Haematoloecha merkli, Santillan & Rédei, 2025

Santillan, Ian Gabriel C. & Rédei, Dávid, 2025, A new micropterous species of Haematoloecha from Vietnam (Hemiptera: Heteroptera: Reduviidae), Zootaxa 5575 (2), pp. 295-304 : 301-303

Comparison of Haematoloecha merkli sp. nov. with related taxa

Character states of Haematoloecha merkli sp. nov. recognized as of diagnostic value are discussed below.

(1) Microptery. —The new species evidently differs from most of the described species of Haematoloecha by its microptery. Although the hemelytra might be shortened to different degree in other congeners, namely H. rufithorax (Breddin, 1903) and H. limbata Miller, 1953 , micropterous morphs (entirely lacking a differentiated membrane) are known in only two other species of the genus: H. puetzi ( China: Sichuan) and H. curta (Taiwan). Both of the latter two species were treated by Rédei & Tsai (2012). The new species is immediately distinguished from them based on its colour (ground colour dark-brown with yellow and red markings on the head, thorax and abdomen dorsally; all legs with broad red annuli surrounding femoro-tibial articulations) ( Figs. 1–12 ); micropterous morphs of the other two species are fairly uniformly dark-brown, at most with some indistinct pale markings in H. curta ( Rédei & Tsai 2012: 4, figs. 1–2). In addition to colour, the female of H. puetzi (male unknown) differs from the female of H. merkli sp. nov., among others, by the distinctly larger eyes, different shape of the postocular lobe of the head, relatively longer anterior lobe of the pronotum (as compared to the length to the posterior lobe), mesothoracic wings surpassing the posterior margin of the metanotum, the fore femur being much less thickened, and the legs being covered by a relatively long and dense pilosity ( Rédei & Tsai 2012: 5, figs. 8–11). Males and females of H. curta conspicuously differ from the respective sexes of H. merkli sp. nov. among others by the highly different shape of the head (more elongate, anteriorly less tapering in lateral view, with a dorsally elevated proximal portion of the clypeus in both sexes of H. curta ) and the smooth anterior lobe of the pronotum. A comparison of specimens of these species suggests that the similarity of their general habitus is superficial, greatly caused by the micropterous condition of the wings, and the three species are probably not closely related phylogenetically.

All other species that are currently placed into Haematoloecha are known from macropterous individuals only. The eventual occurrence of micropterous morphs in these species, however, cannot be excluded; the hypothesis that individuals recognized here as pertaining to H. merkli sp. nov. represent merely micropterous morph of an already described species is considered below. As wing polymorphism always more or less heavily affects the skeletal morphology of all thoracic segments, associating conspecific individuals of different wing morphs might be challenging in Reduviidae ( Zhang & Weirauch 2010, Rédei et al. 2012). However, wing polymorphism normally has no impact of the characters discussed below; therefore, they are offered as potentionally of diagnostic value for distinguishing H. merkli sp. nov. from these species.

(2) Colour and sculpture of pronotum. —In H. merkli sp. nov. the anterior lobe of the pronotum is provided with distinct, broad, conspicuous, symmetrically arranged papillar elevations that are yellowish, contrasting with the dark-brown ground colour; the posterior lobe is distinctly bicolorous, dark-brown with the humeral lobes yellowish ( Figs. 7, 9 ). In macropterous morphs of all species currently placed into Haematoloecha , the surface of the pronotum is smooth and lacks elevated portions. Although different colour patterns occur in the genus (anterior and posterior lobes of the same colour, or only median longitudinal and transverse sulci with dark pigmentation; in other species, the colour of anterior and posterior lobes contrastingly differ; in still other species, the disc and humeral lobes of the posterior lobe also contrastingly differ), none of the described species have a bicolorous anterior lobe of the pronotum.

