Odontomachus xeta, França & Fernandes & Bravo, 2024

França, Eder Cleyton Barbosa, Fernandes, Itanna Oliveira & Bravo, John Edwin Lattke, 2024, Looking at upside-down ants: Taxonomic revision of the Neotropical species of Odontomachus Latreille, 1804 (Hymenoptera: Formicidae: Ponerinae), Zootaxa 5502 (1), pp. 1-166 : 145-153

Odontomachus spissus Kempf, 1962 ( Figures 12-A , 60 , 113 and 114 )

Odontomachus spissus Kempf, 1962: 17 (☿); Kempf, 1975: 345 (♀).

Type specimens: Holotype. BRASIL [ BRAZIL]: MT [Mato Grosso], Utiariti, Rio [River] Papagaio , VII-961[25. vii.1961], K. Lenko col., [Coll. Lenko] 1583, MZSP77725 1☿ [ MZSP].

Paratype. Same data as holotype, MZSP77726 1☿ [ MZSUP] .

Etymology: From Latin word spissus = thick, dense, crowded or slow; probably referring to the compact body and small size of this species.

Diagnosis: (☿) Eyes small (EL= 0.2 mm). Vertex rectangular wider than long, smooth and shining. Scape very short, just surpassing the occipital bridges. Mesonotum almost entirely smooth and shining. Petiolar node scale-like; petiolar spine vestigial. Small brown ants (TL= 7.5). (♀) Vertex, scape and petiole as in worker. (♂) Unknown.

Worker

Holotype measurements: EL 0.19, HL 2.06, HoW 1.61, HvW 1.38, HW 1.54, ML 0.98, SL 1.37, PnW 1.03, WL 2.15, FL 1.63, PTH 0.55, PTL 0.35, PTW 0.35, GL 2.01, TL 7.55. CI 0.74, MI 0.47, PtI 1.57, SI 0.66, VI 0.89.

Non-type measurements: EL 0.20, HL 2.00-2.20, HoW 1.50-1.80, HvW 1.30-1.50, HW 1.40-1.70, ML 1.00, SL 1.50, PnW 0.90-1.00, WL 2.10-2.20, FL 1.60-1.80, PTH 0.70-0.80, PTL 0.30, PTW 0.30-0.40, GL 1.90-2.20, TL 7.30-7.90. CI 0.66-0.77, MI 0.45-0.60, PtI 2.33-2.66, SI 0.68-0.85, VI 0.88-0.93 (n= 4).

Head. Vertex rectangular, wider than long in frontal view. Posterior margin concave medially; occipital carina not forming nuchal collar. Cephalic constriction conspicuous. Frontal lobes striated. Ocular bridges posteriorly forming arc. Eye small (EL= 0.2); slightly elliptical, posterior margin acute. Clypeus smooth and shining with inconspicuous piligerous punctuation on median portion. Malar area with inconspicuous irregular striae anteriorly in latero-oblique view, smooth and shining posteriorly.

Mandible. Shorter than anterior head portion. External margin strongly convex. Masticatory margin with blunt denticle series. Palp formula 4,3.

Antenna. Scape short, surpassing just ocular bridges.

Mesosoma. Pronotum in lateral view rounded to slightly angulated; neck well developed anteriorly in dorsal view; lateral margin rounded, posteriorly forming slightly obtuse angle; central disc of pronotum with regular longitudinal striae, lateral striae forming concentric circles or arcs directed anteriorly. Propleuron smooth and shining. Mesonotum larger than wide, narrow posteriorly, with fine transverse striae effaced centrally. Mesopleuron without carina on anteroventral portion; completely smooth and shining. Mesometanotal sulcus vestigial, smooth and shining, anteriorly continuous to the mesonotum but posteriorly separated from metanotum by slightly coarser striae. Metanotum length 1/3 of mesonotum length. Metapleural gland bulla with irregular transverse striae finer than metapleural striae. Propodeum in lateral view convex and short, as long as pronotum and mesonotum length; posterior face continuous with dorsal face forming a single convex surface. Metasternum with metasternal process close forming thin arc; fine transverse striae.

