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Magris M, Wignall AE, Herberstein ME. Courtship and copula duration influence paternity success in a spider. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.04.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Rivera-Quiroz FA, Schilthuizen M, Petcharad B, Miller JA. Imperfect and askew: A review of asymmetric genitalia in araneomorph spiders (Araneae: Araneomorphae). PLoS One 2020; 15:e0220354. [PMID: 32542042 PMCID: PMC7295216 DOI: 10.1371/journal.pone.0220354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 05/28/2020] [Indexed: 11/18/2022] Open
Abstract
Bilateral asymmetry in the genitalia is a rare but widely dispersed phenomenon in the animal tree of life. In arthropods, occurrences vary greatly from one group to another and there seems to be no common explanation for all the independent origins. In spiders, genital asymmetry appears to be especially rare. Most known species show almost perfectly symmetrical genitals with the right and left sides being mirror images of each other. However, some examples of asymmetric genitalia have been studied and many other reports are scattered in the taxonomic literature. Based on a broad literature survey, we found several species in thirteen families with evidence of genital asymmetry, mostly expressed only in females. Our review suggests that spider genital asymmetries, although rare, are more common than previously thought and taxonomic descriptions and illustrations are a useful but not entirely reliable tool for studying them. Here we also report on directional asymmetry in the liocranid spider Teutamus politus, the first known case of morphologically asymmetric male genitals in Entelegynae spiders. Generalities, evolution and categorization of asymmetry in spiders are further discussed.
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Affiliation(s)
- Francisco Andres Rivera-Quiroz
- Biodiversity Discovery group, Naturalis Biodiversity Center, Leiden, The Netherlands
- Institute for Biology Leiden (IBL), Leiden University, Leiden, The Netherlands
| | - Menno Schilthuizen
- Institute for Biology Leiden (IBL), Leiden University, Leiden, The Netherlands
- Endless Forms Group, Naturalis Biodiversity Center, Leiden, The Netherlands
| | - Booppa Petcharad
- Faculty of Science and Technology, Thammasat University, Rangsit, Pathum Thani, Thailand
| | - Jeremy A. Miller
- Biodiversity Discovery group, Naturalis Biodiversity Center, Leiden, The Netherlands
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Michalik P, Kallal R, Dederichs TM, Labarque FM, Hormiga G, Giribet G, Ramírez MJ. Phylogenomics and genital morphology of cave raptor spiders (Araneae, Trogloraptoridae) reveal an independent origin of a flow‐through female genital system. J ZOOL SYST EVOL RES 2019. [DOI: 10.1111/jzs.12315] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Peter Michalik
- Zoologisches Institut und Museum Universität Greifswald Greifswald Germany
| | - Robert Kallal
- Department of Biological Sciences The George Washington University Washington District of Columbia
| | - Tim M. Dederichs
- Zoologisches Institut und Museum Universität Greifswald Greifswald Germany
| | - Facundo M. Labarque
- Departamento de Ecologia e Biologia Evolutiva Universidade Federal de São Carlos São Carlos Brazil
| | - Gustavo Hormiga
- Department of Biological Sciences The George Washington University Washington District of Columbia
| | - Gonzalo Giribet
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology Harvard University Cambridge Massachusetts
| | - Martín J. Ramírez
- Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” – CONICET Buenos Aires Argentina
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4
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Albo MJ, Costa FG. Female wolf spiders exert cryptic control drastically reducing ejaculate size. Ethology 2017. [DOI: 10.1111/eth.12640] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Maria J. Albo
- Laboratorio de Etología, Ecología y Evolución; Instituto de Investigaciones Biológicas Clemente Estable; Montevideo Uruguay
| | - Fernando G. Costa
- Laboratorio de Etología, Ecología y Evolución; Instituto de Investigaciones Biológicas Clemente Estable; Montevideo Uruguay
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Friesen CR, Uhrig EJ, Mason RT, Brennan PLR. Female behaviour and the interaction of male and female genital traits mediate sperm transfer during mating. J Evol Biol 2016; 29:952-64. [PMID: 26809830 DOI: 10.1111/jeb.12836] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 01/18/2016] [Accepted: 01/19/2016] [Indexed: 02/04/2023]
Abstract
Natural selection and post-copulatory sexual selection, including sexual conflict, contribute to genital diversification. Fundamental first steps in understanding how these processes shape the evolution of specific genital traits are to determine their function experimentally and to understand the interactions between female and male genitalia during copulation. Our experimental manipulations of male and female genitalia in red-sided garter snakes (Thamnophis sirtalis parietalis) reveal that copulation duration and copulatory plug deposition, as well as total and oviductal/vaginal sperm counts, are influenced by the interaction between male and female genital traits and female behaviour during copulation. By mating females with anesthetized cloacae to males with spine-ablated hemipenes using a fully factorial design, we identified significant female-male copulatory trait interactions and found that females prevent sperm from entering their oviducts by contracting their vaginal pouch. Furthermore, these muscular contractions limit copulatory plug size, whereas the basal spine of the male hemipene aids in sperm and plug transfer. Our results are consistent with a role of sexual conflict in mating interactions and highlight the evolutionary importance of female resistance to reproductive outcomes.
