Epierus rubellus: Lectotype herein designated for the purposes of establishing a unique and unambiguous type, as the original description omitted any indication of number of specimens studied: of undetermined sex: “rubellus Er., Carap[ava]. Sellow” / “48997” / “Zool. Mus. Berlin” / “Kaszabister rubellus (Erichson) LECTOTYPE N. DEGALLIER”; ZMHB. Kaszabister mahunkai: holotype: “Hungarian Soil-Zool. Exp., ARGENTINA: Prov. Córdoba, Fanti, Sierra de Córdoba, 11.I.1966” / “Nr. P-B.325 leg.Mahunka” / “Holotype 1972. Kaszabister mahunkai Mazur.” / “HOLOTYPUS” / “Compared with META-Types Epierus rubellus Er., R. L. Wenzel ‘73” / “Kaszabister rubellus (Er.) (= mahunkai Mazur), RLW ‘73” (HNHM).

ARGENTINA: Buenos Aires: Balcarce, iv.1957 (1: NMNH); Rosas – F.C. Sud, with Solenopsis (6: NMNH). BRAZIL: Paraná: Rio Negro, with Solenopsis (1: BMNH); Rio Grande do Sul: Vallée de la Ferradura, Canela, 20.x.1989, from nest of Solenopsis sp. (1: CHND); Santa Catarina: Nova Teutonia, v.1937 (1: FMNH); 31.x.1948, with Solenopsis (2: FMNH); 2–3.xi.1948, with Solenopsis (2: FMNH); 11–14.xi.1948, with Solenopsis (2: FMNH); xii.1948 (1: FMNH); 6.vi.1950 (1: FMNH); 6.vii.1950 (1: FMNH); 2.viii.1950, with Solenopsis (4: FMNH); 26.viii.1950 (5: FMNH); 28.viii.1950, with Solenopsis (4: FMNH); 1.ix.1950 (1: FMNH); 3.ix.1950, with Solenopsis (1: FMNH); 6.ix.1950, with Solenopsis (2: FMNH); 7.ix.1950, with Solenopsis (1: FMNH); 18.ix.1950 (1: FMNH); 20.ix.1950, with Solenopsis (1: FMNH); 23.ix.1950 (1: FMNH); 4–5.x.1950, with Solenopsis (2: FMNH); 21.vii.1951 (1: FMNH); 24.vii.1951, with Solenopsis (1: FMNH); 31.vii.1951, with Solenopsis (8: FMNH); 17.viii.1951 (4: FMNH); 22.viii.1951 (1: FMNH); 5.ix.1951 (1: FMNH); 4.x.1951 (4: FMNH); 6–30.viii.1951, with Solenopsis (5: FMNH); 10.iv.1952, with Solenopsis (1: FMNH); 18.iv.1952, with Solenopsis (3: FMNH); 10.v.1952, with Solenopsis (1: FMNH); 10.v.1952, with Solenopsis (FMNH); 30.vii.1952, with Solenopsis (5: CHPK, CHSM, FMNH); 3.viii.1952, with Solenopsis (1: FMNH); 7.viii.1952, with Solenopsis (2: FMNH); 15.viii.1952 (1: FMNH); viii.1952, with Solenopsis (48: FMNH); ix.1952 (1: FMNH); vi.1954 (2: CHSM); vii.1954, (2: CHSM); xi.1956 (1: FMNH); ‘Bresil’ (1: MNHN). URUGUAY: Rivera: Rivera, Escuela Agraria, 18.ii.1962, nest of Acromyrmex lundii (Guérin-Méneville) (1: FMNH).

Frontal stria descending onto epistoma as a weak carina, epistoma moderately depressed, depression narrower than in Kaszabister barrigai; fourth dorsal elytral stria present in apical half to two-thirds; inner subhumeral elytral stria present in apical two-thirds; fifth and sutural elytral striae strongly reduced or absent; elytral ground punctures sparser and markedly reduced laterad fourth elytral stria; mesometaventral stria somewhat variable, arched forward to one-half to one-third from mesoventral margin; lateral metaventral stria weakly abbreviated mediad, ending about one-fourth to one-fifth metaventral length from mesometaventral margin, mesometaventral stria continuous with postmesocoxal stria; inner postmetacoxal striae nearly forming a complete arc across anterior margin of abdominal ventrite 1 (though often evanescent at very middle), this arc broader (closer to coxae) than in Kaszabister barrigai; abdominal ventrites 2–4 with apical marginal stria; aedeagus narrow, approximately evenly tapered basally and apically; flatter (in lateral view) than in other species.

Known from Brazil (Paraná, Rio Grande do Sul, Santa Catarina), Argentina (Buenos Aires, Córdoba), Uruguay (Rivera).

Most specimens from Santa Catarina bear labels indicating collection with unspecified Solenopsis. The singleton from Uruguay indicates collection from a nest of Acromyrmex lundii.

The synonymy of Kaszabister mahunkai Mazur with Epierus rubellus Erichson was originally designated by Mazur (1984) (citing “Wenzel, in litt.”). We have not studied the type of Kaszabister mahunkai first-hand, but Ottó Merkl of the HNHM very kindly compared the type specimen with our descriptions, keys and figures, and had no doubt that the synonymy is valid. His study also confirmed that Wenzel had compared types of Kaszabister mahunkai and Epierus rubellus side-by-side in coming to his original conclusion that the two were conspecific.