Dinoponera gigantea

Dinoponera gigantea (Perty, 1833)

Figs 13–14, 28A

Ponera gigantea Perty, 1833: 135, pl. 27 fig. 3 (☿).

Dinoponera gigantea – Kempf 1971: 372, figs 8–12 (male description). — Lenhart, Dash & Mackay 2013: 139, figs 1d, 4a, f, k, 5c, 9c, 10c, 11c (redescription, male genitals, key). — Tozetto & Lattke 2020: 5, figs 2–3, 6 (male genitals).

Diagnosis

Female Malar area with weak longitudinal to oblique striae that do not reach anterior eye margin. Ventral head surface mostly strigulate. Anteroventral corner of pronotum in lateral view with tooth or acute angle.

Dorsum of pronotum and abdominal tergite III strongly microareolate and opaque. Body length (BL) greater than 27 mm.

Male

Antenna with long suberect to erect hairs, clearly longer than maximum scape diameter. Mesoscutum with notaulus. Gastral tergites with long hairs. Dorsal margin of basal ring in lateral view broadly convex to straight.

Material examined

Lectotype BRAZIL – Amazonas • ☿; Rio Negro; ZSM HYM-25181.

Paralectotypes (2 ☿☿) BRAZIL – Amazonas • 1 ☿; ZSM HYM-25182 • 1 ☿; ZSM HYM-25183.

Non-type specimens (143 ☿☿, 4 ♂♂)

