Protalaridris aculeata

This is the only Protalaridris species to occur outside of premontane and montane rainforest, being found in a lowland site of the Amazon basin relatively close to the Andes. It represents the southernmost known limits of the distribution range for the genus, being separated by a gap of close to 1500 km from the closest known Protalaridris species from southern Ecuador. The single known specimen of this species was collected from a fruit fall berlesate under a Buchenavia tree, a genus within the family Combretaceae with several species known from the Amazonian forest.

Identification
Lattke et al. (2018) - Worker: Mandibular shaft with massive tooth projecting ventromesad close to mandibular base, mandible with abundant tubercles; labrum in frontal view rectangular and narrow, anterior margin with six long hairs. Basal angle of scape well-developed, lamellate; scape anterior margin with 6 spatulate hairs. Cephalic dorsum with median rectangular raised area. External tibial surfaces with abundant tubercles.

Even though this species is described from a single specimen, its morphology is very distinct within the genus, particularly the tuberculate sculpturing on the mandibular and lateral tibial surfaces. Most Protalaridris have 8 or more spatulate hairs along the anterior margin of the scape but there are only 5 or 6 hairs in P. aculeata and Protalaridris loxanensis. A crust of dirt or debris covers most of the body, ventrolateral cephalic surface, and most of abdominal tergum IV, though the tergal crust is apparently thinner than that of the head. The occiput, propodeal declivity, and a transverse strip anterad to the anterior carina on abdominal tergum IV are contrastingly clean and devoid of any debris. The number and arrangement of erect hairs on the gastral tergum should be considered provisional as it can vary in other species.

Distribution based on Regional Taxon Lists
Neotropical Region: Peru.

Biology
Lattke et al. (2018) - A label accompanying the specimen discloses it was recognized as an undescribed species by B.H. Dietz in 2002.

Protalaridris aculeata is probably a rare ant. A two-week ant taxonomy course in 2012 at Sachavacayoc Centre (–12.8587° –69.3552°, 235 m elevation, 38 km SW of the type locality) and the 2013 Ant Course at Villa Carmen Station (–12.8947° –71.4031°, 500-700 m elevation, 251 km EEW of the type locality) failed to find this ant. Both courses included large groups of students and instructors intensively collecting ants.

This species is only Protalaridris found outside of premontane and montane rainforest. The type locality is a lowland site of the Amazon basin relatively close to the Andes. It represents the southernmost limits of the distribution range of the genus, separated by a gap of close to 1500 km from the closest known Protalaridris in southern Ecuador. Collected from under a Buchenavia (Eichler, 1866) tree, a genus in the Combretaceae family. Several species of this genus of trees are known from the Amazonian forest.

Nomenclature

 *  aculeata. Protalaridris aculeata Lattke & Alpert, in Lattke et al., 2018: 272, figs. 2a-d (w.) PERU.

Worker
Holotype: HL 0.67, HW 0.70, ML 0.37, EL 0.03, SL 0.35, PW 0.38, WL 0.60, PH 0.18, PL 0.25, DPW 0.18 mm. CI 1.05, MI 0.52, OI 0.05, SI 0.50, LPI 0.73, DPI 0.73.

Worker description. With head in frontal view anterior clypeal margin with broad median concavity, laterally broadly convex; lateral cephalic margin posterad of antennal fossa convex, head widest at posterior two-thirds, lateral cephalic margins mostly converging anterad; posterior cephalic margin with medial emargination, posterolaterally convex with inconspicuous occipital lobe; cephalic dorsum posterad of antennal fossa with well-defined, carinate borders. Frontal lobe dorsally convex, anterior margin forms narrow angle with posterior clypeal margin, width less than half that of fossa. Eye with 3–4 relatively indistinct ommatidia, facing anterolaterally, separated from antennal fossa along lateral cephalic margin by not more than 3 diameters, separated from dorsal face less than one diameter in lateral cephalic view. Cephalic dorsum mostly rugulose reticulate, rugulae directed longitudinally posteriorly and obliquely laterally, space between rugulae shining; cephalic dorsum divided into elevated central area, convex transverse posterior area and vertical lateral convex area. Central elevation rectangular, extending posterad approximately two-thirds of cephalic length; lateral margin of elevation vertical, extends from frontal carina, elevation bordered posterad by transverse carina, carina broadly concave medially, rugulose reticulate with longitudinal elevated median area. Cephalic dorsum between transverse carina and posterior cephalic carina convex in lateral cephalic view.

Cephalic dorsum with mesially pointing subspatulate to lanceolate appressed hairs; occiput areolate, posterolateral region areolate-rugulose. Cephalic ventrum mostly areolate to areolate-rugulose, posterolaterally densely punctulate and shining. Antennal scrobe shallow but distinct, posteriorly ending just beyond eye.

