New mid-Cretaceous cryptic slime mold beetles and the early evolution of Sphindidae (Coleoptera: Cucujoidea)

Yan-Da Li,Zhen-Hua Liu,Erik Tihelka,Chen‑Yang Cai,Di-Ying Huang

doi:10.3897/asp.79.e72724

Abstract

Abstract The cryptic slime mold beetles, Sphindidae, are a moderately diverse cucujoid beetle family, whose members are obligately tied to slime molds throughout their life. The fossil record of sphindid beetles is sparse; stem-sphindids and crown-group members of uncertain systematic placement have been reported from Cretaceous ambers. Here we review the Mesozoic fossil record of Sphindidae and report a new sphindid genus and species, Trematosphindus newtonigen. et sp. nov., from Albian/Cenomanian amber from northern Myanmar (ca. 99 Ma). Trematosphindus is set apart from all other sphindids by the presence of distinct lateral cavities on the anterior pronotal angles. Our phylogenetic analysis identifies Trematosphindus as an early-diverging genus within Sphindidae, sister to the remainder of the family except Protosphindus, or Protosphindus and Odontosphindus. The new fossils provide evidence that basal crown slime mold beetles begun to diversify by the mid-Cretaceous, providing a valuable calibration point for understanding timescale of sphindid co-evolution with slime molds.

Highlights

The family Sphindidae, cryptic slime mold beetles, is a group of widespread beetles belonging to the diverse and, as currently conceived, paraphyletic polyphagan superfamily “Cucujoidea” (Forrester and McHugh 2010)
Libanopsis possesses a series of characters different from extant sphindids, including the lack of a clear frontoclypeal suture andcontiguous metacoxae
Libanopsis may be isolated from other sphindid subfamilies, and possibly represent a stem-group of Sphindidae (Kirejtshuk et al 2015)

Summary

Introduction

The family Sphindidae, cryptic slime mold beetles, is a group of widespread beetles belonging to the diverse and, as currently conceived, paraphyletic polyphagan superfamily “Cucujoidea” (Forrester and McHugh 2010). Li et al.: Cretaceous slime mold beetles (J.V. McHugh, personal communication), though much of their biodiversity remains undocumented. Forrester and McHugh (2007) mentioned that they have identified more than a hundred undescribed species in a single sphindid genus, Aspidiphorus Latreille. As their common name suggests, sphindid beetles feed exclusively on slime molds (myxomycetes) in both larval and adult stages, while most other aspects of their ecology remain elusive (Lawrence and Newton 1980; Burakowski and Ślipiński 1987). Four extant subfamilies have been proposed within Sphindidae based on a morphological phylogenetic analysis, i.e., Protosphindinae, Odontosphindinae, Sphindiphorinae, and Sphindinae (McHugh 1993)

Methods

Results

Conclusion