BRAZIL – Amazonas • 1☿; Manaus; D. Dias leg.; MZSP. – Maranhão • 2☿☿; Balsas, Gerais das Balsas; 9 Nov.1999; Brandão, Yamamoto and Dietz leg.; lote 23; MZSP • 1 ☿; Carolina; 7.21533° S, 47.31867° W; 2 Oct. 2015; H. Vasconcelos and J. Maravalhas leg.; DZUP • 1 ☿; Carolina, PN Chapada das Mesas; 7°12′55″ S, 47°19′7″ W; 6 Oct. 2015; H. Vasconcelos, J. Maravalhas and F. Camarota leg.; DZUP • 2 ☿☿; Estreito, assentamento Vitória; 8 May 2004; Herpetologia MZSP, pitfall; MZSP • 1 ☿; Imperatriz; 1 Jul. 1974; Exc. Depto. Zool. exped.; DZUP • 1 ☿; same collection data as for preceding; 4 Jul. 1974; DZUP • 2 ☿☿; same collection data as for preceding; 20 Jul. 1974; DZUP • 1 ☿; Mirador, Reserva Mirador, Geraldina; 6°35′ S, 45°49′ W; 3 Dec. 2009; M.W.A. Mendonça leg.; DZUP • 1 ☿; Miranda do Norte, Babaçual; 30 Oct. 2012; Juliana Alves leg.; CPDC • 2 ☿☿; Nova Colinas; 7°1′10″ S, 46°23′18″ W; 23 Sep. 2009; D. Muniz leg.; DZUP • 1 ☿; Rio Santana, Grajaú; 15 Jun. 1966; H. Reichardt leg.; MZSP. – Mato Grosso • 1 ☿; Barra do Tapirapé; Dec. 1984; B. Malkin leg.; MZSP. – Pará • 1 ☿; Acará, Ilha do Combu; 16 Jul. 1988, J. Dias leg.; MPEG • 1 ☿; Água Azul, Paragominas; 22 Jul. 1974; Exc. Depto. Zool. exped.; DZUP • 2 ☿☿; Alegre, 15 km NE of Marapanim; 10 Sep. 1965; Exp DZ-MG exped.; MZSP • 1 ☿; Ananindeua; Aug. 1964; Machado and Pereira leg.; MZSP • 1 ☿; Barcarena, Reserva Samaúma; 1.4963° S, 48.7088° W; 15–16 Nov. 2001; Iracenir and J. Dias leg.; MPEG • 1 ☿; Belém; 12 Jun. 2000; Delabie leg.; CPDC • 2 ☿☿; same locality as for preceding; 12–19 Aug. 1962; K. Lenko leg.; 2200; MZSP • 1 ☿; same locality as for preceding; 18 Dec. 1994; Gilberto leg.; MPEG • 1 ☿; same locality as for preceding; 22 Jul. 2007; M.A. Rodrigues leg.; DZUP • 1 ☿; same locality as for preceding; 26 Sep. 1934; Carvalho Neto leg.; MZSP • 1 ☿; same locality as for preceding; Jan. 1976; V.P. Daniel and Lucia Repp leg.; MZSP • 1 ☿; same locality as for preceding; Feb. 1956; P. Azevedo leg.; DZUP • 1 ☿; same locality as for preceding; Sep. 1955; Martinez leg.; MZSP • 1 ☿; Belém, Mocambo; 17 Apr. 1997; M.L. Macambira leg.; “ coleta manual, floresta perturbada, área 10m ²”; MPEG • 1 ☿; same locality as for preceding; 18 Apr. 1999; M. Barros leg.; “ coleta manual, floresta perturbada, área 10m ² ”; MPEG • 1 ☿; same collection data as for preceding; M.L. Macambira leg.; MPEG • 1 ☿; Belém, MPEG C. pesquisa; 15–22 May 1997; C. Melo leg.; malaise; MPEG • 1 ☿; Belém, Reserva Guamá; 31 May 1966; Coll Kempf 5074; MZSP • 1 ♂; Benevides; 15 Mar. 1990; W.L. Overal leg.; MPEG HHY03045386 • 1 ♂; same collection data as for preceding; MPEG HHY03034653 • 1 ☿; Bragança, Tracuateua, Sta. Maria; 1 Sep. 1988; F.F. Ramos leg.; MPEG • 1 ☿; Bujaru; 3 Feb. 1979; A.F. Ramos leg.; INPA • 1 ☿; Canindé, Rio Gurupi; 1 May 1963; B. Malkin leg.; MZSP • 1☿; same collection data as for preceding; 1 Oct. 1964; MZSP • 1 ☿; same collection data as for preceding; 1 Dec. 1964; MZSP • 3 ☿☿; same collection data as for preceding; 7–9 Feb. 1966; MZSP • 7 ☿☿; same collection data as for preceding; Apr. 1963; MZSP • 1 ☿; Goianésia; 16–18 Jun. 2003; A.M. Elizabeth leg.; CPDC • 1 ☿; Igarapé Açu; 23–25 Jan. 2008; Santos J.A. leg.; pitfall 20 IASD0608; UFOPA • 1 ☿; same collection data as for preceding; pitfall 18; UFOPA • 1 ☿; same collection data as for preceding; pitfall 21; UFOPA • 1 ☿; same collection data as for preceding; 1.0443° S, 47.5944° W; pitfall 8; UFOPA • 2 ☿☿; same collection data as for preceding; pitfall 13; UFOPA • 1 ☿; same collection data as for preceding; pitfall 7 IASD1138; UFOPA • 1 ☿; same collection data as for preceding; pitfall 20 IASD0609; UFOPA • 1 ☿; “ Igarapé Uruaim, 40 km Rio Gurupi ”; 2 May 1963; J. Carvalho leg.; MZSP • 1 ☿; Marabá; 2017; DZUP • 1 ☿; Marituba; 1°22′ S, 48°20′ W; 21 Oct. 2004; J.R.M. Santos leg.; CPDC • 1 ☿; Óbidos; Dec. 1952; Pedro Telles leg.; MZSP • 2 ☿☿; Ourém, Patauateua; 1 May 1992; Delma leg.; arm. de luz; MPEG • 1 ☿; Outeiro, escola Bosque; 4 Apr. 1993; W. França leg.; MPEG • 25 ☿☿; Paragominas; 1 Mar. 2011; R. Solar leg.; DZUP • 27 ☿☿; same collection data as for preceding; 1 Jul. 2011; DZUP • 1 ☿; same collection data as for preceding; ANTWEB 1038257; UFV • 1 ♂; same locality as for preceding; 2°59′51″ S, 47°21′13″ W; alt. 85 m; Jan–Jul. 2011; R. Solar leg.; UFV LabEcol 449 • 1 ☿; same locality as for preceding; 5 Oct. 1993; Fowler leg.; 3231; CPDC • 1 ☿; Paragominas, Faz. Rio Capim, Empresa Cikel Brazil Verde; 3°33′ S, 48°38′ W; 1 Aug. 2002; DZUP • 1 ☿; Paragominas, Fazenda Sete; 18–23 Sep. 1997; S.M. Ketellhut leg.; “corte seletivo”; T3.3 pitfall 2; MPEG • 1 ☿; Paragominas, Fazenda Vitória; 21 Dec. 1991; Paulo Moutinho leg.; HB-CP T-8 PT4 A15-1 col2; MPEG • 3 ☿☿; same locality as for preceding; 1 Oct. 1999; P.S. Oliveira leg.; “ mata seca ”; MZSP • 1 ☿; Peixe-Boi, Fazenda Santoca, área de mata; 1.13991° S, 47.3006° W; 10 Mar. 2010; J. Dias leg.; “ rede entomológica ”; MPEG • 1 ♂; Primavera, Quadripaum Fal. Feitoria; 27 Nov. 1992; J. Dias leg.; “ armadilha de luz ”; MPEG 03006727 • 1 ☿; Rio Tocantins, base 4; 18 Jul. 1987; Wynes Barbosa leg.; Coleção Diniz; DZUP • 1 ☿; S.C. Odivelas; 19 Nov. 1982; P. Tadeu leg.; MPEG • 2 ☿☿; same locality as for preceding; 27 Feb. 1979; R.B. Neto leg.; INPA • 1 ☿; Serra Norte, Salobo; 17 Sep. 1985; Marcio Zanuto leg.; MPEG • 1 ☿; Tailândia; 30 Jun. 2005; M. Silva leg.; MZSP • 1 ☿; Tucuruí, Vila Brava; 22 Jun. 1980; Nunes de Melo leg.; INPA • 1 ☿; same collection data as for preceding; 27 Jun. 1980; INPA • 1 ☿; Tucuruí, Inajá; 20 Jun. 1980; B.M. Mascarenha leg.; INPA. – Tocantins • 1 ☿; Araguaina; 2 Oct. 2015; H.L. Vasconcelos and J.B. Maravalhas leg.; 251, T70-3S; DZUP • 1 ☿; Babaçulândia; 7°01′03″ S, 47°52′14″ W; 10–15 Dec. 1961; Albuquerque and Silva leg.; “ isca solo ”; MZSP.

