THE ANATOMICAL RECORD 293:1738–1754 (2010) Reproductive System of Female Scorpion: A Partial Review† M.R. WARBURG* Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel ABSTRACT The female scorpion ovariuterus was examined in 10 scorpion species belonging to ﬁve families: Buthidae, Vaejovidae, Scorpionidae, Urodacidae, and Diplocentridae. Two main patterns of development are known in scorpions: (1) The apoikogenic type with an ovariuterus containing yolkrich eggs housed in follicles. This type is found in many scorpion taxa (largely buthids). A peculiar case of apoikogenic ovariuterus is a ‘‘beaded’’ ovariuterus where most of the ova’s embryogenesis takes place inside the ovariuterus rather than on pedicels situated on the external wall of the ovariuterus as in most buthids. This type is found in a few scorpion species. (2) The katoikogenic type with an ovariuterus where the embryo develops in a diverticulum composed of four parts: a stalk (pedicel), a thickened collar, a conical portion containing the ovum, and an appendix containing the oral feeding apparatus where the embryos’ chelicerae grip a ‘‘teat’’-like structure, described in four families: Hemiscorpiidae, Scorpionidae, Urodacidae, and Diplocentridae. There are three kinds of diverticulae: small rudimentary ﬁnger-like diverticulae, embryonic (ED) large projections, and postpartum diverticulae (PPD) empty diverticulae, which are remnants after parturition. The subject is reviewed and its bearing on reproduction in scorpions are discussed. Anat Rec, 293:1738–1754, C 2010 Wiley-Liss, Inc. 2010. V Key words: scorpiones; katoikogenic; apoikogenic; ovariuterus HISTORICAL REVIEW Scorpion reproduction has interested zoologists for more than six centuries. Most of the research on this subject dealt with the ecological aspects of mating and parturition. Already Aristotle and later both Gessner (in the late 16th century) and Swammerdam (1669) observed parturition and recognized that scorpions are viviparous and that after parturition the females carry their young on their back. A comprehensive historical review of the very early research on scorpions was recently compiled by Braunwalder and Cameron (2001). Dissections of scorpions were carried out over three centuries ago by Redi (1688). More than a century later, Meckel (1809) provided an illustration of the female scorpion ovariuteri in his ‘‘Beiträge zur vergleichenden Anatomie der Skorpionen.’’ After a few years, Treviranus (1812) work on the arachnids appeared (Ueber den inneren Bau der Arachniden). He was the ﬁrst to describe three ovariuterus tubes with three connecting tubes (see p 12–14 and Figs. 11–13 there). Dufour (1817) provides illustrations (Figs. 7 and 8 on p 454 there) of the ovariuterus of Buthus occitanus and its egg follicle. In his C 2010 WILEY-LISS, INC. V large monograph, ‘‘Histoire Anatomique et Physiologique des scorpions,’’ Dufour (1856) discusses the reproductive system (see p 634–650 there), and provides illustrations of the ovariuteri of both a buthid and a scorpionid (Plate 4, Figs. 37 and 46, respectively, there). Oscar Müller (1818) published his ‘‘Anatomie des Skorpions,’’ and a decade later Johannes Müller (1828) discussed the scorpion reproductive system in his anatomical monograph: ‘‘Beiträge zur Anatomie des Scorpions’’ (see p 53–59 there). The latter was the ﬁrst to present an illustration of the development in Buthus (see Figs. 14–20 there). The state of the ﬁeld was reviewed by Gervais (1844), who gave a short historical y This paper is dedicated in memoriam of Dr. Gershom Levy (1937–2009); a pioneer in scorpion research in the Middle East. *Correspondence to: M.R. Warburg, Technion City, Haifa 32000. E-mail: email@example.com Received 26 February 2010; Accepted 17 June 2010 DOI 10.1002/ar.21219 Published online 4 August 2010 in Wiley Online Library (wileyonlinelibrary.com). SCORPION REPRODUCTION 1739 TABLE 1. List of 10 scorpion species in which the ovariuterus was studied here 1 2 3 4 5 6 7 8 9 10 Fig. 1. Scheme. a: Apoikogenic ovariuterus. L: large oocyte, S: small oocytes of three generations (1–3), Sc: scar of pedicle left after last parturition. b: Beaded ovariuterus. L: large oocytes found inside ovariuterus tube, S: small oocytes located on top of the large ones and on the tube, Sc: scar. c: Katoikogenic ovariuterus. Rd: rudimentary diverticulae of four generations (1–4), Ed: embryonic diverticulum, Dd: degenerated, postpartum diverticulae ﬁve generations (1–5). review on reproduction (see p 36 there). Duvernoy (1853, see the third fragment in that work, p 183–213 in which he deals with scorpions), provides illustrations of the female reproductive system in Buthus afer, a scorpionid (probably