Placement of Spongiphora lewisi de Bormans, 1903, an enigmatic earwig species of Spongiphoridae (Insecta, Dermaptera), as revealed by integrative taxonomy

Spongiphora lewisi de Bormans, 1903 is a large spongiphorid earwig, known from Japan, China, Laos, and Vietnam. Although many previous authors have placed this species under Nesogaster (Nesogastrinae) focusing on their developed tegminal (forewing) keels, the taxonomy of this species, which shows specific mycophily to fruiting bodies of Cryptoporus volvatus, requires further scrutiny. In this study, multiple lines of evidence for placement of this species under Spongovostox (Spongiphorinae) are provided.

The morphologies of the male and female genitalia (the latter reported for the first time) and DNA barcodes indicate close affinities of Sp. lewisi to two spongiphorine genera, Spongovostox and Marava. Embryonic development in this species begins within the ovaries, indicating ovarian fertilization, a phenomenon previously documented in several species of Spongiphorinae, Labiinae, and Sparattinae, but not in Nesogastrinae.

Although the tegminal keel structures of Spongiphora lewisi resemble those of true Nesogaster, their different orientations support reinstating the combination Spongovostox lewisi (de Bormans, 1903). Our integrative taxonomy analysis reveals instability in the subfamilial classification of Spongiphoridae, which relies heavily on a limited set of traits prone to convergent evolution. A revised key for Spongiphoridae subfamilies is also presented, and a new mainland Sumatra record of Auchenomus javanus (Sparattinae) is reported.