Abstract

The thread-legged bug genus Chinemesa Wygodzinsky, 1966 (Hemiptera: Heteroptera: Reduviidae: Emesinae: Emesini) is a small group of five species endemic to the Oriental Region. However, the species diversity of this genus is still far from completely explored, especially in the mainland of Asia. Here we describe three new species, C. ornata sp. n., C. pulchella sp. n. and C. weilingfengi sp. n., from southern China. Based on the newly sequenced mitochondrial genomes of four Chinemesa species, we detected two gene rearrangement patterns in the genus: a translocation of trnI and trnQ in all four species, and a loss of trnW in C. pulchella sp. n. Both gene rearrangements are novel within Reduviidae as well as Heteroptera, and can be explained by the tandem duplication-random loss (TDRL) model. Phylogenetic analyses based on mitogenomic datasets recovered the monophyly of Chinemesa, with the translocation of trnI-trnQ as a potential molecular synapomorphy for the genus.

Keywords

Heteroptera, mitochondrial genome, gene rearrangement, phylogeny, taxonomy, Oriental Region

1. Introduction

Emesinae, commonly known as the thread-legged bugs, is the second most species-rich lineage within the assassin bug family Reduviidae. To date, it encompasses over 1,000 extant species distributed across seven tribes: Collartidini, Emesini, Leistarchini, Oncerotrachelini, Saicini, Saiciretini and Visayanocorini (Maldonado-Capriles 1990; Standring et al. 2023; Castro-Huertas and Melo 2025). The thread-legged bugs are terrestrial predatory insects characterized by typically elongated body, slender antennae and legs, and raptorial forelegs (Schuh and Weirauch 2020). They inhabit diverse environments including grasslands, shrublands, forests, and even caves (Wygodzinsky 1966; Ishikawa and Miyamoto 2012). Many species exhibit close associations with spiderwebs, acting as obligate predators of web-building spiders or facultatively feeding on spiders and spider prey (Wygodzinsky 1966; Wignall and Taylor 2011; Soley and Taylor 2012; Resende et al. 2016). Emesinae, with its rich phenotypic diversity and natural history, represents an ideal subject for studying predatory behavior and its associated phenotypic evolution (Soley 2016; Standring et al. 2023; Castro-Huertas and Melo 2025). However, the phylogenetic relationships and evolutionary history of Emesinae have not yet been comprehensively investigated, and mitochondrial data from this subfamily remain largely unexplored and underutilized in the context of systematic and evolutionary studies.

Mitochondrial genomes (mitogenomes), owing to their unique genetic characteristics and the presence of multiple copies within each cell, have been extensively utilized in studies of insect phylogenetics, population genetics, and adaptive evolution (Sterling-Montealegre and Prada 2024; Cameron 2025; Zhao et al. 2025; Zhu et al. 2025). Beyond sequence variation, current research highlights the remarkable diversity in mitogenome size and structure, including alterations in gene order, gene duplication, and gene loss (Song et al. 2019; Tyagi et al. 2020; Pei et al. 2024). Although most insect lineages retain the putative ancestral pancrustacean gene order, mitochondrial gene rearrangements have been observed in many orders such as Hymenoptera (Mao et al. 2014; Tang et al. 2019), Hemiptera (Thao et al. 2004; Li et al. 2012), and Trichoptera (Ge et al. 2023; Peng et al. 2025). Hemiptera exhibits multiple types of mitochondrial gene rearrangements, some of which are inferred to be molecular synapomorphies for specific lineages (Song et al. 2016; Liu et al. 2019; Ye et al. 2021). Currently, only a limited number of Emesinae species have had their mitogenomes reported, with tRNA gene rearrangements found in a single species, Ischnobaenella hainana (Hsiao, 1965) (Ye et al. 2021).