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Affiliation(s)
- C R Friesen
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA.,School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, USA
| | - E J Uhrig
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - R T Mason
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - P L R Brennan
- Department of Biological Sciences, 104 Clapp Laboratory, Mount Holyoke College, South Hadley, MA, USA
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6
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Lipke E, Michalik P. Evolutionary Morphology of the Primary Male Reproductive System and Spermatozoa of Goblin Spiders (Oonopidae; Araneae). BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2015. [DOI: 10.1206/906.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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7
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Michalik P, Ramírez MJ. Evolutionary morphology of the male reproductive system, spermatozoa and seminal fluid of spiders (Araneae, Arachnida)--current knowledge and future directions. ARTHROPOD STRUCTURE & DEVELOPMENT 2014; 43:291-322. [PMID: 24907603 DOI: 10.1016/j.asd.2014.05.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Revised: 05/20/2014] [Accepted: 05/21/2014] [Indexed: 06/03/2023]
Abstract
The male reproductive system and spermatozoa of spiders are known for their high structural diversity. Spider spermatozoa are flagellate and males transfer them to females in a coiled and encapsulated state using their modified pedipalps. Here, we provide a detailed overview of the present state of knowledge of the primary male reproductive system, sperm morphology and the structural diversity of seminal fluids with a focus on functional and evolutionary implications. Secondly, we conceptualized characters for the male genital system, spermiogenesis and spermatozoa for the first time based on published and new data. In total, we scored 40 characters for 129 species from 56 families representing all main spider clades. We obtained synapomorphies for several taxa including Opisthothelae, Araneomorphae, Dysderoidea, Scytodoidea, Telemidae, Linyphioidea, Mimetidae, Synotaxidae and the Divided Cribellum Clade. Furthermore, we recovered synspermia as a synapomorphy for ecribellate Haplogynae and thus propose Synspermiata as new name for this clade. We hope that these data will not only contribute to future phylogenetic studies but will also stimulate much needed evolutionary studies of reproductive systems in spiders.
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Affiliation(s)
- Peter Michalik
- Allgemeine und Systematische Zoologie, Zoologisches Institut und Museum, Ernst-Moritz-Arndt-Universität, J.-S.-Bach-Straße 11/12, D-17489 Greifswald, Germany.
| | - Martín J Ramírez
- Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" - CONICET, Av. Angel Gallardo 470, 1405 Buenos Aires, Argentina
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8
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Cabra-García J, Hormiga G, Brescovit AD. Female genital morphology in the secondarily haplogyne spider genus Glenognatha Simon, 1887 (Araneae, Tetragnathidae), with comments on its phylogenetic significance. J Morphol 2014; 275:1027-40. [PMID: 24788235 DOI: 10.1002/jmor.20280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/06/2014] [Accepted: 03/24/2014] [Indexed: 11/06/2022]
Abstract
Female genital morphology of secondarily haplogyne spiders has been poorly studied, hampering the analysis of its possible phylogenetic significance. We conduct a comparative morphological study of 12 species of the secondarily haplogyne spider genus Glenognatha Simon, 1887 using scanning electron microscopy. Representatives of the closely related genera Pachygnatha Sundevall, 1823 and Dyschiriognatha Simon, 1893 were also examined. The female genitalia of Glenognatha, Dyschiriognatha, and Pachygnatha species examined are composed of a spiracle-shape gonopore, a membranous chamber, a pair of copulatory ducts (CD) leading to spermathecae and a large uterus externus (UE). The most significant variation among Glenognatha species, previously unregistered within Araneoidea, is related with the absence or presence of CD and spermathecae. In addition, several characters as the form and distribution of long stem gland ductules and compartmentalization of the UE may be important for phylogenetic inference at species and generic level. Our results corroborate the close relationship between Dyshiriognatha and Glenognatha. A table with potentially informative female genitalic characters for phylogenetic inference within Glenognatha is provided. Understanding the general structure of the female genitalia in secondarily haplogyne taxa is a crucial step in order to propose characters for phylogenetic inference and to understand its possible functional significance.
