On the basis of detailed anatomic-hislological studies a reconstruction of the male reproductive system in six species representing Palaearclic species of genus ...
Folia biologica (Krakow), vol. 41 (1993), No 3-4
Anatomy of Male Reproductive System of the Psylla Geoffr. s.l. (Homoptera, Psyllodea) - Validity for the Systematic Relations within the Genus Elzbieta
GLOWACKA
and Anna
MARYANSKA-NADACHOWSKA
Accepted September 15, 1903
GLOWACKA E . , MARYANSKA-NADACHOWSKA A. 1993. Anatomy of male reproductive system of the Psylla GeoKr. s. I. (Homoptera, Psyllodea) - validity for the systematic relations within the genus. Folia blol. (Krakow) 41: 55-64. On the basis of detailed anatomic-hislological studies a reconstruction of the male reproductive system in six species representing Palaearclic species of genus Psylla Geoffr. 5. /. was described and presented on figures. The authors discuss anatomical differences between species, mostly on the basis observed in testes, (generally related to (he number of existing sperm tubes and location of the sperm cysts), seminal vesicles and acces.sory glands. The valid! ly of systematic classifications within the genus Psylla used by authors in further analysed with the help of new anatomical data. Key words: male reproductive system, Psylla. Homoptera, systematic classification. Elzbieta GLOW.\CK.A, Poland.
Department of Zoology, Uiiiversitv of Silesia, Baiikowa 9, PL 40-007Katowice,
Anna MARfA.NSKA-N.\n.\CHOV,SK.\, Department ofExperimentalZoology, Institute ofSystematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, PL 31-016 Krakow, Poland.
Since many years the genus Psylla Geoffr. has been treated as a homogenous group, consisted of closely related species. E N D E R L A I N (1921) designated the genus Asphagidella Endr. for the distinct species Psylla buxi ( L . ) , but it has not been accepted for many years by other authors (KLIMASZEWSKJ 1975;
LOGlNOVA
1978;
HODKINSON &
W H I T E 1979). Fifty years later, on the basis of morphological features of the last instiir larvae and differences in feeding behaviour, OSSIANNILSSON (1970) subdivided the genus Psylla Geoffr. to 5 subgenera: Psylla sensu stricter, Lahirynthopsylla Oss.; Ha/naepsylla Oss.,- Cacopsylla Oss. and Hepatopsylla Oss. A l s o K L I M A S Z E W S K I (1972) took into account the differences in anatomical features and nymphal morphology subdividing this group into two genera: Psylla Geoffr. and Cacopsylla Oss. In the late seventies other systematic classification of Psylla was proposed by L O G I N O V A (1978) and BURCKllARDT (1979), thus confirming unabated interest in this group thus resulted from both the lack of univocal criteria and the strong arguments for accepting a uniform tiixonomic status. Even in the recent years publications the
range and classification of Psylla is different. W H I T E & H O D K I N S O N (1985) selected 7 subgenera, while OSSIANNILSSON (1992) accepted the system proposed by B U R C K H A R D T (1979) with distinguished four separate genera. Bearing all these in mind the use of other taxonomic criteria might be important for improvements of systematic cla.ssification of the genus. Anatomical features of male reproductive system would be relevant for that purpose ( G L O W A C K A 1975, 1991). A m o n g Psylla species Cacopsylla mali (Schmidb.) was the only object of intensive studies because of economic importance in horticulture, but this data is very old and vague (VlTLACZIL
1885;
BRITTAIN
1923;
PFLUGFELDER
1941). For other species only incomplete data were presented, i.e. on a numberof testicular tubes. More detailed description of the male reproductive system was presented only for Psylla fusca ( G L O WACKA
&
KLIMASZEWSKI
1970).
Anatomical
studies for gther Psylla Geoffr. species should be valid for verification of systematic classification of that group.