The thread-legged bug genus Chinemesa Wygodzinsky, 1966, belonging to the tribe Emesini, is a rarely-collected group of five extant species. Four species (C. feminata Wygodzinsky, 1966, C. murudiana Wygodzinsky, 1966, C. poiana Wygodzinsky, 1966 and C. uniannulata Rédei, 2007) are endemic to Borneo, while the fifth (C. chinensis Chen, Li & Cai, 2020) was recently discovered in southwestern China (Wygodzinsky 1966; Rédei 2007; Chen et al. 2020a). Members of this genus exhibit significant sexual dimorphism, with males being macropterous and all known females being apterous (Wygodzinsky 1966). Chen et al. (2020a) speculated that additional species of Chinemesa may be discovered elsewhere in the Oriental Region including the Indochinese Peninsula. However, the species diversity of this genus is still poorly explored in the Asian continent, and no molecular data for this genus is currently available.

In the present study, we further investigate the species diversity of Chinemesa, describe three new species from southern China, and accordingly update the species-level key for the genus. Based on the newly sequenced mitogenomes, we reveal unique mitochondrial gene rearrangements within the genus, which are also novel within Reduviidae. The possible mechanism of the gene rearrangements is inferred, and their phylogenetic implication is also discussed.

2. Material and methods

2.1. Material depository and morphological study

Specimens examined in this study are deposited in the following collections: CAU – Entomological Museum of China Agricultural University, Beijing, China; RMNH – Naturalis Biodiversity Center, Leiden, Netherlands; NHMUK – Natural History Museum, London, UK. Details of specimens used for morphological comparison are shown in Table S1.

External morphological characters were examined using a Nikon SMZ745 stereoscopic microscope. Male and female genitalia were soaked in a heated 10% KOH solution for approximately ten minutes to remove soft tissue, rinsed in distilled water, and dissected under a stereoscopic microscope. Dissected genitalia were placed in a plastic vial containing glycerol and, after examination, pinned under the corresponding specimen. Photographs were taken using a Canon 7D Mark II digital camera with a Canon macro lens EF 100 mm f/2.8L IS USM and MP-E 65 mm f/2.8 1-5X for habitus, and a Nikon Z7 II digital camera with an Olympus BX51 microscope for dissected body parts. Figures were stacked with Helicon Focus v.5.3 and assembled using Adobe Photoshop 2020. The distribution map was constructed using the online version of SimpleMappr (Shorthouse 2010).

Morphological terminology mainly follows Wygodzinsky (1966) and Standring et al. (2023). Measurements were obtained using a calibrated micrometer.

2.2. Taxon sampling for molecular analysis

Seven specimens belonging to four species of Chinemesa were used for DNA extraction and mitogenome sequencing. Voucher information of the sampled specimens is listed in Table S2.

Five species from other genera of Emesinae, as well as 29 non-emesine Reduviidae were included in the present phylogenetic analysis. Three species from Miridae, Nabidae and Pachynomidae were selected as outgroups. GenBank accession numbers of the newly-sequenced and published data used in this study are listed in Table S3.

2.3. DNA extraction, sequencing and data processing

Total genomic DNA was extracted nondestructively from the right foreleg using the Qiagen DNeasy Blood and Tissue Kit following the manufacturer's protocol. Each sample was soaked in tissue lysis buffer for about twenty hours to improve the quality of DNA extraction. An Illumina TruSeq library with a 350 bp average insert size was prepared for each sample. All libraries were sequenced using the Illumina NovaSeq 6000 platform with 150 bp paired-end reads. Raw reads were trimmed of adapters with Trimmomatic (Bolger et al. 2014) and removed of short and low-quality reads (>15 bp Ns, or >75 bp bases with a quality score ≤3) with Prinseq 0.20.4 (Schmieder and Edwards 2011). Clean reads were assembled de novo using IDBA-UD (Peng et al. 2012) with minimum and maximum k values of 41 and 141 bp, respectively. The mitogenome sequences were initially annotated by MitoZ 2.4 (Meng et al. 2019). The resultant gene boundaries were checked in Geneious Prime 2023 (Kearse et al. 2012) by alignment with homologous genes of the published Emesinae mitogenomes (GenBank accession numbers PV626514 and PV626532).

