A revision of the genus Mecistostethus Marseul (Histeridae, Histerinae, Exosternini) Author Caterino, Michael S. Author Tishechkin, Alexey K. Author Degallier, Nicolas text ZooKeys 2012 213 63 78 http://dx.doi.org/10.3897/zookeys.213.3552 journal article http://dx.doi.org/10.3897/zookeys.213.3552 1313-2970-213-63 Mecistostethus loretoensis (Bruch, 1932) comb. n. Figs 3A4A7 Tarsilister loretoensis Bruch, 1932: 279. Type material. Holotype, of undetermined sex: "Tarsilister loretoensis Bruch (written by Bruch) C. BRUCH DETERM. (printed)" (label white with black frame) / "Nido de Pachycondyla striata F Sm" (handwritten) / "Typus" (handwritten) / "Est. Exp . Loreto (Misiones - Arg.) [ 27.32°S , 55.53°W ] Dr. A.A. Oglobin" (printed); reverse: "20.ix.1931" (handwritten), MACN. Other material: 1 male, locality as for type, 15.VIII.1932, with Pachycondyla striata , MACN; 1 female: BRAZIL: Sta. Catarina: Nova Teutonia, 27°11'S , 52°23'W , Fritz Plaumann (no date), FMNH-INS0000069073. Diagnosis. Length 2.4-2.6mm, width 2.0-2.1mm (n=3); body completely lacking microsculpture; frontal stria/carina complete; frons and epistoma without microsculpture; anterior submarginal pronotal stria long, ends strongly recurved (Fig. 3A); pronotum with>10 discal setae, scattered on disk without well-defined submarginal row (Fig. 3A); lateral pronotal punctures numerous and conspicuous; prosternal striae present (Fig. 4A); metaventral stria complete at middle (Fig. 4A); elytral stria 1 not continuous, effaced at middle (despite presence of setae); elytral stria 2 barely abbreviated at base; male not examined. Figure 3. Pronota of all Mecistostethus spp. A Mecistostethus loretoensis B Mecistostethus seagorum C Mecistostethus pilifer D Mecistostethus marseuli E Mecistostethus carltoni F Mecistostethus flechtmanni . Figure 4. Ventral views of Mecistostethus spp. showing striae. A Prosternum, meso- and metaventrites of Mecistostethus loretoensis B Meso- and metaventrites of Mecistostethus pilifer (identical in Mecistostethus marseuli & Mecistostethus carltoni ) C Meso- and metaventrites of Mecistostethus seagorum D Meso- and metaventrites of Mecistostethus flechtmanni . Figure 5. Genital segments 8-10 of Mecistostethus ( Mecistostethus carltoni pictured, others essentially identical). A Eighth tergite, dorsal view B Eighth sternite, dorsal view C Ninth and tenth tergites, dorsal view D Ninth tergite, lateral view E Spiculum gastrale (ninth sternite), dorsal view. Distribution. Known from Atlantic forest areas of Santa Catarina, Brazil, and subtropical forests near the Rio Parana in Misiones province, Argentina. Remarks. The type collection from the nest of Pachycondyla striata (Ponerinae) provides the only known host record for this genus.