56
E . GLOWACKA, A. MARYANSKA-NADACHOWSKA
Material and Methods Material was collected in Finland, except of Psylla buxi (L.) from Poland and Psylla colorata L o w from Bulgaria. Males of the following species were taken for analyses: Psylla alni (L.), P. betulae (L.), P. buxi (L.), P. colorata Low, P. foersteri Flor, and P. fusca (Zett.). Insects were briefly fixed in the Carnoy solution after catching, and histological slides were prepared according to standard histological procedures used for Psyllodea ( G L O W A C K A & K L I M A S Z E W S K I 1968). Specimens, fixed previously with Carnoy solution, were immersed in 1% solution of celloidin in methyl benzoate, then embedded in paraplast ( S I G M A ) and serially sectioned (7 ^m) for light micro.scopy. Xylidene ponceu and E r l i c h h e m a t o x y l i n e were used for staining. The slides were further used for the reconstruction of male reproductive system. Total anatomical preparations were also used for the analysis of the investigated system.
Results and Discussion A n overall view of the reproductive system in matured males does not differ much within selected species represented by the genus Psylla Geoffr. (Figs 1-6). The essential parts include a pair of testes {Testes - T ) ; a pair of lateral ducLs (Vasa deferentia - V.d); a pair of seminal vesicles (Vesicula seminalis - V.s.); a pair of accessory glands (Glandulae accesoria - G.a.) and a single ejaculatory duct (Ductus ejaculatorius- D.e.). A l l elements of male genital systems are generally situated in the abdomen below the digestive tract (Figs 7-10). The t e s t e s ( T ) . Each testis consists of a different number of sperm tubes. In Psylla alni, P. betulae and P. colorata the testis is built of four sperm tubes (tubules) and its number was consUmt in all anatomical preparations made from more than a hundred specimens. The number of sperm tubes in Psylla fusca is flexible, five being the average, but six or seven tubules were also observed. The range of variability is even higher in P. foersteri from 4 to 8 tubules. The most frequent number of sperm tubes in males of that species collected in Finland was seven. The lowest number of tubules was stated in P. buxi, which characterizes two tubules in each testis (Fig. 6). U s i n g the number of tubules as the criteria of testicular differentiation, three groups of psyllids may be selected. The first group, with two tubules in each testis, are represented by species examined earlier (GLOWACKA &. KlJMASZEWSKI 1969) and suggested by KLIMA-
SZEWSKI (1975) to the genus Cacopsylla, and P. hartigi F l o r (GLOWACKA, unpublished data), which was reported by OSSIANNILSSON (1970) to the subgenus Chamaepsylla, while BURCKHARDT (1979) made it in the rank of genus. A l s o recently studied P. buxi represents this group. For the second group {P. alni, P. betulae, P. colorata) four sperm tubes are characteristic. A l l other species with higher (5-8) number of tubules belong to the third one. Within this group six sperm tubes were found in P. fusca and P. foersteri, but their number is fluctuating from four to seven. The number of tubules in testis does not correspond to the size of an insecL Testis of the largest studied species-P. alni, 4.8-5.5 m m long (OSSIANNILSSON 1992), arc built of four tubules. Slightly smaller P. foersteri (4.14-4.52 m m long) of six, P. fusca (4.29-4.86 mm long) even eight, while the smallest P. buxi (3.57-3.95 mm long) have only two tubules (Figs 1-6 ). According to the rule of oligomerization created by Dogiel, species with higher number of sperm tubes in testis are accepted as more archaic, unlike the species with reduced tubular number, for example Cacopsylla mali or P. buxi, which are stated evolutionary younger (GLOWACKA 1991). The tubules contain germary cells in various stages of development, surrounded by a peritoneal sheath (Figs 13-20). In young individuals a whole sperm tube is filled by the germarium ( F i g . 15). After one month of their life, in older males, zones of growth, maturation and transformation are easily distinguished (Fig. 16). In a l l mature males of the examined species sperm cysts are located in the one row (Figs 13-20). In a distal part cysLs were degenerated, but mature sperm cells remain grouped in bundles, in the same position as they were in cysLs. Such position of mature sperm cells was also observed in the total preparation after tearing the cysLs open in P. alni, P. betulae, P. fusca and P. foersteri. The v a s a d e f e r e n t i a ( V . d . ) . Longevity of thin wall seminal ducts leading from each of the testis is different within examined species (Figs 1-8). The posterior part is thicker with a stronger musculature and bigger epithelial cells than the anterior one (Fig. 13). The posterior ducts are much longer in P. biai than in other examined species. In about half of the distance anterior seminal ducts dilate to form the seminal vesicles. The s e m i n a l v e s i c l e s . ( V . s . ) . TTiey are well visible, of oval shape in mature insects.