PERU – Loreto • 2 ☿☿; Estirón, Río Ampiacú; 15 May 1966; B. Malkin leg.; 5881; MZSP • 1 ☿; same collection data as for preceding; DZUP.

Redescription

Female

MEASUREMENTS. Lectotype: HL 5.85; HW 5.35; MDL 4.52; SL 5.98; MSL 8.8; HFL 8.2; HBL 6.64; PL 2.44; PH 3; PW 1.73; ATS 8; BL 29.63 (mm); CI 0.91; SI 1.11; DPI 0.7. Paralectotypes ZSM HYM- 25183 and ZSM HYM-25182 (NA = not available): HL 5.35 and 5.95; HW 5 and 5.6; MDL 4.07 and 4.5; SL NA and 5.92; MSL 7.6 and 8.7; HFL 7 and 8.4; HBL 5.67 and 6.9; PL 2.24 and 2.57; PH 2.97 and 3.25; PW 1.78 and 1.89; ATS 6.96 and 8.4; BL 26.23 and 30.12 (mm); CI 0.93 and 0.94; SI NA and 1.05; DPI 0.79 and 0.73. Non-types (n = 26): HL 5.35–6.23; HW 5.29–6.11; MDL 4.09–4.97; SL 5.41–6.36; MSL 7.76–9.3; HFL 7.24–8.9; HBL 6.16–7.5; PL 2.32–2.69; PH 3.03–3.6; PW 1.67–2.07; ATS 7.52–9.6; BL 27.11–32.23 (mm); CI 0.94–1.03; SI 0.98–1.09; DPI 0.68–0.82.

HEAD. Malar area without striae or with weak longitudinal to oblique striae that do not reach anterior eye margin. Gena microareolate and opaque, usually without rugulae. Apressed brownish pubescence present between eye and frontal lobe, extending posteriorly to frons. Frons microareolate and opaque; with flexuous, brownish and suberect hairs, longer than scape diameter; pubescence densest laterally. Occipital corner strongly microareolate and opaque. Antennal scape microareolate and silky, suberect and long hairs usually present on antennal segments 1–3. Ventral surface of head microareolate with arched strigulae covering entire surface or at least anterior half; posterior to postgenal suture with well-marked transverse strigulae. Hypostomal tooth with longitudinal strigulae. Labrum with median longitudinal sulcus weakly marked or absent; transverse rugulae absent. Mandibular dorsum weakly longitudinally strigulate on inner base, sculpture gradually fading apicad.

MESOSOMA. Dorsal margin of pronotum in lateral view broadly convex, usually with no pronounced dorsoposterior swelling; anteroventral corner of pronotum toothed or forming acute angle. Pronotal dorsum strongly microareolate, rugulose and opaque. Metapleural-propodeal suture weak and sinuous, with at least one curve ventral to position of propodeal spiracle.

