Brentidae

Oberprieler, Rolf G., Marvaldi, Adriana E. & Anderson, Robert S., 2007, Weevils, weevils, weevils everywhere *, Zootaxa 1668, pp. 491-520 : 501-503

Brentidae

In the wide sense as adopted here, the family Brentidae is about as diverse as the Anthribidae , with approximately 400 genera and 4 0 0 0 species described, and it also has a cosmopolitan distribution. About 90% of the species belong to the derived subfamilies Brentinae and Apioninae , which are about equal in size (ca. 1 700 and 1 900 species, respectively), while the Nanophyinae (ca. 270), Microcerinae (67), Eurhynchinae (31) and Ithycerinae (1) are much poorer in species and also geographically more restricted. Brentidae are almost exclusively associated with angiosperms, only very few and unrelated apionines occurring on conifers, and since nearly all the putatively basal groups ( Ithycerinae , Microcerinae , Eurhynchinae , Nanophyinae , Brentinae : Cyladini, Apioninae : Tanaini, Mecolenini) live on angiosperms, it appears that the family was ancestrally associated with this group of plants. Conspicuous in Brentidae is also the absence of associations with monocotyledons, and although the family is indicated to be at least as old as Curculionidae (extending back to the mid-Cretaceous in the fossil record), it species richness reaches not even 8% of that of the latter. The larvae of Ithycerinae and Microcerinae (fig. 10) feed on roots in the soil, those of Eurhynchinae (fig. 8) and Brentinae (fig. 11) tunnel in living or dead branches and trunks (where some Brentinae may be predaceous on other xylophagous beetles) and those of Apioninae (fig. 12) and Nanophyinae develop mostly in young stems and inflorescences, fruits or seed pods.

The family concept of the Brentidae remains in dispute, some authors (e.g., Crowson 1955, Zimmerman 1994b, Wanat 2001) treating some or all of the subfamilies recognised here as distinct families. The case for amalgamating them (except for the African Microcerinae ) into a single family was first made by Morimoto (1962, 1976) and consolidated by later studies ( Thompson 1992, May 1993) and phylogenetic analyses ( Kuschel 1995, Marvaldi & Morrone 2000, Oberprieler 2000, Marvaldi et al. 2002). The Microcerinae (fig. 9), which had previously been included in the curculionid subfamily Brachycerinae (e.g. Thompson 1992, Kuschel 1995), were included in Brentidae by Oberprieler (2000) on the basis of mainly larval characters. A number of characteristic morphological features occur in Brentidae in this expanded concept, such as stepped abdominal ventrites (3–5 on a higher level than 1–2), eyes covered by a corneal lens, labial palps sunk into grooves on the ental surface of the prementum and with a reduced number of segments (2 or 1), male tergite 8 pouch-like with medially inflexed posterior margin, aedeagus with frenal sclerities, tegminal ring laterally constricted or articulated; however, none of these conditions are present in all taxa and can be regarded as synapomorphies defining the family Brentidae as a monophyletic group. Only two characters have been identified so far as shared by all of them. One is the single median sensillum on the larval labrum, which is otherwise only known in Ocladiini ( Curculionidae : Brachycerinae ) but does not occur in the more primitive families (which have a median pair) or in other Curculionidae (which have a median sensillum plus a lateral pair). The other is the reduced number of Malpighian tubules (four), a condition that almost never occurs in Curculionidae (only a few isolated cases reported in Cossoninae and Rhamphini , see Calder 1989). It does, however, also occur in some Nemonychidae and Anthribidae ( Calder 1989, May 1993), and although such a reduction is likely to have evolved independently in various groups, its consistent occurrence in all Brentidae suggests that it may indeed be a synapomorphic feature in this family. Further morphological and molecular studies are needed to test this hypothesis and to establish the relationships among the subfamilies as recognised here. Phylogenetic relationships within the subfamilies have been addressed in Microcerinae ( Louw 1986) and Apioninae ( Wanat 1995, 2001) but remain to be extended and especially studied in the other large subfamily, Brentinae .