Mandible in full length view with both shafts converging until just anterad of mandibular mid-length, then each is weakly convex, bending at base of apical tooth. Mandible with prominent ventromedially directed tooth, situated closer to mandibular base than apex in mandibular full length view; ventral tooth in dorsal view tapering apicad, internal margin edentate, apically broadly concave. Internal surface of ventral tooth mostly smooth and shining. With mandibles closed the apices of each ventral tooth cross; apical and ventral tooth ferruginous brown, smooth and shining. Mandibular dorsum with low but distinct, blunt tubercles and rugulae, ventral surface anterior of ventral tooth rugulose and with appressed pilosity directed apicad; smooth and shining sculpture limited to posteroventral area, ventral tooth, and mandibular apex.

In cephalic lateral view mandibular dorsal margin forms broad concavity with dorsal cephalic surface, ventral tooth tapers posteroventrally, mostly straight, its length about 1/3 that of lateral mandibular width. Mandibular dorsum with short, arched, slender hairs pointing apicad or mesad. Dorsal mandibular margin with 5–6 preapical denticles, besides medium sized tooth set at mid-length between massive ventral tooth and base of apical tooth; dorsal mandibular margin with decumbent slender hairs, directed anteromesad. Ventral mandibular margin with 8 denticles between base of apical tooth and ventral massive tooth.

Labrum rectangular and narrow, lateral margins visible in dorsal view with mandibles closed, basal ridge broadly arched; apically rounded with distinct but shallow median notch. Median ventral surface with abundant hairs, dorsal surface sculpted, not smooth and shining. Anterior margin of labrum with six long hairs, third and second hairs from labral cleft the longest, slender and weakly lanceolate. In-ternal hairs weakly spatulate with rounded apex. Labral cleft with 2 very short hairs. Palpal formula unknown. Scape in dorsal view with weak basal lobe, anterior margin broadly convex and lamellate; scape in general broadly arched. External margin dorsad of lamella with 6 elongate spatulate hairs, ventral margin with 10 slender hairs; anterior scape face rugulose and shining, anterobasal lobe weakly expanded anterad, dorsum with very fine short hairs. Cross-section of scape at mid-length triangular, anterior convex margin, dorsal margin broadly convex, ventral margin mostly straight.

Mesosomal dorsal margin in lateral view convex, promesonotal suture marked by shallow concavity, mesonotum with narrow anterior margin, mesonotal dorsal margin mostly straight, dorsal propodeal margin brief; declivitous margin covered by triangular tooth; base of tooth broadly concave, apex pointed, posterior margin lamellate, briefly concave. Mesosomal dorsum and dorsolateral half of pronotum rugulose, with decumbent and arched weakly lanceolate hairs, mostly directed posteromesad. Half of lateral pronotum, part of mesopleuron, and propodeum punctulate to areolate, wanting pilosity, metapleuron punctulate; mesopleuron with rugulae. Pronotum with anterior transverse areolate strip with scattered rugulae, not marked off by transverse carina from dorsal surface; promesonotal suture marked as shallow transverse trough.

Petiolar node strongly convex in lateral view, anterior petiolar margin mostly straight to broadly concave, anteroventral process triangular small, postpetiolar dorsal margin in lateral view broadly convex. Petiole with long straight hair on ventrolateral surface, posterolaterally directed. Postpetiole transverse in dorsal view, anterior margin concave and shorter than convex posterior margin, dorsum of petiolar node and postpetiole areolate-rugulose with posteriorly directed appressed, arched hairs. Dorsal margin of abdominal tergum IV broadly convex in lateral view, ventral margin markedly convex, with greatest height just anterad of gastral mid-length; abdominal tergum IV with transverse carina along anterodorsal margin that separates dorsum from brief transverse anterior surface; dorsal pilosity consisting of sparse arched subdecumbent lanceolate hairs, and some 22–26 suberect, spatulate hairs. Abdominal sternite IV densely areolate anterad becoming punctate posterad, sparsely clothed by arched decumbent hairs pointing posterad. Tarsal claws simple, long and slender; legs stout, not elongate; protibial apex with lateral spatulate hair. Meso- and metatibial apices each with anterolateral and posterolateral spatulate hairs, anterior hairs largest. External surface of tibiae with numerous low tubercles. Body mostly ferruginous, darker tint on transverse cephalic carina and cephalic dorsum posterad of carina, apex of mandible and ventral mandibular tooth, mesosomal dorsum and propodeal lamella, including tooth, and gaster throughout.

Type Material
Holotype worker. Peru. Madre de Dios: Cuzco Amazónico, 15 km NE Puerto Maldonado [–12.5312° –69.0713°], 200 m, 16.VII.1989, SP Cover, JE Tobin.

Etymology
The species epithet is derived from the Latin neuter plural of acūleātus "having stingers or spines”, also “stinging”, and alludes to the numerous tubercles on the mandibles and tibiae of this species.