Taxonomic notes on the tribe Ectinoderini (Hemiptera: Heteroptera: Reduviidae: Harpactorinae) from the Indochinese Peninsula

The identities of two species of assassin bugs in the tribe Ectinoderini (Hemiptera: Heteroptera: Reduviidae: Harpactorinae) from the Indochinese Peninsula are reviewed, resulting in the following new synonymy and new combinations: Amulius Stål, 1865 = Parapanthous Distant, 1919, syn. n.; Amulius spinicollis (Distant, 1919), comb. n. (transferred from Parapanthous) and Ectinoderus confragosus (Distant, 1919), comb. n. (transferred from Amulius). Lectotypes of these species are designated. The hemelytral venations of Amulius and Ectinoderus Westwood, 1843 are briefl y discussed and their diagnoses accordingly revised. Amulius is newly reported from Vietnam and Ectinoderus is recorded from Cambodia for the fi rst time. ZooBank Article Registration: http://zoobank.org/urn:lsid:zoobank.org:pub:BE2F1E95-52A7-4C96-8C92-4021C3DA224C * Corresponding author; e-mail: caiwz@cau.edu.cn INTRODUCTION Members of the Oriental and Pacifi c assassin bug tribe Ectinoderini (Hemiptera: Heteroptera: Reduviidae: Harpactorinae) are noteworthy for applying sticky plant resins to their fore legs to help them catch their prey (Schuh & Weirauch, 2020). Twenty species in two genera (Amulius Stål, 1865 and Ectinoderus Westwood, 1843, each with ten species) belong to this tribe (Maldonado-Capriles, 1990). The species are robust, somewhat dorsoventrally fl attened bugs, usually colourfully patterned, and can be distinguished from other harpactorines by the following characters: ocelli lateral and more widely separated than eyes; labium short and straight, reaching or slightly surpassing anterior margin of prosternum; pronotum strongly expanded posteriorly, leaving apex of scutellum exposed; prosternal groove nonstriated; fore tarsus not segmented; membrane of hemelytron with three cells (Davis, 1969; Cai et al., 1994). The group based on Ectinoderus was fi rst proposed by Stål (1859) as “Ectinoderida”. It was regarded as a distinct subfamily of Reduviidae or included in the Apiomerinae (now Apiomerini of Harpactorinae), but more recently Eur. J. Entomol. 118: 225–239, 2021 doi: 10.14411/eje.2021.024


INTRODUCTION
Members of the Oriental and Pacifi c assassin bug tribe Ectinoderini (Hemiptera: Heteroptera: Reduviidae: Harpactorinae) are noteworthy for applying sticky plant resins to their fore legs to help them catch their prey (Schuh & Weirauch, 2020). Twenty species in two genera (Amulius Stål, 1865 andEctinoderus Westwood, 1843, each with ten species) belong to this tribe (Maldonado-Capriles, 1990). The species are robust, somewhat dorsoventrally fl attened bugs, usually colourfully patterned, and can be distinguished from other harpactorines by the following characters: ocelli lateral and more widely separated than eyes; labium short and straight, reaching or slightly surpassing anterior margin of prosternum; pronotum strongly expanded posteriorly, leaving apex of scutellum exposed; prosternal groove nonstriated; fore tarsus not segmented; membrane of hemelytron with three cells (Davis, 1969;Cai et al., 1994).
The group based on Ectinoderus was fi rst proposed by Stål (1859) as "Ectinoderida". It was regarded as a distinct subfamily of Reduviidae or included in the Apiomerinae (now Apiomerini of Harpactorinae), but more recently Revised diagnosis. Amulius can be distinguished from Ectinoderus by a combination of the following characters: antennal scape distinctly shorter than head, pedicel longest; anterolateral angles of pronotum produced into a pair of long, spine-like processes; hemelytron with m-cu cross vein connecting M and cubital cell present, cubital cell broad, pentagonal.