Petiole. Sessile. Scale-like node. Anterior margin in lateral view straight to slightly concave; posterior margin convex on dorsal portion, forming two blunt lateral projections in latero-oblique view. Spine vestigial forming short blunt projection. Completely smooth and shining. Subpetiolar process longer than wide; tip rounded; posterior portion slightly concave.

Gaster. First tergum almost higher than long; anterior and dorsal margin meeting in an obtuse angle; dorsal face convex. dorsal face of all terga smooth and shining.

Color and size. Body brown to light brown. Legs and antennae yellowish. Relatively small size.

Pilosity. Sparse, conspicuous and short pubescence spread over the body, separated each other more than its length. Pubescence on petiole shorter. Short hairs on pronotum and dorsum of gastral terga, smaller than procoxa width.

Gyne

Non-type measurements: EL 0.30, HL 2.20, HoW 1.80, HvW 1.50, HW 1.60, ML 1.10, SL 1.60, PnW 1.20, WL 2.70, FL 1.80, FWL 5.10, PTH 0.80, PTL 0.40, PTW 0.40, GL 2.90, TL 9.30. CI 0.72, MI 0.50, PtI 2.00, SI 0.72, VI 0.93 (n= 1).

Mesosoma. Pronotum slightly longer than high in lateral view, dorsal margin concave forming obtuse angle, separating in anterior and dorsal margin; lateral margins converging anteriorly forming a neck in dorsal view; pronotal dorsum with regular transverse striae becoming irregular posteriorly; anterior portion with longitudinal striae gradually forming arcs posteriorly in lateral view, ventral portion with irregular striae. Subalar area separated from pronotum by coarse stria; with microsculpture. Mesoscutum anterior and dorsal margins meeting in convex surface, form an almost rounded right angle; smooth and shining with effaced longitudinal striae medially in dorsal view; striae between parapsidial line and parascutal area effaced, oblique directed medially. Parapsidial line straight, well-marked. Parascutal area smooth and shining. Notopropodeal sulcus scrobiculate. Axilla smooth and shining with sparse punctures. Mesoscutellum smooth and shining with inconspicuous punctures with longitudinal carina. Metascutellum smooth and shining with longitudinal carina. Propodeum in posterior view with striae forming concentric circles.

Wing. Color pale yellow, translucid. Forewing ML1 curved. RsL1 straight; shorter than Rs+M. RSL2-3 sinuous. Rs+M and ML2 forming single slightly curved line, not forming angle with RsL2-3. Vein cu-a not reaching M+Cu ML1 angle by almost its half-length. Hindwing 1rs-m vein straight. 9 hamuli.

Petiole. Scale-like node, anterior face straight, dorsal portion of posterior face rounder than worker petiole. Petiole apex forming blunt denticle standing-out from lateral margins.

Pilosity. Pubescence on mesosoma strongly curved, dense separated each other less than its length. Pubescence on mesoscutellum less dense. Pronotum and mesoscutellum with pair of long hair curved posteriorly.

Natural history: Little is known about its biology. There is a record of specimens collected in a globular nest of Armitermes Wasmann, 1897 ( Termitidae : Nasutitermitinae ), however, it is not known if these specimens were walking on the nest or if they were in there as inquilines. The reduced eyes, antennae, and body size, along with the petiolar node without spine, suggest that O. spissus have hypogeic and cryptic habits ( Wong & Guénard, 2017). Therefore, this would explain the lack of information about its biology, its relative rarity in collections, and its patchy distribution throughout the Amazonian Forest and transition areas of Amazon and Cerrado ( Fig. 60 ).

Comments: Among the Odontomachus species with vertex smooth and shining, O. spissus is easily recognizable due to its small size (TL= 7.30-7.90), the reduced eyes, the short scape, and the scale-like petiolar node. The two species that are also small in size or can have small specimens are O. biolleyi and O. meinerti , but in both cases, the combination of large eyes, long scape, and conical petiolar node are enough to distinguish O. spissus from them.

