ABSTRACT: Comparisons of structural features (principally mouthparts, elytral-abdominal locking mechanism, and female genitalia) of the ardistomine genera (Aspidoglossa Putzeys, Ardistomis Putzeys, and Semiardistomis Kult) with those features of members of the subtribe Clivinina (Clivina Latreille, Oxydrepanus Putzeys, Schizogenius Putzeys,Ancus Putzeys, Nyctosyles Putzeys, and Obadius Burmeister) confirm the taxonomic validity of the subtribe Ardistomina. Based on morphological features, the ardistomine genera are postulated to be related as follows: [Aspidoglossa [Ardistomis + Semiardistomis]]. Knowledge of this subtribe is further extended by taxonomic treatment of the genus Semiardistomis Kult. Of the 30 valid names of Semiardistomis previously recognized, four were proposed as variety names, and are listed as junior synonyms: Ardistomis labialis picipes Bates, 1881, Ardistomis labialis nanus Bates, 1881, and Ardistomis labialis dilatatus Bates, 1881; and Ardistomis pallipes caerulea Putzeys, 1846. Eight names, treated as specific epithets, are junior synonyms, as follows: Ardistomis (Semiardistomis) balthasari Kult, 1950 = Semiardistomis glabratus (Putzeys, 1866); Ardistomis (Semiardistomis) emdeni Kult, 1950 = Semiardistomis deletus (Putzeys, 1846); Ardistomis aenea Putzeys, 1866, Ardistomis (Semiardistomis) brittoni Kult, 1950, and Ardistomis (Semiardistomis) marani Kult, 1950 = Semiardistomis flavipes (Dejean, 1831); Ardistomis tuspanensis Putzeys, 1846 = Semiardistomis labialis (Chaudoir, 1837); Ardistomis (Semiardistomis) vlastae Kult, 1950 = Semiardistomis subglabra (van Emden, 1949); and Ardistomis striga Putzeys, 1866 = Semiardistomis pallipes (Dejean, 1831). Two new species described are Semiardistomis exspectatussp. n.(type locality PERU, Madre de Dios, Rio Manu, 11°56'47"S, 071°17'00"W), and Semiardistomis majorsp. n. (type locality PERU, Loreto, Rio Samiria, 05°12'S, 75°20'W). The 20 species of Semiardistomis are arranged intwo species-groups here proposed: the puncticollis group, including 12 species; and labialis group, including eight species. The species recognized are keyed, described or redescribed, and notes are provided about their Geographical distribution, habitat and activity. Distribution maps show known geographical ranges, from which are inferred patterns of speciation from a center of radiation in northern South America of both lineages.