Diversity and distribution. This genus currently contains ten species, occurring throughout the Oriental Region to the Malay Archipelago. One species is transferred to, and another one is removed from this genus, therefore the number of species of Amulius remains ten.
Remarks. Stål (1865) separated Amulius from Ectinoderus on the basis of its considerably shorter fi rst antennal segment. He later noticed that these two genera were as genus-level diagnostic characters is carried out, and the diagnoses of Amulius and Ectinoderus are accordingly modifi ed.

MATERIAL AND METHODS
Label data of type specimens are copied verbatim in quotation marks (" "); lines on the same label are separated by a backslash (\), different labels are separated by a semicolon (;), and comments on label data are provided in square brackets ([ ]); printed (pr.) and handwritten (hw.) texts are indicated. Abbreviations for depositories: BMNH -Natural History Museum, London, U.K.; CAU -Entomological Museum of China Agricultural University, Beijing, China; MZH -Finnish Museum of Natural History, Helsinki, Finland; OUMNH -Oxford University Museum of Natural History, Oxford, U.K.; RBINS -Royal Belgian Institute of Natural Sciences, Brussels, Belgium.
Male genitalia were soaked in hot 20% lactic acid solution for approximately ten minutes to remove soft tissue, rinsed in distilled water and dissected under a Motic binocular dissecting microscope. Dissected genitalia were placed in a vial containing glycerine and, after examination, pinned under the corresponding specimen.
Photographs were taken using a Canon 7D Mark II digital camera with a Canon micro lens EF 100 mm and MP-E 65 mm for habitus, and an Olympus BX51 microscope for dissected body parts. Helicon Focus version 5.3 was used for image stacking. Figures were assembled using Adobe Photoshop CC 2015. Although the copyright is with the Trustees of the Natural History Museum, London, photographs of BMNH specimens may be used under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 (CC BY-NC-SA 4.0) international license. Photographs of specimens from other institutions remain the copyright of these institutions.
The distribution map was built using the online version of SimpleMappr (Shorthouse, 2010). Coordinates were inferred by looking up the names of the localities on the data labels on Mapcarta (https://mapcarta.com/).
Measurements were obtained using a calibrated micrometer. Morphological terminology mainly follows Weirauch (2008a) and Schuh & Weirauch (2020). The length of the head and that of the postocular part include the collum; the visible labial segments are numbered from II to IV because the fi rst segment is lost or fused into the head capsule in most Reduviidae (Weirauch, 2008b;Schuh et al., 2009).  (Distant, 1919), comb. n.
also differentiated by the shape of the anterolateral pronotal angles, which are more developed in Amulius than in Ectinoderus, and these two characters were historically used for distinguishing the two genera (Walker, 1873a;Stål, 1874;Distant, 1904). Despite some new species of Ectinoderini being subsequently described (e.g., Bergroth, 1913;Roepke, 1932;Miller, 1954Miller, , 1958, the ratio of the antennal scape to the pedicel as well as the development of the anterolateral pronotal angles are still useful characters for separating Amulius and Ectinoderus. During the present study we examined eight species of Amulius and nine species of Ectinoderus (Table 1), and observed differences in hemelytral venation between the two genera. "Amulius sp." in Table 1 is very similar to A. quadripunctatus (the type species of Amulius) and may be that species, but we have not examined its type specimen(s). In species of Amulius, the section of M between the bifurcation of R + M and the base of the apical external cell is connected to the cubital cell by a well-developed m-cu cross vein, forming a small but distinct cell in the corium, thus the corium contains three cells; the cubital cell is relatively broad and pentagonal in shape (Figs 1-4). In con-trast, the m-cu cross vein connecting M and the cubital cell is absent in members of Ectinoderus, and the cubital cell of this genus is quadrate in shape, with the apical border of the cell (cu-an1 cross vein) almost absent . In E. philippinensis Westwood, 1845, however, the section of Cu basal to the cubital cell is connected to M beyond the bifurcation of R + M by a weakly developed, oblique cross vein (Fig. 7), but this is completely different from that observed in Amulius. A similar but more "degraded" condition is present in E. bipunctatus (Amyot & Serville, 1843), which has a remnant of the cross vein connecting M and Cu basal to the cubital cell (Fig. 5). Based on the above-mentioned differences in the hemelytral venation, we concluded that the presence or absence of the m-cu cross vein connecting M and the cubital cell and the shape of the cubital cell can be used to distinguish Amulius and Ectinoderus, therefore herein these features are added to the revised generic diagnoses. However, examination of further species of the two genera is necessary for testing the applicability of these characters.