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Affiliation(s)
- Jimmy Cabra-García
- Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, 05508-090, Brazil; Laboratório Especial de Coleções Zoológicas, Instituto Butantan, São Paulo, SP, 05503-900, Brazil
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Fannes W. THE GOBLIN SPIDER GENUS ZYNGOONOPS (ARANEAE, OONOPIDAE), WITH NOTES ON RELATED TAXA. BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2013. [DOI: 10.1206/805.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Wouter Fannes
- Royal Museum for Central Africa, Leuvensesteenweg 13, B-3080, Tervuren, Belgium
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Rodriguez-Enriquez CL, Tadeo E, Rull J. Elucidating the function of ejaculate expulsion and consumption after copulation by female Euxesta bilimeki. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1518-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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Copulatory behavior in a pholcid spider: males use specialized genitalic movements for sperm removal and copulatory courtship. Naturwissenschaften 2013; 100:407-16. [PMID: 23571707 DOI: 10.1007/s00114-013-1038-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 03/11/2013] [Accepted: 03/15/2013] [Indexed: 10/27/2022]
Abstract
Sexual selection may operate on pre-copulatory, copulatory, and post-copulatory traits. An example of a copulatory target of sexual selection is the genitalic movements a male performs during copulation. These movements may function either to prevent sperm competition or to influence a female's fertilization decision. Here we investigated how copulation duration, pedipalp movements, and abdominal movements that males of the pholcid spider Holocnemus pluchei produce during copulation influence sperm removal and/or patterns of successful sperm transfer. We compared mating events with virgin and mated females for differences in copulatory and post-copulatory behavior. We expected longer copulation duration, longer pedipalp movement duration, and more complex and frequent pedipalp and abdominal movements when males mated with mated females compared to virgin females. Except for abdominal movements, our results corroborated these predictions. Furthermore, when we investigated mating events with mated females, we observed sperm mass ejection from the female gonopore and physical removal of sperm by males' procursi. Females with interrupted second mating events showed a significant reduction of stored sperm masses compared to females with completed mating events. We suggest that males use alternating pedipalp movements to remove most of the rival sperm stored by mated females prior to sperm transfer. Copulation duration and pedipalp movements can be further used to transfer sperm and/or as a form of genitalic copulatory courtship.
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12
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Burger M. Genital morphology of female goblin spiders (Arachnida: Araneae: Oonopidae) with functional implications. ACTA ZOOL-STOCKHOLM 2011. [DOI: 10.1111/j.1463-6395.2011.00553.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Burger M. Functional morphology of female goblin spider genitalia (Arachnida: Araneae: Oonopidae) with notes on fertilization in spiders. ZOOL ANZ 2011. [DOI: 10.1016/j.jcz.2010.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Izquierdo MA, Rubio GD. Male genital mutilation in the high-mountain goblin spider, Unicorn catleyi. JOURNAL OF INSECT SCIENCE (ONLINE) 2011; 11:118. [PMID: 22225476 PMCID: PMC3391919 DOI: 10.1673/031.011.11801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 12/28/2010] [Indexed: 05/31/2023]
Abstract
Male genital mutilation is a common mechanism by which males reduce sperm competition by plugging female insemination ducts with different parts of its own genital system. This behavior is frequent in many spider families but is uncommon in Haplogynae. The reproductive biology of Dysderoidea is not well studied and the data is fragmentary; male genital mutilation has been reported only for one species of Oonopidae. This study provides evidence of male genital mutilation in Unicorn catleyi Platnick and Brescovit (Araneae: Oonopidae). Pieces of the embolus were found in the female posterior receptaculum. This behavior is a strategy used by the males in order to guarantee their paternity and not for escape from female attacks as has been reported for other species of Araneae, since cannibalism is unlikely in this species. The presence of embolus in the posterior receptaculum suggests this is the first place where sperm is received. The similarity of the female genitalia of U. catleyi to those of Orsolobidae, along with sclerotization of the seminal duct in the male copulatory bulb that is also present in Orchestina, Xiombarg, and Orsolobidae, provide strong evidence of the basal position of this genus in the family Oonopidae.