The anterior lobe of the pronotum is smooth in the majority of the genera of Ectrichodiinae occurring in Indomalaya. A distinctly sculptured anterior lobe occurs in a number of ectrichodiine genera, at least in some, or frequently in all species of e.g. Cimbus Hahn, 1831 , Tamaonia China, 1940, Scadra Stål, 1859 , Parascadra Miller, 1953 , Labidocoris Mayr, 1865 , Bayerus Distant, 1904 , Libavius Distant, 1904 and Caecina Stål, 1863 , but in all of these the condition is fairly different from H. merkli sp. nov., and all of these genera are different from H. merkli sp. nov. at generic level based on various other characters (cf. Cook 1977). A condition comparable to H. merkli sp. nov. apparently occurs only in Rhysostethus Hsiao, 1973 . This genus is currently monotypic; its type species, Rhysostethus glabellus Hsiao, 1973 ( China: Sichuan), is known from a macropterous male holotype and a micropterous female (the latter is the holotype of Parascadra breuningi Kerzhner & Günther, 2004 , now a junior synonym of R. glabellus ) (Rédei et al. 2012). The micropterous morph of this species is superficially similar to micropterous individuals of H. merkli sp. nov., but it can readily be distinguished by its uniformly dark-brown colour except pale bands along anterior margins of dorsal laterotergites of abdominal segments III–VII, the different shape of the pronotum (with a pair of broad tubercles at the two sides of the meson anteriorly), and most importantly the highly modified prothoracic legs considered as diagnostic for Rhysostethus : ventral margin of femur concave, forming a sharp keel, abruptly narrowed subapically, distal portion of tibia strongly bent (Rédei et al. 2012: 345, figs. 8 and 11).

(3) Conspicuously bicolorous legs (dark, femorotibial articulations broadly yellow to red).—Among the species known from macropterous individuals, legs with areas of more or less contrastingly different colour are found only in H. rubescens ( Japan, Vietnam), H. bicoloripes ( Vietnam), and H. pusilla (Taiwan). The first two species are highly similar to each other, and based on the re-examination of their type materials, the latter might be a junior synonym of the former. The main difference is the colour of the corium and legs. Because H. bicoloripes is known from only a single female syntype (deposited in the Natural History Museum, London), and so far no male matching its colour has been seen from the region, they are here tentatively maintained as distinct at the species level. In H. rubescens , the ground colour of the femora and the tibiae are dark-brown, the femora possess a proximal pale-reddish annulus, and the femoro-tibial articulation is broadly bright-red ( Rédei & Tsai 2012: 21, figs. 61–63), differing from the condition seen in H. merkli sp. nov., where the femora lack a proximal annulus ( Figs. 1–6 , 11–12 ). In H. bicoloripes , the legs are coloured similarly to H. rubescens , but the extreme tips of the femora are dark-brown and the proximal red annulus of the tibiae lacking. In both of these species, the head and the pronotum are uniformly yellowish-red to bright-red, and the pregenital abdominal segments III–VII are decorated with broad black fasciae occupying posterior halves of the respective ventrites. Because no case in which wing polymorphism affects colour of the head, pronotum, abdomen or appendages has been documented in Reduviidae , it can safely be concluded that H. merkli sp. nov. does not represent the micropterous morph of H. rubescens or H. bicoloripes but differ from the latter two at species level. In H. pusilla , the legs are provided with a broad red annulus on the femoro-tibial articulations ( Rédei & Tsai 2012: 4, fig. 3) in a way that is fairly similar to the condition seen in H. merkli sp. nov.; the small size (8–10 mm, vs. in 9.5–12.5 mm in H. merkli sp. nov.) and the relatively elongate head ( Rédei & Tsai 2012: 10, figs. 25–26, cf. Figs. 7 and 8 for H. merkli sp. nov.) are also similar in these two species. A comparison of the male genitalia of H. pusilla , figured by Rédei & Tsai (2012: 10, figs. 28–30, and 11, figs. 33–38), and H. merkli sp. nov. ( Figs. 14–21 ) leaves no doubt that the two species are different at the species level: the shape of the genital capsule (lateral outline more strongly constricted close to the anterior aperture in H. merkli sp. nov.), particularly its dorsoapical process (forming a pair of distinct tubercles laterally somewhat below middle in H. merkli sp. nov., lacking in H. pusilla ), and the paramere (relatively gracile, apical denticle placed near tip in H. pusilla , vs. more robust, with apical denticle placed distinctly subapically in H. merkli sp. nov.) are all markedly different between these species.

