Vietnam

Holy conglobulation, Batman!

/ Ted C. MacRae / 24 Comments

It’s a pill bug… no, it’s a roach. It’s a pill roach!

Earlier this month I made a quick trip out to California to see my good friend Chuck Bellamy receive his Honorary Membership in The Coleopterist Society. While I was there, I got a chance to spend some time with Chuck’s labmate Martin Hauser. Although Martin is a specialist of flies, he shares my fascination with unusual arthropods of all types and made available for me to photograph this adult female Perisphaerus sp. (order Blattodea, family Blaberidae), or “pill roach”. Seventeen species from southeast Asia and Australia have been described in this genus (Beccaloni 2007), but which (if any) this individual represents remains unknown.

In contrast to ”normal”-looking males, adult females exhibit a ”wingless, half-ellipsoid” morphology.

The most obvious characteristic of species in this genus is the ability of females to roll up into a ball; i.e., conglobulate.¹ Clearly this is a defensive morphotype, but curiously only females possess this ability—males are winged and exhibit the more flattened morphology typical of many cockroaches. Martin and I were unable to get this particular individual to completely enroll (we must not have been scary enough), but when it does the posterior abdomen fits tightly against the pronotal margin, covering all sensory organs and leaving no soft tissues exposed, gaps to enter or external projections to grab (Bell et al. 2007).

¹ I must thank Brady Richards, who, in his answer to ID Challenge #18, used this word to coin the phrase that would eventually become the title of this post.

Adult females apparently exhibit not only maternal protection but also nutrition.

But why should only females and not males exhibit this defensive morphotype? One would think that both males and females are equally threatened by predators. Apparently this is related to their unusual form of uniparental (maternal) care (Choe & Crespi 1997).  Early-instar nymphs in this genus remain closely associated with their mother and cling to her underside until they reach the third instar. These early-instar nymphs are not only blind, but they also exhibit a narrowed head with specially modified mouthparts that fit precisely into two pairs of orifices located on the female underside between the middle and hind pairs of legs. Whether the nymphs are feeding on glandular secretions or female hemolymph remains unknown, but regardless only a limited number of nymphs can be handled by a female at one time. This represents an unusual level of energetic investment in offspring among insects—especially among cockroaches, and thus the female has an interest in protecting that investment. Sealing them up inside an impenetrable ball is certainly one way to protect the nymphs.

Despite first impressions, six legs and a very ”cockroach-ish” head belie its true identity.

Conglobulation has actually arisen several times amongst arthropods. Obviously pill bugs (a.k.a. roly-poly bugs) are the first group that comes to mind in this regard, but Eisner & Eisner (2002) illustrate nearly identical morphology in two oniscomorph millipedes as well as isopods and Perispharus and also describe strikingly similar behavior by the larva of Leucochrysa pavida  (family Chrysopidae).

Many thanks to those of you who participated in ID Challenge #18. As of now, the comments for that challenge are closed, and I will reveal the comments and award points shortly. My sincere thanks again to Martin Hauser for allowing me to photograph this most interesting insect!

Edit 5/28/12, 12:55 a.m.: For the first time ever, we have a 3-way tie for a BitB Challenge win—Sam Heads, Brady Richards, and Mr. Phidippus all earned 12 points to share the top spot in this challenge. Since these three gentlemen were already the three leaders in BitB Challenge Session #6, there is no change to the leaderboard in the overall standings (44, 42 and 37 points, respectively). However, Dennis Haines (34 points) is hanging close, and Tim Eisele (25 points) still has a shot at the podium. Any number of others following closely behind could also find themselves on the podium if any of the three leaders should falter down the stretch.

REFERENCES:

 Beccaloni, G. W. 2007. Blattodea Species File Online. Version 1.0/4.1. World Wide Web electronic publication. <http://Blattodea.SpeciesFile.org&gt; [accessed 27 May 2012].

Bell, W. J., L. M. Roth & C. A. Nalepa. 2007. Cockroaches: Ecology, Behavior, and Natural History. The Johns Hopkins University Press, Baltimore, Maryland, 230 pp.

Choe, J. C. & B. J. Crespi. 1997. The Evolution of Social Behavior in Insects and Arachnids. Cambridge University Press, Cambridge, U.K., 541 pp.

Eisner, T. & M. Eisner. 2002. Coiling into a sphere: defensive behavior of a trash-carrying chrysopid larva Leucochrysa (Nodita) pavida (Neuroptera: Chrysopidae). Entomological News 113:6–10.

Copyright © Ted C. MacRae 2012

ID Challenge #18

/ Ted C. MacRae / 41 Comments

It’s time for another identification challenge. Currently we are in Challenge Session #6, with two challenges down (SSC#12 and IDC#17) and probably four more to go (including this one). Can you identify the critter in this photo? I’ll give 2 pts each for class, order, family and genus.

I think it would be good to restate the ground rules that I use in these challenges, as they have evolved somewhat since I first began these challenges and don’t seem to be easily accessible in their entirety to those who have begun participating more recently. They are:

  1. Points will be awarded for correctly named taxa—usually 2 pts each for order, family, genus and species.
  2. Points will only be awarded for the taxa requested.
  3. Taxa must be correctly spelled to receive full credit (this includes italicization for genus and species—and yes, italicization is easy in HTML, just look it up). Misspelled or non-italicized names may receive partial credit.
  4. Taxa must be explicitly stated to receive full credit. For example, if I request order, family, genus and species for Buprestis rufipes, but only genus and species are given in the answer, then “Coleoptera” and “Buprestidae” are “implied” taxa. I can’t give full credit for implied taxa but may give partial credit.
  5. In the case of outdated nomenclature, I won’t judge too harshly if the taxon is obscure or there is still disagreement about rank. However, obvious or easily referenced obsolescences (e.g. “Homoptera”) will get dinged.
  6. Bonus points may be given (at my discretion) for providing additional relevant information (e.g., diagnostic characters, biological/ecological uniquities, clever jokes, etc.). I’m more inclined to give bonus points for unusual features of biology/morphology/ecology, etc. that are not readily found in easily-found, Wikipedia-type summaries of the subject.
  7. Be sure to examine each post carefully in its entirety for the possible presence of clues 🙂
  8. Comments will be moderated during the 1- to 2-day open challenge period to allow all a chance to participate (i.e., you don’t have to be first to win!).
  9. In the case of multiple correct answers, “early-bird” tie-breaker points will be awarded to those that answered correctly first. The more people you beat to the punch with the correct answer, the more early-bird points you get.
  10. Submitted answers will be revealed at the end of the challenge period along with the number of points earned. This is generally followed closely by a new post discussing the subject in greater detail. Also, because I’m such a big Survivor and Jeff Probst fan, I’ll also say that “once the points are read the decision is final!”
  11. Winners of individual challenges get nothing more than my accolades; however, session winners get real loot! Thus, it pays to play consistently and try even when you don’t think you know the answer. Top three points earners at the end of each session (usually 5 to 6 individual challenges) get to choose from selection of gifts that will be communicated to the winners by email.

Copyright © Ted C. MacRae 2012