First journal post and some clarifications on the documented Reduviidae of Singapore

1. Introduction

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.

2. Reduviidae photo identification

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):

  1. Antennal shape and segments
  2. Head dorsal features (spines at base of antenna, presence of ocelli, relative lengths of anteocular and postocular regions, etc)
  3. Rostrum structure and relative lengths of segments (can forget about it if no lateral/ventral shots)
  4. Pronotum dorsal features (spines, relative lengths of lobes, etc)
  5. Scutellum shape and presence of spines
  6. Legs - Femora and tibiae (especially front pair)
  7. Connexival segments (how drawn out they are/presence of spines or other protrusions)
  8. Hemelytra - generally how much the wings exceed the abdominal margin

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.

3. Amendments to identified Reduviidae in Singapore

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.

3.1 "Campsolomus" nr. sp. "1" → Rhynocoris aulicus Stål, 1866

Some examples of "Campsolomus" on iNaturalist:

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:

R. aulicus Stål --- (Body) Croceus, sprasely with gray pubescence. Two large spots on the upper part of the head, one on the front, the other behind the middle, the antennae, the two apical segments of the rostrum, a transverse impression on the thorax, a basal spot on the scutellum, some small lateral spots on the thorax, transverse lines on the lateral sides of the ventre, the apical part of the femur, the base and apices of the tibiae, and the tarsi black. Clavus, corium internally and membrane black-violaceous. Ventrally, before the black lines, decorated with whitish spots. Male. Length 14mm, width 3.5mm.
From: Malacca.
The anteocular part of the head is somewhat shorter than the postocular part. The first rostral segment is much shorter than the second, and a little longer than the anteocular part of the head. Scapus subequal to head + half the length of the thorax. Anterior pronotral lobe posteriorly obsoletely and obtusely bituberculate, posterior lobe with posterior corners slightly prominent. The scutellum apically slightly foliaceous. Hemelytra exceeding apex of abdomen. Legs long, not nodulose.

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.

3.1.1 So what is a Campsolomus anyway?

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:

The body is very oblong. The head is slightly shorter than the thorax, unarmed, postocular part longer than the anteocular part, gradually tapering towards the posterior when seen on the side, anteocular part not elevated. Ocellar tubercule distinctly elevated. Antennal segment 1 about 1.5 times the length of head. First and second rostral segments equal in length. Thorax distinctly constricted, with anterior corners drawn up into sharp conical tubercles. The impression of the anterior pronotal lobe does not extend to the tip. Posterior pronotal lobe twice as long as the anterior lobe, the lateral corners obtuse, rounded, very slightly prominent, with the rear and lateral-posterior margins totally conjoinedly reflexed, the latter depressed, obtusely rounded. Scutellum triangular, with a very distinct trivial sulcus. Hemelytra somewhat exceeding the distal end of the abdomen. Mesosternum deprived of an anterior tubercle. Abdomen somewhat wider than hemelytra, rounded on both sides. The legs are of moderate size, unarmed, anterior femora a little thicker than posterior. Tarsi of moderate size. Toothed claws.

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.

3.2 "Graptoclopius" nr. sp. "1" → Hagia sp.

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.

3.2.1 So what is a Graptoclopius anyway?

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:

The scutellum is very elevated. Head a little shorter than thorax; the first rostral segment somewhat shorter than the second, the anterior of the posterior pronotal lobe and the anterior pronotal lobe conjointly longitudinally impressed, the region posterior to the impression somewhat convexly elevated, the posterior edges of the latter neither raised nor reflected, the posterior margin straight; abdomen slightly expanded; the legs are long, thick, the tibia, especially in females, thickened before the middle.

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:

הועלה ב-פברואר 24, 2024 06:55 לפנה"צ על ידי eggshe11 eggshe11


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