nomenclature mandibule lucanid

[africaone]

I am looking for a reference that explain clearly what are the terms
prionodont, mesodont, amphiodont, mesamphiodont, telodont and others ...
for the nomenclature of Lucanid mandibules.

and what are the reasons why a male is telodont or not ? Does exist a scientific explanation ?

thanks
Thierry

[thanos]

All these are Greek names. 'Prioni'* means 'saw' and 'donti' means 'tooth', so a 'prionodont' male Lucanid has many small teeth across the inner edge of its mandibles.
'Telos' means 'end',so a 'telodont' has well-developed teeth at the edge(and/or close to the edge/end) of its mandibles(and can have also -for example in Prosopocoilus or in Odontolabis- 1 more,smaller pair of teeth close to the base of mandibles) . 'Meso' means 'in the middle', so a 'mesodont' has a well-developed pair of teeth in about the middle of the inner edge/side of its mandibles(e.g. mesodonts of Prosopocoilus),and can have an additional pair of(smaller)teeth close to the base of mandibles(e.g. mesodonts of Odontolabis). 'Amphi' means 'both'...,and so on .'Amphiodont' Lucanids are the smallest males of a species,and have many very small pairs of teeth across the whole inner edge of mandibles(like a saw). Now,,an 'amphiodont' male Lucanid,of course can be characterised also as 'prionodont'. In 'mesamphiodont' there is a pair of teeth in the middle of the inner edge of the mandibles,which is longer/bigger than all the rest small teeth pairs.
Many Lucanids,for example many Odontolabis species(or also Prosopocoilus),have different male forms and,according to the size,they have different shape of mandibles. The largest males are 'telodonts', the medium ones 'mesodonts',and the smallest 'amphiodonts'. 'Telodonts' have the longest and more impressive mandibles in each species,'mesodonts' shorter ones,while 'amphiodonts' the shortest ones(but wide).
Our member Benjamin (poisonarrow) has a nice example on his site,of Odontolabis sommeri pahangensis,where are shown 3 different males(telodont,mesodont,amphiodont).You can check it here:
www.harink.com/benjamin/G%20Odontolabis.htm

Another example that comes on my mind is Prosopocoilus fabricei takakuwai.I have a small 'amphiodont' male in my collection from exchange.The big 80+ 'telodont' males are impressive and quite expensive.

And many other examples of Lucanids.
Also,the terms 'amphiodont','telodont' etc are valid in some Prioninae Cerambycids like the ones in the genuses Acanthophorus or Anthracocentrus..For example the biggest 'telodont' males of Acanthophorus serraticornis from India(+90-95mm) or of Anthracocentrus rugiceps from Pakistan(+80mm) have some well-developed pairs of teeth from the middle and close to the end of mandibles,while the smallest 'amphiodont' ones have many tiny pairs of teeth across the whole inner side of mandibles(the mandibles of the females are of the 'amphiodonte' form).


Thanos

* PS : The Prioninae Cerambycids are named after the 'saw',too,cause the antennae of many species(Prionus etc) are toothed from the one side,like a saw.

[thanos]

Here(this photo and the next one are both taken from the net) you can see a 'telodont' big male of P.fabricei takakuwai,which I mentioned above.

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[thanos]

And here a 'mesodont' (medium-sized male) of the same(fabricei takakuwai).

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[africaone]

thanks for this interesting and helpful lesson Thanos !

I seen (in some litterature) that prionodont are treated as the smallest, and smaller than amphiodont. probably a nuance due to the continue variation of the mandibules !

I also have in collection medium sized and big sized telodont in the same sp. Even the majority of telodont seems also the biggest (in body size POV), it seems not exhautiv. It is the reason why I asked if one knows how telodont forms arises.

Thierry

[thanos]

Yes I know that in some species there are,for example,big(in terms of total length) and smaller mesodontes(e.g. in Dorcus alcides,I have seen mesodontes with about the same body size,where the one had longer mandibles,and so bigger total lenth).Also, in some species(e.g. Dorcus titanus) some mesodonte males(according to ssp.) reach bigger lengths than some telodontes(big males of ssp.titanus which are telodontes reach lesser total lengths than the huge males of the ssp.palawanicus which are mesodontes). But the majority of the telodontes in most species are the biggest.
In response to your question about how each of these forms arise,I think that it has to do with the nutrition of the larvae..

Thanos

[africaone]

I also read something with food.
Personally I don't think it is enough as distribution of telodont (in Africa) is more relied with center of distribution of a species (food is probably the same in many places).
then may be there could be also at least genetic and "preferendum ecologic" components that play.

may be somebody knows or published on the subject ??

[Chris Grinter]

I might be incorrectly remembering - but isn't there sexual selection/cheating happening here with males that look like females? Instead of fighting other males with large mandibles they save their resources and sneak in on females while the males are fighting?

