Rasahus albomaculatus, the White-Spotted Corsair

Though the Hemiptera began their long evolutionary history as plant-feeders, many of their subgroups later switched to a predatory lifestyle, their suctorial mouthparts being just as suited for stabbing flesh as vegetation. Among the most successful of the predatory bugs where the assassin bugs of the family Reduviidae.

Image copyright Jacob Gorneau.

This is Rasahus albomaculatus, a widespread assassin of the Neotropical region, found from Mexico to Argentina (Coscaron 1983). Though not one of the largest members of its genus, R. albomaculatus is a decent-sized bug, growing close to an inch in length. Rasahus is a genus of the reduviid subfamily Peiratinae, commonly known as corsairs for their fearsome aspect. Features distinguishing Rasahus from other genera of corsairs include their large eyes, a deep grove across the head in front of the ocelli, long procoxae, and well-developed spongy pads on the fore- and mid-tibiae. Rasahus albomaculatus is distinguished from other species of the genus by its colour pattern. The body is mostly black with white patterning on the wings. Stripes along the top of the wing and across the mid-length form a crude H-shape when the wings are closed, with separate spots towards the base of the wing and towards the tip. Other noteworthy features include a lack of granulation on the pronotum, and a rounded apex to the scutellum (Swanson 2018).

Corsairs are mostly predators of other insects and not often dangerous to humans (though their bite is supposed to be very painful). Indeed, they may be beneficial to humans as among their prey are believed to be other reduviids of the subfamily Triatominae, the blood-sucking "kissing bugs" that spread Chagas disease (contrary to the Wikipedia page on the western corsair R. thoracicus, corsairs do not spread Chagas themselves). Rasahus albomaculatus may provide its vertebrate co-habitants with far more comfortable living conditions.

REFERENCES

Coscarón, M. del C. 1983. Revision del genero Rasahus (Insecta, Heteroptera, Reduviidae). Revista del Museo de La Plata (nueva serie) (Zoologia) 13: 75–138.

Swanson, D. R. 2018. Three new species of Rasahus, with clarification on the identities of three other Neotropical corsairs (Heteroptera: Reduviidae: Peiratinae). Zootaxa 4471 (3): 446–472.

The Mirines

Every profession has its quirks, tricks of the trade that are difficult to learn and appreciate except through direct experience. One quirk of entomology is that specimens of each distinct type of insect will have their own nuances for the best method to preserve and present them. And there are some particular types of insect that can be particularly challenging in that regard. Which is a roundabout way of saying: I am not a great fan of mirids.

Green mirid Creontiades dilutus, copyright CSIRO.

Mirids are the largest recognised family of the true bugs in the Heteroptera, with over 11,000 species known worldwide and presumably many more remaining undescribed. They can be distinguished from most (though not, it should be stressed, all) other bug families by the presence of the cuneus, a distinct cross-fold near the outer tip of the hemelytron (the toughened basal part of the fore wing). Most mirids can be further recognised by the absence of ocelli. They are mostly smaller bugs, generally somewhat soft-bodied, and mostly plant feeders though there are some notable exceptions. They also (and this is the reason why they have sometimes been the object of my animus in the past) have a tendency to be what I can only describe as weirdly flimsy. Most insect specimens, at least while stil fresh and relaxed, hold together reasonably well when subject to basic handling. Mirids, on the other hand, will throw off legs if you so much as look at them too hard.

An ant-mimicking mirid, Dacerla inflata, copyright Judy Gallagher.

Mirids are divided between several subfamilies, with the type subfamily Mirinae including well over 4000 species (Kim & Jung 2019). Mirines tend to be relatively large compared to other mirids (up to a bit over half a centimetre in length) and are characterised by features of the genitalia, together with a pair of lamellate, divergent parempodia (fleshy structures that may help in gripping onto things) at the end of the legs between the claws. Other notable features (shared with the closely related Deraeocorinae) include a deeply punctate pronotum, and a relatively long beak that extends beyond the mid coxae at rest. Several species of Mirinae are notable pests. The green mirid Creontiades dilutus is one of the more significant bug pests of crops in Australia, attacking a wide range of hosts including cotton, stone fruit, potatoes, legumes and many more (Malipatil & Cassis 1997). It generally feeds from growing points, killing new buds and inhibiting the production of flowers and new growth. Other polyphagous pests causing similar damage include the tarnished plant bugs of the genus Lygus, whose vernacular name is somewhat self-explanatory, and the alfalfa bug Adelphocoris lineolatus.

Tarnished plant bug Lygus pratensis, copyright Hectonichus.

Six tribes have been recognised within the Mirinae, distinguished by their overall habitus. The Mirini, the largest tribe, have a more or less ovoid body shape with a distinct, raised pronotal collar and opaque hemelytra. The Hyalopeplini have a similar body shape to Mirini but transparent hemelytra. The Restheniini have a reduced evaporative area on the abdomen. The Stenodemini and Mecistoscelini are long and slender with long appendages, with the head directed forward in the Stenodemini. The Herdoniini are ant mimics, presumably for defence from predators. The appearance of an ant waist is achieved by a narrowing of the mirid's own body and wings, and/or an appropriately placed white triangular marking across the hemelytron. Despite the superficial distinctiveness of the tribes, however, a phylogenetic study of the Mirinae by Kim & Jung (2019) found at least two of them to be paraphyletic, with Mecistoscelini being nested within Stenodemini, and Hyalopeplini and Restheniini within Mirini. The affinities of the Herdoniini, unsampled by Kim & Jung, remain to be established.

REFERENCES

Kim, J., & S. Jung. 2019. Phylogeny of the plant bug subfamily Mirinae (Hemiptera: Heteroptera: Cimicomorpha: Miridae) based on total evidence analysis. Systematic Entomology 44: 686–698.

Malipatil, M. B., & G. Cassis. 1997. Taxonomic review of Creontiades Distant in Australia (Hemiptera: Miridae: Mirinae). Australian Journal of Entomology 36: 1–13.