First published online August 4, 2005
Journal of Experimental Biology 208, 3145-3158 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01753
Geometry of elytra opening and closing in some beetles (Coleoptera, Polyphaga)
Leonid Frantsevich1,2,*,
Zhendong Dai2,
Wei Ying Wang2 and
Yafeng Zhang2
1 Schmalhausen-Institute of Zoology, 15 B. Khmelnitsky Str., Kiev 30, 01601,
Ukraine
2 Nanjing University of Aeronautics and Astronautics, 29 Yudao Street,
Nanjing, Jiangsu 210016, China
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Fig. 1. The external reference frame. (A) Still frame of a tethered flying female
of Allomyrina dichotoma at tilted body orientation. (B) Directions of
coordinate axes of the external reference system in real and mirror
images.
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Fig. 2. Traces of the landmark dots on the elytra in Chalcophora mariana
shown as three projections in the external reference system during opening
(open dots) and closing (filled dots). Locked positions are near the zero
x value. Traces coincide on their opening and closing courses. Pitch
47°, 33 episodes, 195 frames. Body silhouettes in the top (real image) and
middle (mirror image) panels are drawn from still frames, while the silhouette
in the bottom (reconstructed) panel is shown with closed elytra.
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Fig. 3. Traces of landmark dots on the elytra in Melolontha hippocastani
in two projections in the external reference system during opening and
closing. For designations, see Fig.
2. Pitch 35°, 7 episodes, 354 frames.
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Fig. 4. Traces of landmark dots on the elytra in Prionus coriarius in two
projections in the external reference system during opening and closing. Top
panel: rear view in the real image, bottom panel: top view in the mirror. For
designations see Fig. 2. Note
(i) parallel rising at the start of opening and sinking down at the finish of
closing (box in the top panel) and (ii) traces of wingbeats of the elytra
after opening and before closing seen as mushroom heads in both panels. Zero
pitch, 9 episodes, 157 frames.
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Fig. 5. Traces of landmark dots on the opening elytra of Prionus
coriarius, subtended at different aspects in the external reference
system. Open dots, left elytron; filled dots, right elytron. The side of the
cube is 40 mm, bold ribs converge at the point (+20, +20, +20 mm). The 3-D
graph can be tilted so that dots lie approximately along a straight line on
either trajectory, or both trajectories are seen as arcs.
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Fig. 6. Visualization of the small inward turn of elytra at the very beginning of
opening in Melolontha hippocastani. Real images with tripods from
still frames. (A) Initial closed position of elytra; (B) intermediate
position; (C,D) final position of mini-opening. Negative images of white arms
at the start position (now black) are overlaid onto B and C. Straight body
orientation.
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Fig. 7. Opening in tethered beetles with and without tripods. (A,B) Melolontha
hippocastani (different specimens, pitch about zero); (C,D) Prionus
coriarius (same specimen, pitch 21°). Still frames. Real image is
below.
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Fig. 8. (A) Traces of tripod arms in the real image plane in Prionus
coriarius (rear view). (B) A silhouette of the beetle, drawn from a still
frame, illustrates the positions of the tripod arms: LP, LV, arms of the left
tripod; RP, RQ, arms of the right tripod; P, longitudinal arm; Q, transverse
arm; V, vertical arm. Arrows indicate movement direction on opening. Rear
view, pitch 21°, 13 episodes, 184 and 177 frames for two tripods.
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Fig. 9. Traces of tripod arms in the body-fixed reference system in Melolontha
hippocastani. (A) Top view; (B) rear view. Body silhouettes at the top of
each panel illustrate positions of the left tripod arms, clearly seen at the
half-opened stage. Designations as in Fig.
8. Zero pitch, 4 episodes, 90 and 94 frames for two tripods. Note
the elevation of elytra in the closed position (arms LP and RP in B) and the
capture of wingbeats in the open position (arms LP, LV in A).
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Fig. 10. Projections of two right tripod arm tips (P and either V or Q) on the axis
of abduction–adduction in Melolontha hippocastani (A) and
Prionus coriarius (B). Abscissa shows turn of elytra, in degrees,
while the ordinate shows values in mm, positive upwards. HP, HQ, HV, location
of projections relative to the center of rotation. Small scatter about zero
for the arm P confirms proper reconstruction of flat rotation of this arm;
trends in arms Q or V indicate additional supination.
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Fig. 11. Traces of two landmarks (tripod arms) in two arm-fixed coordinate systems,
reconstructed for the left elytron in Melolontha hippocastani. (A,B)
Traces of two arms in the arm P-fixed system; (C,D) Traces of two arms in the
arm V-fixed system. A and C show traces of the referent arm in its own fixed
system, while B and D show traces of another arm in the former system. The
reference arm-fixed system rotates together with the elytron about the
body-fixed axis, while the other arm turns about the radius-vector of the
reference arm. Each arm may be set as the reference one. Zero pitch, 4
episodes, 90 frames.
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Fig. 12. Profiles of the sutural structures in some beetles. (A) Catharsius
molossus L. (Scarabaeidae, Coprinae); (B) Calosoma maximoviczi
Morawitz (Carabidae); (C) Carabus elysii Thompson (Carabidae); (D,E)
Allomyrina dichotoma L. (Scarabaeidae, Dynastinae); (F)
Chalcophora japonica Gory (Buprestidae); (G) Rhomborhina
unicolor Motschulsky (Scarabaeidae, Cetoniinae). DR, dorsal ridge; VR,
ventral ridge; G, groove. A, B and D show the female parts of the lock; the
rest are male parts. Scale in A, 100 µm; B–G, 500 µm.
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Fig. 14. Scheme of cooption of sutural ridges of two elytra in formation of the
lock. (A) Transverse section across two closed elytra. Locks: FL, frictional
to the metepisternum; SL, sutural clamp between elytra; SSL, subsutural click
to the metanotum. (B) Parts of the sutural lock in closed elytra. (C)
Direction of engagement by Fiori
(1975 ). (D) Direction of
engagement according to the present study.
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© The Company of Biologists Ltd 2005
, elevation 
, abduction 
, bend ß,
supination 
. Isometric view in the body-fixed reference frame. Inset
below each model, we show the trace of relative divergence in projection on
elytron-fixed axes t and b (i.e. across the suture) upon
initial abduction in the hypothetical range ±10°. The tracer moves
to the left on opening. Trace in D is computed for parameters in Cetonia
aurata.