Basiceros militaris ( Weber 1950 )

Probst, Rodolfo Da Silva & Brandão, Carlos Roberto Ferreira, 2022, A taxonomic revision of the dirt ants, Basiceros Schulz, 1906 (Hymenoptera, Formicidae), Zootaxa 5149 (1), pp. 1-75 : 43-47

Basiceros militaris ( Weber 1950)

( Figs 17–20 , 31 )

Aspididris militaris Weber 1950: 3 , Fig 1 (worker*, gyne*). Trinidad & Tobago.

Wheeler & Wheeler 1955: 114, Plate 6, Figs 11–15 (larva).

Combination in Basiceros: Brown 1974 , 134.

* Intercastes.

Type material. Holotype. TRINIDAD & TOBAGO: Trinidad , Nariva Swamp: 23.iv.1935. Weber #140 [ AMNH] and two paratypes (one paratype, same locality, same data, Weber#140.1, MCZ 28746; one paratype, same locality, 22.iv.1935, Weber#139, MCZ 28476;) [ MCZ] (all intercastes) (examined).

Diagnosis. In full-face view, head with vertical margin in the form of a continuous crest, anteriorly separated from the central head convexity by a wide and uninterrupted sulcus.

Description. Worker (first description (see Type Material above and Comments section)) (n=5). HL 1.40–1.50, HL2 1.39–1.51, HW1 1.37–1.40, MdL 0.62–0.65, SL1 0.78–0.84, SL2 0.84–0.87, PDL 0.09–0.12, A3L 0.03, AFL 0.33–0.34, FuL 0.90, EL 0.13, EW 0.09–0.11, ML 1.43–1.62, MfL 1.05–1.13, MtL 0.89, PH 0.37, PL 0.59–0.65, PW 0.31–0.34, PPL 0.43–0.48, PPW 0.56, GL 1.54–1.65, GW 1.19–1.25, TL 6.04–6.58, CI 93–97, CS 1.39–1.45, MCI 43–44, SI 61–62, ESI 14–14, SAI2 245–266, EI1 0.15–0.16, MFI 125–131, PTI 158–175.

Size small compared to other Basiceros . Coloration dark brown to black; appendages lighter, brown to light brown. Mandibles slightly lighter than the predominant integument coloration; dorsa covered by sparse and minute piligerous punctures, apex with short yellowish setae; interdental setae present, yellowish and filiform, subequal to length of teeth. Suberect clavate hair on the dorsum of each stipe, on its median region. Dorsal surface of head covered by piligerous punctuations; pilosity on head dorsum restricted to a pair of clavate hairs in the posteromedian region, close to the posterior limit of central tumosity. Head lateral and vertexal margins covered by whitish to yellowish erect and clavate hairs, in the following configuration: 10 hairs on the lateral, starting from the region above the eyes and bordering the anterior limit of antennal scrobe and the posterior limit of vertexal crest; five hairs on either side of the dorsal (anterior) edge of vertexal crest; ten hairs on vertexal margin. Ventral surface of head densely covered by filiform suberect hairs, of two sizes: at the center, long hairs arranged in pairs, medium hairs on head sides, densely distributed. Mesosoma and metasoma with slightly clavate subdecumbent pilosity surrounding the anterolateral margin of pronotum and on the sides of propodeal slope. Dorsum of the meso- and metasoma with erect clavate hairs as follows: a pair close to the promesonotal suture; a pair on metanotal flange; a pair on the center of postpetiolar dorsum; 2–3 pairs on the dorsum of first gastral tergite; row of six hairs on the visible portion of the second, third and fourth gastral tergites (similar conformation of gastral dorsum also present on ventral region of this somite, in this case, hairs are slightly clavate). Posterior margin of petiole and dorsum of postpetiole with whitish decumbent and squamiform hairs. Filiform and long hairs on propleura, on the anterior portion of procoxae, and gastral sternites. Squamiform hairs on the anterolateral portion of procoxae and dorsum of meso- and metacoxae. Remaining leg surface densely covered by decumbent hairs from clavate to squamiform. Other pilosity appressed and short, part of thin or thick piligerous punctuations.