Heterometrus or Pandinus), and the buthids Androctonus occitanus (¼Buthus occitanus?), Scorpius europaeus (see Planche V there). He was the ﬁrst to illustrate two different organizations of the female reproductive system, distinguishing between those found in Scorpionidae (Buthus afer see Plate V, ﬁg. 1 there), and the Buthidae (see Fig. 8. Androctonus occitanus, and Fig. 12. Scorpius europaeus, there). In the ﬁrst, the egg remains inside the diverticulum throughout its development, whereas in the buthids, the ova move inside the lumen of the ovariuteran tube. He too (as did J. Müller in 1828) noticed the length of the cord (which he named: ‘‘Baguettes’’) passing from the appendix of the follicle to the mouth of the embryo comparing it with an umbilical cord. Later, Dufour (1856) studying the ovariuteri of the buthids, Buthus europaeus (¼Isometrus maculatus?) and Katoikogenic Scorpionidae Scorpio maurus fuscus Ehrenberg, 1829 from the Galil Mts and from the Golan Heights Israel Pandinus imperator (Koch, 1841) from Cote d’Ivoire Diplocentridae Nebo hierichonticus (Simon, 1872) from the Galil Mts, Israel Urodacidae Urodacus manicatus (Thorell, 1876) from Warumbungle Mts, NSW, Australia Apoikogenic Buthidae Hottentotta judaicus (Simon 1872), from the Galil Mts. and Mt. Carmel, Israel Leiurus quinquestriatus (Hemprich and Ehrenberg, 1828), from the Negev Desert, Israel Mesobuthus nigrocinctus (Ehrenberg, 1828) from the Golan Heights Orthochirus scrobiculosus negebensis (Shulov and Amitai, 1960) from the Negev desert Israel Compsobuthus werneri judaicus (Birula, 1905) from Mt. Carmel, Israel Vaejovidae Vaejovis spinigerus (Wood, 1863) from Arizona, USA Buthus occitanus, mentioned the two kinds of reproductive patterns in scorpions: the oviparous and the viviparous (ovigère et vivipares). He also noticed the different degrees of development of the ova in the ovarian tubes (of the ovigères on p 641–642 there). Laurie (1890, 1896a) gives a brief historical account on the subject. He was the ﬁrst to name these two main types of ovariuteri in scorpions, the same types that were identiﬁed almost 40 years previously by Duvernoy. The ﬁrst type: the Apoikogenous (Greek meaning ‘‘away from home’’ found in the Buthidae, Chactidae, and Vaejovidae), and the second type: the Katoikogenous (Greek meaning ‘‘at home’’, typical of the Scorpionidae and Diplocentridae). The ﬁrst system with yolk-rich ova is common to most scorpions, and the second with yolk-poor ova is found in a few scorpion families. The female reproductive system is bilaterally symmetrical with a short atrium; one pair of oviducts (birth canals) bifurcates into medial and lateral branches of variable numbers of paired transverse anastomoses. Pawlowsky in 1924, and in a more detailed study in Pavlovskij 1925, distinguished between two main kinds of ovaries in scorpions based on the number of anastomoses connecting between the three long ovarian tubes. Thus, the buthids (i.e., Buthus eupeus (¼ Mesobuthus eupeus), Parabuthus planicauda) have 10 (ﬁve pairs) anastomoses (or ‘‘Die Zehnbögige’’, i.e., connecting ovariuterine tubes) connecting between the three ovarian tubes. All remaining scorpion families studied by him: Chactidae, Bothriuridae, Vaejovidae, and Scorpionidae have eight (four pairs) anastomoses (Die Achtbögigen). Both the longitudinal and transverse tubes bear ova. Thus in Heterometrus fulvipes, the ovariuterus consists of three longitudinal hollow tubes interconnected by four pairs of transverse anastomoses with six quadrilateral meshes (Subburam and Reddy, 1981). 1740 WARBURG Fig. 2. Leiurus. A and B: Four generations of small oocytes (3 and 4 labeled) (LM, A: 35; B: 25). C: Three generations of oocytes (2–4) (SEM, 100). D: Three generations of oocytes (2–4) (LM, 30). E: Section through part of the ovariuterus. Two generations of the smaller oocytes are visible (W1 and W2). (LM, 150). F: Remnants of postpartum oocytes seen as warts (W1 and W2) they will later become scars visible only in sections (SEM, 200). Fig. 3. Vaejovis LM. A: Three oocytes situated inside the ovariuterus tube and some small ones (arrows) on top of it (40). B: Part of the ovariuterus showing small oocytes (arrows) situated on the surface of the ovariuterus tube (20). C: Beaded ovariuterus depicting oocytes inside the ovariuterus tube (6). SCORPION REPRODUCTION Recently, six distinct types of ovariuteri were identifed in 55 scorpion species (Volschenk et al., 2008). These differ in the number of cell meshes formed between the ovarian tubes and the anastomoses. The authors distinguish between 2, 6, 8, and 9 such cell meshes. Reviews on various aspects of scorpion reproduction can be found in Millot and Vachon (1949), Williams (1969), Francke (1982), Polis and Sissom (1990), and more recently by Farley (1999, 2001), Benton (2001), Warburg (2001), Volschenk et al. (2008), and in Peretti (2010). MATERIALS AND METHODS In this study, the ovariuteri were examined in 10 scorpion species belonging to ﬁve families: Buthidae, Vaejovidae, Urodacidae, Scorpionidae, and Diplocentridae (see Table 1). 