Male reproductive system in Psylla Geoffr.
57
V.S.
^\f}f I^^ male reproductive system\ Psylla Geoffr. species. Fig. 1. P. hetulae (L.); Fig. 2. P. alni (L.); Fig. 3. P. colorata (Low); F,g. 4. P. M c a ( ^ „ 0 ; Fig. 5. P. foersteri Flor; Fig. 6. P. W (L.). Abbreviati^ns'x. - testes; V.s' - sLinal v J c l e l G.a. - accessory glands; V.d. - vas deferens; D.e. - ductus ejaculatorius. Bar equals 100 |im.
Figs 7-10. A reconstruction of male reproductive system in the abdomen of four Psylla Geoffr. species. Fig. 7. P. fusca (Zett.); Fig. 8. P. betulae (L.); Fig. 9. P. colorata (Low); Fig. 10. P. foersteri Flor. Abbreviations: T. - testes; V.s. - seminal vesicles; G.a. - accessory glands; V.d. - vas deferens; D.e. - ductus ejaculatorius. Bar equals 100 jira.
Male reproductive system \n Psylla Geoffr.
11
59
12
Figs 11-12. Areconstruction of seminal vesicles and accessory glands in young premature adult male (Fig. 11) and after a month ofthe adults life (Fig. 12). Bar equals too nm.
with closely connected walls. O n l y in P. buxi they are spherical and their inner walls are fused (Fig. 22). Such a feature is recognized as the progressive one ( G L O W A C K A & K L I M A S Z E W S K I 1970). In P. alni
and P. foersteri elongated vesicles, located in the middle of ventral abdomen, are very close to each other but their walls are not fused (Figs 7-10). In young males seminal vesicles are rather small, with strongly stained walls and lack sperm cells in their internal part (Fig. 13). They are repeatedly wider in older mature insects, for example in P. betulae (Fig. 12) with the interior part full of sperm cells. The walls of seminal vesicles in mature males P. foersteri are thick, more folded and intensively stained with hematoxilin as compared with vesicles of P. fusca of similar dimensions (Figs 17 & 19). T h e a c c e s s o r y g l a n d s ( G . a . ) . Their shape and dimensions are more variable during the
ontogeny than seminal vesicles. Small glands and the lack of secretes in their lumen is characteristic for young males (Figs 11 & 13). Later in time they increase and the internal part is filled up with intensively alcaline stained secretions (Fig. 14). The accessory glands in mature individuals of P. buxi are the biggest element of their genital system and the biggest in comparison with other analysed species (Fig. 6). Irregularity in shape of these thin-walled glands, filling up almost all abdomen, is related to its secretory activity. A s it was mentioned in earlier studies, the size of accessory glands depends on the physiological state of an insect ( G L O W A C K A 1987). T h i s suggests that ac-
cessory glands in males oiP. buxi, collected during August in Southern Poland, were examined during their period of maximum secretory activity. In P. alni, P. betulae a n d P . foersteri accessory
60
E. GLOWACKA, A . MARYANSKA-NADACHOWSKA
glands form two connected lobes, well differentiated in older males (Figs 1,2,5,11 & 12). In some P. foersteri their walls are strongly folded and well haematoxilin stained. The glands in males of P. fusca are crescent-shaped, overlay the sperm pump (Figs 4, 7 & 18). In all examined species very short and w e l l developed ducts of the accessory glands met with the posterior part of the seminal ducts in front of the sperm pump where they connect themselves with ductus ejaculatorius (Fig. 21). Thus it is supposed that accessory glands in all analysed psyllids are of ectodermal origin ( G L O WACKA
&
KLIMASZEWSKI
1968,
1970;
GLO-
W A C K A 1987). Dimensions of the sperm pump is different within species. Other features of this part using the 1 ight microscopy techniques are invisible. D u c t u s e j a c u l a t o r i u s ( d . e . ) . It sUirLs from the sperm pump and is always a long tube localized in distal part of the abdomen, well differentiated because of cuticular lining. The distill part of the duct is connected with the copulatory organ (Figs 7-10). Anatomical studies showed many discrepances in the male reproductive system between analysed Psylla Geoffr. species, thus indicating heterogeneity of this group. Fragmentiiry anatomical studies of P. fusca