METASOMA. Petiolar node in lateral view elongate (usually DPI <0.8); anterodorsal corner at same level as posterodorsal corner, sometimes slightly higher; anterior margin straight or slightly concave, forming blunt angle with dorsal margin; dorsal and posterior margin each broadly convex and forming blunt to rounded angle. Node lateral face microareolate and opaque (rarely silky). Node anterior margin in dorsal view slightly convex; posterior margin straight to broadly convex; lateral faces broadly convex. Abdominal tergite III strongly microareolate and opaque; densely punctulate on dorsal and lateral surfaces; distance between each punctulae approximately equal to their diameter; densely covered with brownish, flexuous, erect hairs and appressed pubescence on all surfaces.

Male

MEASUREMENTS. Non-types (n = 4): HL 2.28–2.58; HW1 2.76–3.12; MDL 0.58–0.75; SL 0.9–0.92; EL 1.64–1.87; MOD 0.52–0.57; LOD 0.5–0.52; MSL 7–7.5; HFL 5.4–6.33; PL1 1.96–2.12; PH 1.68–2.01; PW 1.2–1.38; ASL 4.7–5.12; BL1 16.75–18.1 (mm); CI1 1.1–1.21; SEI 1.82–2.02; SI1 0.29–0.33.

HEAD. Frontal carina forming short longitudinal swelling. Lateral ocellus clearly surpassing posterior head margin in full-face view. Head punctulate, weakly microareolate and shining; with yellowish decumbent pubescence and long suberect to erect hairs longer than ocellus height in full-face view. Antenna with appressed pubescence and long suberect to erect hairs clearly longer than maximum scape diameter; third to fourth most apical antennomeres with few sparse hairs. Ventral surface of head punctulate and slightly microareolate with silky sheen.

MESOSOMA. Mesoscutum with notaulus slightly impressed. Mesopleural sulcus punctate or slightly scrobiculate. Scutoscutellar sulcus scrobiculate. Mesoscutellum longitudinally strigulate laterally. Metapleural-propodeal suture with same microsculpture as rest of integument. Mesosoma mostly slightly microareolate and with silky sheen, becoming coarsely punctate on declivitous surface of propodeum; with decumbent to suberect pubescence and suberect hairs, distance between each hair usually less than half its length. Legs densely covered by decumbent pubescence; also with sparse suberect long hairs, greater than femur diameter, from coxa to tibia. Protibial apex with at least one robust seta.

METASOMA. Petiolar node microareolate and shining, densely covered by decumbent pubescence and abundant suberect hairs. Abdominal tergite VIII spiniform. Gaster very slightly microareolate and shining; tergites densely covered by appresed to decumbent pubescence and sparse suberect hairs.

GENITALIA. Basal ring in dorsal view having slightly concave lateral margins, anteriorly narrower than posteriorly; fenestra rounded to slightly transversally directed; median invagination U-shaped; in lateral view, dorsal margin broadly convex to straight; anteroventral process rounded or slightly subquadrate. Gonostylus narrow and sharp. Dorsal margin of volsella in lateral view anteriorly straight to broadly convex and posteriorly concave; anteroventral corner with two anterior teeth; posteroventral margin strongly concave and forming sharp, triangular posterior lobe; digitus volsellaris with posterior margin straight or with a slight concavity. In lateral view, penisvalva with continuous dorsal and posterior margins, ending in rounded apex; ventral margin even and serrated; concave; anteroventral corner sharply pointed.

COLOR. Body mostly chestnut brown.

Remarks

A robust set of characters separate females of D. gigantea from the other species of the genus. It differs from D. hispida, D. longipes, D. mutica and D. nicinha sp. nov., all species with either an overlapping or close distribution, by the opaque and microareolate pronotal dorsum and abdominal tergite III. Additionally, D. gigantea usually has the anteroventral pronotal corner with a tooth or an acute angle in lateral view. The other species with a toothed pronotum are D. lucida and D. grandis. Dinoponera lucida has bluish iridescence on abdominal tergite III and striae on the malar area that reach the anterior eye margin. Dinoponera grandis has a body length (BL) less than 27 mm and a relatively shorter petiolar node in lateral view (DPI>0.8), besides the presence of well-marked striae on the malar area.

Rarely, some specimens may either have a small tooth or obtuse angle on the anteroventral pronotal corner or the third abdominal tergite with very sparse piligerous punctulae, and occasionally both. In such cases, D. gigantea may be confused with D. quadriceps, but this may be avoided by examining the ventral surface of head, which has arched strigulae covering the entire surface or at least the anterior half in D. gigantea. These variants are more commonly found in Maranhão and Tocantins, where the distribution of these species may overlap. Dinoponera gigantea and D. quadriceps are nevertheless maintained separate, as argued in the remarks for D. quadriceps.