Thirteen protein-coding genes (PCGs) and two ribosomal RNA genes (12S and 16S) were used in phylogenetic analysis. Each gene was aligned using MAFFT 7.450 (Katoh and Standley 2013) with the L-INS-i algorithm. The alignment of the thirteen PCGs was based on amino acid sequences translated with the invertebrate mitochondrial genetic codon table. All alignments were trimmed with trimAl 1.4.1 (Capella-Gutiérrez et al. 2009) and concatenated with FASConCAT-g 1.04 (Kück and Longo 2014). Two datasets were generated for phylogenetic analysis: the PCGRNA matrix, which includes all three codon positions of the PCGs, and the two rRNA genes (12,622 bp); the PCG12RNA matrix, which includes the first and second codon positions of the PCGs, and the two rRNA genes (9,068 bp).

2.4. Phylogenetic analysis

Phylogenetic relationships were reconstructed using Bayesian inference (BI) and Maximum-likelihood (ML) methods. BI analyses were conducted using PhyloBayes-MPI 1.8 (Lartillot et al. 2013) with the site-heterogeneous mixture CAT-GTR model. Two independent Markov Chain Monte Carlo (MCMC) runs of 100,000 generations each were executed. Convergence was evaluated with the “bpcomp” and “tracecomp” procedure in the PhyloBayes package with a burn-in of initial 25% by the recommended criterion of maximum discrepancy <0.1. A consensus tree was generated simultaneously by pooling the remaining MCMC trees of both runs, with Bayesian posterior probabilities (PP) on each node. ML partitioned analyses were conducted in IQ-TREE 2.1.2 (Minh et al. 2020). The best partitioning schemes and substitution models were selected using ModelFinder (Kalyaanamoorthy et al. 2017) based on the Bayesian information criterion (BIC). The node support was evaluated with 1,000 SH-aLRT (Guindon et al. 2010) and 1,000 UFBoot2 (Hoang et al. 2018) replicates. The resulting trees were visualized and edited in Figtree 1.4.4 (Rambaut 2018) and iTOL 6.8.1 (Letunic and Bork 2021). Genetic distances of the standard COX1 barcoding region (658 bp) were calculated using MEGA 7.0 (Kumar et al. 2016) with the Kimura 2 Parameter (K2P) model (Kimura 1980).

3. Results

3.1. General structure and gene rearrangements in mitogenomes of Chinemesa

The complete mitogenomes of the four newly sequenced species of Chinemesa ranged from 15,604 to 15,655 bp in length. Except for C. pulchella sp. n. which lacks the trnW gene, all species possessed the entire set of 37 genes (13 PCGs, 22 tRNA genes, and two rRNA genes) typically present in insect mitogenomes, along with a putative control region. These mitogenomes exhibited the typical A + T biased composition (73.5%–74.8%), with positive AT-skew (0.22–0.23) and negative GC-skew (-0.26–-0.18).

A unique tRNA gene rearrangement was observed in all four species: the trnI and trnQ have translocated between trnW and trnC (Fig. 1). Although the trnW was absent in the mitogenome of C. pulchella sp. n., a 17-bp region was identified sharing 91.8% similarity with the homologue sequences of trnW in the other three species.

Figure 1.

Phylogenetic tree of Reduviidae inferred from the Bayesian inference (BI) analysis based on the PCGRNA dataset. Colour-coded circles at nodes indicate support values as specified in the bottom-left legends. Asterisks denote new mitogenomes generated in this study.

3.2. Phylogenetic analysis

ModelFinder merged the original 15 partitions of the PCGRNA and PCG12RNA datasets into six partitions, with the best-fitting model for each partition shown in Tables S4, S5. All analyses recovered the monophyly of Reduviidae and the sister relationship between the Phymatine Complex and the Trichobothrial Clade (formerly termed “Higher Reduviidae”), but the internal relationships within the Trichobothrial Clade varied across analyses (Figs 1, S1–S4). All subfamilies with two or more representatives were supported as monophyletic in ML analyses. However, in BI analyses, Reduviinae was recovered as paraphyletic (PCG12RNA) or polyphyletic (PCGRNA). All analyses generated an identical topology within Emesinae. Our results support the monophyly of Chinemesa, with Gardena + Ghilianella recovered as its sister group. Chinemesa ornata sp. n. is sister to C. weilingfengi sp. n., together forming a sister clade to C. chinensis + C. pulchella sp. n.

