Forelius antarcticus ( Forel 1904 ) Guerrero, 2021

Guerrero, Roberto J., 2021, Transfer of two South American ant species from Tapinoma Foerster 1850 to Forelius Emery 1888 (Hymenoptera: Formicidae: Dolichoderinae), Zootaxa 4920 (3), pp. 428-438 : 430-433

Forelius antarcticus ( Forel 1904) comb. nov.

( Fig 1–4 )

Tapinoma antarcticum Forel 1904: 17 . Syntype series [two workers, three queens], Valparaíso, Chile (Hoffmann) [MHNG, examined]. One syntype worker (bottom specimen on the pin, CASENT0909784) here designated lectotype; remaining syntypes here designated paralectotypes (MHNG).

Tapinoma fazi Santschi 1923: 270 . Syntype worker, male: Valparaíso, Chile (Faz) [NHMB and MZLS, AntWeb images of syntypes examined]. As junior synonym of Tapinoma antarcticum: Menozzi (1935) : 321.

Forelius eidmanni Goetsch 1933: 28 . Syntype worker, queen: Several localities (Cerro San Cristobal, Copiapó, Puntas Coloradas, Cerro de Provincia, and Zapallar), Chile [not examined] comb. rev. As junior synonym of Tapinoma antarcticum: Menozzi (1935) : 321.

Forelius fazi (Santschi) . Combination in Forelius (comb. nov.): present study.

Additional Material examined. Chile: Santiago de Chile, Curva 18, road below Farallones ; manual collection; 22.Dec.1985; foraging in Kageneckia bush; SP Courtney, coll. (3w, one of those imaged CASENT0249758) ( PSWC) . Santiago de Chile, Rio Clarillo ; 31.Mar.1993; AMD Aguiar (18w) ( CEPLAC) . Valpariso , no more data. (2w) ( MZSP) .

Additional specimen images examined, provided by www.antweb.org. Chile: same data as lectotype; (1w) Staatliches Museum für Naturkunde Karlsruhe ( SMNK, Karlsruhe, Germany), FOCOL0717; Valparaíso, (1w) Musee Zoologique ( MZLS, Lausanne, Switzerland), CASENT0907582; Valparaíso, (1w) Natural History Museum Basel ( NHMB, Switzerland), CASENT0911576; Punta Colorada, (1w) Natural History Museum Basel ( NHMB, Switzerland), CASENT0911575 .

Worker measurements. Lectotype worker CASENT0909784: HL 0.61, HW 0.49, SL 0.51, WL 0.65, CI 81, SI 104.

Non-type and paralectotype workers (n= 13): HL 0.57–0.61, HW 0.49–0.51, SL 0.48–0.51, WL 0.61–0.65, CI 81–86, SI 98–104.

Diagnosis. Head with convex sides and posterior margin with a wide but relatively shallow concavity mesad. In profile, wide mesopropodeal depression formed by the posterior face of the mesonotum and the anterior propodeal face. Propodeal declivity twice as long as its dorsal face. Dorsum of pronotum with two erect setae, longer and thinner than those found in F. heyeri . Concolorous brown ants.

Worker description. Head dorsoventrally flattened, posterior cephalic corners rounded and evenly continuing to vertex; head width increasing behind compound eyes; dorsal surface densely punctate-reticulate, relatively shiny; abundant decumbent whitish setae on surface, lateral ventral margin with shorter setae; two pairs of long, thick erect setae directed anteriorly, one pair in the middle of the length of the frontal carina, the other one in the middle of the lateral-posterior margin of the clypeus close to the antennal toruli; maxillary palps long, with segments 2 to 6 similar in length; eyes slightly convex and bulging. Mandibles wide, with the external margin curved especially in the area near the apical tooth, subtriangular in shape; dorsal surface in the mid-posterior region finely striated with abundant decumbent setae on the surface, the anteromedial portion smooth and relatively shiny, with long setae separated and curved downwards; ventral face near the external margin with some long protruding setae curved inwards; masticatory margin armed with a long, falcate apical tooth, subapical tooth triangular and slightly larger than the remaining three, 3rd and 4th teeth small and similar in size, 5th tooth separated from the penultimate by a diastema similar to the length of the 3rd tooth, clearly separating the masticatory margin of the basal one. Anteroclypeal margin completely entire and convex with one long erect central seta, slightly above and equidistant to the central two long erect setae directed anteriorly, the three setae exceeding the length of the closed mandibles; dorsal surface of the clypeus with some scattered suberect short setae. Scape with subparallel sides, slightly widened at the tip; relatively long, exceeding the posterior margin of the head capsule by a length equal to the length of the pedicel (~ 0.14 mm ± 0.02); pedicel cuneiform, twice as long as the second flagellomere, penultimate flagellomere subrectangular and of similar length, the last a little longer but as wide as the rest; scape and flagellomeres with abundant scattered suberect setae.