Material examined: 11☿ and 1♀. BRAZIL: Amapá: Laranjal do Jari (1☿) . Mato Grosso: R [Rio] Sol [Solimões] 150km N Xavantina (1☿) ; Utiariti (1☿) ; [ Vera ] (1♀) ; Pará: Terra Santa (1☿) . Tocantins: Lizarda (4☿) . FRENCH GUIANA: Cayenne: Régina, Nourages Inselberg Sta. [Station] (1☿) ; Nouragues Natural Reserve (1☿) . VENEZUELA: Bolivar: Cerro Los Pijiguaos (1☿) .

Odontomachus xeta França, Fernandes & Lattke new species urn:lsid:zoobank.org:act:5A9FBFDB-EA09-4F96-B6C3-5229E75B8B0A ( Figures 21-A , Fig. 22-B , Fig. 32-A , 41-A , 64 , 115 , 116 and 117 )

Type specimens: Holotype. BRAZIL: PR [Paraná], Res. [Reserva] Guaricica, 25.316°S 48.696°W [-25.316000, -48.696000], 50m, 05-10.xi.2015, Curso de Entomologia UFPR, DZUP548915 1☿ [ DZUP].

Paratypes. BRAZIL: PR [Paraná], Antonina, Reserva Rio Cachoeira [Reserva Guaricica], 25.315°S 18.696°W [-25.315000, -48.696000], 50m, 20-25.xi.2014, Entomologia UFPR, DZUP548916 1♀ [ DZUP] . BRAZIL: PR [Paraná], Antonina, Reserva Sapitanduva , 03.xi.1986, -25.4452 -48.8098, 29m, PROFAUPAR, arm. luminosa [light trap], DZUP549187 1♂ [ DZUP] .

Note: The label of the paratype DZUP548916 has a typo in the west geolocation. The correct is 48.696°W

Etymology: The species name xeta honors the indigenous people Xetá from Paraná state ( da Silva, 2021), used as a proper noun in apposition to refer to this indigenous people who lived in the type-locality of this species.

Diagnosis: (☿) Vertex rectangular. Eyes elliptical, longer than large with posterior margin acute. Propleuron with fine regular transverse striae, central portion smooth and shining. Metasternum with irregular transverse striae; metasternal process forming an arc bilobate medially. Petiolar node cylindrical. (♀) Vertex, eyes and Metasternum as in worker. (♂) Body color dark brown with lighter areas. Mesoscutellum in antero-dorsal view with dorsal margin concave. Posterior face of propodeum with concentric striae parallels to median longitudinal carina. Metasternum as in worker.

Worker

Holotype measurements: EL 0.4, HL 3.2, HoW 2.5, HvW 2.0, HW 2.2, HW 2.2, ML 1.9, SL 2.7, PnW 1.3, WL 3.6, FL 3.1, PTH 1.3, PTL 0.6, PtW 0.5, GL 3.1, TL 12.4. CI 0.68, MI 0.59, PtI 2.16, SI 0.84, VI 0.90.

Paratype measurements: EL 0.5, HL 3.5, HoW 2.8, HvW 2.3, HW 2.5, ML 2.1, SL 3.0, PnW 1.4, WL 3.8, FL 3.4, PTH 1.4, PTL 0.6, PTW 0.5, GL 3.7, TL 13.7. CI 0.71, MI 0.6, PtI 2.33, SI 0.85, VI 0.92 (n= 1).

Head. Vertex rectangular, wider than long in frontal view; with regular longitudinal striae. Posterior margin concave medially; occipital carina not protruding. Cephalic constriction conspicuous. Frontal lobes striated. Ocular bridges posteriorly forming arc. Eye relatively large (EL> 0.4); elliptical, longer than larger; posterior margin acute. Clypeus with inconspicuous longitudinal striae on median portion posteriorly. In latero-oblique view, malar area with irregular transverse to oblique striae on anterior portion, posterior portion smooth and shining.

Mandible. Almost as long as anterior head portion. External margin slightly convex. Masticatory margin with denticles that serially increase in size apically. Palp formula 4,3.

