Based on examination of its holotype, Helonotus pallidulus Walker, 1873 is transferred to the genus Heza Amyot & Serville, 1843 with the resulting new combination: Heza pallidula (Walker, 1873), comb. nov. (Hemiptera, Heteroptera, Reduviidae, Harpactorinae, Harpactorini). A comparison with the similar Heza ventralis Stål,1872 is provided.

Ecuador, Neotropical region, new combination, Ploeogaster pallidulus

Harpactorinae is the largest subfamily of Reduviidae and is represented by the tribes Apiomerini and Harpactorini in the Neotropical region (Gil-Santana et al. 2015). Harpactorini is the most diverse Reduviidae tribe with 53 recognized genera in the Neotropical region (Forero et al. 2008, McPherson and Ahmad 2011, Forero 2011, 2012, Swanson 2012, Gil-Santana 2015, Gil-Santana et al. 2015, Zhang et al. 2016, Lapischies et al. 2019). The only key to separate the genera is by Stål (1872), now badly out of date (Forero 2011). Of all genera of Harpactorini in the Neotropical region, just a few have been revised taxonomically or redescribed.

Walker (1873) described Helonotus pallidulus Walker, 1873 based on a specimen (described as a male) from “Cuenca”, thereby placing a New World species in the Old World genus, Helonotus Amyot & Serville, 1843. In the catalog of Lethierry and Severin (1896) this species was included among the Harpactoridae “Genera et species Harpactoridarum subfam. incerti loci systematici”. Distant (1903) included it in the New World genus Ploeogaster Amyot & Serville, 1843, stating that he had “not sufficiently compared this [Ploeogaster pallidulus] with other species of the genus [Ploeogaster] to say that it is not a synonym.” Since then, Ploeogaster pallidulus has only been cited in catalogues (Wygodzinsky 1949, Maldonado Capriles 1990).

In the current work, we confirm that the holotype of Helonotus pallidulus, deposited in the Natural History Museum, London, does not belong to either Helonotus or Ploeogaster. The main differences being that in P. pallidulus a postantennal spine is present (rather than a short tubercle in Ploeogaster or both absent in Helonotus) and the disc of the hind lobe of the pronotum has a pair of spines in P. pallidulus (rather than a pair of tubercles in Ploeogaster and one or two pairs of tubercles in Helonotus) (Amyot and Serville 1843, Malipatil 1986, 1991). However, as commented in detail below, the above characteristics observed in the holotype of H. pallidulus are entirely concordant with members of the New World genus Heza Amyot & Serville, 1843, a genus revised by Maldonado Capriles (1976, 1983).

For the present study, the holotype of Helonotus pallidulus, deposited in the Natural History Museum, London, United Kingdom (BMNH), was directly examined (Figs 1–6).

After imaging the specimen (Figs 1, 3–5), the antennae were relaxed and moved forward in order to obtain a clearer image of the postantennal spine. Additional photographs were taken for a better visualization of the pronotum and postantennal spines (Figs 2, 6).

General morphological terminology mainly follows Schuh and Slater (1995). However, the [visible] segments of the labium are numbered as II to IV, given that the first segment is lost or fused to the head capsule in Reduviidae (Weirauch 2008, Schuh et al. 2009).

When describing label data, a slash (/) separates the lines and a double slash (//) different labels.

The previous placement of this species in Ploeogaster by Distant (1903) is incorrect, as some characteristics of the latter are different, such as the absence of postantennal spines (only short postantennal tubercles are present) and the hind lobe of the pronotum without four sharp spines; only with two (lateral) spines, while on the disc, instead of spines, there is a pair of rounded tubercles. Had Distant (1903) “sufficiently compared [Helonotus pallidulus] with other described species”, he possibly would have placed the species in a different genus.

The transfer of Helonotus pallidulus to Heza is in accordance with the following features considered as diagnostic for the genus (Amyot and Serville 1843, Maldonado Capriles 1976): head shorter than pronotum, with postantennal spines (Figs 1, 2, 5, 6); pronotum: fore lobe with a pair of blunt or pointed spines on the disc (Figs 5, 6, tf), hind lobe with four sharp spines (Figs 1, 2, 5, ds); mesopleura with a plica (Fig. 5, p); abdomen spatulate, somewhat widened before apex but behind middle of abdomen (Fig. 3).

Besides confirming that the characteristics of Heza pallidula are entirely in accordance with those attributed to Heza, it is also possible to conclude by consulting the revision, keys, descriptions and redescriptions provided by Maldonado Capriles (1976, 1983) and Maldonado Capriles and Brailovsky (1983) that this species does not correspond to any previously described species of this genus and must be maintained as a valid species.

Heza pallidula seems to be most similar to Heza ventralis Stål, 1872. The latter was described by Stål (1872) and a photo of its type has been made freely available by the Swedish Museum of Natural History (Naturhistoriska riksmuseet, NRM) at http://www2.nrm.se/en/het_nrm/v/heza_ventralis.html. Maldonado Capriles (1976) redescribed H. ventralis based only on female specimens. The females of H. pallidula and H. ventralis share some structural similarity, such as approximate length and shape of the body, similar size of postantennal spines (Fig. 6), and both size and shape of the pronotal spines (Figs 1–3, 5, 6), and the absence of spines on all connexival segments; the three latter characteristics shared with very few species of the genus. Most species of Heza have one or more connexival segments spined on its apical angle (Maldonado Capriles 1976, 1983, Maldonado Capriles and Brailovsky 1983). On the other hand, the sericeous white areas on the thorax and more extensively on abdominal sternites are a clear-cut characteristic to separate H. ventralis from all other species in the genus, including H. pallidula. In H. pallidula, the reddish portions of the hemelytra (base and distal portion of corium and basal half of the clavus) and connexivum faintly darkened dorsally at basal half of segments IV–VII (Fig. 1) differ from the uniformly brownish-gray clavus, corium and connexivum of H. ventralis. Whereas the postantennal spine is conspicuously bowed with the apex slightly directed anteriad in H. pallidula (Fig. 6), it is straight and directed dorsad in H. ventralis (Stål 1872, Maldonado Capriles 1976).

The original spelling of the specific name pallidulus was changed to pallidula in the new combination because, according with the International Code of Zoological Nomenclature (ICZN 1999), if a species-group name is a Latin adjective in nominative singular, it “must agree in gender with the generic name with which it is at any time combined” (Art. 31.2).

We thank Ken Merrifield and Stuart Cole (BMNH) for taking the type images. We are also very grateful to Jocelia Grazia (Universidade Federal do Rio Grande do Sul, Brazil), Tadashi Ishikawa (Tokyo University of Agriculture, Japan), Catarina Lopes (Instituto Oswaldo Cruz, Rio de Janeiro, Brazil), Daniel Swanson (University of Illinois at Urbana-Champaign, USA), and Guanyang Zhang (Arizona State University, USA), for their valuable comments and suggestions.