During the latter half of 2023, I became increasingly active on iNat, spending a considerable amount of time identifying assassin bugs (family Reduviidae) in east Asia, most of which belong to the subfamily Harpactorinae.
I've decided that it might be good to note down some of my thoughts (about Reduviidae) in the form of iNat journals, primarily so that I don't lose track of them, but also to showcase the basis of my ID framework and thought process so that anyone can challenge them when I mess up (I'm not an expert). I'll try to keep the language used simple, andnpretty much all the body parts I'll refer to can be found in this key for assassin bug subfamilies on page 6.
Species level identifications can be extremely difficult from photos, but generally, I find most observations can at least be identified to genus based on these important identfiying features (refer to the images in the key if unfamiliar with terminology):
Usually these should be checked first before relying on colouration. This is not to say that the other features are not diagnostically important, just that they aren't usually (clearly) visible in photographs.
Since I'm from Singapore, I thought it'd be fitting to write about the identification of two Reduviids on the "Biodiversity of Singapore" website as the primary subject for my first journal post. They are Campsolomus nr. sp. "1" and Graptoclopius nr. sp. "1". The former is generally more concerning as it has caused a chain of misidentifications, as it resulted in the genus Campsolomus being added to iNaturalist for the wrong reasons.
In this post, the "first rostral segment" refers to the first visible labial segment (L2) and the "second rostral segment" refers to L3.
Some examples of "Campsolomus" on iNaturalist:
https://www.inaturalist.org/observations/39205450
https://www.inaturalist.org/observations/8051023
I don't think this is Campsolomus, but instead, Rhynocoris aulicus, a species described from penninsular Malaysia. Dorsal and ventral views of its type image are published by the Swedish Museum of Natural HIstory. It's good to note that this species basically looks like a yellow version of Rhynocoris fuscipes, a relatively widespread and well-documented species in Asia.
The species description is given by the entomologist Carl Stål in 1866, a rough translation is as follows:
Now, it's important to note that the BoS website isn't necessarily wrong, as "nr." indicates a degree of uncertainty about the genus. The misidentifications are mainly a result of the genus Campsolomus being added to the site and applied without independent verification of the genus diagnosis from the ID-er.
Campsolomus Stål, 1870 is also a reduviid genus, and its type species is Campsolomus strumulosus Stål, 1870, described from the Philippines. Sadly, there are no observations of it on iNaturalist (yet), but fortunately its type images are also available online. At first glance, structurally, the genus actually resembles Rhynocoris aulicus quite a bit. Separating them requires checking the original genus description (little work has been done on it since its inception), once again given by Stål in 1870. It is available here.
A rough translation is as follows:
From here, by comparing this description with the specimen on the BoS website, we can see that the first rostral segment in the Singapore species is shorter and very much not equal to the second. Additionally, the lateral to lateral-posterior margins of the posterior pronotum in the SG species does not match the profile of Campsolomus, along with some other differences.
The genus tentatively identified as "Graptoclopius" on BoS belongs to the genus Hagia Stål, 1863. The original description is available here for reference, but generally Hagia are a bunch of elongated red and black bugs where the posterior-lateral edge of the pronotum is almost parallel to the longitudinal axis, which clearly contrasts things like Rhynocoris and many other robust Harpactorines where the corresponding portion curves inwards towards the scutellum. It's hard to give a species level identification, as species delineations in Hagia are weak, mostly due to being extremely dated. The specimen on BoS more or less fits both the description of Hagia punctoria Stål, 1863 and Hagia sarawakensis Miller, 1941.
The type species of Graptoclopius is Graptoclopius helluo Stål, 1863, described from New Guinea. You notice that the species name preceeds the genus name, and that's because Stål initially described it as Reduvius helluo, the type image of which can be found here. The original genus description of Graptoclopius by Stål can be found here, and is translated roughly as follows:
This description is actually quite applicable for Hagia too, except that in Hagia, the first rostral segment is longer than the second. From comparing the type specimen of G. helluo with Hagia, I think another distinguishing character would be the high pilosity on the legs of Graptoclopius.
Here are some observations on iNaturalist which are likely G. helluo, for a better idea of what a member of the genus looks like:
https://www.inaturalist.org/observations/176023730
https://www.inaturalist.org/observations/181960968
https://www.inaturalist.org/observations/177679070
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