Antenna. Scape surpassing occipital corner about pedicel half-length or less.

Mesosoma. Pronotum in lateral view angulate, dorsal margin slightly convex; neck well developed anteriorly in dorsal view; lateral margin forming obtuse angle posteriorly; central disc of pronotum with longitudinal to diagonal striae forming spiral-like shape, lateral striae forming concentric circles or transverse ellipses. Propleuron with fine transverse striae, central portion smooth and shining. Mesonotum wider than long, slightly concave medially; with regular transverse striae. Mesopleuron with rounded carina on anteroventral portion; mostly smooth and shining, anterior portion with regular transverse striae. Notopropodeal sulcus scrobiculate, slightly curved anteriorly. Metanotum as long as notopropodeal sulcus; with irregular transverse striae. Metapleural gland bulla with transverse striae effacing posteriorly. Propodeum in lateral view irregular with two shallow impressions; posterior margin length about 1/3 of dorsal length. Metasternum with metasternal process open, lateral cuticle border converging medially forming bilobate arc; completely dense punctate, with irregular transverse striae.

Petiole. Sessile. Cylindrical node, ventral portion slightly wider than dorsal portion in lateral view; posterior margin convex on dorsal portion, forming two blunt lateral projections in latero-oblique view. Spine acute, straight to slightly curved posteriorly. Regular to irregular oblique striae on ventral portion of lateral face extending posteriorly. Subpetiolar process wider than long keel-shaped; tip acute; posterior portion concave.

Gaster. First tergum almost higher than long; anterior and dorsal margin meeting in an obtuse angle; dorsal face convex; dorsal face of all terga weakly imbricate, almost smooth and shining.

Color and size. Body brown to dark brown almost black. Legs and antennae brown to light brown. Relatively medium to large size.

Pilosity. Hook-shaped, dense, conspicuous and short pubescence on head, mesosoma and petiole, separated each other about their length. Pubescence on petiole limited to anterior face extending to lateral faces. Pubescence on gastral terga sparse, separated each other more than its length. Short hairs on anterior portion of procoxa smaller than coxae width. Pronotum with three or four pairs of long, curved erect hairs longer than maximum procoxa width. Long subdecumbent hairs on posterior 3/4 of gastral terga directed posteriorly, as long as pronotum hairs.

Gyne

Paratype measurements: EL 0.5, HL 3.2, HoW 2.7, HvW 2.2, HW 2.3, ML 2.0, SL 2.7, PnW 1.7, WL 4.0, FL 3.1, FWL 8.7, PTH 0.7, PTL 0.7, PtW 0.6, GL 4.3, TL 14.2. CI 0.71, MI 0.62, PtI 2.14, SI 0.84, VI 0.95.

Mesosoma. Pronotum slightly longer than high in lateral view, dorsal margin concave forming obtuse angle, separating in anterior and dorsal margin; lateral margins converging anteriorly forming a neck in dorsal view; pronotal dorsum with regular transverse striae, becoming irregular posteriorly, forming concentric arcs on anterior portion in lateral view. Subalar area conspicuous with pronotum, with irregular striae. Mesoscutum anterior and dorsal margin forming single convexity in lateral view; with regular longitudinal striae in dorsal view; striae between parapsidial line and parascutal area oblique, directed medially; longitudinal carina on medial line standing out from striae. Parapsidial line curved, well-marked. Parascutal area smooth and shining. Notopropodeal sulcus scrobiculate. Axilla with fine longitudinal striae effacing laterally. Mesoscutellum smooth and shining. Metascutellum smooth and shining with longitudinal carina.

Wing. Color brown translucid. Forewing ML1 curved. RsL1 straight; shorter than Rs+M. RSL2-3 slightly sinuous. Rs+M and ML2 forming single slightly curved line, not forming angle with RsL2-3. Vein cu-a not reaching M+Cu ML1 angle by less than its half-length. Hindwing 1rs-m vein curved. 12 hamuli.

Petiole. Conical node, anterior face straight to slightly concave, dorsal portion of posterior face rounder than worker petiole. Petiolar spine robust.