The genera of the tribe Ectinoderini can be distinguished using the following key.  The identity of Parapanthous. Distant (1919a) established the genus Parapanthous to accommodate the new species P. spinicollis from "Indochina". He regarded this genus as "most nearly allied to the genus Panthous" and placed it in the subfamily Harpactorinae, whereas the genera Amulius and Ectinoderus were assigned to Apiomerinae by the same author (Distant, 1904(Distant, , 1919b. This genus and species have not been recorded since and there are no subsequent works presenting original data about them. Miller (1956Miller ( , 1971) treated Parapanthous as a member of Ectinoderinae and specifi cally pointed out that it might be a synonym of Amulius. Davis (1969) and Hsiao & Ren (1981) also included this genus in their Ectinoderini and Ectinoderinae, respectively. Maldonado-Capriles (1990), nevertheless, placed Parapanthous in Harpactorinae and kept Amulius and Ectinoderus in Ectinoderinae and these placements were followed in several subsequent works (e.g., Schuh & Slater, 1995;Ambrose, 2006;Schuh & Weirauch, 2020).
An examination of the type material of P. spinicollis supports the placement of Parapanthous in Ectinoderini, as it shares the main diagnostic characters presented by Davis (1969) for defi ning the tribe, including the widely separated ocelli, short and straight labium, posteriorly expanded pronotum with partially exposed scutellum, nonstriated prosternal groove, and non-segmented fore tarsus. Likewise, the synonymy of Parapanthous with Amulius suggested by Miller (1956Miller ( , 1971) is confi rmed. The short antennal scape with a much longer pedicel, the strongly produced anterolateral pronotal angles, the presence of the above-mentioned m-cu cross vein in the corium, and the pentagonal cubital cell fulfi l the diagnosis of Amulius, and there seems to be no reliable morphological characters to support the generic differentiation of P. spinicollis and the species currently placed in Amulius. Therefore, the following new subjective synonymy is proposed: Amulius Stål, 1865 = Parapanthous Distant, 1919, syn. n. (Distant, 1919), comb. n.
Redescription. Macropterous male . Coloration. Body generally blackish-brown. Head as general body colour, with ventral surface and neck slightly lighter . Antenna with prefl agelloid yellowish-brown (Fig. 18). Labium as general body colour (Fig. 16). Pronotum dark-brown, with apical third of processes of anterolateral angles blackish (Fig. 15); propleuron and sternum dark-brown. Scutellum as general body colour, with apical half of median ridge whitish-yellow (Fig. 15); meso-and metapleura and sterna dark-brown, with midpart of mesosternum lighter (Fig. 17). Legs as general body colour; coxae and trochanters brown; fore femur dark-brown, with a vague, light-brown annulus subapically; fore tibia lightbrown, with a vague, dark-brown annulus subbasally, apical fourth blackish (Fig. 19); mid and hind femora each with a vague, light coloured annulus subapically. Hemelytron as general body colour, with a small, narrow, whitish wax spot on cu-an1 in cubital cell, and a larger, round, whitish wax spot before r-m near apex of corium ( Fig. 20). Abdomen as general body colour; basal fourth of dorsal and ventral laterotergites of abdominal segments II to VII yellowish-brown (Figs 20, 21); in lectotype (present designation) the majority of sternites VI and VII yellowishbrown (Fig. 21).
