A comparative study of the morphology of some Sympetrum larvae (Odonata: Libellulidae) from eastern Canada

1969 ◽  
Vol 47 (3) ◽  
pp. 457-460 ◽  
Author(s):  
Robert Trottier
Keyword(s):  
Comparative Study ◽  
Morphological Study ◽  
Setal Formula ◽  
Eastern Canada ◽  
Larval Instars ◽  
Qualitative And Quantitative

A comparative morphological study of the first five larval instars of Sympetrum vicinum (Hagen), S. rubicundulum (Say), and S. obtrusum (Hagen) supports a subgeneric grouping, based on adults, suggested by Walker (unpublished). Qualitative and quantitative comparisons verify that S. vicinum belongs to one group and that S. rubicundulum and S. obtrusum belong to another. It is recommended that the setal formula for the labium of the second and third instar be used as a criterion for further studies of subgeneric grouping in Sympetrum.

scholarly journals A comparative morphological study of the ligamentum lamina nuchae and ligamenta interspinalia reveals enthesis patterns at the sites of attachment from the second to seventh cervical vertebrae in four extant species of Equus

2020 ◽  
Vol 8 ◽  
Author(s):  
Sharon May-Davis ◽  
Robert Hunter ◽  
Wendy Brown
Keyword(s):  
Comparative Study ◽  
Morphological Variation ◽  
Morphological Study ◽  
Cervical Vertebrae ◽  
Environmental Influences ◽  
Dorsal Spine ◽  
Spine Morphology ◽  
Size And Shape ◽  
Attachment Sites ◽  
Extant Species

Morphological variation in the attachment sites of the ligamentum lamina nuchae and ligamentainterspinalia to the 2nd to 7th cervical vertebrae is described in four species of Equus, and enthesis patterns inrelation to these attachment sites are explored. This comparative study provides new insights with respect tothis variation in the zebrine and asinine clades within Equus. In zebrines (Equus caballus, E. quagga boehmiand E. przewalskii), the ligamentum lamina nuchae attaches to the eminence of the cervical dorsal spinesfrom either the 2nd to 5th, and or 2nd to 7th. These attachments resemble digits and between each digit anaperture is apparent. The ligamenta interspinalia attach to the base of each cervical dorsal spine from the 2ndto 7th before progressing caudally onto the thoracic dorsal spines. Three enthesis patterns per cervical dorsalspine correspond to the size and shape of these ligaments. In contrast, in asinines (as represented by Equusasinus), the ligamentum lamina nuchae attaches without digitation to the complete sagittal ridge of the cervicalvertebra including the dorsal spine and exhibits no ligamenta interspinalia. Consequently, the enthesispattern is represented by a raised sagittal ridge only, excluding the 7th cervical dorsal spine. These differencesbetween the ligamentum lamina nuchae and ligamenta interspinalia attachment sites create distinct enthesispatterns that differentiate zebrines from asinines. Findings include: differing ligamentous morphology; associatedenthesis patterns corresponding to attachment sites of the ligaments to the cervical vertebrae; influencesin dorsal spine morphology subject to the presence or absence of the ligaments; and the postulation ofevolutionary functional adaptions in response to environmental influences between the two Equus clades.These results may be useful for palaeontologists in the identification of isolated cervical vertebrae.

scholarly journals Twisting to freedom: The evolution of copulation termination techniques across 48 species of sepsids (Diptera, Sepsidae)

2021 ◽  
Author(s):  
Mindy Jia Min Tuan ◽  
Diego Pitta Araujo ◽  
Nalini Puniamoorthy ◽  
Jeremy M Woodford ◽  
Rudolf Meier
Keyword(s):  
Comparative Study ◽  
Related Species ◽  
Mating Behaviour ◽  
Variable Separation ◽  
Female Fitness ◽  
Close Attention ◽  
Closely Related Species ◽  
Male And Female ◽  
Qualitative And Quantitative ◽  
A New Technique

Studies of insect mating behaviour usually focus on what happens before and during copulation. Few pay close attention to the actions needed to end copulation. However, genital separation after copulation is likely to be an important cause of mechanical stress and injuries because it often involves the withdrawal of heavily armoured male intromittent organs from membranous female reproductive tracts. Difficult and/or slow separations can also reduce male and female fitness by increasing their exposure to predation. We here report the results of a comparative study of separation behaviour in 48 species of Sepsidae (Diptera) and one outgroup. We find a surprising amount of qualitative and quantitative behavioural variability within and between species. We characterize and reconstruct three types of behaviours: 1) The sepsid ancestor likely used `back-off; a gentle separation technique that does not involve any pulling or twisting (https://youtu.be/EbkJvOaubZ0). 2) This potentially gave rise to the most common `pull' technique where the male turns 180 degrees and pulls in an opposite direction from the female (https://youtu.be/oLf4xGpkk1s). This separation can be quick and straightforward, but in some species the `pull' is slow and protracted and we routinely find dead males and/or females attached to their living partners in the latter (difficult: https://youtu.be/MbYPbXN6jr0; failure: https://youtu.be/leTiXefFzCc). 3) Finally, several species use `twist', a new technique where the male rotates >360 degrees from the initial mounting position (https://youtu.be/WMUXbIPyLbk). We document that species capable of using `twist' have shorter and less variable separation times than those using "pull". However, many species capable of `twist' also retain the ability to use `pull' (`back-off'/'pull'= 8%; `pull' only= 41%; `twist'/ `pull'= 24%; `twist' only = 27%). Overall, our study suggests that separation behaviour can vary among closely related species and highlights the significance of studying variable behavioural traits in a phylogenetic context.

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