Possible genetic deformities on B. craniifer or...?

crepsis

crepsis

Third Instar
Well, I'm seeing a slight "notch" on the underside of the last segment of the abdomen in the *exact* same place on several (if not all) males of my adult B. craniifers. It makes the underside of the last segment appear asymmetric, and if the underside of the male roach looked like the letter U it would be on the left side of the last segment, with a single very, very small "bristle" sticking out of the notched area. The notched area also appears lighter in pigment, almost white or tan, to the rest of the segment, which is black. It almost looks like some kind of injury, but since it appears in literally the exact same place on them, it leads me to believe it's something else. Does anyone know what I'm talking about? What is this? I've attached the best photo I could snap at the moment...if needed, I'll see if I can get a better one later...the tiny bristle that I was talking about is the tiny little black "triangle" that appears inside and near the bottom of the white "notch" area.

Also, some of the roaches, both male and female, seem to be missing all or part of just one of their antennae, since they were nymphs. Would this be the result of injury or something else. If the antennae are damaged as a nymph, do they grow back fully in the successive molts?

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...it's more aesthetic than anything else, they don't appear to be physically affected by this. This is my first colony, and I'm just wondering if this is something that all male captive bred B. craniifer have and if it can be bred out through selective breeding, or if maybe this is a husbandry issue, or if this is a natural phenomenon? And as far as I can tell most of the males have this, short of picking out the roaches one-by-one to verify that they all do. Again, I must reiterate, it looks almost exactly the same, in the exact same spot on the males that I have gotten a look at, I've counted at least 4 that are like this so far and at that point, they either move around too much and I can't tell who's who anymore, or the rest are in hiding (it's very hard to see the underside of a roach in it's container!)...actually, come to think of it, I don't think I've seen a male that does not have this.

Orin, have you noticed this before?

 
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...If you look to any male Blaberus sp. you will find the same thing.....B. craniifer, B. giganteus, B. colosseus, B. bolivianus, B. parabolicus, B. fusca, B. atropos all show this same trait. Nothing to worry about! This is present in some other genus as well.

 
Ok! I still have some questions though...

So then is it a genetic trait, or is this a type of injury obtained when mating? I noticed that when mating, one of the roaches may try to run away, and ends up dragging the other around for a bit...which is why I was wondering if it could be a 'natural phenomenon' ( a result of being pulled apart after mating is finished) as opposed to a genetic trait.

Are there males that do not have this trait, or is it something that 100% of males from B. craniifer, B. giganteus, B. colosseus, B. bolivianus, B. parabolicus, B. fusca, B. atropos carry?

What about B. discoidales?

Do you know if wild specimens carry this trait as well?

Thanks! You eased my mind quite a bit! In addition, I'm finding this all very interesting to think about the genetics of it all...

 
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Could you post a pic of the female so those of us who don't have any mature Blaberus can see the difference? That'd be good.

 
I have 4 male B. Giganteus that have that. They have never seen a female and still have it, so it's nothing brought about by mating.

 
RosenKrieger said:
I have 4 male B. Giganteus that have that. They have never seen a female and still have it, so it's nothing brought about by mating.
Click to expand...
So it's definitely genetic.

Rosenkreiger: Do you have any males that do not have that, or do they all have it? Did you happen to notice when they were nymphs if the "notch" was apparent at that time?

I've just been doing some thinking about it, and if there are males that do not have that trait, it would probably be fairly easy to breed a line that do not show it in as little as 2-3 generations from several (or many!) initial pairings - with a LOT of work (fun), time, and LOTS of space/containers! But, if all males show that trait, then it's probably not possible...which it sounds like it is the case, since males from all those other species show the same trait :( It would be fun to give a massive project like that a go, and achieve the results though! I haven't been able to inspect every one of my males at this point yet, to see for myself, because ...(see below)

BugmanPrice: I took that photo from about 12 inches away with a 12MP camera...my females are carrying oothecae right now, and I don't want to do anything that might jeopardize the babies! These are my first roaches, they just matured from nymphs about 2-3 months ago, so I want some successful 'births' before I go mucking about in their tank too much. I'll see if I can get a photo of one of the females, but for some reason they are harder to get pics of the underside as they seem to be a bit less outgoing than the males.

 
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All of my males have that notch. The nymphs don't. It's just something that is there with that genus, apparently.

 
A few notes:

There are about as many mating strategies in roaches as there are species. Most species seem to be identified by the male of the species and more specifically by the male genitalia. Imagine 5000 species of roaches, and 5000 different shapes of male roach genitalia. The add into this the fact that roaches all have various ways of maintaining copulation and courtship via different mechanisms and mate-holding devices. Male roach genitalia is often formed into a single, dual, or multi part or multi functional apparatus or set of apparatus designed to either maintain contact during copulation or otherwise facilitate opening and fertilizing the female.

Male genitalia in roach genus and species is such a complicated topic..... an internet search for images (diagrams) of cockroach genitalia may turn up a few examples of why this is. They do not have the simple utilitarian organs that humans do.

LONG story short- that 'notch' is there to allow the shape of the genitalia to manuver as it needs to for contact/connection.

 
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