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Affiliation(s)
- Matías A. Izquierdo
- CONICET. División de Aracnología, Museo Argentino de Ciencias Naturales, Av. Ángel Gallardo 470, C1405DJR Buenos Aires, Argentina
| | - Gonzalo D. Rubio
- CONICET. División de Aracnología, Museo Argentino de Ciencias Naturales, Av. Ángel Gallardo 470, C1405DJR Buenos Aires, Argentina
- CONICET. Diversidad Animal I, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sarsfield 299, X5000JJC Córdoba, Argentina
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15
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Burger M. Goblin spiders without distinct receptacula seminis (Arachnida: Araneae: Oonopidae). J Morphol 2010; 271:1110-8. [PMID: 20730923 DOI: 10.1002/jmor.10857] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Matthias Burger
- American Museum of Natural History, New York, NY 10024, USA.
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Herberstein ME, Schneider JM, Harmer AMT, Gaskett AC, Robinson K, Shaddick K, Soetkamp D, Wilson PD, Pekár S, Elgar MA. Sperm storage and copulation duration in a sexually cannibalistic spider. J ETHOL 2010. [DOI: 10.1007/s10164-010-0213-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Female genital morphology and mating behavior of Orchestina (Arachnida: Araneae: Oonopidae). ZOOLOGY 2010; 113:100-9. [DOI: 10.1016/j.zool.2009.08.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 08/05/2009] [Accepted: 08/07/2009] [Indexed: 11/21/2022]
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18
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PERETTI AV, EBERHARD WG. Cryptic female choice via sperm dumping favours male copulatory courtship in a spider. J Evol Biol 2010; 23:271-81. [DOI: 10.1111/j.1420-9101.2009.01900.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Complex female genitalia indicate sperm dumping in armored goblin spiders (Arachnida, Araneae, Oonopidae). ZOOLOGY 2009; 113:19-32. [PMID: 19939658 DOI: 10.1016/j.zool.2009.04.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 04/08/2009] [Accepted: 04/27/2009] [Indexed: 11/29/2022]
Abstract
In promiscuous females, sperm ejection from the sperm storage site can be a strong mechanism to influence sperm priority patterns. Sperm dumping is reported from different animals including birds, insects, and humans. In spiders, it has been documented for four species including the oonopid Silhouettella loricatula. Oonopidae are a diverse spider family comprising many species with peculiar female genitalia. Especially in species where studies of mating behavior are difficult, morphological investigations of the genitalia help to understand their function and evolution. In the present study, the genitalia of the oonopids Myrmopopaea sp., Grymeus sp., and Lionneta sp. are investigated by means of histological serial sections and scanning electron microscopy (SEM). The results are compared with previous findings on S. loricatula. In Myrmopopaea sp. and Grymeus sp., the same morphological components are present that are involved in sperm dumping in S. loricatula. Inside the receptaculum, sperm are enclosed in a secretory sac which can be moved to the genital opening and dumped during copulation by muscle contractions. The female genitalia of Lionneta sp. are asymmetric. They show the same characteristics as S. loricatula but all the investigated females were unmated. The results strongly suggest that sperm dumping occurs in Myrmopopaea sp., Grymeus sp., and Lionneta sp. and happens by the same mechanism as in S. loricatula. Sperm dumping might even be common within a clade of oonopids. As in S. loricatula, the sperm transfer forms in the investigated species consist of several spermatozoa. Papillae with unknown function occur on the receptacula of all females.