Based on a consideration of all species of Haematoloecha known from macropterous individuals only, it might be concluded that H. merkli sp. nov. can safely be recognized as different at species level from all described congeners.

Generic placement and affinities of Haematoloecha merkli sp. nov.

Although the sculptured anterior lobe of pronotum ( Figs. 8, 10 ) is unique within the genus, Haematoloecha merkli sp. nov. matches all important characters used for defining Haematoloecha , including the shape of head, the lack of a lamelliform process surrounding antennal insertion, the basiflagellum being subdivided to two and distiflagellum to four secondary flagellites, the relative length of labiomeres (apparent labiomere I distinctly longer than II), the median longitudinal sulcus of the pronotum being deep, reaching the collar anteriorly, and closely approaching a series of transverse median ridges on posterior lobe that represent the highly reduced median sulcus of the posterior lobe (due to a general reduction of the posterior lobe, as a result of microptery). Species with a sculptured and smooth anterior lobe of the pronotum occur in some other reduviid genera as well, e.g. Rhynocoris incertis (Distant, 1903) has a distinctly sculptured pronotum, whereas in most congeners it is smooth.

Within Haematoloecha , the phylogenetic affinities of H. merkli sp. nov. are not particularly clear. The new species appears to be most similar to H. pusilla , a species endemic to Taiwan; this similarity includes a moderate size, a dull-brownish to brownish ground colour of body (instead of bright-red colours that are found in the majority of the other congeners), reddish annuli surrounding the femoro-tibial articulations, a generally similar shape of the head, and a somewhat similar shape of dorsoapical process of the genital capsule. The polarities of these character states (whether they represent apomorphic or plesiomorphic conditions) are unknown, and none of them are considered as particularly convincing to support a phylogenetic relationship between these two species.

The morphology of the new species is consistent with the definition of Haematoloecha ( Rédei & Tsai 2012) , except for its unusual pronotum. Moreover, it exhibits a distinct morphological similarity to H. pusilla (a species more clearly pertaining to this genus, lacking the unusual structure of the pronotum). Currently, there seems no reason to treat H. merkli sp. nov. as different from species of Haematoloecha at the generic level. The genus in the current sense, however, seems heterogeneous, including species with distinct specializations of the prothoracic femora ( H. chapana , H. obscurata , and some undescribed species from Indochina); therefore, a future study might conclude that it should be divided into several genera.

Figures

FIGURES 1–6. Haematoloecha merkli sp. nov. 1, male, dorsal view; 2, same, lateral view; 3, same, ventral view; 4, female (individual with posterior part of abdomen slightly distorted), dorsal view; 5, same, lateral view; 6, same, ventral view. Scale bar in mm.

FIGURES 7–13. Haematoloecha merkli sp. nov. 7, head and thorax of male, dorsal view; 8, same, lateral view; 9, head and thorax of female, dorsal view; 10, same, lateral view; 11, left prothoracic leg of male, posterior (external) view; 12, left prothoracic leg of female, posterior (external) view; 13, terminalia of female, posterior view. Scale bars in mm.

FIGURES 14–22. Haematoloecha merkli sp. nov. 14, male, genital capsule, dorsal view; 15, male, genital capsule and segment VIII, left lateral view; 16, male, dorsoapical process of genital capsule, posterior view; 17–19, right paramere, three different views; 20, phallus, dorsal view; 21, same, left lateral view; 22, terminalia of female, posterior view. Scale bars in mm.