In lateral view, the promesonotum almost continuous, with the profile slightly broken by the promesonotal suture, pronotum convex meso-anteriorly, the rest flattened continuing towards the mesonotum, the latter smoothly sloping posteriorly; pronotal sides and mesopleuron smooth and shiny; in profile, metanotal suture impressed; in profile, dorsal face of the propodeum inclined upwards and forming a blunt angle with the declivitous face, this corner as high as the mesonotum; propodeal declivity smooth and shiny, almost twice the length of the dorsal face; propodeal spiracle small and circular, located below the margin of the declivity. Mesosoma with very short pilosity, surface punctate with some longitudinal reticulation on the dorsum of the pronotum.

Petiolar node with a very pronounced scale, directed forward; scale with a straight anterior face, posteriorly directed dorsal face, straight ventral face without a lobe of any kind; Gastral tergites with abundant decumbent whitish setae sparse enough to reveal the gastral surface; First gastral tergite without setae, 2nd and 3rd gastral terga with a pair of setae, 4th tergite with six thick setae; first gastral sternum with many long thick erect setae anteriorly and two or three on the posterior margin, 2nd gastral sternum with two thick erect setae.

Ants with short decumbent whitish setae. Relatively opaque body surface except in the meso and metapleural areas, which are smooth and shiny.

Queen. Measurements (n=3): HL 0.83–0.85, HW 0.73–0.77, SL 0.69–0.77, WL 1.59–1.63, CI 88–91, SI 92–105.

Diagnosis. Head rectangular, twice as long as wide (CI ± 46). Relatively long antennal scapes, SL> 0.70 mm. Large ants with shorter mesosomas (WL ± 1.65 mm) than Forelius pruinosus (WL 1.74) and Forelius mccooki (WL 1.67).

Description. Head with lateral margins straight, converging from the anterior half of the eyes towards the insertion of the mandibles, wider above the middle of the compound eye, cephalic vertex straight to where it meets the lateral margins, with a relatively shallow narrow medial concavity, cephalic vertex corners blunt and continuous with lateral margins; three large ocelli close to the concavity of the cephalic vertex; compound eyes large, surpassing the lateral margins of the head capsule more or less from the anterior half of the eyes in full-face view; integument surface densely punctate but punctures well separated from each other, abundant whitish and decumbent pilosity on the surface. Mandibles wide and elongate, with the external margin longer than the basal one; masticatory margin oblique, giving the mandibles a triangular shape; masticatory margin with six teeth: a long apical tooth, three times as long as the subapical, wide at the base and very acute, a triangular subapical tooth, a 3 rd tooth slightly smaller than the preceding, 4 th and 5 th similar to the subapical tooth, and a 5 th tooth reduced to an angle differentiating the masticatory margin from the basal tooth; two small projections present between the 3 rd and 4 th and 4 th and 5 th teeth; basal margin smooth. Mandibular dorsal surface with striae, slightly foveate with suberect setae, ventral face of the mandible smooth, with the same type of setae; mandibles reddish. Anterior clypeal margin complete, strongly convex medially; anteroclypeal rim with ventrally curved setae and one long central seta; dorsal face with few short, suberect and erect setae. Antennal scapes surpassing the posterior cephalic corners by less than half the pedicel length; the latter long (0.18 mm), wider distally and tapering towards the base; scapes and flagellomeres densely punctate and with subdecumbent setae; scapes with smooth and shiny surface, but flagellomeres opaque; last flagellomere almost twice the length of previous one.