Pilosity. Pubescence on mesosoma strongly curved, dense separated each other less than its length. Pubescence on mesoscutellum. Pronotum with two pairs of short hairs, shorter than procoxa width. Mesoscutellum with pair of short hairs curved posteriorly, shorter than pronotum hair.

Male

Paratype measurements: EL 0.71, HL 1.1, OW 0.15, OES 0.37, IOW 0.21, WL 3.10, FWL 5.90, PTH 0.90, PTL 0.70, PtW 0.40, GL 3.20, TL 8.1. PtI 1.28.

Non-type measurements: EL 0.74, HL 1.08, OW 0.15, OES 0.34, IOW 0.21, WL 3.00, FWL 5.80, PTH 0.90, PTL 0.60, PtW 0.50, GL 2.90, TL 6.98. PtI 1.5 (n= 1).

Color and size. Entire body dark brown. Gastral terga with posterior portion gradually becoming lighter. Relatively medium size.

Head. Palp formula 4,3. Lateral ocelli partially surpassing posterior margin in frontal view; posterior margin between lateral ocelli straight, not reaching median ocellus.

Mesosoma. Pronotal dorsum with sparse punctures; with micro sculpture effaced on anterior portion in lateral view. Propleuron with micro sculpture. Mesoscutum anteriorly with effaced fine transverse striae; dorsal surface with longitudinal median carina, effaced longitudinal regular striae next to it and parapsidial lines. Axilla with sparse and fine longitudinal striae, micro sculpture between them. Mesoscutellum concave; with irregular sparse longitudinal striae anteriorly effacing posteriorly. Metascutellum with dense micro sculpture, with longitudinal carina. Anepisternum mostly with fine sparse oblique striae. Katepisternum with dense micro sculpture of reticulate aspect. Metepisternum and metapleuron with fine sparse and irregular oblique striae posteriorly. Metapleuron and propodeum separated by longitudinal carina. Propodeal dorsum with fine sparse oblique and irregular striae, dense micro sculpture of reticulate aspect between them; dorsal and posterior face of propodeum delimitated by short coarser striae.; posterior face of propodeum with median irregular carina, dorsal portion with micro sculpture, sparse irregular oblique to transverse striae on ventral portion.

Wing. Light brown translucid. Hamuli equal 8. Pterostigma brown, darker than wing surface.

Petiole. Sessile; dorsal portion acute, slightly concave laterally; longitudinal carina extending posteriorly from the spiracle; with dense micro sculpture of reticulate aspect. Sternum concave posteriorly forming a blunt lobe posterior to subpetiolar process.

Pilosity. Head, mesosoma and gaster with dense appressed pubescence. Pronotum with two pairs of thin erect hairs on posterior portion, two of them larger. Thin, erect short hairs on posterior portion of petiole, directed posteriorly. Thin, erect short hairs on posterior portion of gaster segments I and II, hairs on segments III, IV and V almost two times longer.

Natural history: The biology of this species remains unknown. Two specimens were collected with subterranean traps, one of them in 1,000 m elevation area, and other specimens have been collected with Winkler’s collectors. Odontomachus xeta occurs in forested areas of the Atlantic rainforest at sea level to the 1,000 m elevation ( Fig. 64 ), and probably has cryptic habitus, like nocturnal activity. Its relative medium size and massive head, as in O. biumbonatus , does not suggest cryptic or hypogeic biology.

Comments: Odontomachus xeta sp. nov. highly resembles O. biumbonatus and most of the specimens were initially identified as the latter. The workers’ metasternal process is the most reliable character to distinguish them. In O. xeta , the metasternal process is closed, forming a bilobate projection, and it is densely punctate and has irregular transverse striae posteriorly. On the other hand, in O. biumbonatus the metasternal process is open, forming a pair of acute deeply impressed lobes, and has irregular longitudinal striae. Even considering the variation in the thickness and the number of the longitudinal striae on the metasternum of O. biumbonatus , none of these specimens have the metasternal process closed like in O. xeta . The males of both species are also very similar and can be distinguished by the sculpture of the posterior face of propodeum. In O. xeta , the transverse striae on the posterior face of propodeum are limited to the ventral portion while in O. biumbonatus it has concentric striae.