Glabrous regions of body ranging from mostly smooth and shiny to subopaque and slightly grainy. Head evenly punctuate; punctuations denser on the cephalic sulcus; surface of antennal scrobe predominantly punctuate-foveate, anterior portion sometimes smooth, posterolateral portion punctuate-rugose; ventral margin rugose. Pronotum punctuate-foveate. Dorsum of mesonotum, anterodorsal region of the propodeum, dorsal surface of meso- and metacoxae and dorsum of petiolar and postpetiolar nodes punctuate-rugose. Mesopleuron and metapleuron predominantly smooth or subopaque, with a granular appearance. Mesosternum shelf (surrounded by epicnemial carina) with short, filiform setae along its length. Anterior portion of mesopleuron punctuate-rugose. Side of propodeum with sparse punctuations. Surface of propodeal declivity smooth. Petiolar peduncle irregularly rugulose. Gaster densely punctuate; tergite surface of abdominal segments V, VI, and VII finely and densely punctuate, slightly opaque, tergal margins smooth and shiny; sculpture of first gastral sternite slightly more sparse, anterior portion of this sclerite sometimes subopaque to shiny. Antennal scapes smooth or finely rugose, usually shiny. Funiculi densely and finely punctuate, usually opaque. Legs mostly smooth or rugose; procoxae smooth, lateroposterior portion rugose; dorsum of meso- and metacoxae transversely rugose, short and irregular rugae forming foveae of different sizes.

Head disc-shaped, convex posteriorly; sides bordered by a raised margin that extends from the height of compound eyes to posterolateral region and behind the head, forming a crest. Face with central tumosity from the frontoclypeal portion to the posterior portion of head. Frontal sulcus present above the tumosity, separating it from the vertex crest. Vertex margin with convex corners, slightly projected backwards; vertexal crest conspicuous and continuous. Cervical margin carinate. Palp formula 2,2; palps strongly fused, giving the impression of being unsegmented. Stipes subrectangular. Labrum cuneiform; distal margin bilobed, lobes separated by cleft. Mandibles triangular; in full-face view, lateral margins slightly concave; masticatory margin with 10–14 triangular teeth; in lateral view mandibular apex slightly curved ventrally. Clypeus heavily lamellated anteriorly; anterolateral portion gently convex; anterior margin delicately concave on its median portion, hiding the basal angle of mandibles. Scapes with a slightly obtuse basal angle and straight/slightly convex limit before the lamellar crenulate portion. Antennal fossa deep and tapered.

Mesosomal profile with bulging promesonotal complex, slightly curving in its posterior portion; promesonotal suture practically imperceptible in dorsal view. Metanotal flange present, slightly oblique to its posterior portion; metanotal suture broad and strongly impressed, longitudinally costulate. Propodeum oblique, anterior margin raised and abruptly followed by the sloping face. In dorsal view, dorsum of propodeum anteriorly narrowed, slightly triangular. Propodeal slope laterally carinate, transverse costulae connecting to short projections, triangular and apically lamellar. Opening of propodeal spiracle round. Metapleural gland bulla protruding, prominent; opening transverse and covered by cuticular lamella. Mesopleuron anteriorly emarginate, interrupted at the epicnemial fossa. In dorsal view, petiolar peduncle longitudinally carinate. In lateral view, petiole claviform; petiolar node with slightly concave anterior surface, dorsal margin domed to convex; postpetiole convex. Subpetiolar process highly variable: from absent to composed of anteroventral projection followed by digitiform protuberances and lamellar region. In dorsal view, petiolar node longitudinally trapezoid, anterior margin narrower and rounded, posterior margin straight; postpetiole slightly wider than long; anterior margin emarginate; posterior margin convex and widely inserted into anterior concavity of gaster. Gaster anteriorly emarginate; longitudinal gastral sulcus present on median portion, shallow and extending over the entire dorsum of first tergite, slightly narrower posteriorly. Calcar of strigil pectinate. Tarsal claws simple.