Vestiture. Body sparsely covered with tiny, decumbent curly setae on head (including antennal scape), thorax, legs, corium of hemelytron and abdomen. Head with dense, short, decumbent to suberect curly setae on dorsal and lateral surfaces, and dense, short, erect curly setae on ventral surface; antennal pedicel and fl agellomeres densely covered with tiny, decumbent to suberect setae; labium with tiny to short, suberect to erect setae; disc of pronotum largely glabrous, anterior and lateral margins as well as anterolateral processes densely covered with short, decumbent to suberect curly setae; meso-and metasterna largely glabrous; ventral surfaces of coxae and trochanters with dense, short, decumbent curly setae; fore femur with a row of tiny to short, erect curly setae on ventral surface, and several long, erect pubescence on apical third of dorsal surface; fore tibia densely covered with long, erect pubescence, length of pubescence longer than diameter of segment; fore tarsus densely covered with short to long, decumbent to erect, straight and curly setae; mid and hind tibiae with short, decumbent curly setae gradually becoming denser towards apex of segment; mid and hind tarsi densely covered with short to long, decumbent to suberect setae.
Fore leg long and robust; fore coxa spherical, nearly contiguous in ventral view (Fig. 17); fore trochanter simple in shape; fore femur strongly thickened, slightly curved, somewhat fl attened laterally; fore tibia ( Fig. 19) slender, fi nely curved, 1.5 times as long as fore femur, slightly swollen at apex; fore tarsus 0.2 times as long as fore tibia, with a pair of tiny claws at apex. Mid and hind legs shorter and slenderer; mid and hind coxae widely separated; mid and hind femora moderately and strongly thickened, respectively; mid and hind tibiae 1.2 times as long as respective femur; mid and hind tarsi three-segmented, with a pair of small, simple claws at apices. Hemelytron (Fig. 20) nearly reaching apex of abdomen in midline; corium with pentagonal cubital cell and two additional cells, outer one formed by R, M and their cross vein, inner one formed by M, Cu and their cross veins; membrane with apical external cell longer and broader than apical internal cell, and one additional cell formed by R, M and their cross veins.
Abdomen (Figs 20, 21) broad oval, 1.2 times as long as its maximum width; dorsal laterotergites largely exposed in dorsal view; ventral lateral tergites separated from respective sternite by a distinct connexival suture; anterior margin of sternite VII angularly curved anteriorly; abdominal spiracles situated on inner margin of basal third of ventral connexival sutures.

Measurements
Comparative notes. Amulius spinicollis comb. n. is not conspecifi c with other species of Amulius. The uniformly dark-brown pronotum and the nearly unicoloured fore, mid and hind femora of this species are very distinct within the genus, whereas its congeners usually have brilliant yellow-orange to reddish colour patterns and sometimes are conspicuously bicolorous. Amulius spinicollis comb. n. is morphologically similar to A. malayus Stål, 1867 from the Indochinese Peninsula and Southern China, but it can be clearly distinguished from the latter by the completely different body colour and the shape of the anterolateral pronotal processes (long, reaching the posterior margin of the ocelli, curved inwardly in A. spinicollis comb. n. vs. short, far removed from the posterior margin of the ocelli, straight in A. malayus).
Remarks. This species was originally described based on specimens from "N. Indochina; Muong Va" (Distant, 1919a). The locality Muong Va currently belongs to Sop Cop, Son La, Vietnam. Ambrose's (2006) statement that this species occurs in "India and China" may be due to a misinterpretation of "Indochina". This species has, as yet, neither been reported from China nor from India.

Revised diagnosis.
Ectinoderus can be distinguished from Amulius by a combination of the following charac-ters: antennal scape longest, distinctly longer than head and pedicel; anterolateral angles of pronotum produced into a pair of very short processes; hemelytron with m-cu cross vein connecting M and cubital cell absent, cubital cell quadrate.
Diversity and distribution. The genus now contains eleven species distributed in India, the Indochinese Peninsula and Malay Archipelago.