The interspecific genetic distances among the four Chinemesa species ranged from 11.6% to 22.8%, with the maximum value between C. chinensis and C. ornata sp. n., while the minimum value is between C. chinensis and C. pulchella sp. n. The intraspecific distance within each species ranged from 0 to 0.2% (Table S6).

3.3. Taxonomy

Family Reduviidae Latreille, 1807

Subfamily Emesinae Amyot & Serville, 1843

Tribe Emesini Amyot & Serville, 1843

Genus Chinemesa Wygodzinsky, 1966

Chinemesa Wygodzinsky 1966: 225; Maldonado-Capriles 1990: 83; Rédei 2007: 213; Chen et al. 2020a: 20; Yi and He 2025: 270. Type species by original designation: Chinemesa poiana Wygodzinsky, 1966.

Diagnosis.

Recognized within Emesini by the following combination of character states: anteocular region of head longer than postocular; labium conspicuously curved between visible segments I and II; mesonotum bearing long, erect, spine-like process; profemur armed ventrally with two series of small to medium-sized spines, posteroventral series beginning near base of segment, anteroventral series beginning at some distance from base; protarsus three-segmented; protarsal claws asymmetrical; hemelytron with pentagonal basal cell in addition to large discal cell, M and Cu veins extending basad from basal cell with M free-ending proximally; hind wing with m-cu crossvein and 2A vein present.

Diversity and distribution.

Including the three new species described herein, the genus comprises eight species, four distributed in Borneo and the other four in southern China (Fig. 8).

Chinemesa ornata sp. n.

https://zoobank.org/1AB25846-FAD9-4ABB-910B-23F08626BFCE

Figures 2, 3

Chinese vernacular name: 堂皇钟蚊猎蝽

Type material.

Holotype: ♀, CHINA, Fujian, Sanming, Youxi, Banmian Tw. [坂面镇], Luohanshan [罗汉山], 3.vi.2024 (CAU).

Figure 2.

Habitus and morphological details of Chinemesa ornata sp. n.: A Apterous female, holotype, dorsal view; B apterous female, holotype, ventral view; C anterior part of body of apterous female, dorsal view; D anterior part of body of apterous female, lateral view; E foreleg of apterous female, ventral view; F abdomen of apterous female, dorsal view. Scale bar 5 mm (A, B), 1.5 mm (C–F).

Figure 3.

Female genitalia of Chinemesa ornata sp. n.: A Dorsal view; B lateral view; C ventral view. Scale bar 0.5 mm.

Diagnosis.

Body medium-sized, 11.4 mm; anterior lobe of pronotum nearly as long as head (Fig. 2C, D); profemur with two light-colored annuli and one subapical light-colored spot (Fig. 2E); mesofemur with six alternating dark and light annuli in apical half (Fig. 2A, B); metafemur with 17 alternating dark and light annuli (Fig. 2A, B); femorotibial articulations of mid and hind legs broadly whitish and tinged with red (Fig. 2A, B); female abdominal tergite IX 1.3 times as long as tergite VIII (Fig. 3A); posterior margin of styloides weakly incised at midpoint (Fig. 3C).

Description.