Gyne (first description) (n=3): HL 1.48–1.56, HL2 1.47–1.53, HW1 1.38–1.50, MdL 0.63–0.72, SL1 0.81–0.90, SL2 0.75–0.95, PDL 0.10–.12, A3L 0.03–0.04, AFL 0.33–0.38, FuL 0.85–0.91, EL 0.20–0.25, EW 0.17–0.20, LOD 0.03–0.06, MOD 0.03–0.06, OOD 0.3–0.56, ML 1.73–1.86, MSL 0.76–0.88, MSW 0.82–0.88, MLL 0.28–0.30, MLW 0.46–0.50, MfL 1.11–1.19, MtL 0.84–1.00, PH 0.38–0.43, PL 0.65–0.79, PW 0.35–0.40, PPL 0.48–0.53, PPW 0.55–0.62, GL 1.63–1.95, GW 1.28–1.40, TL 6.61–7.40, CI 93–96 CS 1.43–1.53, MCI 41–46, SI 63–64, ESI 26–27, SAI2 240–290, EI1 0.27–0.28, MTI 100–108, MLI 132–168, MFI 120–127, PTI 173–178.

Size and coloration similar to conspecific workers; mesosomal sculpture more developed. Cephalic dorsum with three ocelli: median ocelli inserted slightly below and lateral ocelli inserted just above a pair of clavate and erect hairs. Head pilosity as in workers. Pilosity of anterolateral margin of pronotum denser and longer than on workers. Clavate and erect hairs on mesosoma in the following conformation: three pairs close to the humeral angles and surrounding the posterior limit of pronotum; around four pairs on the dorsum of mesoscutum, one near the center of the scutoscutellar suture; two pairs on the parascutal flange; one pair on each parapside; one pair on the lateral axillar region; two pairs on the dorsum of mesoscutellum; a pair on the metanotal flange, suberect. One pair of erect hairs on the posterodorsal region of petiolar node, other pilosity on petiole same as on workers; pilosity of the postpetiolar dorsum more abundant; postpetiolar sternite with four pairs of curved and subdecumbent clavate hairs. Hairs on the gaster same as on workers. Dorsum of mesoscutum with coarse and irregular longitudinal rugae, forming fovea of different sizes. In lateral view, pronotum and propodeum with coarse and/or foveal punctuations, both sparse. Surface of metepisternum and metakatepisternum either smooth or slightly grainy, subopaque; dorsum of propodeal declivitous face covered by transversal rugae. In dorsal view, mesoscutum anteriorly rounded, slightly cuneiform and with smooth and shiny median carina; posterior margin slightly convex medially at the meeting with the scutoscutellar suture; notauli indistinct; parapsidal lines narrow, slightly curved; distinct (located in a slight depression surrounded by rugae); parapsides shallow; tegulae subrectangular and apically rounded. Pre-scutellum narrow; axillae short, projected posteriorly, rounded and slightly depressed. Scutoscutellar sulcus well-marked, semicircular; broad and relatively shallow. Mesoscutellum transversely subrectangular, projected posteriorly, anterior limit concave. Dorsal face of propodeum strongly inclined; in lateral view, declivitous margin emarginate; projection as in the workers. In lateral view, anapleural sulcus anteriorly broad, smooth or subopaque, with a submedian transverse carina. Gaster with shiny band on the anterior portion of the sternite of first segment. Forewings type 2; hindwing with five submedian hamuli.

Intercastes: Holotype. Weber#140. Ocelli present, fully developed. In dorsal view, mesoscutum clearly delimited, although shorter than on conspecific gynes. Subalar area vestigial, residual tegula and axillary sclerite partially covered by the integument. Wing fossae present. Metanotal suture broad, carinate. Metanotal strip present, scutellum rudimentary.

Paratype Weber#139, MCZ 28746. Lateral ocelli present, fully developed, median ocellus slightly covered by integument. In dorsal view, mesoscutum vestigial; although fairly delimited, shorter than on conspecific gynes. Subalar area vestigial, almost imperceptible, presenting residual tegula partially covered by the integument. Directly below the tegular residue, slightly spiniform projection present, with globular setae on its apex. This same structure is not present on true gynes, although gynes have a prominence bearing setae under their tegulae. Simple setae over the tegulae can be observed in this paratype, same type of pilosity present on the anterior wing fossae of gynes. Metanotal suture extremely broad. In profile view, epicnemial fossa broad, triangle-shaped, pointing posteriorly. Anterolateral region of propodeum, where it meets the metanotal suture, with flap, apparently a metanotal strip. Midportion of mesonotum slightly concave, due to the presence of a vestigial scutum.

