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Hao Wu, Liqin Li, Ming Ding. 2018.
The first cyclaxyrid beetle from Upper Cretaceous Burmese amber (Coleoptera: Cucujoidea: Cyclaxyridae).
Cretaceous Research, 2018, 91: 66-70.
Introduction
Cyclaxyridae is a very small family of Cucujoidea, containing only two extant species
(Cyclaxyra politula and C. jelineki) assigned in one genus confined to New Zealand (Leschen et al.,
2010). Cyclaxyrid adults process a very distinguishable character: a single pair of large deep foveae
located at the anterior half of elytral epipleuron. This feature is otherwise not known in any other
groups of Coleoptera, except the New Zealand leiodid Baeosilpha rufescens (Gimmel et al., 2009),
but the latter displays a reduced antennomere 8 and other typical characters of Leiodidae.
Historically, Cyclaxyra has been considered as a member of Nitidulidae (Broun, 1881), Sphindidae
(Crowson, 1955), or Phalacridae (Crowson, 1981; Lawrence 1982). Until 2009, Gimmel et al. (2009)
formally raised the enigmatic genus to its own family. Their phylogenetic relationship within
Cucujoidea is not fully confirmed up-to-now. Some authors placed it as a sister group of
Tasmosalpingidae (Leschen et al., 2005), an Australian family, or weakly supported it as the sister
group of Phalacridae (Gimmel, 2013), according to adult characters; whereas some authors placed it
close to Lamingtoniidae based on larval characters (Lawrence and Leschen, 2003). Recent
molecular-based phylogeny revealed Cyclaxyridae as a sister group to Passandridae, within the
laemophloeid clade (McElrath et al., 2015), or sister to Myraboliidae, outside the laemophloeid
group (Robertson et al., 2015).
Living cyclaxyrids, as both adults and larvae, are all collected from sooty-mould fungi
(Ascomycota: Dothideomycetes: Capnodiales), which mainly grow on Nothofagus bark, and their
growths are associated with some kind of Hemiptera (Klimaszewski and Watt, 1997). The
distribution of cyclaxyrids is very limited, only found in New Zealand. No true fossil species have
been found yet, and the Quaternary subfossil C. impressa from silt sediments of Taranaki, New
Zealand (ca. 33~34 kya), reported by Marra et al. (2008), has been proved to be a synonym of C.
politula (Gimmel et al., 2009). In this paper, the first definitive fossil species of Cyclaxyridae is
described from the well-known Cretaceous Burmese amber.