Ultrastructure of male genital system and spermatozoa of the camel-spider Eremobates hessei (Arachnida, Solifugae, Eremobatidae)

KLANN, A., PERETTI, A. V., ALBERTI, A.

Ghent, Bélgica

Congreso; 16th International Congress of Arachnology; 2004

International Arachnological Society (ISA)

Camel-spiders live in tropical regions preferably in arid environments. Their position within the Arachnida is not yet fully defmed, since Solifugae comprise both apomorphic and plesiomorphic characteristics, but they are usually considered to be a sister-group of the Pseudoscorpiones. So far, only a few electron microscopic studies on this animal group have been done. According to present literature the male genital system of Solifugae is classically divided into three different parts: a) a common genital chamber with its accessory glands, b) the paired tubular vasa deferentia and c) the long thin testes. On each side the vas deferens splits into two smaller branches resulting in the thin extremely long testes so that a male camel-spider possesses four tubular testes in total. The epithelium of the testis consists mainly of a meshwork of somatic cells surrounded by a small layer of muscles. Within the testis the sperm cells can be discovered as groups consisting of a few probably four mature sperm cells each surrounded by thin extensions of the somatic cells. These cells can clearly be distinguished from a glandular part formed by cells containing high amount of rough endoplasmic reticulum. Once released into the narrow testicular lumen, the sperms float more or less individually in proteinic secretion. Earlier stages of spermatogenesis could not be detected, suggesting that spermatogenesis may occur in sub adult male camel-spiders. In general, the sperm is rather simple representing a round or slightly elongated cell devoid of a flagellum. The relatively small and flat acrosomal vacuole is directly attached to the slightly elongated nucleus. The acrosomal filament is coiled several times around the nucleus. In contrast to species of the family Ammotrechidae or Karschiidae, for which sperm cells have already been described by other authors, the sperm cells of the Mexican species Eremobates hessei, which belongs to the family Eremobatidae, show no tendency to form any piles or well ordered groups in the lumen of neither the testes nor the vasa deferentia.