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Chelicerae as male grasping organs in scorpions: sexual dimorphism and associated behaviour. ZOOLOGY 2009; 112:332-50. [PMID: 19660924 DOI: 10.1016/j.zool.2009.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Revised: 12/24/2008] [Accepted: 01/09/2009] [Indexed: 11/21/2022]
Abstract
Specialised structures that enable males to grasp females during sexual interactions are highly susceptible to selection and thus diverge relatively rapidly over evolutionary time. These structures are often used to test hypotheses regarding sexual selection such as sexually antagonistic co-evolution and sexual selection by female choice. In the present study, we determine whether there is a relationship between a novel record of scorpion sexual dimorphism, the sexual dimorphism of chelicerae (CSD), and the presence of the mating behaviour termed "cheliceral grip" (CG). The presence of both traits in the order Scorpiones is also reviewed from a phylogenetic perspective. The results confirm a strong relationship between CSD and the presence of CG. The morphological and behavioural patterns associated with "CSD-CG" are opposed to the predictions postulated by the hypothesis of sexually antagonistic co-evolution. However, if the female shows resistance after the deposition of the spermatophore, the possibility that the male exerts pressure as a "cryptic form" of coercion to prevent the interruption of mating cannot be ruled out completely. Female choice by "mechanical fit" could be another explanation for some aspects of the CG's contact zone. The possibility that the "CG-CSD" complex has evolved under natural selection in order to ensure sperm transfer is also considered.
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Welke K, Schneider JM. Inbreeding avoidance through cryptic female choice in the cannibalistic orb-web spider Argiope lobata. Behav Ecol 2009. [DOI: 10.1093/beheco/arp097] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Burger M. Functional genital morphology of armored spiders (Arachnida: Araneae: Tetrablemmidae). J Morphol 2008; 269:1073-94. [PMID: 18563703 DOI: 10.1002/jmor.10640] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This study describes the female genitalia of the tetrablemmid spiders Brignoliella acuminata, Monoblemma muchmorei, Caraimatta sbordonii, Tetrablemma magister, and Ablemma unicornis by means of serial semi-thin sections and scanning electron microscopy and compares the results with previous findings on Indicoblemma lannaianum. Furthermore, the male palps and chelicerae are briefly described. The general vulval organization of females is complex and shows similarities in all of the investigated species. The copulatory orifice is situated near the posterior margin of the pulmonary plate. The opening of the uterus externus lies between the pulmonary and the postgenital plate. Paired copulatory ducts lead to sac-like receptacula. Except for A. unicornis, the male emboli of all investigated species are elongated and thread-like. However, they are too short to reach the receptacula. Hence, the spermatozoa have to be deposited inside the copulatory ducts. The same situation was also found in I. lannaianum. Females of this species store sperm encapsulated in secretory balls in their receptacula. The secretion is produced by glands adjoining the receptacula. The presence of paired fertilization ducts and spermatozoa in the uterus internus suggested that fertilization takes place internally in I. lannaianum. Secretory balls in the receptacula are found in all of the investigated species in this study, showing that sperm are stored in the same way. The place of fertilization may also be identical since dark particles, presumably spermatozoa, are located in the uterus internus of all investigated species except for T. magister. However, fertilization ducts are only found in B. acuminata and M. muchmorei. A sclerotized central process with attached muscles is present in A. unicornis, M. muchmorei, C. sbordonii and T. magister. Only in A. unicornis does the central process show an internal lumen and hold spermatozoa. In the other species, it could be used to lock the uterus during copulation in order to prevent sperm from getting into it as suggested for certain oonopid species. The uterus externus of all investigated species shows a sclerotized dorsal fold with attached muscles, previously described as "inner vulval plate." Contractions of the muscles lead to a widening of the dorsal fold, thus creating enough space for the large oocytes to pass the narrow uterus externus. The males of all investigated species have apophyses on their chelicerae. At least in B. acuminata and A. unicornis, where females have paired grooves on the preanal plate, these apophyses allow males to grasp the female during copulation as described for I. lannaianum.
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Affiliation(s)
- Matthias Burger
- American Museum of Natural History, Division of Invertebrate Zoology, Central Park West, New York 10024, USA.
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