Maybe this doesn't apply here, but it seems like males with small mandibles must be successful in some respect since they would most likely be out-competed by a better fed, larger, male. The more I think about it the more it would make sense that a poor diet would result in small mandibles - but cheating evolved to keep those lesser males alive. ?

There are papers out there but I'm too lazy to go find them all...

[thanos]

I also thought about genetic factors,which,together with larval nutrition,must be responsible for the size and the mandible type of a specimen.
Also,the evolutionary approach(natural choice due to success) of Chris makes sense,as in most populations of most species the big males are rarer to much rarer than the small ones(I have noticed it with Lucanus cervus here in Greece,after quite many years of systematic collecting of the species).But this that is strange is why the small males exist more frequently than the large ones,as in most of the pairs the males are big ones cause they are the strongest and seem most successful in mating..(in almost all the pairs of L.cervus I've seen here,the males were big to giants). Which are actually the most successful in mating?The small males by cheating,as Chris said,or the large ones by their strenth? At least with my experience with L.cervus,it seems they are the bigger ones.
Also: The smaller specimens survive better than the big ones: Big males of L.cervus are eaten more frequently by birds,as they have more food,they are more visible/be hidden more difficultly in the trees and they escape difficultly(heavy specimens which fly slowly).And Lucanids are much hunted by birds.So this could be a reason why,through evolution,the small males are the most.
And something else: In species like Dorcus alcides for example,exist inside the same population mesodontes,telodontes etc,some of the telodontes are smaller in total length(smaller body but longer mandibles) than some big-bodied with shorter mandibles mesodontes.These smaller telodontes maybe survive better,cause they are lighter and fly/move more quickly and escape easier from predators,and it seems they are also more successful in mating,due to their larger mandibles with which they can win a fight with a larger-bodied/with shorter mandibles mesodonte. All these different forms possibly exist due to evolution and the forms that will be even more ascendant in a population,will be the most successful ones both in mating and survival/protection from predators,etc.(Of course,always a part will be eaten by predators,so for the natural control of insect populations,and the survival of predators).

These were all my thoughts on this subject,can't help more,there are works of Lucanid allometry available,I think also on the net,but haven't searched much for them.

Thanos

[africaone]

small males are probably the minimum-minimorum condition for a male to exist (because time and food necessited to produce big body and mandibules in energy cost POV) and in stressed conditions, the most important for a species is to survive to mate.
That can help to explain why ideal environemental condition favorise the apparition of telodont.
Also, in stressed conditions, population is not so important than in ideal condition and then the competion is reduced (in this case the need of large body and big mandibules to fight is reduced !)
genetic component is suspected as it seems that in breeding experiences big (telodont) male favorise the character. The fact that telodont character disappeared in some species or population also go in this genetic way.

[thanos]

The DNA,with evolution/adaptation of the species to the environmental changes,is affected by these changes if they are continuous(for example the stressed conditions),and the information of the genes which are responsible for the size of specimen and the mandible type,changes.In ideal conditions of well-established,big,rich Quercus forests,you can see a quite high percentage of giant telodont males in the population of,for example, Lucanus cervus cervus or c.turcicus,or c.judaicus etc -I mention subspecies which have giant telodonts- (still the small males,or the medium-sized telodontes, are the most). The population is big in these habitats,and the good percentage of giant males is due to the ideal nutrition(rich Quercus wood/soil in ingredients) of many larvae in these rich habitats.This happens for example in Landes in France with the ssp.cervus,where you can find not difficultly male of 80+mm.But in most other places there,the percentage of the big males is very low.Same happens in Greece with the ssp.turcicus,ssp.cervus,and the intermediate populations(cervus x turcicus). And in any other EU country,the populations that have good percentage of big males are few.Meaning that most populations are stressed,so to have few and small males,and that the habitats are(or have become)not ideal for the species(not rich larval nutrition).Long time ago,maybe these populations were not stressed,the habitat was of greater quality,and the percentage of big males was higher.But after many stressed generations,the genes changed,so that almost all males to emerge small to medium(the species was adapted to survive).And I think the same will happen to the present good populations where you can find many big males,if their rich habitats be put under continuous environmental stress.So,I think that the nutrition of the larvae and its quality and quantity,affects the genes,so that different populations(at different localities of different quality/quantity of Quercus/Fagus wood/soil)are characterised by high or lower ascendance(in numbers/percentage in a population) of the smaller mesodonte males.
Concluding,I think(and maybe am wrong) that food -and maybe also the usual less vulnerability of the small specimens- affects the percentages of each form(mesodonte,telodonte,etc) in each population of each (sub)species in Lucanids,by affecting them genetically. And I don't think that a reduction of a population(due to stressed conditions) makes telodonts to tend to disappear cause of lower competition in mating.If the population will become lower,then there is also lower competition of the larvae for food..,so they become bigger than before,and so the adults bigger. -Here note that the very small (mes)amphiodont(<36-37mm)of male L.cervus is even rarer than the giant telodonts(I have collected only 2 such minor males here all these years,among quite more 78+mm,in a good-sized population to which has happened interbreeding between the ssp.cervus and turcicus) in every population of subspecies that have big telodonts(like ssp.cervus,turcicus,etc),even in stressed,small populations, SO less competition in mating(due to smaller population),possibly doesn't mean something for the specimens' size/mandible type.- Many not-needed chatacteristics(e.g. the tail in humans)have been disappeared or reduced with evolution,but I don't think this happens here: It is in the behaviour of the male Lucanids(and this happens also in low populations) to fight with others for mating with the female(so they need good mandibles)and this is strongly written in their genetic code.
Such subjects are among the most difficult in entomology.

