Browsing by Author "Michalik, Peter, 1976-"
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Item Evolutionary morphology of the primary male reproductive system and spermatozoa of goblin spiders (Oonopidae; Araneae). (Bulletin of the American Museum of Natural History, no. 396)(American Museum of Natural History., 2015-09-24) Lipke, Elisabeth.; Michalik, Peter, 1976-; Goblin Spider Planetary Biodiversity Inventory.Goblin spiders (Oonopidae Simon, 1890) are distributed worldwide and among the most species-rich spider taxa. However, goblin spiders are understudied in many aspects and their phylogenetic relationships are not well resolved. As previously shown for numerous other spider groups the male and female reproductive system bears many characters of phylogenetic relevance. Moreover, the diversity of sperm structures within spiders is astonishingly diverse and often taxon specific. In the present study, we analyzed the primary male reproductive system and spermatozoa of goblin spiders for the first time. We investigated 18 species of 13 genera representing the subfamilies Orchestininae and Oonopinae by means of light and transmission electron microscopy. We scored 44 characters from the gross morphology of the reproductive system as well as spermatozoa including four new characters for the male spider reproductive system. All investigated species transfer sperm as synspermia, a method corroborating with the recently proposed "Synspermiata" clade unifying all ecribellate Haplogynae. Furthermore, goblin spiders show by far the highest diversity of sperm structures in spiders. In total, we recovered 30 unambiguous synapomorphies for different oonopid taxa. In a comparison with all other spider taxa studied to date, we identified the longest sperm (Neoxyphinus termitophilus) and longest sperm conjugates (Orchestina). Moreover and most remarkable is the presence of aflagellate sperm in Opopaea apicalis, which is the first report of the loss of a sperm flagellum in tetrapulmonate arachnids. These findings are of high interest not only because of their phylogenetic implications, but also with regard to their contribution to our understanding of postcopulatory sexual selection in spiders.Item The male genital system of goblin spiders : evidence for the monophyly of Oonopidae (Arachnida, Araneae). (American Museum novitates, no. 3675)(New York, NY : American Museum of Natural History., 2010) Burger, Matthias, 1976-; Michalik, Peter, 1976-The male reproductive system of spiders consists of paired, tubular testes and often long and convoluted deferent ducts, which are fused near the genital opening to form an ejaculatory duct. In rare cases and as revealed in previous studies the testes can be partly fused (anteriorly or posteriorly), as reported, for example, for Dysderidae (Dysderoidea). In order to determine whether this pattern is also present in other dysderoids, we studied the genital system of Oonopidae for the first time by means of light microscopy. The following species were included, covering both conventionally recognized subfamilies (Gamasomorphinae and Oonopinae): Neoxyphinus ogloblini Birabén, 1953; Silhouettella loricatula (Roewer, 1942); Opopaea recondita Chickering, 1951; Myrmopopaea sp.; Scaphiella hespera Chamberlin, 1924; Lionneta sp.; Orchestina moaba Chamberlin and Ivie, 1935; Oonops balanus Chickering, 1971, and Stenoonops reductus (Bryant, 1942). In contrast to other spider taxa observed to date, all studied goblin spiders possess an unpaired (completely fused) testis, which seems to be a synapomorphic trait for Oonopidae supporting the monophyly of the family. The deferent ducts of goblin spiders are mostly convoluted and of varying diameter whereas the ejaculatory duct is very small. Moreover, we found a remarkable diversity in the organization of the testis and spermatozoa, which underlines the high potential of the reproductive system for systematic studies on Oonopidae as well as other dysderoids. The putative sister group of Oonopidae is Orsolobidae; since the organization of the male genital system of orsolobids is unknown as well, we included one species (Ascuta media Forster, 1956) in the present study. It possesses the typical genital organization for male spiders represented by paired and unfused tubular testes.Item Supplemental Material for 'Evolutionary morphology of the primary male reproductive system and spermatozoa of goblin spiders (Oonopidae; Araneae). (Bulletin of the American Museum of Natural History, no. 396)'(American Museum of Natural History., 2015-09-24) Lipke, Elisabeth.; Michalik, Peter, 1976-; Goblin Spider Planetary Biodiversity Inventory.Supplemental Material for 'Evolutionary morphology of the primary male reproductive system and spermatozoa of goblin spiders (Oonopidae; Araneae). (Bulletin of the American Museum of Natural History, no. 396)' - http://hdl.handle.net/2246/6611Item Ultrastructure of the spermatozoa in the spider genus Pimoa : new evidence for the monophyly of Pimoidae plus Linyphiidae (Arachnida, Araneae). (American Museum novitates, no. 3682)(New York, NY : American Museum of Natural History., 2010) Michalik, Peter, 1976-; Hormiga, Gustavo.The spermatozoa of spiders (Araneae) show a high structural diversity, resulting in several potential phylogenetic characters. In the present paper, we describe the spermatozoa of the spider family Pimoidae for the first time. We investigate four species of the genus Pimoa (P. altioculata, P. curvata, P. laurae, and P. edenticulata) by means of light and transmission electron microscopy. The male reproductive system consists of paired testes and long convoluted paired deferent ducts. The spermatozoa are generally characterized by: (1) a cylindrical acrosomal vacuole, (2) an acrosomal filament restricted to the precentriolar part of the nucleus, (3) a nuclear canal running in the periphery but projecting towards the posterior portion of the nucleus, (4) a short postcentriolar elongation of the nucleus, (5) a 9+0 axonemal pattern, and (6) cleistospermia as transfer form. The organization of the axoneme is of particular phylogenetic interest, since a 9+0 axonemal pattern was described within spiders only for the megadiverse family Linyphiidae, the sister group of Pimoidae. We have reconstructed the evolution of the axoneme using comparative spermatozoal data for 54 orbicularian species representing 11 families. We propose that the 9+0 axonemal pattern is a new synapomorphy for Pimoidae + Linyphiidae. The phylogenetic and evolutionary implications of other potential sperm characters (e.g., length of the postcentriolar elongation of the nucleus) are discussed.