Dull. Kitakyushu Mus. Nat. Hist., 4: 15-22. December 31, 1982
On the copulation mechanism of Eligma narcissus
(Cramer) (Lepidoptera: Noctuidae)
Kyoichiro Ueda
Kitakyushu Museum of Natural History. Nishihonmachi,
Kitakyushu. 805 Japan
and
Toyohei Saigusa
Biological Laboratory. College of General Education. Kyushu University.
Ropponmatsu. Fukuoka. 810 Japan
(Received on Aug. 31, 1982)
Abstract The structure and musculature of male external genitalia and terminal
external structure of female abdomen of Eligma narcissus (Cramer) are figured and
described. The mode of firm connection between male and female external genitalia
is effected in the following sequences: 1) the acute lips of valvae. which are characteri
stically curved outwards, are applied to the membranous ridges oi" female, which are
present laterad to the ostium bursae, 2) the valvae are strongly expanded laterally
by the contraction of Mb and male and female genitalia are firmly fixed, then 3) the
phallus is inserted into the ostium.
1.
Introduction
When many adults of Eligma narcissus (Cramer) was captured at the Hakozaki
campus of Kyushu University, Fukuoka in autumn of 1971, wc succeeded in
hand-paring of this species using anesthetized males and found that the copula
tion mechanism of this species was very characteristic and had not hitherto been
recorded in Lepidoptera. Ueda
(1974) briefly reported this mech
anism in comparison with the
male and female external geni
talia of Gadirlha inexacla uniformis
Warren. Since then, we got
the male specimens fixed in 70%
ethanol and observed the muscu-
w
lature of male external genitalia
besides the structure of female
terminalia.
Therefore the pre-
.
s
Figi ,. migm mrcissus (Cramer): female,
KMNHIR 000,001
16
Kyoichiro Ueda and Toyohei Saiousa
sent paper deals with this peculiar copulation mechanism of Eligma narcissus in
detail.
Before going further we express our cordial thanks to Professor Emeritus
Takashi Shirozu of Kyushu University for his continuous encouragement. The
senior author also expresses his hearty thanks to Professor Ryuzo Toriyama and
Dr. Masamichi Ota of Kitakyushu Museum of Natural History for their kind
encouragement. We are much indebted to Dr. M. Oba and Dr. M. Takagi of
Institute of Biological Control, Kyushu University, Mr. N. Kashiwai of Entomo
logical Laboratory, Tokyo University of Agriculture and Mr. S. Sugi, Tokyo for
their kind helps giving us valuable informations and specimens.
2.
Method
For the musculature of male external genitalia, field collected specimens
were fixed in 70% ethanol, then the apical portion of abdomen was dissected and
stained with Mayer's Haematoxylin. For the external structure, the dried spec
imens were macerated with 15% KOH solution. The materials were dissected
under a binocular microscope at magnification of 25X-100X.
Hand-paring method using anesthetized male: Saigusa (1970) succeeded in hand-
paring on some species of Psychidae using anesthetized males and got fertilized
eggs. This is a paring method applying the phenomenon that the external gen
italia of male moths under chloroform anesthesia show movements similar to
coupling, being given some stimuli (rubbing, pushing, etc.). A similar method
is also used in Limenitis popidi (Takakura, 1978). The method is very effective
for some of the species which show no active copulation movement of external
genitalia in artificial condition, even though fully stimulated, or for some species
of which a pair in copula are inclined to apart from each other just after handpaired.
In this species, male specimen is anesthetized with chloroform till the flattering
of wings and the movements of legs to contact substratum stop. When the legs
are flexed and applied to sides of thorax, the specimen is drawn away from the
tube.1) Shortly after the external genitalia of the anesthetized male are given
some stimuli by rubbing the terminal portion of abdomen or pushing the apical
portion of valva, the male genitalia show the movements for copulation along
the sequences to the insertion of phallus. Then, the female terminalia is applied
to the male external genitalia showing the above-mentioned movements, and the
hand-paring is completed.