Additional support for this separation is provided by the huge differences between their habitats, as D. gigantea is typically from the Amazon and D. quadriceps is from the Caatinga (IBGE 2019). It is worth noting that Maranhão and Tocantins, where the ‘problematic’ specimens are found, are mostly within the Cerrado Biome, which is located between the Amazon and Caatinga Biomes (IBGE 2019).

The lectotype and two paralectotypes of D. gigantea from the ZSM were examined. Diller (1990) designated the only labelled specimen as the lectotype in the type series of six ants. One of the examined paralectotypes (ZSM HYM-25183) is unusual in having a body length (BL) less than 2.7 cm, a straight metapleural-propodeal suture, a relatively short petiolar node in lateral view (DPI = 0.79), the ventral cephalic surface weakly strigulate, abdominal tergite III with sparse piligerous punctulae and relatively short and thick body hairs, especially on the cephalic venter. Collectively these characters do not correspond with the typical characterization of any species in this genus. Nevertheless, recognizing a new species was not considered, as the exact collection locality is unknown. Perhaps this specimen is an atypical variant of D. gigantea. The worn integument and caked dirt may have abraded some hairs or made others appear more rigid than they should be, potentially complicating character interpretation. The specimen designated as lectotype by Diller (1990) is the one that better represents the forms described as D. gigantea and more resembles the specimens found in the North of Brazil.

Kempf (1971: 372) gave a diagnostic description of the male based on specimens from Belém, and Lenhart et al. (2013) described the genitalia of a male from Belém. Tozetto & Lattke (2020) described the genitalia of 3 males, all from different sites in Pará. This last study found greater similarities between the basal ring, gonopod, volsella and penisvalva of D. gigantea and D. quadriceps than between other species. Lenhart et al. (2013), in their identification key to the males of the genus, separated D. gigantea and D. quadriceps from those of other species by the long and erect hairs of the funiculus. Kempf (1971) noted the similarities between these two species on account of eye and ocellus size. The aforementioned similarities between these two species suggest they are more closely related to each other than with any of the other known species. Nevertheless, males of D. gigantea can easily be separated from D. quadriceps by the presence of a notaulus on the mesoscutum and the abundant hairs on the body.

Biology

Within their known range these ants are found in areas where the average temperature of the coldest month is higher than 18°C and the annual precipitation is higher than 1000 mm (Alvares et al. 2013). They may be found at sites with different phytophysiognomies, ranging from dense forests to savannas with small woody plants (IBGE 2012). Their nests, which may be polydomic, are usually built at the base of trees and may be up to 40 cm deep (Fourcassié et al. 1999; Fourcassié & Oliveira 2002). Each nest has from one to eight entrances surrounded by loose soil never piled into a mound (Fourcassié & Oliveira 2002). On average, each nest has some 41 adult workers (Monnin et al. 2003).

Workers forage alone searching for a broad variety of resources such as seeds, fruits, and dead or live arthropods (Fourcassié & Oliveira 2002). Foraging may be diurnal or nocturnal, with activity decreasing during the hottest hours of the day (Fourcassié et al. 1999; Fourcassié & Oliveira 2002). Workers exhibit general fidelity, with minor deviations, to a foraging route (Fourcassié et al. 1999). Spatial orientation during foraging apparently uses relatively large-scale reference points in the landscape, as minor changes, such as sweeping the leaf litter, do not change their path (Fourcassié et al. 1999). Workers from different colonies may find themselves at the edge of their foraging routes and exhibit territoriality, beating each other with their antennae (Fourcassié & Oliveira 2002). Hierarchical relationships within a colony are determined by the same agonistic interactions described for D. quadriceps, although with a lower frequency (Monnin et al. 2003).

Distribution (Fig. 28A)

Dinoponera gigantea has been recorded in northern Brazil and eastern Peru. In Brazil, the northernmost record is the type-locality along the Rio Negro (probably close to Barcelos, Amazonas, according to Kempf 1971). It is important to note that, except for the type-series, D. gigantea has only one record for Amazonas.All other records are mostly from Pará and Maranhão, with the southernmost record from Rio Tapirapé, Mato Grosso. The examined records from Peru date from 1966 and are close to the border with Brazil, more than 900 km from any other record. This may indicate a much more extensive distribution in the recent past. Lenhart et al. (2013) examined a specimen from Bartica, Cuyuni-Mazaruni, Guiana but this single record may be an artefact of a misplaced label, as it is 500 km from any other record for the genus. Despite numerous surveys and collecting, Dinoponera has yet to be recorded from the Guiana Shield (Wheeler 1916, 1918; Lapolla et al. 2007; Alonso 2012; Alonso & Helms 2013; Helms et al. 2016; Groc et al. 2014; Franco et al. 2019).