1741 For this study, some of the females were dissected soon after their collection, and the ovariuteri were excised and placed into ﬁxatives. For details of light (LM), electron (TEM), and scanning electron microscopical (SEM) techniques (see previous publications Warburg and Rosenberg, 1990, 1992a, b, 1993, 1994, 1996; Warburg and Elias 1998; Warburg et al., 1995). Both ooocyte follicles and diverticulae were counted under a dissecting microscope, and their dimensions were measured. In buthids, the diameter of the oocytes was measured, whereas in the scorpionids and diplocentrids diverticular length was measured, in both cases using a binocular dissecting microscope (DM) with graticules. Smaller oocytes and diverticular buds were observed by using the SEM. In the buthids, the scars left by resorbed pedicles (after parturition) and in scorpionids or diplocentrids the warts remaining on the ovariuterus could be counted only by using a SEM. They could not be seen under DM. Two-micrometer thick sections of ovaries that were embedded in Epon blocks were examined using LM. All data presented in this study refer to the number of small oocyte follicles or diverticulae as counted under a DM. When counted under a SEM these numbers almost doubled due to better resolution. STRUCTURE AND FUNCTION OF OVARIUTERUS Makioka (personal communication) considers that ‘‘the ovarian network of scorpions, consisting of ovarian tube with a number of stalked oocytes, is a prototype of chelicerate ovaries.’’ The Apoikogenous Ovariuterus Fig. 4. Compsobuthus LM (6) showing ovariuterus containing 12 large oocytes (O) and a few smaller ones (arrows). A scheme depicting the three different types of ovariuteri is given in Fig. 1. The ovary is embedded in the digestive gland the hepatopancreas, which lies dorsal to it (Laurie, 1890). Lobes of the hepatopancreas pass through the meshes of the ovariuterus network. Laurie distinguished between two main patterns of Fig. 5. Compsobuthus A (SEM -100), B (SEM -50), C (LM -6). Asterisks, arrows indicate maturing oocytes. Fig. 6. Urodacus LM (A, C, and D 6; B 12; E 20) E-Embryonic diverticulase; 1 and 2, two generations of postpartum divericulae; Rudimentary diverticulae-3. Fig. 7. Urodacus LM. Different steps in clearing the ovariuterus while removing the hepatopancreas (H) A–D (6). Emryonic diverticulae-1, postpartum diverticulae-2. SCORPION REPRODUCTION 1743 Fig. 8. Nebo LM. Depicting two generations of postpartum diverticulae (PPd-1 and P-Pd-2). There are no embryonic diverticulae to be seen only various sized rudimentary diverticulae. A (6); B (6); C (12); D (6). development: embryo developing in a diverticulum typical of the katoikogenic ovariuterus (Laurie, 1890, 1896b), which he described in Scorpionidae and Diplocentridae, and the apoikogenic ovariuterus found in Buthidae with egg follicles containing an ovum þ envelop(s) of the ovocyte or ovum. These follicles are attached by a short pedicle to the uterus tubes (see Fig. 2, Leiurus; Fig. 3, Vaejovis; Figs. 4 and 5, Compsobuthus; Figs. 6 and 7, Urodacus; Figs. 8–11, Nebo; Figs. 12–14, Scorpio). Apoikogenic scorpions have a simple ovariuterus without diverticulae; embryonic development takes place inside follicles on the ovariuterus wall (Farley, 1996). Ova differentiate from the inner germinal epithelium of the ovariuterus tubules (Laurie, 1890). Ova of all stadia are attached to the ovarian tube at any given time. Each ovum forms a follicle on the surface of the ovariuterine tubules. Laurie (1896b) described the apoikogenic development with large, yolk-rich eggs inside follicles; embryonic development takes place in the lumen of the ovariuterus (typical of the Bothriuridae, Buthidae, Chactidae, and Vaejovidae). Laurie also described katoikogenic development with small alecithal ova inside diverticulae on the wall of ovariuterus (Diplocentridae, Scorpionidae). The ﬁrst sign of the formation of an ovum is the increase in size of one of the cells of the inner layer of the ovarian tube doubled to increase in size. As the apoikogenic egg develops, the pedicle becomes short and its lumen increases in size (Laurie, 1890). In most apoikogenic scorpions, oocytes develop in follicles in direct contact with the ovariuterus (Francke, 1982; see also Fig. 2 here). In the katoikogenic scorpions, ova are