According to Brown (1976), O. biumbonatus probably would occur in the Atlantic rainforest, but all of the examined specimens from the Atlantic region and previously identified as O. biumbonatus , have the metasternal process like in O. xeta . Also, the males were different from the males collected in the Amazonian. Furthermore, there are no variations of O. biumbonatus that link them. Considering the morphological delimitation of workers and males, and the geographic isolation from Amazonian and Atlantic populations ( Fig. 64 ), O. xeta is considered as a new species.

Material examined: 7☿, 4♀, 1♂. BRAZIL: Bahia: Wenceslau Guimarães (1☿) . Espírito Santo: Linhares (2♀); Santa Tereza (1☿, 1♀) . Rio de Janeiro: Nova Iguaçu (2☿); Picinguaba (1☿); DF [Distrito Federal, now Rio de Janeiro] (1♀) . São Paulo: Caraguatatuba (1☿). Sete Barras (1☿, 1♂) .

Figures

FIGURE 12. Heads of Odontomachus workers in cephalic frontal view.A, reduced eyes, scape not reaching the posterior head margin (O. spissus); B, not reduced eyes, scape surpassing the posterior head margin (O. affinis). Dash lines highlighting scape lengths and arrows pointing to the eyes.

FIGURE 21. Petiolar node shapes of Odontomachus workers in lateral view. A, node cylindrical (O. xeta sp. nov.); B, node conical (O. haematodus). Dash lines highlighting anterior and posterior face shapes.

FIGURE 22. Metaesternal process of Odontomachus workers in ventral view, middle coxae on superior portion and hind coxae on inferior portion. A, metasternal process open, posterior border deeply invaginated anteriorly forming two lobes (O. biumbonatus); B, metaesternal process close, cuticle border forming bilobate projections (O. xeta sp. nov.). Dash lines highlighting the metasternal process shapes.

FIGURE 32. Pronotum of Odontomachus gynes in lateral view. A, dorsal face anteriorly concave forming obtuse angle posteriorly (O. xeta sp. nov.); B, anteriorly straight becoming convex posteriorly (O. cupreus sp. nov.). Dash lines highlighting the pronotum shapes.

FIGURE 41. Petiolar nodes of Odontomachus males in latero-oblique view. A, apex pointed, posterior portion not forming blunt projection and subpetiolar process with vestigial blunt lobe (O. xeta sp. nov.); B, apex blunt, posterior portion with lateral blunt projections and subpetiolar process with well-developed lobe (O. biumbonatus). Dash lines highlighting the posterior face projections and subpetiolar lobe shapes.

FIGURE 60. Map of distribution of O. spissus, O. biolleyi, O. insularis and O. mormo. Triangles representing the typelocalities.

FIGURE 64. Map of distribution of O. biumbonatus, O. opaciventris and O. xeta sp. nov. Triangles representing the typelocalities.

FIGURE 113. Odontomachus spissus worker.A, head in frontal view; B, full lateral view; C, metasternum in ventral view with middle coxae at superior portion and hind coxae at inferior portion; D, mesosoma in dorsal view; E, petiole in lateral view; F, gaster in dorsal view.

FIGURE 114. Odontomachus spissus gyne. A, head in frontal view; B, mesosoma in dorsal view; C, full lateral view.

FIGURE 115. Odontomachus xeta holotype. A, head in frontal view; B, full lateral view; C, metasternum in ventral view with middle coxae at superior portion and hind coxae at inferior portion; D, mesosoma in dorsal view; E, petiole in lateral view; F, gaster in dorsal view.

FIGURE 116. Odontomachus xeta gyne paratype. A, head in frontal view; B, mesosoma in dorsal view; C, full lateral view.

FIGURE 117. Odontomachus xeta male paratype. A, head in frontal view; B, mesosoma in dorsal view; C, propodeum in posterior view; D, full lateral view.