The sperm ultrastructure of Caurinus dectes Russell (Mecoptera: Boreidae) and its phylogenetic implications

Spermatozoa provide an unusual character system, with a limited number of components organized in a single cell. Similar spermatozoa occur in groups widely separated in the phylogenetic tree of Metazoa. Nevertheless, the character system contains phylogenetic information. Hexapoda have acquired spermatophores along with the switch from aquatic to terrestrial habitats, and related to this, a multitude of different sperm types. The aim of this study is a formal evaluation of the phylogenetic information content of spermatozoa. For the first time, sperm characters are coded for formal phylogenetic analyses. Different approaches are used and compared. Mainly due to a high level of homoplasy, the evaluation of sperm characters alone is insufficient for a reconstruction of the phylogeny of the group. Yet, a reliable reconstruction of the evolution of insect sperm is possible when character transformations are assessed using a phylogeny based on extensive molecular data. Important changes took place in the early evolution of Hexapoda. Sperm characters support some major clades (e.g. Hexapoda, Dicondylia, Polyneoptera, Psocodea), but important steps in the evolution are not reflected by transformations of spermatozoa, notably the rise of Pterygota or Holometabola. Important innovations are the formation of mitochondrial derivatives and the acquisition of accessory microtubules. Some features are conservative, whereas others evolved rapidly (e.g. presence or absence of the acrosome vesicle). Some groups are conservative in their sperm features (e.g. Odonata, Heteroptera), whereas the evolution of spermatozoa was distinctly accelerated in others (e.g. Ephemeroptera). The rate of evolution can change drastically in closely related groups. Profound changes in the morphologically uniform Zoraptera underline that sperm evolution can follow a pattern very different from the general somatic morphology. The mode of character reconstruction preferred here will be useful for the evaluation of specialized morphological character systems and strengthen the concept of evolutionary morphology.

show abstract

“…f) and in the mecopteran genera Caurinus (Boreidae) (Russell et al. ) and Panorpa (Panorpidae) (Fig. g) (Dallai et al.…”

Section: Resultsmentioning

confidence: 99%

“…A monolateral groove occurs in Cryptocercus (Blattodea) ) and a bilateral groove other Blattodea ( Fig. 1f) and in the mecopteran genera Caurinus (Boreidae) (Russell et al 2013) and Panorpa (Panorpidae) ( Fig. 1g) (Dallai et al 2003b).…”

Section: Acrosomal Complexmentioning

confidence: 99%

The evolution of insect sperm − an unusual character system in a megadiverse group

Gottardo

Dallai

Mercati

et al. 2016

J Zool Syst Evol Res

Self Cite

View full text Add to dashboard Cite

show abstract

“…In Mecoptera the sperm ultrastructure has been investigated in six species of three families (Panorpidae, Bittacidae and Boreidae) (Baccetti et al, ; Breland et al, ; Dallai et al, ; Gassner et al, ; Russell et al, ). This study is likely the first attempt to describe the sperm ultrastructure of Panorpodidae, and contributes additional sperm knowledge of Panorpodidae for future phylogenetic analysis of the Mecoptera.…”

Section: Discussionmentioning

confidence: 99%

“…Accessory microtubules were regarded as a synapomorphic feature of the Holometabola (Kristensen, ) because they appear in the spermatozoa of all the insect orders of Holometabola except Phthiraptera, Mecoptera, and Siphonaptera (Dallai and Afzelius, ). Russell et al () argued that the 9 + 2 microtubular pattern of axoneme is a potential synapomorphy of Mecoptera and Siphonaptera. Baccetti () considered that the absence of accessory microtubules may indicate an evolutionary reversal or, alternatively, a symplesiomorphy.…”

Section: Discussionmentioning

confidence: 99%

“…Comprehensive study of sperm structure has been made in many groups of insects, such as the Polyneoptera, Paraneoptera, Neuropteroid orders, Hymenoptera, and Diptera (Jamieson, ; Jamieson et al, ). In the Mecoptera, sperm ultrastructure has only been examined in six species of three families (Panorpidae, Bittacidae, and Boreidae) (Baccetti et al, ; Breland et al, ; Dallai et al, ; Gassner et al, ; Russell et al, ). The spermatozoa of Panorpodidae, however, have not been studied to date.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Sperm ultrastructure of Panorpodes kuandianensis (Mecoptera: Panorpodidae)

Zhang

Hua

2014

Microscopy Res & Technique

View full text Add to dashboard Cite

The sperm ultrastructure of the short-faced scorpionfly Panorpodes kuandianensis Zhong et al. was investigated using transmission electron microscopy. The spermatozoon is composed of a short head containing a bilayered acrosome and an elongate nucleus, a neck transition region, and a long flagellum. The acrosome consists of an acrosomal vesicle and a central perforatorium. The nucleus has two deep, U-shaped lateral grooves and its chromatin contains a series of parallel, regularly arrayed nuclear fibers. The barrel-shaped centriolar adjunct occupies the most volume of the neck region. The flagellum is helical for its whole length and is formed by an axoneme, two mitochondrial derivatives, a pair of accessory bodies, and peculiar accessory structures. The axoneme has nine accessory microtubules at the anterior flagellum region, displaying a 9 + 9 + 2 microtubular pattern, but the accessory microtubules are short and disappear quickly. The two mitochondrial derivatives differ in length and diameter. In the more posterior region, the remaining anchor-shaped mitochondrial derivative has a circular crystalline region, differing from other mecopteran species. The filiform materials are peculiar and lie beside the nucleus and in the flagellum region. Sperm ultrastructural comparison of P. kuandianensis with other families supports a close affinity of Panorpodidae with Panorpidae. In addition, the occurrence of the nine accessory microtubules in the sperm axoneme of Panorpodes indicates that the 9 + 9 + 2 axonemal pattern might be a symplesiomorphy of the Mecoptera.

show abstract

Spermiogenesis of the hangingfly Terrobittacus implicatus (Huang and Hua) (Mecoptera: Bittacidae)

2019

View full text Add to dashboard Cite

The sperm ultrastructure of Caurinus dectes Russell (Mecoptera: Boreidae) and its phylogenetic implications

Cited by 9 publications

References 12 publications

The evolution of insect sperm − an unusual character system in a megadiverse group

The evolution of insect sperm − an unusual character system in a megadiverse group

Sperm ultrastructure of Panorpodes kuandianensis (Mecoptera: Panorpodidae)

Spermiogenesis of the hangingfly Terrobittacus implicatus (Huang and Hua) (Mecoptera: Bittacidae)

Contact Info

Product

Resources

About