situated inside diverticulae on the external side of the ovariuterus wall (see Figs. 1 and 2 in Warburg and Rosenberg, 1992a and Figs. 4a–c in Warburg and Elias, 1998). It appears that Fig. 9. Nebo LM. Embryonic diverticulae (Ed) containing embryos. Arrows indicate rudimentary diverticulae. A (15); B (18). apoikogenic scorpions have ovariuteri designated as Type B Makioka (1988; see Fig. 10 there). Measurements of oocyte dimensions were summarized by Francke (1982, p 29). He found that in Centruroides vittatus oocyte dimensions ranged between 0.4–0.51 mm 0.49–0.63 mm. The dimensions of oocytes in some other species are summarized in Table 2. Counts and measurements of six buthids are given in Fig. 15. In none of these species was there an indication of any relationship between either number of oocytes or their diameter and the female’s mass. Likewise, no such 1744 WARBURG Fig. 10. Nebo SEM. Three generations (1–3) of Rudimentary (arrows), embryonic, and postpartum diverticulae (Ed and PPd). A (35); B (50); C (75); D (100). Fig. 11. Nebo sections LM. Four generations of rudimentary (Rd1-4) and a postpartum diverticulum (PPd) are noticeable. A (40); B (50). relationship was forthcoming in a vaejovid (Fig. 16), a diplocentrid, and a scorpionid (Fig. 17). Soranzo et al. (2000) studied changes in ultrastructure during oocyte development in Euscorpius carpathicus. During previtellogenesis, the oocyte is <100 l. This is followed by two vitellogenic stages characterized by the accumulation of yolk. The oocyte becomes ovoid meas- uring 270–360 l. The corpora-lutea are irregular-shaped bodies (12 mm diameter) with many nuclei. They are the collapsed remains of the follicles after the egg passed out (Laurie, 1890). Remnants of these stems connecting the oocyte with ovarian tube can be seen (Farley, 1996). The number of oocytes in the ovariuterus of Tityus bahiensis and Tityus trivittatus ranged between 200 and SCORPION REPRODUCTION 1745 Fig. 12. Scorpio LM. Large Embryonic diverticulae (E) and two generations of small rudimentary diverticulae (arrows). A (15); B (6); C (12); D (9). 350 oocytes (Bücherl, 1971). Only 20–35 (10%) of these are fertilized each year, sometimes twice a year. In Paruroctonus mesaensis (¼Smeringurus mesaensis) many ova fail to develop (Farley, 1996). The percentage of the various types of oocytes is given for ﬁve buthids in Fig. 18, a diplocentrid and a scorpionid (Fig. 19). Usually studies on the scorpion ovariuterus are limited to one season. In some species, this was followed over the whole year. Seasonal changes in numbers and diameters of different-sized oocytes (small, large, and degenerated) are given for Compsobuthus, Hottentotta, and Leiurus (Fig. 20). The Beaded Ovariuterus A peculiar case of apoikogenic scorpions was described in Scorpiops montanus (Pawlowsky (1924; Fig. F there), and Pavlovskij (1925; Plate VII Fig. 5, see also Figs. 1, 3, 19 there). Pawlowsky describes sphere-shaped swellings (named by him ‘‘Kugelartigen Anschwellungen’’) in the ovariuterus and named this kind of ovariuterus: ‘‘Perlenschnurartig’’ (meaning pearl string-like or pearl necklace-like). A similar ovariuterus containing the ova inside the tube is illustrated for the buthid Lychas tricarinatus (Mathew, 1960; Figs. 2 and 3 there). Normally, in apoikogenous scorpions, the ova increase in size while situated (inside the follicle) outside the ovariuterus tube. When embryogenesis starts, the ova move into the ovariuterus lumen, and can be clearly identiﬁed inside the tube as the embryo enlarges (in preparation). Both Scorpiops montanus (¼Euscorpiops montanus), and Scorpiops leptochirus appear to have a similar such beaded ovariuteri (Plate VII, Figs. 5 and Fig. 13. Scorpio LM. Embryonic (Ed) and postpartum diverticulae (PPd) (arrows). A (9); B (9); C (12); D (18). 13, respectively, in Pavlovskij, 1925) as does another buthid, Tityus serrulatus (Matthiesen, 1970a,b). It was later illustrated by Mathew (1962; see Figs. A–D there). 1746 WARBURG Fig. 14. Scorpio SEM. Three generations of Rudimentary (1–3), and postpartum diverticulae (PPd). A (100); B (75); C (50); D (75); E (100); F (100). This pattern of development of the ova can be seen also in the vaejoviid Paruroctonus mesaensis (¼Smeringurus mesaensis) (Farley, 1996, 1998). On the other hand, in the beaded ovariuterus, ova do not seem to develop as they normally would in most apoikogenous scorpions: inside follicles on top of pedicels situated outside the ovarian tube. A case of beaded ovariuteri was described in Vaejovis spinigerus (Fig. 3 here, and Fig. 1 in Warburg and Rosenberg, 1996). According to illustrations in Volschenk et al. (2008), the following buthids have beaded ovariuteri: Centruroides gracilis, Orthochirus scrobiculosus, and Odonturus dentatus (see Figs. 1 and 2. there). It is possible that although scorpions generally have ovariuteri of Makioka’s (1988) Type B, the beaded ovariuterus belongs to Type C (described by Makioka, 1988; see Fig. 10 there). Farley (1998; see Figs. 1–6) describes in a sketch (no micrograph of sections are provided) the early stages of blastulation when the follicle is still on the exterior wall of the ovariuterus. The stage of blastula invagination is depicted in Fig. 5 (on p 192 there). Volschenk et al. (2008) on p 668 there, wrote that they ‘‘observed regular follicles in Vaejovis spinigerus, conﬁrming to typical apoikogenic development.’’ Also in this study, no microcraph is provided. To be certain that this unusual case is just a phase in the normal apoikogenic development, convincing histological proof will be needed to demon- TABLE 2. Oocyte dimensions in some apoikogenic scorpion species Species Buthidae Hottentotta rugiscutis Lychas tricarinatus Centruroides vittatus Hottentotta judaicus Leiurus quinquestriatus Compsobuthus werneri Orthochirus innesi Euscorpiidae Euscorpius italicus Scorpionidae Heterometrus fulvipes Dimension (mm) Source 130 lm Sareen and Monga, 1973 Mathew, 1960 Francke, 1982 0.028–0.054 0.4–0.51 0.49–0.63 0.39–1.06 0.49–1.09 0.26–0.6 0.4–0.7 1.2 0.83 2 This This This This study study study study Laurie, 1891 Sareen and Monga, 1973 strate that in Vaejovis, Paruroctonus, and other apoikogenous scorpions, development in follicles outside the ovariuterus stops during oogenesis at gastrulation before reaching the embryonic stage. In other words, the main development of the embryo that takes place inside the ovariuterus in these species needs to be demonstrated by micrographs. Moreover, an attempt should be made to ﬁnd an explanation. It appears that the oocytes SCORPION REPRODUCTION 1747 Fig. 15. Relationship between numbers, and diameter of oocytes and female mass in Compsobuthus. Hottenttota Leiurus and Orthochirus. In all there was no relationship between the oocyte numbers or diameter and the female’s mass. Note that in Compsobuthusands Orthochirus only a few females had any degenerated oocytes. moved into the ovariuterus at a much earlier stage of oogenesis or embryogenesis. What could be triggering this? The matter needs careful histological investigation of female scorpions dissected at intervals during their gestation period. However, since no histological data (microscopical sections) are available, a more deﬁnite decision on whether the beaded ovariuterus indicates a developmental stage or a different form of ovariuterus, will have to await conclusive evidence for the former. There is some histological evidence found in the euscorpiid, Euscorpio italicus that ‘‘unfertilized eggs’’ are situated outside the ovariuteran tube (Laurie 1890, see Plate IX Fig. 7), and that inside the ovariuterus there are ‘‘embryos’’ (Laurie 1890, see Plate IX, 8) both statements are not supported by sections. The fact that in most buthid species, the major part of embryogenesis takes place inside the follicle situated at the external side of the ovariuterus’ wall, needs to be explained as well. 1748 WARBURG The Katoikogenous Ovariuterus Fig. 16. Relationship between numbers and diameter of Vaejovis oocytes. Structure and function of the diverticulum. Numbers and measurements of diverticular dimensions are given in Fig. 17. Again there was no positive relationship between either numbers or dimensions of diverticulae and the mother’s mass. Likewise, no signiﬁcant relationship was found between the ovariuterus mass and the body mass in 18 Scorpio females (Fig. 18A). Nor was there a relationship between the ovariuterus mass and the diverticular numbers (Figs. 18B). The percentage of different kinds of diverticulae are given for two katoikogenic species: Scorpio and Nebo (Fig. 20A,B). The proportion of small diverticulae ranged between 44.7–46.2%, that of large diverticulae ranged between 24.1–27.5% and that of postpartum degenerated diverticulae ranged between 27.8–29.7%. A scheme depicting the structure of the katoikogenic ovariuterus is given in Fig. 1 (see also Figs. 8–14 here). Fig. 17. Numbers and length of Nebo and Scorpio diverticulae. No signiﬁcant relationship between either number of diverticulae or their length and the female’s mass. SCORPION REPRODUCTION 1749 Fig. 18. Female (A) and ovariuterus (B) mass as related to ED and RD numbers in Scorpio. There was no signiﬁcant relationship between these diverticulae and either the female’s or the ovariuterus’ mass. In diplocentrids and scorpionids, there are numerous diverticulae each bearing small alecithal