and C . mali ( G L O W A C K A & K L I M A -
SZEWSKI 1970) were used by the last author for differentiation of this group inio Psylla Geoffr. and Cacopsylla Ossian., basing on the anatomy of testes ( K L I M A S Z E W S K I 1972). These features were also tJiken into account by B U R C K H A R D T (1979), but a construction of his dendrogramme was based on species which had not been used for dcU'iiled studies of the male gcnil;il system. He suggested therefore P. buxi to the group of species with a larger number of testicular tubules. Despite this, other features (host plant, overwintering developmcnUil sUige, a structure of nymphal antenna, gallforming by the larvae) allowed him to place that species in the subgenus Asphagidelta E n d . of the ganusPsylla Geoffr. ( B U R C K H A R D T 1979). Unfortunately, L O G I N O V A (1978) consequently placed P. buxi in the genus Spaimmeura ( L . ) , as it was also proposed by K L I M A S Z E W S K I (1975). Other authors did not accept these proposals ( B U R C K H A R D T 1979;
W H I T E & H O D K I N S O N 1985;
frons in adults, number of apparent antennal segments make it significantly different. O n the other hand, P . />«xj differs also from the group P . alni and P. foersteri with four or four-eight seminal tubules respectively. In the recent paper H O D K I N S O N (1988) did not use consequently his own classification ( W H I T E &. H O D K I N S O N 1985) and wentback
to that proposed earlier by K L I M A S Z E W S K I (1972) with two genera: Psylla and Cacopsylla. He placed P . buxi in the genus Cacopsylla. Anatomical studies confirm such placement of P. buxi, since in 22 of Palaearctic species representing that genus only two testicular tubes were found with sperm cysts located in one row ( G L O W A C K A , unpublished data). Differences between the number of tubules in P. foersteri, w h i c h utilizes the same host plant {Alnusglutinosa) during similar period of the season is striking. Some authors distinguish P . foersteri as a separate genus, returning to the former name Baeopelma, which was proposed by E N D E R L A I N in 1926
( B U R C K H A R D T 1979;
OSSIANNILS-
SON 1992). The number of tubules in testis refers P. foersteri close lo P. fusca, VwingonAlnus incana and A. glutinosa (full development of P. fusca was observed in Finland only on the latter host plants), but both species differ with nymphal morphology and the structure of circumanal pore-fields in particular. BURCKI1ARDT(1979) indicated close similarities of circumanal pore-fields in the larvae of P. colorata and P. foersteri. Despite of monophagous character of both species (Ostrya carpinifolia and A. glutinosa respectively) he placed them in a separate genus Baeopelma Enderl. The number of four testicular sperm tubes of P. colorata indicates close relations with the group "alni", in which the same number of tubes is characteristic for P . alni and P. betulae. Only P . fusca has more tubes and its accessory glands arc not two- lobular but crescentshaped. Such features as the host-plant, numberand lluctuations of sperm tubes in testis, similarities in the structure of seminal vesicles relate P . / w i c a with P. foersteri, butnymphal morphology differentiate them completely. Searching for other characteristics is necessary therefore, in order to confirm one of the proposed systematic classification of the genus Psylla.
OSSIANNILS-
SON 1992). The numberof seminal tubes, fusion of seminal vesicles, long posterior parLs of seminal ducts would place P. buxi within the genus Cacopsylla in the sense of K L I M A S Z E W S K I (1972), but according to B U R C K H A R D T (1979) other features, as nymphal morphology, formation of well visible
Only 6 out of about 320 known psyllid species from the genus Psylla were used in this study. Differentiation of anatomical features discussed here should be used therefore only as an additional criterion, helpful in i m p r o v i n g the systematic classification within the Psyllodea.
Male reproductive system in Psylla Geoffr.
64
E . GLOWACKA, A . MARYANSKA-NADACHOWSKA
Figs 13-22 bar equals 100 (xm.
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