1) If the male is kept in the tube till the legs stretch again, he completely dies.
Copulation mechanism of Eligma narcissus
3.
17
Structure of male external genitalia and their musculature
Description of integumental morphology of male genitalia: Tegumen very slender,
long and about 3 timesas longas vinculum;vinculumshort, completely fused with
valva and its border region indistinct; saccus small and rounded. Valva simple,
gradually tapering towards apex; tip of valva very slender, acute and curved out
wards ; inner wall of valva uniformly sclerotized as well as outer wall and not
subdivided into costa, sacculus, harpe, etc.; outer wall of valva swollen at dor-
soproximal portion; ventral margin of base of valva membranous.
The sclerites
of 10th somite of abdomen such as uncus, gnathos, etc. absent; a small weakly
sclerotized plate present on dorsal region just behind apical portion of tegumen
and posterior margin of this plate excavated at the middle. Juxta absent. Phal
lus very large and as long as tegumen; dorsal and ventral portions of suprazonal
sheath sclerotized and with dense serrations towards apex; lateral regions of suprazonal sheath membranous and continuing perivesical area; subzonal sheath very
large and strongly sclerotized; coecum not developed; posterior portion of vental
margin of suprazonal sheath produced ventrally. A weakly sclerotized longitu-
Fig. 2. Terminal segments of male abdomen.
Lateral aspect (left).
Kyoichiro Ueda and Toyohci SAIGUSA
18
dinal plate on midvcntral region
of diaphragma.
Musculature:
The muscula
ture of male external genitalia of
Eligma narcissus is very simple in
comparison with known Noctuids genitalia. But this simple
musculature closely participates
in a peculiar copulation mechan
ism of this species. The nomen
clature of musculature system of
Forbes (1939) is adopted in the
following description.
M1-M5:
M6:
3
Absent.
Broad and well de
veloped large muscle, originated
from anterior portion of phallus
(anterior portion of subzonal
sheath) and inserted on inner
side of outer wall of valva from
Fig. 3.
Terminal segments of male abdomen.
Ventral aspect.
its dorsoproximal swelling ob
liquely to ventroproximal por
tion.
M7:
Moderately large muscle, originated from saccus and inserted on
Fig. 4. Male genitalia showing their musculature.
Lateral aspect (left).
Copulation mechanism of Eligma narcissus
19
subzonal sheath from its dorsal region near zone to its ventral region.
M8:
Absent.
4.
Structure of female terminalia
Eighth abdominal tergum small, strongly broadened posterolaterally forming
a triangular lateral expansions. Ostium bursae covered anteriorly with a thin,
creamy white plate (lamella antevaginalis) which is swollen and has a short lon
gitudinal median slit from its posterior margin. A large and well sclerotized plate
(lamella postvaginalis) present posterior to ostium; this plate dilating posteriorly,
on both anterior and posterior margins broadly excavated, and its posterolateral
corners strongly produced arm-like and ended in a rounded tip. Genital cavity
laterad of ostium bursae broadly membranous and a pair of narrow ridge-like
swellings present at the middle portion of this membranous area; this swellings
hardened, and many slender folds present around them.
Fig. 5. Terminal segments of female abdomen. Lateral aspect (left).
20
Kyoichiro Ueda and Toyohei Saigusa
Fig. 6. Terminal segments of female abdomen. Ventral aspect.
5.
Hand-paring
The scales on external genitalia and their surrounding portionswere removed
from the anesthetized male. The fully stimulated male began to move his geni
talia in the following sequence: 1) valvae were strongly expanded (stretched)
laterally (tips of valvae diverging from each other)2) (contraction of M6); during
this condition, the middle portion of outer wall of the base of valva (just distad of
M6 attachment) wasstrongly concaved; 2) proximal margins of both sacculi were
tightly met on the medial portion of ring; 3) phallus was protruded above them
and the vesica began to be everted; 4) valvae were closed and the phallus was
retracted (relaxation of M6, contraction of M7).