oocyte. These are katoikogenous scorpions characterized by having a pseudoplacental viviparity (Francke, 1982). Müller (1828) noticed the peculiar elongated appendix (‘‘Fortsatz’’ see p 57 there) and suggested its function in uptake of nourishments. Duvernoy (1853) called it ‘‘Baguette’’ (p 194 there). The differentiation of the diverticulum into regions was described by Laurie (1891) in the katoikogenic Scorpio fulvipes (¼Heterometrus fulvipes). He distinguished between four distinct regions: a long stalk (pedicle), a thickened collar, a conical part housing the ovum and an elongated, and a coiled appendix longer than the rest of the diverticulum. The latter region contains the oral feeding apparatus. Likewise Pﬂugfelder (1930; see Fig. 11 there), describing the diverticulae in Hormurus (¼ Liocheles), distinguished between four parts: the ‘‘Endknöpfchen’’ (the equivalent of the button-shaped structure described by Laurie, 1896a), the appendix connected by a stem (Stiel) to the distal part housing the embryo. The latter is the main diverticular cavity especially formed to accommodate the developing embryo: the Truncus diverticulum. Finally, the appendix that contains the feeding apparatus of the embryo. The proportions of these parts change with growth and development of the embryo inside the cavity. Pawlowsky (1924) identiﬁed in the diverticulum ﬁve parts: Radix, Ampulla, Truncus, Collum, and Appendix. Fig. 19. The percentage of different kinds of oocytes in ﬁve apoikogenic species. The proportion of small follicles ranged between 42.4– 67.1% that of large follicles ranged between 41.7–49%, and that of postpartum, degenerated oocytes ranged between 7.3–12.2%. Mathew (1948) in his study on Palamnaeus scaber distinguished between the end piece, handle, swollen middle region and the ‘teat’. In later studies on the same species (Heterometrus scaber), Mathew (1959) suggests that the truncus diverticulum encloses the chamber 1750 WARBURG TABLE 3. The different parts composing the katoikogenic diverticulum in Scorpions Species Family Heterometrus fulvipes Scorpionidae Heterometrus fulvipes Heterometrus scaber Scorpionidae Parts Long stalk Thickened collar Conical portion Long appendix Radix Source Laurie, 1890 Pawlowsky, 1924 Ampula Truncus Collum Appendix Heterometrus Scorpionidae End piece Mathew, scaber Handle 1948 Swollen middle region Teat Liocheles Hemiscorpiidae Radix, Pawlowsky, australasiae Ampula 1924 Truncus Collum Appendix Liocheles Hemiscorpiidae Endknöpfchen Pﬂugfelder, australasiae Appendix 1930 Stiel Diverticle Fig. 20. The percentage of different kinds of diverticulae in two katoikogenic species: Scorpio (A) and Nebo (B). The proportion of small diverticulae ranged between 44.7–46.2% that of large diverticulae ranged between 24.1–27.5% and that of postpartum degenerated diverticulae ranged between 27.8–29.7%. specially formed for the accommodation of the embryo. When the diverticulum is 3.5 mm the embryo is a gastrula the appendix is 7 mm long (Mathew, 1959). Our present knowledge on this subject is summarized in Table 3, and the proportions between the appendix and the rest of the diverticulum are shown in Scorpio (Figs. 22–25). Thus, the changes in diverticular length during embryogenesis are seen in Figure 22. The proportions between the diverticular appendix length are shown for 16 Scorpio females in Figure 23. Finally, the percentage average length of each of the four diverticular components and the range are given for Scorpio (Fig. 24). The largest variation in both percentage and range of length is seen in the Radix followed by the appendix. The smallest is noted in the cavity. In another katoikogenic scorpion, Urodacus novae-hollandiae, Laurie (1896) described a well marked, ‘‘bunshaped’’ thickened region at the top of the appendix. Similar enlargements of the appendix’s tip were described also in both Nebo hierichonticus (Warburg and Rosenberg, 1992a; Fig. 2. there also Fig. 10 here), and Urodacus manicatus (Warburg and Rosenberg, 1994; Figs. 1 and 6, there also Figs. 6 and 7 here). In immature females, the ovarian tube is very slender and does not possess diverticulae (Subburam and Reddy, 1981, 1989). Polis and Sissom reviewing the subject in 1990, distinguished between four parts of the diverticulum: a stalk (pedicel), a thickened collar, a conical portion containing the ovum, and an appendix containing the oral feeding apparatus, where the embryo’s chelicerae grip the teatlike structure of the appendix. Diverticular differentiation. Duvernoy (1853) provided an illustration showing the different kinds of diverticulae (a–f in Fig. 7b in Plate V there). Pﬂugfelder (1930) distinguished between three kinds of diverticulae: those containing embryos, the degenerated diverticulae, and the young diverticulae. Rosin and Shulov (1963) studying Nebo hierichonticus, recognized two sizes of small spherical diverticulae, developed diverticulae and degenerated diverticulae of two sizes (see Fig. 4. there). Smith (1966) named the three kinds of diverticulae he found in Urodacus abruptus: small rudimentary (RD) ﬁnger-like projections, embryonic (ED) large projections with knob-like structures containing the developing embryo at their tip, and postpartum diverticulae (PPD) that are small, infolded remnants left of the EDs in the wake of parturition. Probst (1972) studying Isometrus maculatus, distinguished in the ovariuterus between these same three types of follicles: RD before an embryo is formed, ‘‘embryonic’’ and ‘‘postpartum’’ (¼corpus luteum), degenerated follicles, the latter being yellow. Figure 1 depicts in a scheme these three types of diverticulae: RD, embryonic and degenerated, and PPD. After birth, the empty diverticulum shrinks. Smith (1990) suggested that the sum of the diverticulae is a measure of lifetime fecundity. SCORPION REPRODUCTION 1751 Fig. 21. Seasonal changes in numbers and diameter of Compsobuthus, Hottenttota, and Leiurus oocytes. In Compsobuthus, the number of small and large oocytes increased from winter to spring. Most degenerated oocytes were observed during autumn. The diameter of the large oocytes peaked in autumn. In Hottentotta, the number of large oocytes decreased from winter to autumn. In Leiurus, the number of large oocytes decreased from winter to summer increasing greatly during autumn. The diameter of the large oocytes showed an opposite pattern increasing signiﬁcantly from winter to summer dropping signiﬁcantly toward autumn. The degenerating PPD. In both scorpionid and diplocentrid ovaries, the follicles shrink after parturition following the collapse of the extended diverticulae due to the embryos moving inside the ovariuterus; they degenerate into irregular-shaped, folded, brown bodies in the lumen containing still remnants of substance (Pavlovskij, 1925). Degenerating remnants of these PPD can be seen in the ovariuteri of katoikogenic scorpions for a long period of time (Pfugfelder, 1930). Even after their disappearance they can be identiﬁed until the follicle turns into a wart-like structure. In Heterometrus scaber, the empty diverticulae contract rapidly, becomes ﬂabby and degenerate. They remain attached to the ovarian tubes but will never again serve for developing a new batch of embryos. Vestiges of earlier series in various stages of breakdown are noticeable (see Fig. 10 in Mathew, 1959) Shorthouse (1971) and Shorthouse and Marples (1982) studying Urodacus yaschenkoi found that the number of PPDs ranged from 8 to 15. The average number in brood was 11.75. They noticed that in two Urodacus yaschenkoi females, the number of PPDs was doubled, composed of two generations indicating remnants of more than one (probably two) parturitions. Makioka (1992a,b) found in Liocheles australasiae that the number of empty diverticulae present between pregnancies, corresponds to the number of broods. Thus, after a second parturition, females had two sizes of empty 1752 WARBURG Fig. 22. The change in average length of diverticulae during four stages of embryogenesis from the onset (1) to parturition (4). The radix greatly increases toward parturition. Fig. 24. Average percentage of length (A), and average range in length (B) of the four diverticular components as measured in 16 Scorpio females. The longest component of the diverticulum is the radix, followed by the appendix. Fig. 23. Average (total) diverticular length in 16 Scorpio females. The length of the diverticulae varies greatly among the different females. diverticulae. This was conﬁrmed by Yamazaki and Makioka (2001), who showed that the number of empty diverticulae roughly equals the number of neonates. Mahsberg and Warburg (2000) studying laboratory raised Pandinus imperator found that virgin females had no embryonic EDs or PPDs, whereas the mother did not have EDs but had the same number of PPDs as the number of juveniles born in the laboratory 2 years earlier. The relationships between large, small, and degenerated diverticulae are shown in a scorpionid and a diplocentrid (Figs. 18, 19), and their percentages in the ovariuteri are shown in shown in Figures 19 and 20. In a Nebo female (weighing 5.74 g) that gave birth to 25 juveniles and was dissected 3 months later, four different kinds of degenerated diverticulae were distinguished by their different coloration and length (Fig. Fig. 25. Number and length of Nebo diverticulae 3 months after parturition. No large diverticulae were seen. Two generations of small diverticulae were observed. Although their numbers was almost equal they differed in length. There were four generations of degenerated diverticulae. The number of the fourth generations (D-4) was signiﬁcantly higher than the others. The reason could be that the rate of resorption drops, and thus, D-4 includes perhaps two or more generations. 