|Rhyzobius chrysomeloides (Herbst, 1792)|
|Introduced as a British species by Menzies (1999) in 1998 from a colony
in Surrey, this species was first recognised in Britain in 1996 in Surrey by Hawkins (2001) who beat a single
specimen from young pine (Pinus sylvestris) growing near the M23 motorway. Hawkins gives clear line
drawings of the pronotum, prosternal carinae and male genitalia, all of which are diagnostic, of both
chrysomeloides and R.litura and states further that subsequent to the original discovery over three
hundred Rhyzobius from grassland have been dissected and all males have proved to be litura.
Fursch (1967) states that the species is found more especially on pine but also on shrubs and often near water
while Hurka gives 'mainly on pine trees and shrub
vegetation'. The species is not mapped on the NBN website and we have been unable to find further records but we have
found the species at several local localities.
During September 2006 a single specimen was beaten from Oak (along with the pine ladybird Exochomus quadripustulatus (L.)) in Cassiobury park, and another single specimen was swept from dense vegetation alongside the river Gade on Common moor. During March 2007 a single specimen was swept froom Broom (Cytisus) on Common moor, again we have found Exochomus quadripustulatus in this locality and on this plant but so far as we are aware pine is absent. Interestingly, during 2005 and 2006 we recorded Pine Hawk moth on the moor. A further chrysomeloides was swept from the moor during April 2007. No specimens were recorded during 2008 for the simple reason that we did not recognise the species until November of that year.
Differences between chrysomeloides and litura are often obvious, especially the elytral pattern, but they are variable and need to be examined carefully.
See ID Aids
2.5-3.5mm. (Fursch). Broad elongate oval and very convex, entirely testaceous or dark testaceous but for eyes and elytral markings. Entire upper surface with fine recumbent pale pubescence. Head a little less shiny than pronotum and elytra, finely and quite densely punctured, eyes coarsely faceted, convex and protruding. Antennae longer than head across eyes, basal segment elongate and only weakly thickened (cf. R.litura), 2-8 elongate, 9-11 forming a weakly defined club, 10 and 11 obliquely truncate apically. Last segment of maxillary palpi dilated, almost triangular. Pronotum finely bordered to lateral and basal margins. Lateral margins subparallel in basal half, smoothly contracted in front, hind margin strongly sinuate. Hind angles weakly obtuse, front angles rounded. Surface shining, sparsely and finely punctate. Elytra slightly dull due to microsculpture which is just visible at X20, puncturation coarser than on pronotum. Dark marks vary (Fursch) but those local specimens we have examined have more or less the same pattern, as shown. Variation means there may be a resemblance to R.litura. Lateral margin sinuate and finely bordered. Legs testaceous. Claws appendiculate
Fursch 1967. In Freude, Harde and Lohse, Die Kafer Mitteleuropas. Vol 7 239-240. Goecke and Evers, Krefeld
Hawkins, R.D. 2001. Rhyzobius chrysomeloides new to Britain. Br.J.Ent.Nat.Hist. 13:193-195
Menzies, I.S. 1999. (BENHS Exhibit, 1998) Br.J.Ent.Nat.Hist. 12:176