In lateral view, pronotum as a broad band located anteriorly; dorsum of the mesonotum higher than the metanotum and propodeum; in dorsal view, mesoscutum diamond-shaped and convex anteriorly, higher amplitude medially and posterior face straight; conspicuous and slightly deep notauli, arising on each side of the posterior region of the mesoscutum, notauli running parallel and diverging towards the anteromedial region of the sclerite; in dorsal view, scutellum broad at the base, tapering posteriorly; anepisternum and katepisternum divided by almost imperceptible anapleural sulcus, impressed only in the center of the mesoepisternum; propodeal suture deeply impressed; in lateral view, propodeum inflated, with the dorsal face almost the same length as the posterior face but without an angle differentiating the faces, forming a continuous inclined profile; propodeal spiracle circular and located in the middle of the lateral face of the propodeum; metapleural gland open, with a thick, protruding ventral flange; integument finely and abundantly punctate, with relatively long, abundant, and well separated whitish setae; pronotum with two erect setae near the neck, four long erect setae spaced on the upper part of the posterior pronotal margin, three long erect setae on the anterior part of the mesoscutum and two long erect setae in the middle of the scutellum; bulla of the metapleural gland with abundant silver-gold setae, short erect setae on the ventral rim of the gland; legs with setae like those on the mesosoma.

Petiolar node with a very pronounced scale inclined strongly forward, ventral face with a well-formed posterior lobe; first gastral tergite with a deep frontal concavity to receive the petiolar scale; gastral tergal plates with silver pubescence, many long erect setae distributed near the posterior border and in the middle of the gastral plates.

Concolorous brown like the worker caste.

Comments. The nominal taxon Tapinoma antarcticum and its junior synonyms, Tapinoma fazi Santschi and Tapinoma eidmanni (Goetsch) , are transferred to the genus Forelius . The syntype specimens used by Forel (1904) to describe T. antarcticum are consistent with the diagnostic features of Forelius and not Tapinoma . The anterior clypeal margin is completely entire and convex, with three setae as follows: a medial long erect seta, and two flanking long erect setae directed anteriorly, which together exceed the closed mandibles. In addition, the masticatory margin of the mandible is armed with five conspicuous teeth of different sizes, and the smooth basal margin is clearly differentiated from the masticatory margin by a tooth relatively smaller than the others. The characters examined correspond to those proposed by Shattuck (1992) and Cuezzo (2000) for the diagnosis of Forelius workers, contrasting notably with the diagnostic morphology for Tapinoma workers (see Shattuck 1992).

Several taxonomic problems have been associated with the name Tapinoma antarcticum , perhaps derived from morphological misinterpretations or the lack of systematic comparison of previously described specimens. Forel (1904) described Tapinoma antarcticum from workers and queens collected in Valparaiso ( Chile). Later Santschi (1923) described Tapinoma fazi from the same locality as T. antarcticum . Goetsch (1933) described Forelius eidmanni , but Menozzi (1935) suggested that this species corresponded to the genus Tapinoma and not to Forelius , thus deriving the new combination Tapinoma eidmanni (Goetsch) . Menozzi (1935) also suggested that both T. fazi (Santschi) and T. eidmanni (Goetsch) corresponded to Tapinoma antarcticum , therefore, those two names were proposed as junior synonyms of T. antarcticum . It is evident that sometimes the use of material from the same locality, by several authors or perhaps by the same author, can result in the description of the same species under different names, as is the case with Tapinoma panamense Wheeler 1934 and its junior synonym Tapinoma canalis Wheeler 1942 , both described from the same series of ants from Panama ( Shattuck 1992).

The queen of Forelius antarcticus is relatively smaller than those of F. pruinosus (Roger 1863) . The head length of the queen of F. antarcticus is longer that the F. pruinosus queen (HL 0.75), but the mesosoma is relatively short (WL ± 1.65) compared to that of F. pruinosus (WL 1.74–2.7). Forelius antarcticus and F. pruinosus queens bear abundant decumbent whitish setae on the surface of the head and scapes, although they are relatively longer in F. pruinosus queens.

Figures

FIGURE 1–4. Forelius antarcticus (Forel, 1904) workers. 1–2) Full face view of the head, and profile of lectotype worker (CASENT0909784). 3–4) Full face view of the head, and profile of worker from Santiago de Chile (CASENT0249758). Images 1–2 by Will Ericson, and images 3–4 by Estella Ortega. All images from www.antweb.org.