25). The largest type was white and was 5.5 mm long (the appendix 3 mm). These diverticulae apparently harbored the most recent embryo generation. The second type, yellowish in color, was 4.5 mm long (appendix, 3 mm). These diverticulae contained resorbed embryos. The third kind of degenerated diverticulae was light brown in color and shorter (3.5 mm and a shorter appendix). 1753 SCORPION REPRODUCTION Finally, a fourth kind of degenerated diverticulum was dark brown and half the size of the third kind. These two latter types of diverticulae are most likely remnants of previous parturitions that took place in previous years. (These are not necessarily subsequent years since Nebo females do not necessarily breed on consecutive years). Altogether, the ovariuterus of that female contained 25 diverticulae of the ﬁrst kind, 11 of the second kind, 23 of the third kind, and 35 of the fourth kind. The high number of third and fourth kinds of PPDs may indicate that they are remnants of a larger number of parturitions. ACKNOWLEDGMENTS The author is indebted to many persons for their help in his scorpion research throughout the many years: Dr. Marlow Anderson for his kind hospitality and help in my research on the Chihuahuan Desert fauna in the late 1950s to Samuel Geiser and Herbert Stahnke, for their kind help with scorpions from the Sonoran Desert in the late 1950s; Neil Hadley, Victor Fet, and Stanley Williams for their help in his research in later years. Thanks are due to both Drs. Adam Locket and Graeme Smith for their help and collaboration on scorpion research in South Australia and Western Australia, respectively. Finally, the author wishes to thank Dr. Gershom Levy, Mr. Avinoam Luria, and Mr. Pinhas Amitai, and his son Ittai Warburg of the Hebrew University, Jerusalem for helping in various aspects of his scorpion research in Israel. Over the many years of his research on scorpions several colleagues helped by advice or literature coverage. Among them are Drs. Chris Brown, Roger Farley, Oscar Francke, F.R. Matthiesen, Alfredo Peretti, Lorenco Perendini, Gary Polis, Dave Sissom, Dave Shorthouse, Roland Stockmann, and Marco Vannini. For all the help they rendered he is most grateful. Likewise, he is grateful to Prof. John Cloudsley-Thompson for providing an outlet to publish some of his earlier papers on scorpion physiological-ecology, to Dr. Gary Polis for inviting him to write a chapter in a book he was editing, and to Drs. Victor Fet and Phil Brownell who asked him to participate in the book in memory of Gary. Finally, the author wishes to thank Dr. Dieter Mahsberg for enabling our collaboration on studying Pandinus imperator raised in his laboratory. During this long-term study, the author was assisted by several students: (alas, too many to be mentioned by name) who helped in maintaining the many live scorpions each of which was kept individually and for maintaining the auxiliary mealworm culture over 27 years. Skillful technical assistance in my physiological studies was provided by Mrs. Shoshi Goldenberg, in my ecological studies by Dr. Dina Rankevitch, and in microscopy (LM, SEM) by Mrs. Mira Rosenberg my collaborator in this scorpion research for more than 10 years. Two of his students who studied scorpions, A. Ben-Horin and Ms. Rivka Elias, helped in obtaining valuable scientiﬁc information. Several projects on scorpion life history were conducted in his laboratory over the years by Horacio Bach, George Kasabrah, Gamal Abu-Salah, Meital Cohen, Yoram Ronen, Murad Hayat, Wasim Daher, Idit Lehrer, Raﬁ Feinsud, Yael Schwartz, Jakob Slutki, and Salim Halabi, all of whom contributed to their knowledge. Finally, the author is grateful to the late Prof. Aharon Shulov, whom, as a young lad in the early 1940s, the author helped collect scorpions on the slopes of Mt. Carmel, and about 10 years later, as an undergraduate student at the Hebrew University, he invited the author to be his teaching assistant in the Entomology laboratory. During that period, his laboratory was very active in scorpion research. LITERATURE CITED Benton T. 2001. Reproductive ecology. Chapter 11. In: Brownell P, Polis G, editors. Scorpion Biology and Research. New York: Oxford University Press. p 278–301. Braunwalder ME, Cameron HD. 2001. 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