Thanos

(A note: in many Lucanidae,2 same-sized L3 larvae,can give 2 different males,of about the same length,but the one to have bigger body and be mesodont,and the other to have smaller body and bigger mandibles and be telodont.I'm not sure why this happens.I think that the reasons are genetic for each specimen(e.g.like people with tall and short feet),so that each of 2 same-sized larvae,gives more to mandible structure and less to body structure than the other).

[africaone]

my POV is based on a more general view than only Lucanus cervus (but restricted to Africa).
My question about works existing on the subject is to have a more scientific approach of the question i.e. regarding the genetic rules about mandibules.
- Is it ordered by regulation of different alleles (and / or genes) ? (i don't know)
- Is it due to hormonal regulation (quantity depending for the length of mandibules) ? (I suppose)
- Is this hormonal regulation depending of food / environemental / stress condition / etc. and / or is it "decided" well before just ordered by alleles frequences ? (probably a combination)

ps : note that a character can disappear if depending of alleles, in small population (bottle neck effect)

ps 2 : the fact that mesodont males of cervus are rare may be simply due an inversed pyramidal effect !

ps 3 : stressed condition means also that the stress occurs also for food (or time available to become adult) !

[thanos]

'the fact that mesodont males of cervus are rare may be simply due an inversed pyramidal effect '
- The very small (mes)amphiodonte,and the very large telodonte males of L.cervus are the rare ones(as I mentioned above),not the mesodontes (and this happens in most species and subspecies,not only in cervus) .
'stressed condition means also that the stress occurs also for food '
- Mainly to this(food:quality and quantity) I was refering above,when I told about ideal or stressed environmental/habitat condition for a species.

Hormones maybe are also involved,but they depend on the food.

[jackblack]

Its an interesting subject re teledonte ect .
Here in Australia nth qld where I live Prosopocoilus has major minor intermediates ect with mandible sizes I think its availability of food to the larva , also Phalocrognathus muelleri major males generally have longer antler like jaws but some have major body size and minor jaws but this I feel may be hereditary.
I recently posted a pic of my favourite Lamprima spm male with teledonte /jaws these are not too common at all , yet in Australia we have a number of Lamprima species and only the nth Queensland ones some males are teledonte .I once reared one specimen from a larva and it had a teledonte mandible on one side and a normal mandible on the other side , I have seen specimens like this being collected also years ago but rarely , unfortunately I sold mine to a Japanese high roller collector some years ago , I couldn`t refuse his offer , but know only a matter of time I will come across another .I reared mine in the mushroom bottle and several other teledonte males at the same time.

[thanos]

Did your Lamprima specimen with the one telodonte mandible,had the other mandible to be a smaller(e.g.mesodonte)mandible of smaller male ? Or it had female's mandible from the one side(and maybe any other female's characteristic?)so to be a gynandromorph ?

Well,I found a very nice work on our subject..! There are written many of the things that I supported above..,like that the vast range of body forms/sizes in Lucanids,is due to EVOLUTIONARY modifications to the sizes of body parts(especially mandibles), and like that mandibles are NUTRITIONALLY-DEPENDENT .(But the mechanisms for coupling nutrition with mandible growth remain unknown). The new interesting thing came out from the experiments of this work -and well-supposed by africaone- is that JUVENILE hormone REGULATES EXTREME MANDIBLE GROWTH.(Increased juvenile in prepupal stage,increased size of the body parts,especially the mandibles). And the conclusion is that juvenile has a role in the nutritionally-dependent regulation of extreme mandible growth(so the hormone depends on food,as I said above),and that mechanisms are lying behind the evolution of trait proportion(mandibles). You can read the article here:

www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0021139

Thanos

PS: Note that juvenile is the hormone produced by the corpora allata and its role is to prevent the developement of adult characteristics and to allow the ecdysis during the larval developement.When the production of this hormone tends to stop,the metamorphosis happens.