Ultrastructure of the sperm of Adelobothrium sp. (Cestoda: Lecanicephalidea)

Abstract

This study provides the first description of the ultrastructure of the spermatozoon of a lecanicephalidean cestode. Based on our observations on Adelobothrium sp. (Cestoda: Lecanicephalidea), we confirm the placement of the spermatozoa of lecanicephalideans in the Type IV spermatozoan category. A new feature, the anterior spiral structure, is described at the anterior extremity of the mature spermatozoon. The crested body is present in the anterior half of the spermatozoon and is identified by its ovoid to lunar shape, becoming circular and decreasing in size near its posterior limit. A row of ten parallel cortical microtubules persists in the anterior region of the mature spermatozoon, terminating at the level of the nucleus. The nucleus continues after the disassociation of the axoneme in the posterior region. A review of other cestodes with Type IV spermatozoa is presented, including confirmation that members of the Rhinebothriidea have spermatozoa of this type. That phyllobothriid tetraphyllideans have Type IV spermatozoa is called into question. Spermatozoa of a mere 2.6% of all cestode species have been studied. Further studies are needed to better understand spermatozoan character variation, especially if it is to be useful in elucidating evolutionary patterns among cestodes.

A new genus with two new species of lecanicephalidean tapeworms (Cestoda) from the mangrove whipray, Urogymnus granulatus (Myliobatiformes: Dasyatidae),from the Solomon Islands and northern Australia

“…1" of Jensen et al (2016). This is the first record of lecanicephalidean tapeworms from U. granulatus, and the third report of lecanicephalideans from the Solomon Islands (see also Cielocha et al 2013, Jensen et al 2016.…”

Spermatological Characterization of the Cestode Meggittina gerbilli (Cyclophyllidea: Catenotaeniidae), a Parasite of Gerbils, Gerbillus gerbillus and Gerbillus campestris (Rodentia: Muridae) in Tunisia

“…Thus, sperm cells with two axonemes are present in the orders Diphyllobothriidea, Spathebothriidea, Haplobothriidea, Onchoproteocephalidea, and Trypanorhyncha [21][22][23][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60]. Contrarily, spermatozoa with one axoneme are present in the orders Caryophyllidea, Cyclophyllidea, Lecanicephalidea, Nippotaeniidea, Phyllobothriidea, and Tetrabothiidea [21][22][23][26][27][28][29][30][31][32][61][62][63][64][65][66][67][68][69][70][71][72]. In the order Diphyllidea, there are some discrepancies between the spermiogenesis process and the resulting spermatozoa.…”