Remarks. Ectinoderus was originally described by Westwood (1843) as a "Subg. nov.", without mention of its genus. Westwood (1845) then redescribed Ectinoderus as a genus and stated in the fi rst paragraph: "the third species [referring to its type species, E. longimanus] differs in its structural characters so materially from the other groups in the family, that I have not hesitated in adding another to the already numerous genera of Reduviidae". Westwood (1845) compared Ectinoderus with three other genera (Arilus Hahn, 1831, Notocyrtus Burmeister, 1835 and Diaspidius Westwood, 1837), which have a posteriorly dilated pronotum, but still did not mention its original genus. Subsequent works, such as Herrich-Schäffer (1853), Stål (1867Stål ( , 1874, Walker (1873b), Lethierry & Severin (1896), Distant (1904) and Maldonado-Capriles (1990), all simply treated it as a genus without any comment on its original subgeneric placement.
The original description of Ectinoderus (Westwood, 1843) was recorded based on Westwood's oral narration on 1 st Aug. 1842, and its later published redescription (Westwood, 1845) could be considered its more formal taxonomic arrangement. However, since the oral records were formally published on 1 st Jun. 1843 the description is considered valid from that date (Wheeler, 1912;Kerzhner, 1992). This indicates that Ectinoderus has never been formally treated as a subgenus of a particular genus, therefore the name longimanus is originally combined with Ectinoderus rather than with any other genus. (Distant, 1919), comb. n.

Diagnosis.
Recognized within the genus by the following characters: body length 22.0-29.7 mm, generally brown to dark-brown; pronotum nearly uniformly brown; anterior pronotal lobe nearly half as long as posterior lobe; fore femur light-brown basally, gradually darkened towards apex, dark-brown subapically, apical third yellowishbrown; mid and hind femora dark-brown basally, gradually darkened towards apices, apices blackish-brown, each with two subapical, light-yellowish-brown spots forming an incomplete annulus; laterotergites of abdominal segments II to V bicolorous, of VI and VII uniformly yellowish-brown.
wax at base (Fig. 38); corium with a large, round, whitish wax spot before r-m near apex, section of Cu at base of apical internal cell whitish-yellow (Fig. 38), in some specimens with fi ve additional whitish wax spots located in cubital cell, each side of Cu before cubital cell, front and back of bifurcation of R + M, respectively. Abdomen yellowishbrown; laterotergites of abdominal segments II to V darkbrown with basal fourth yellowish-brown (Fig. 38).
Vestiture. Body sparsely covered with tiny and short, erect curly setae on head (including labium), thorax, legs, corium of hemelytron and abdomen; antennal scape with sparse, tiny, suberect to erect setae, pedicel with dense, tiny, suberect setae, fl agellomeres with dense, tiny, suberect setae and tiny, decumbent pubescence; pronotum, meso-and metapleural and sterna largely glabrous; ven-tral surfaces of coxae and trochanters with dense, short, erect setae; femora with sparse, tiny, erect setae, fore femur with relatively long, erect setae on venter and apical third of dorsum, gradually becoming denser towards apex of segment; fore tibia densely covered with long, erect pubescence, length of pubescence longer than diameter of segment; fore tarsus densely covered with short to long, decumbent to erect, straight and curly setae; mid and hind tibiae with short, decumbent curly setae gradually becoming denser towards apex of segment; mid and hind tarsi densely covered with short to long, decumbent to suberect setae.