When the valvaejust began to be expanded, the acute tipsofboth valvaewere
applied to the female ridges on the membranous portion laterad to the ostium.
More the valvae were stretched laterally, more the female genital cavity was
expanded being hooked the ridges with the tip of stretching valvae. Then, the
male and female external genitalia were firmly connected and the ostium was
2) When the male external genitalia were not applied to female external genitalia, the angle
taken by expanded valvae reached to almost 180°.
Copulation mechanism of Eligma narcissus
opened.
21
After that the phallus was inserted and the transfer of spermatophore
began.
Duration of copulation:
about 30 minutes.
6.
Discussion
As mentioned above, the male genitalia of Eligma narcissus are very different
from those widely observed in the Noctuidae, e.g., Hadeninae, Acontiinae, etc.,
not only in the sclerotic composition but in musculature. The characteristics
in this species are summarized as follows: 1) the absence of sclerites as uncus,
gnathos, etc. observed in 10th somite of abdomen, 2) the completely fused condi
tion between valvae and vinculum, 3) the absence of subdivision on the inner wall
of valva, 4) the apical portion of valva acutely pointed and curved outwards,
5) the absence of juxta, and 6) the absence of intrinsic muscles M1-M5 and M8.
These characteristics are undoubtedly considered to be unique apomorphies in
the Noctuidae. However these specializations are all well adapted to the special
copulation mecahnism of this moth, namely not the general Noctuid one, in which
7
Fig. 7. Diagrams showing the movements of maleand female genitalia on coupling.
A:
B:
before coupling.
in copula.
22
Kyoichiro Ueda and Toyohei Saigusa
the male holds and grapples the female terminalia by the valvae and uncus of his
external genitalia, but the specialized one, in which the male applies the apexes
of valvae to the ridge-like structures situated laterad of ostium, and tightly keeps
the female terminalia by the extension of valvae and opens the ostium.
In Japanese Sarrothripinae, we found some species lacking in uncus, such as
Gadirtha inexacta, but they have normal valvae and are inferred to be normal
"grasping" type in copulation. Moreover, judging from the figures of Mell
(1943) and Holloway (1976), the male external genitalia of Triorbis, which has
been considered to be one of the closely related genera with Eligma by Hampson
(1912), is inferred to be normal "grasping" type. Therefore, the problems are
still uncertain on the evolutional process to this specialized male and female genital
structures, and consequently on the systematic position of this species. Even in
the entire scope of the Lepidopteran genitalia morphology, the male genitalia of
this species are considered to be one of the most specialized types both in the
structure and function.
References
Forbes, W. T. M., 1939. The muscles of the Lepidopterous male genitalia. Ann. ent. Soc.
Amer. 32(1): 1-10.
Hampson, G. F., 1912. Catalogue of the Lepidoptera Phalaenac 11.
Holloway, J. D., 1976. Moths of Borneo with special reference to Mount Kinabalu. Malayan
Nature Society.
Mell, R., 1943. Beitrage zur Fauna sinica XXIV. Uber Phlogophorinae, Odontodinae, Sar
rothripinae, "Westermanniinae" und Camptolominae (Noctuidae, Lepid.) von Kuangtung.
Zool. Jahrb. (Syst.) 76: 171-226.
Saigusa, T., 1970. On the hand-paringofPsychid moths by the anesthetizations of malespecimen
(in Japanese).
Pulex 48: 180.
Takakura, T., 1978. Nature Conservancy and Butterflies-A blueprint for mass-production
(in Japanese).
The Insectarium 15 (9): 4-9.
Ueda, K., 1974. Notes on thegenital structures and behaviors (mating behavior, death mimicry
and stridulationof pupae) of Eligma narcissus and Gadirtha inexacta (Noctuidae) (in Japanese).
Japan Heteroc. Journ. 78: 296-300.