Shield Bug Nymph

Description:

Pentatomidae; Pentatominae; Unidentified Pentatominae – Shield Bug Nymph. A few days ago (Feb 21, 2023), I posted a spotting of a spider which was on bamboo swaying in the wind - https://www.projectnoah.org/spottings/14... Most of my photos were failures and when I uploaded the few successful shots, I didn’t even notice that there was a tiny bug right next to the spider, in one of them. I am grateful to tomk6886 for spotting the bug and pointing it out to me (very gently, by the way, so as not to make me feel too foolish). I guess that is why professionals use proof readers - an extra pair of eyes is a great help, thanks Tom. The little bug which intruded on my spider photo was so interesting that I just had to try and identify it and this spotting is the result. I cannot definitively identify the bug as there seems to be very little information out there on this one, but I think I can say, with some confidence that it is a nymph of the Hemipteran subfamily Pentatominae. The reason is that, as we all know, the family Pentatomidae gets its name from the fact that all Pentatomids have antennae with five segments (Classical Greek for “five” is “penta”) and in all my searching online, I keep arriving at two main “suspects”, both of which are in the subfamily Pentatominae. I believe this bug is either Brachymna tenuis Stål, 1861 [Synonymous with Balsa extenuata Walker, 1867] (documented present in China, Japan, Taiwan and South Korea) or Aenaria lewisi (Scott, 1874) (documented present in China, India, South Korea and Japan). I have not found any confirmation of Brachymna spp. or Aenaria spp. being present in Philippines and my only reliable sources of information on Brachymna tenuis Stål, 1861 and Aenaria lewisi (Scott, 1874) are – https://bdj.pensoft.net/article/58476/ and https://www.semanticscholar.org/paper/Ch... One small remaining piece of information. I went back to the bamboo and measured the exact twig that the bug was sitting on – it is 2mm thick (closer to 3mm at the node. So, by simple scaling I can say that the bug is almost exactly 4mm long “nose-to-rump” i.e. excluding antennae. That makes me think it must surely be 1st or 2nd instar.

Habitat:

This Unidentified Pentatominae was in the rice mill backyard on a slender twig of a Spiny Bamboo (Bambusa blumeana) locally called Kawayan Tinik.

Notes:

In https://bdj.pensoft.net/article/58476/ there are pictures of Brachymna tenuis nymphs, but only 3rd, 4th and 5th instars. None are a match for my nymph, but if you look at them in reverse order i.e. 5th , 4th and 3rd , the general appearance gets closer to mine – possibly 2nd instar? I have no way of knowing. I cannot find any pictures of Aenaria lewisi nymphs. The most important information I gleaned from this document is that B. tenuis and A. lewisi are the only Pentatomidae species known to be pests of bamboo. The other document in semanticscholar.org was only useful in that it provided distribution information, but neither of the two docs. included Philippines in distribution. Basically what I am left with is the fact that I have a picture which undeniably shows a nymph of the Pentatomidae. It was on bamboo in the Philippines and since it has not yet developed wings, it must have emerged from an egg on that huge bamboo clump.