Comparative morphology of the spermatheca within the family Dinidoridae ( Hemiptera : Heteroptera )

The spermathecae of eleven genera of the family Dinidoridae (Dinidorinae and Megymeninae) were studied. Four types of spermatheca morphology were observed. Possible use of the morphology of spermathecae in the taxonomy of Dinidoridae is dis­ cussed.


INTRODUCTION
The spermatheca is an accessory female reproductive organ which, occurs in all orders of insects except for Protura and Collembola (Matsuda, 1976).It is a complex organ and varies greatly in shape and histology between groups (Pendergrast, 1957).In some Heteroptera the sper matheca has been completely lost, in others it has lost its primary function of storing sperm (Dupuis & Carvalho, 1956;Dupuis, 1970;Schuh & Slater, 1995).The sper matheca is present in all Pentatomoidea and usually con sists of a spermathecal duct, leading from the vagina to a dilated spermathecal bulb, and is characterised by a well marked pumping region with proximal and distal flanges (McDonald, 1966).The spermathecal bulb is covered by secretory cells located outside the epithelium of the sper matheca.The spermatheca plays a significant role in many functions e.g.: sperm storage, copulation, fertiliza tion, oviposition (Gaffour-Bensebban, 1991, 1994).
The first study on spermathecae was carried out by Dufour (1833), who erroneously regarded this organ as a sebaceous gland in which oil may have been produced.Von Siebold (1837) published the earliest correct descrip tion of a spermatheca (as receptaculum seminis) in Pentatomomorpha.For Dinidoridae, the first study of the morphology of spermatheca was published by Yang (1940) for some species of Chinese Dinidoridae.In the fifties, three fundamental works on the structure of the female genitalia in Heteroptera were published by Dupuis (1955), Pendergrast (1957) and Scudder (1959).A very important work on the male and female genitalia of Pen tatomoidea was published by Kumar (1962) andMcDonald (1966).All the above works demonstrated that the structure of the genitals of insects might be used in taxonomic studies.Servadei (1964) gave a detailed description of spermathecae of Acanthosomatidae, Pentatomidae and Scutelleridae (as Scutellerinae), with an original key to subfamilies and genera.Some additional, although incidental, information on the pentatomoid sper matheca in single species can be found in the many taxo nomic studies.For Dinidoridae the most valuable is the revision made by Durai (1987), however, even here sper matheca was not treated in great detail.
This study examines the morphology of the sper matheca in Dinidoridae and also establishes their taxo nomic importance.

MATERIALS AND METHODS
The specimens used in this study were selected from dried museum material obtained from the following institutions: Representatives of eleven (out of 16) genera of Dinidoridae were studied which includes all the types of spermatheca.Alto gether, 85 females from the following 34 species were studied (the classification follows that ofKocorek & J. A. Lis, 2000).
To prepare the spermatheca we first soaked the abdomen in 10% KOH for 1 to 5 minutes to soften it.Then tissues were removed and the spermatheca was exposed by fine dissection.Cleared spermatheca was placed in glycerine.Observations were made using standard optical equipment (stereoscopic microscope with a magnification of 32x).The terminology used follows that of Pendergrast (1957), Scudder (1959), andMcDonald (1966).
The following morphological characters of the spermatheca were used to characterize the types; 1. the shape of the spermathecal bulb 2. the size of the proximal and distal flange 3. the shape and size of the spermathecal duct 4. the presence of additional outgrowths 5. the presence of sclerites

Dinidorinae: Dinidorini
Cyclopelta Amyot & Serville, 1843 (Figs 1-4) -sper mathecal bulb large, spherical; pump flanges in: C. obscura -very well developed and almost equal in size, C. funebris -flanges developed, the distal one larger than the proximal one, sometimes the proximal flange reduced, C. bechynei -flanges very small; in all these cases the distal flange adheres closely to the bulb; the spermathecal duct diverse, divided into two parts: a very short, proximal (psd) and a long, flattened distal part (dsd), which is relatively wide, helically curved with a small outgrowth (osd); sclerites absent.
Dinidor Latreille, 1829 (Fig. 29) -spermathecal bulb small, spherical; pump flanges well developed, medium sized, the proximal one larger than the distal one, the distal flange does not adhere to the bulb; the spermathecal duct very light and membranous, dilated along its whole length (balloon-like dilation); outgrowths and sclerites absent.
Note.Spermatheca of Thalma biguttata Walker, 1868, is very similar to that of T. secunda J.A. Lis & Kocorek, 1996, in the shape of spermathecal duct, which is divided into two parts: short and narrow distal part and large dilated proximal part (Durai, 1987).
Note.Material of this genus was not available; it is a monotypic genus (Folengus papuensis Distant, 1914); data presented is that of Durai (1987).

