP 550873) was identified as L. aff. unistimulosa as it differs from L. unistimulosa by having a pointed mandible apex, forming a small tooth, and relatively larger ocelli. A male from Mato Grosso do Sul, Brazil (DZUP 550886) represents another form close to L. unistimulosa , as it has a large compound eye, large ocelli, and the mesoscutum in dorsal view only punctate. However, its petiole is mostly rounded, and the specimen is considerably smaller (WL 2.37) thanL. unistimulosa males (WL 2.62–3.05). These specimens could represent two different species, but a decision should await the availability of additional material given its similarity with L. unistimulosa .

Material studied

Bolivia. La Paz: Mapiri-Sarampiuni , 13.ii.2055, Malaise, J. Rodriguez, 1 male DZUP 550873 [ DZUP] . Brazil. Amazonas: Estirão do Equador, R. Javari, ix.1979, Alvarenga , 1 male [ MZSP]. Pernambuco: Caruaru , v.1972, J. Lima, 2 males [ MZSP]. Goiás: Jataí , 12.xii.1972, 8983, F. M. Oliveira, 3 males [ MZSP]. Mato Grosso do Sul: Aquidauana , 20°26’12.53”N 55°39’40.05”W, 05.xii.2012, M. Savaris & S. Lampert, 1 male, DZUP 550886 [ DZUP]. Pernambuco: Caruaru , v.1972, J.Lima, 2 males [ MZSP]. Roraima: Caracaral , Parque Nacional do Viruá , 01.4412° -61.0437°, 406m, 06-12.xii.2017, J. Lattke #3889, 1 worker DZUP 550889 [ DZUP]. Sergipe: N. S. das Dores, 1.ix.2014, Area RL Parcela 24, Almeida, R. P. S. Leg. 1 male DZUP 550878 [ DZUP]; Laranjeiras, 10°49’16.3”S 37°11’15.3”W, 21.vi.2012, E.Gomes, 1 worker UVF LABECOL 001237 [ CELC] . Peru. Cusco: Quincemil, 13°20’10”S 70°50’57”W, 23-31.viii.2012, Malaise, 19KmW Rio Araza tributary, 874m, R.R. Cavichioli, J.A. Rafael, A.P.M. Santos & D.M. Takiya, 1 male DZUP 550875 , 1 male DZUP 550876 [ DZUP] . Venezuela. Carabobo: Sector Palmichal , 5.3km ENE Canoabo, 10.2932° -68.2342°, 14.vi.1998, J.L. García, F.I.T., 1 male DZUP 550877 [ DZUP] .

Figures

Figure 10. Leptogenys unistimulosa male, DZUP 550877. (A) full-face, (B) lateral, (C) mesosoma in profile and (D) dorsal view, (E) fore wing and (F) hind wing.

Figure 11. Figure 11. Distribution maps. (A) L. bohlsi; (B) L. elzasoares; (C) L. parensis; (D) L. unistimulosa, Miranda et al. (2012), Salazar & Donoso (2013), Gomes et al. (2014), Miranda et al.(2017), Santos et al. (2017), Fernandes & Souza (2018), Prado et al. (2019), Nascimento et al.(2020). Red circles:type locality; White circles:material studied; Black circles: material studied by Lattke (2011), Black triangles: records not examined from literature after 2011.