Iridoprinus, Lackner, Tomas & Leschen, Richard A. B., 2017

Lackner, Tomas & Leschen, Richard A. B., 2017, A monograph of the Australopacific Saprininae (Coleoptera, Histeridae), ZooKeys 689, pp. 1-263 : 41-42

Iridoprinus gen. n. Figs 202, 203-211, 212-218, 757

Type species.

Iridoprinus myrmecophilus sp. n.

Diagnosis.

Cuticle light brown, elytra with strong blue iridescent metallic luster; frontal stria prolonged far onto clypeus; antennal club large, oval and depressed dorso-ventrally; pronotal disc on apical two-thirds coriarious-punctate, punctures forming elongate wrinkles, confluent; elytra densely imbricate-punctate, punctures with microscopic setae; five dorsal elytral striae present, curved and carinate; inner subhumeral and sutural elytral striae absent; abdominal segments dorsally with microscopic setae; prosternal foveae absent; metepisternum with deep elongate groove for reposing mesotarsus; pro- and mesotibiae slightly dilated.

Biology.

The paratype has been collected in the nest of Meat Ant Iridomyrmex purpureus (Smith, 1858). Based on the collecting circumstances of the paratype, as well as its morphological characters (dilated tibiae, metepisternum with groove for reposing mesotarsus) we presume that the newly described taxon is a myrmecophile.

Distribution.

Endemic to Australia; known from Northern Territory and New South Wales (Fig. 757).

Etymology.

The generic epithet is created by combining part of the name of the host ant ' Iridomyrmex ' with part of the word Saprinus (- prinus); the specific epithet of this new taxon relates to its apparently myrmecophilous biology.

Remarks.

By the presence of five strongly curved and carinate dorsal elytral striae and absence of inner subhumeral and sutural striae and presence of peculiar deep longitudinal groove on the metepisternum for the accommodation of mesotarsus, this myrmecophilous Australian genus cannot be confused with any other currently known higher taxon of Saprininae . This is a highly autapomorphic genus ( Lackner 2014d), though, due to the paucity of material, critical characters from the antenna and mouthparts were not examined. However, this is the only Saprininae from the Australopacific and Indo-Malayan Regions collected from ant nests, indicating that it may be an obligate myrmecophile (for the outline of ant-inquilinous Saprininae see Lackner 2017). The deep longitudinal groove of the metepisternum to accommodate the mesotarsus while retracted as well as setose body (the micro setae are presumed to exude appeasing liquid substances which are licked by ants), dilated tibiae that probably serve to cover larger space of the venter when retracted, are possible adaptations to life inside ant nests. Its role inside the ant community is unknown, and it does not have obvious trichomes as in other obligate inquilines such as Chlamydopsinae . This taxon was included in the published phylogeny of the subfamily by the senior author ( Lackner 2014d) under the name ' Saprininae gen. n. (Australia)'. In the published cladogram it was recovered as sister to another Australian taxon of unknown biology ( Saprinodes falcifer Lewis, 1891); this relationship was supported by one ‘strong’ and two ‘weaker’ synapomorphies. It is interesting to note that another apparent myrmecophile, Euspilotus (Platysaprinus) latimanus (Schmidt, 1890) has been recovered sister to this clade, but this purported monophyly should be regarded as spurious since it might be based on homoplasy rather than homology (the characters supporting this triad are among the ‘weak’ synapomorphies and the resolution of the tree is rather low).