Hypononera ergatandria (Forel, 1893) – a cosmopolitan tramp species different from H. punctatissima (Roger, 1859) (Hymenoptera: Formicidae)

Abstract

Strong evidence is presented that the ponerine tramp ants frequently found in hothouses around the globe and named for many decades Hypoponera punctatissima consist of two clearly separable species: Hypoponera punctatissima (Roger, 1859) and H. ergatandria (Forel, 1893). Exploratory data analyses using eleven morphometric characters were performed in a total of 95 samples with 213 specimens from the worldwide range. They showed that both species are clearly separable in ergatoid males, gynomorphic females, workers and ergatoid females. Hierarchical NC-Ward clustering, non-hierarchical NC-K-Means clustering, NC-NMDS-K-Means ordination and principal component analysis provided identical classifications with a striking clustering structure. A linear discriminant analysis confirmed the results of these exploratory data analyses by 100 % and allocated each of the 27 type specimen to either cluster with posterior probabilities of p > 0.989. As junior synonyms of Hypoponera punctatissima(Roger, 1859) were established by type investigation: Hypoponera androgyna (Roger, 1859), Hypoponera tarda (Charsley, 1877), Hypoponera punctatissima r. jugata (Forel, 1892) and Hypoponera punctatissima var. exacta (Santschi, 1923). As junior synonyms of Hypoponera ergatandria (Forel, 1893) were established by type investigation: Hypoponera kalakauae (Forel, 1899), Hypoponera punctatissima var. schauinslandi (Emery, 1899), Hypoponera dulcis var. aemula (Santschi, 1911) and Hypoponera ergatandria subsp. bondroiti (Forel, 1911). Both species are highly sympatric in Europe with one known example to occur in the same greenhouse. Not a single nest sample in the global material contained workers of both H. punctatissima and H. ergatandriaand there was also no nest sample containing conflicting ergatoid males or gynomorphic females. The species obviously maintain separate reproductive cycles under conditions of a broadly sympatric occurrence and developed significant differences in phenology of sexual development, dispersal of alate gynes, habitat selection in the temperate zone and global distribution. These data clearly rebut the recent judgement of Bolton & Fisher (2011) ‘…that the discriminant functions applied by Seifert (2004) do not isolate discrete species, but rather indicate allopatric populations of the same species, or even different eco morphs of a single species.’ A simple method providing a complete separation of the two species and taking a trained investigator three minutes of working time is presented for males, workers, ergatomorphic females and gynomorphs.