This post turned out to be a bit of a mess and much longer than I originally intended as I gradually unearthed more and more information about the bugs, I may return to clarify and elaborate more on certain things in the future, especially the bit on Toxocamptellus.

1. Introduction

Vesbius Stål, 1865 is a genus of relatively small Harpactorines (Reduviidae: Harpactorinae) distributed in the Indomalayan realm. One particular species, Vesbius purpureus (Thunberg, 1783), is widespread throughout the region. It often inhabits urban habitats, a trait which may have contributed to its range. The 15 Vesbius species that have been described more or less all have red bodies and mostly black heads and legs. This aposematic motif is adopted by some Harpactorines in other genera which inhabit the same region, causing many of them to have been misidentified as Vesbius on iNaturalist. This post seeks to clarify the generic position of these bugs, and also to act as a reference for my own future identifications.

2. TLDR - What is NOT Vesbius

A concise (although somewhat lacking) diagnosis of Vesbius can be found here provided by W. L. Distant. Notably:

Distinguished by the structure of the head, the postocular region being nearly three times longer than the anteocular area, the eyes are inserted near the apex of the head.

(shown in image below)

This head structure is not found in any of the other genera which may resemble Vesbius superficially. This characteristic can also be observed in nymphs.

3. Further elaboration on the non-Vesbius genera

More information for differentiating between the aforementioned species not belonging to Vesbius.

3.1 "Sphedanolestes"

In 1874, in an attempt to provide better taxonomic treatment for Sphedanolestes Stål, 1866, the entomologist Carl Stål assigned a number of subgenera to the growing genus. This consisted of:

1. Aulacosphodrus (later raised to genus) - Afrotropical species with long postocular regions
2. Graptosphodrus - New Guinea "Sphedanolestes"
3. Haemactus
4. Lissonyctus
5. Sphedanolestes - What I interpret Stål to have considered the "typical" Sphedanolestes, based on resemblance to the East Asian Sphedanolestes impressicollis Stål, 1866 (type of genus)
6. Sphactes

These classifications were discontinued and are not used today, but they still give us an idea into the species that superficially resemble Vesbius.

He keyed the subgenera here along with the Sphedanolestes species described at the time. The dichotomous key is presented in an unsual way by today's standards and is a little hard to follow, so I've converted it into this flow chart:

The species that resemble Vesbius, based on my interpretation, belong to what Stål considered Lissonyctes and Haemactus. Here is what Sphedanolestes politus (type of Lissonyctes) looks like: http://www2.nrm.se/en/het_nrm/p/sphedanolestes_politus.html . Its similarity to Vesbius purpureus is noted in its original description available here ("Vesbio purpureo haud dissimilis" → "Not unalike Vesbius purpureus"). This makes the subgenus a good fit for Harpactorines similar to the smaller of the two Sphedanolestes featured in the first image.

Stål used pronotum colouration to separate these two subgenera (along with others) from the "typical" Sphedanolestes (b, bb), and the angles of the posterior pronotal lobe to separate them from each other (i, ii). Interestingly, he notes that the first (visible) rostral segment of Haemactes widens posteriorly. This character, combined with the unusually robust body shape and S. trichrous being observed to be stenophagous on Crematogaster ants (pers. comms with @psophis_zelun), suggests that species described under this subgenus might not belong to Sphedanolestes at all.

3.2 Toxocamptellus

Toxocamptellus Breddin, 1900 is perhaps the most poorly documented genus featured in this post, and was first described by Breddin in 1900 here, with minimalistic drawing of the head and pronotum available here (Fig 11). Notably, it is the most robust of the bunch, and a characteristic to distinguish it from the other species/genera featured in this post would be to compare the length of the head and posterior pronotal lobe (length of head < length of posterior pronotal lobe).

Bonus: Toxocamptellus misidentified as Vesbius purpureus on flickr - https://www.flickr.com/photos/61827574@N03/49854803707

Posted on May 28, 2024 06:01 PM by eggshe11