Fore leg long and robust; fore coxa spherical, nearly contiguous in ventral view (Fig. 36); fore trochanter simple in shape; fore femur ( Fig. 37) strongly thickened, slightly curved, somewhat fl attened laterally, basally forming a small tubercle with apex of fore trochanter on ventral surface; fore tibia ( Fig. 37) slender, fi nely curved, 1.3 times as long as fore femur, slightly swollen at apex; fore tarsus 0.2 times as long as fore tibia, with a pair of tiny claws at apex. Mid and hind legs shorter and slenderer; mid and hind coxae widely separated; mid and hind femora moderately and strongly thickened, respectively; mid and hind tibiae 1.2 (♂) / 1.25 (♀) and 1.25 (♂) / 1.1 (♀) times as long as respective femur; mid and hind tarsi three-segmented, with a pair of small, simple claws at apices. Hemelytron (Fig. 38) nearly reaching or slightly surpassing apex of abdomen in midline; corium with quadrate cubital cell and one additional cell formed by R, M and their cross vein; membrane with apical external cell longer and broader than apical internal cell, and one additional cell formed by R, M and their cross veins.
Fifth instar nymph (Fig. 53). Coloration. Body generally light brown, colour similar to adult; midparts of metasternum and abdominal tergite I, abdominal spiracles lightyellowish-brown; midparts of abdominal tergites II and III dark-greyish. Vestiture. Similar to adult; wing pad and abdomen with many small, wart-like tubercles each bearing a tiny, erect seta at apex. Structure. Similar to adult in body shape; body surface relatively well sclerotized. Head 1.6 times as long as width across eyes; anteocular part 0.4 times as long as postocular part; width across eyes 2.1 times as broad as interocular space; antennal scape 1.1 times longer than head, 1.2 times longer than pedicel; labium distinctly surpassing anterior margin of prosternum. Pronotum 0.6 times as long as its maximum width. Fore leg long and robust, fore tibia 1.3 times longer than fore femur; mid and hind legs short and stout. Apex of wing pad reaching anterior margin of abdominal tergite III. Abdomen relatively weakly sclerotized; lateral margin of each abdominal segment rounded, making outline of abdomen undulated; dorsum and venter with regularly arranged sclerotized plates; dorsal abdominal glands present on posterior parts of tergites II, III and IV.
Type material examined. Lectotype (here designated) (♀): blue-margined syntype disc [pr.]; red-margined holotype disc  Comparative notes. Ectinoderus confragosus comb. n. has a long antennal scape and weakly developed anterolateral pronotal angles, and the m-cu cross vein in the corium is absent, therefore it should be placed in the genus Ectinoderus. Photographs of type material (Figs 22-27) and of non-types of each sex (Figs 28-33; the resin coating has been removed) are provided here to facilitate the identifi cation of this species. This species is clearly distinct among the species within the genus in its overall bicoloured abdominal connexivum, in which segments II to V are darkbrown with basal fourth light-coloured, and segments VI and VII are homogeneously yellowish-brown. A similar colour pattern is recorded in E. caedens Miller, 1958 from New Guinea, but in this species the laterotergites of abdominal segments II to V are completely blackish, and those of segments VI and VII are light-yellowish-brown. Ectinoderus caedens also has a different colour pattern on the pronotum (light-yellowish-brown with a wide, blackish suffusion posteriorly vs. generally dark-brown in E. confragosus comb. n.) and the legs (generally blackish, coxae, trochanters and bases of femora light-yellowish-brown vs. generally brownish with light-coloured patterns in E. confragosus comb. n.), and its pronotum expands into two angular lobes posteriorly (vs. rounded in E. confragosus comb. n.).
Ectinoderus confragosus comb. n. resembles the Myanmar species E. exortivus Distant, 1903 in general appearance, but clearly differs from the latter by the completely different colour patterns on its legs (mid and hind femora dark-brown to blackish-brown, each with two subapical, light-yellowish-brown spots forming an incomplete annulus, mid and hind tibiae blackish-brown in E. confragosus comb. n. vs. mid and hind femora brown to dark-brown on basal two thirds, yellowish-brown on apical third, mid and hind tibiae yellowish-brown on basal fourth, blackish-brown on apical three fourths in E. exortivus) and the connexivum (segments II to V bicolorous, VI and VII uniformly yellowish-brown in E. confragosus comb. n. vs. all segments bicolorous in E. exortivus).