Megymeninae: Megymenini
Megymenum Guerin-Meneville, 1831 (Figs 20-28)spermathecal bulb spherical, small or of medium size; pumping region well defined, distal and proximal flanges distinct and large (in M. spinosum the distal one smaller than the proximal one, in M. brevicorne the proximal one smaller than the distal one, in other species equal in size); distal flange clearly separated from the spermathecal bulb; spermathecal duct dilated along its whole length (sack-like), sometimes light, membraneous, sometimes sclerotized with numerous folds containing minute spines (thorny or point-like) specific for each species; ring sclerite present; outgrowths absent.Durai, 1987 (Fig. 30) -spermathecal bulb large and spherical; distal and proximal flanges dis tinct and large, equal in size; distal flange separated from spermathecal bulb; the spermathecal duct dilated along its whole length, sac-like, membranous; without outgrowths; ring sclerites present.

Megymeninae: Byrsodepsini
Byrsodepsus Stal, 1872 (Fig. 32) -spermathecal bulb large and spherical; distal and proximal flanges distinct and large, distal one much bigger, does not adhere to the bulb; the spermathecal duct very long and thin, dilated proximally (forming a large spherical sac); outgrowths and sclerites absent.

DISCUSSION
The results of our study show that there is no uniform type of spermatheca in the Dinidoridae.Analysis of its structural characters has demonstrated that four main types of spermatheca can be distinguished in this family: type I "cyclopeltic", type II "coridious", type III "megymenic" and type IV "mixed".In some cases it is difficult to specify unambiguously the type (e.g. in the genus Folengus).
Type I "cyclopeltic" (Figs 1-4) -occurs in the genus Cyclopelta -the main features distinguishing it from other types are: the bulb is large and spherical, flanges not clearly marked, distal one closely embracing the bulb, the spermathecal duct divided into two parts: proximal partshort, in the form of a narrow duct, and the distal partlong and flattened, relatively wide, helically curved, the border between the proximal and the distal parts marked by a small outgrowth; sclerites absent.In all the cases there are no sclerites.
Type III "megymenic" (Figs 20-30) -occurs in: Megymenum, Doesbergiana and Dinidor and is character ized by: spherical bulb of a medium size, large flanges, protruding from the bulb (exception Dinidor -small flanges); spermathecal duct strongly enlarged and wid ened, sack-like; outgrowths absent; ring sclerite present, in the genus Megymenum small, numerous spines present.mathecae or the tribes may not be monophyletic.In addi tion, a number of genera within the Dinidorini might have been wrongly deliminated and their systematic position needs reconsideration.The structure of spermatheca cannot be the sole basis for such radical changes; it does, however, indicate that the above mentioned taxons should be revised.
Type II "coridious" (Figs 5-19) -is characteristic of the genus Coridius; this type was divided into two sub types according to the presence of one (subtype A) or two (subtype B) outgrowths.The spermathecal bulb is spherical and large, the flanges are of medium size or sometimes small, the distal one protrudes, in some cases it adheres slightly to the bulb (C.viduatus, C. nubilus, C. ianus); spermathecal duct dilated, with one or two out growths: IIA (Figs 5-10) -with one outgrowth: long or very long, ribbon-like outgrowth (osd) or of medium length, sometimes short, sack-shaped; IIB (Figs 11-19) -with two outgrowths: outgrowth 1 (osd1) -of medium size, varies in individual species (C.castaneus -very short), and outgrowth 2 (osd2) -not large, bulge-like.