Niarchos scutatus Platnick

Lipke, Elisabeth & Michalik, Peter, 2015, Evolutionary Morphology Of The Primary Male Reproductive System And Spermatozoa Of Goblin Spiders (Oonopidae; Araneae), Bulletin of the American Museum of Natural History 2015 (396), pp. 1-72 : 33-36

Niarchos scutatus Platnick and Dupérre´, 2010

SPERM TRANSFER FORM ( fig. 21 ): Synspermia comprising four sperm. Information on sperm transfer forms and sperm characteristics refer to sperm obtained from the testis. Within the lumen of the testis large sperm conjugates are visible. Sperm are located in the center of the sperm conjugation, surrounded by an electron-dense vesicular area ( fig. 21F ) and large quantities of cytoplasm.

SPERMATOZOA ( fig. 21 ): For the identification of sperm characters, only material from the testis was available, thus the following sperm characters refer to spermatogenic stages. Acrosomal complex: AV conical ( fig. 21B ), widened proximally, but narrow subacrosomal space for the most part ( fig. 21 B ). AF originates from the subacrosomal space and extends into the nuclear canal ( fig. 21C, D ), ends before the base of the axoneme. Nucleus: prcN compact with small implantation fossa that comprises only the two centrioles ( fig. 21D ). peN not identifiable. NC located in the periphery of the nucleus ( fig. 21C ), elongated and bend toward the nucleus ( fig. 21D, F ). Axoneme: centrioles are arranged in tandem position ( fig. 21D ), 9+3 microtubular pattern ( fig. 21E, F ).

NOTES ON SPERMIOGENESIS: Within the testis early and late stages of spermiogenesis are present. Already early spermatids (four) fuse entirely, forming very large, developing

synspermia ( fig. 21A ). The cytoplasm of this syncytium is characterized by large quantities of smooth endoplasmic reticulum. The AV is sunken into the anterior pole of the nucleus ( fig. 21B ), which is surrounded by a manchette of microtubules. Two centrioles migrate toward the posterior pole of nucleus, inducing the formation of a small implantation fossa ( fig. 21D ). The chromatin condenses heterogeneously ( fig. 21C, D ). The NC is extremely stretched, resembling a slender band in late spermatids ( fig. 21F ). The peripheral microtubules of the two centrioles are surrounded by little electron-dense material ( fig. 21E ). Further development includes the complete condensation of chromatin, resulting in a homogeneously electron-dense nucleus ( fig. 21F ) and formation of a vesicular area ( fig. 21F ).

Figures

Fig. 21. Characteristics of spermiogenesis and mature spermatozoa of Niarchos scutatus. A: Early spermatids already fused entirely, thus all developing spermatids are surrounded by a common membrane. B: The posterior portion of the elongating AV is sunken into the anterior pole of the nucleus in early spermatids. C: Both centrioles (proximal and distal centriole) arrange in tandem position and migrate toward the posterior pole and thus induce the formation if the very small IF that comprises only the two centrioles (magnification in inset). D: The elongated NC is located in the periphery and usually bent toward the nucleus. E: The chromatin condenses irregularly and with distinct electron-lucent portions opposed to the portion in which the NC is running. F: At the end of spermiogenesis the four spermatids arrange closely attached to each other in the middle of the large sperm conjugate. The Ax of each spermatid coils within the cell membrane and a small, electron-dense VA that surrounds the main sperm cell components secondarily is formed.