Paratype Weber#140.1, MCZ 28746. Head with complete and developed ocellar triangle. Left ocellus appears to be slightly cover by the integument. In dorsal view, mesoscutum clearly delimited, although shorter than on conspecific gynes. Transscutal articulation present. Scutoscutellar sulcus not integrally developed, but presenting a medial carina and irregular foveae typically found on true gynes. Parascutal flange vestigial. Prescutellum indistinct, only recognizable by margin lines. Specimen was probably brachypterous, as the whole wing apparatus is somewhat present, including tegular rudiments. On the right side, pair of specialized hair found on the parapsides of gyne, in the same position. On the left side, only one hair present. Hair on the right side of the specimen on what would be the axilla, the latter undeveloped. Scutellum present, although smaller than on conspecific gynes. Wing fossa developed, with setae similarly as on gynes. The spiniform projection of Weber#139 also present, near the anterior tegula. Hindwing on right side of this specimen glued to specimen’s body, short and rudimentary. Propodeal projection more developed than on Weber#139, narrow metanotal arc present.

Figures

FIGURE 1. Wing venation of Basiceros males. A. forewing and B. hindwing of B. conjugans (RSPPC, Peru). C. forewing of B. manni male (MCZ, Costa Rica: Heredia). Fused veins are indicated with a plus sign and crossveins by a dash. Cell names (in white) are indicated in italics. Scale bars: 1 mm.

FIGURE 11. Basiceros disciger, worker (MZSP, Brazil: São Paulo); A. full-face view, B. lateral view. C. dorsal view. Scale bars: A = 0.5 mm, B–C =1 mm.

FIGURE 12. Basiceros disciger, gyne and male (MZSP, Brazil: São Paulo); A and D. full-face view, B and E. dorsal view, C and F. lateral view. Scale bars: A, D = 0.5 mm, B, C, E, F =1 mm.

FIGURE 13. Basiceros manni, worker (CASENT0914888, Costa Rica: Heredia); A. full-face view, B. lateral view, C. dorsal view. Images by Michele Esposito (CAS).

FIGURE 14. Basiceros manni, gyne (MCZ 546486, Costa Rica: Heredia) and male (MCZ, Costa Rica: Heredia); A and D. fullface view, B and E. dorsal view, C and F. lateral view. Scale bars: A, D = 0.5 mm, B, C, E, F =1 mm.

FIGURE 15. Basiceros manni, larva (MZSP, Nicaragua: Boaco); A. head in anteroventral view, B. dorsal pilosity, C. lateral view. Scale bars: A = 0.1 mm, C = 1 mm, B = 0.05 mm.

FIGURE 17. Basiceros militaris, worker (CASENT0280778, Ecuador: Tiputini); A. full-face view, B. lateral view, C. dorsal view. Image by Estella Ortega (CAS), edited.

FIGURE 18. Basiceros militaris, gyne (MCZ, Trinidad & Tobago: Arima Valley) and male (MCZ, Trinidad & Tobago: St. Andrew); A and D. full-face view, B and E. dorsal view, C and F. lateral view. Scale bars: A, D = 0.5 mm, B, C, E, F =1 mm.

FIGURE 19. Basiceros militaris, type-series (all intercastes)—holotype (AMNH, Trinidad & Tobago: Nariva Swamp) and paratypes (MCZ 28746, same locality as holotype); A, D, G. full-face view, B, E, H. lateral view, C, F, I. dorsal view. Inset on A highlights ocelli. Scale bars: A, D, G = 0.5 mm, others = 1 mm.

FIGURE 20. Basiceros militaris, lateral view of intercastes. A. (MZSP) Brazil: Rondônia, B. (MZSP) Brazil: Pará, C. (MCZ 534522) Trinidad & Tobago: Arima Valley, D. (MCZ) Trinidad & Tobago: St. Andrew, Scale bars: 1 mm.

FIGURE 31. Distribution map of Basiceros species from the disciger clade (in part).