Apterous female (Fig. 2A, B). Colouration: Generally reddish-brown. Lateral and ventral surfaces of head dark brown; lateral and ventral surfaces of thorax and abdomen blackish-brown. Anteclypeus dark brown; labrum whitish-yellow. Antenna blackish-brown; extreme base and apex of scape and extreme apex of pedicel whitish-yellow. Labium blackish-brown, with base and apex of visible segment III yellowish-brown (Fig. 2D). Spine-like process on mesonotum blackish-brown (Fig. 2D). Profemur reddish-brown to dark brown, with two whitish-yellow annuli at midportion and one small whitish-yellow spot subapically (Fig. 2E); protibia dark brown (Fig. 2E); protarsus brown (Fig. 2E). Mid and hind legs yellowish-brown; meso- and metafemora each with three indistinct, broad, dark brown annuli and two narrow whitish-yellow annuli in apical half, apically broadly whitish and tinged with red (Fig. 2A, B); metafemur with five indistinct, narrow, dark brown annuli in basal half (Fig. 2A, B); meso- and metatibiae each with two indistinct dark brown annuli in basal third, basally broadly whitish and tinged with red (Fig. 2A, B); meso- and metatarsi pale brown. Abdominal tergites IV–VII each with one pair of submedian, longitudinal, yellowish-brown stripes (Fig. 2F); tergites VIII and IX yellowish-brown at midportion (Fig. 2F); tergite X yellowish-brown (Fig. 2F); connexival segments IV–VII each with one small yellowish-brown spot at anterolateral angle (Fig. 2F); sternites IV–VI each with one indistinct, small, yellowish-brown spot on both sides, and one indistinct, small, yellowish-brown spot before spiracle. — Vestiture: Body surface smooth, strongly polished, covered with dense, very short, decumbent to suberect pubescence and sparse, long, erect pubescence. Meso- and metapleura gently wrinkled. Profemur with several long, erect, strong setae ventrally; protibia with short, erect, strong setae ventrally. Connexivum gently wrinkled. — Structure: Head (Fig. 2C, D) subfusiform, 1.9 times as long as width across eyes; width across eyes twice as broad as interocular space. Eye (Fig. 2C, D) small, far remote from dorsal and ventral margins of head in lateral view. Antennal scape 1.15 times as long as pedicel, four times as long as head; basiflagellomere slightly longer than distiflagellomere. Labium (Fig. 2D) with visible segment I 1.25 times as long as visible segment II; visible segment III 1.7 times as long as visible segment I. Pronotum (Fig. 2C, D) subcylindrical, 1.8 times as long as its maximum width; anterior lobe nearly as long as head, gradually narrowed posteriorly; posterior lobe short, collar-like. Mesonotum (Fig. 2C, D) slightly convex dorsally, with faint longitudinal carina along midline, posteriorly with erect spine-like process; metanotum (Fig. 2C, D) 0.45 times as long as mesonotum, flattened dorsally; meso- and metasterna with longitudinal carina along midline. Foreleg (Fig. 2E) robust; procoxa 1.5 times as long as pronotum; profemur gently curved, 11.5 times as long as its maximum width, 1.8 times as long as procoxa; posteroventral series composed of eight long spines and many smaller ones inserted on distinct basal processes, and of some small, denticle-like spines apically; protibia 0.75 times as long as profemur, armed ventrally with two irregular rows of small denticles. Meso- and metatibiae 1.45 and 1.5 times as long as respective femur. Abdomen (Fig. 2F) elongate, 4.6 times as long as its maximum width. Female genitalia: tergite VIII (Fig. 3A, B) transverse, subsemicircular; tergite IX (Fig. 3A, B) trapezoidal, 1.3 times as long as tergite VIII; tergite X (Fig. 3A, B) clearly exposed; valvifer I (Fig. 3B, C) broad, with rounded posterolateral margin and nearly straight posteromedial margin; valvula I (Fig. 3B, C) small, apically obtuse; posterior margin of styloides weakly incised at midpoint (Fig. 3C). — Measurements: [in mm, ♀ (n = 1)]. Length of body: to apex of abdomen 11.40; length of head 1.50; length of anteocular region 0.60; length of postocular region 0.90; width across eyes 0.80; interocular space 0.40; length of antennal segments 5.95, 5.10, 1.05, 1.00; length of visible labial segments 0.50, 0.40, 0.85; length of anterior pronotal lobe 1.30; length of posterior pronotal lobe 0.25; maximum width of anterior pronotal lobe 0.86; maximum width of posterior pronotal lobe 0.70; length of procoxa, femur, tibia, tarsus 2.35, 4.25, 3.20, 0.50; maximum width of profemur 0.35; length of mid femur, tibia, tarsus 7.05, 10.30, 0.40; length of metafemur, tibia, tarsus 9.20, 13.80, 0.45; length of abdomen 6.40; maximum width of abdomen 1.40.

Distribution.

China – Fujian: Youxi (Fig. 8).

Etymology.

The specific epithet is derived from Latin ornata (meaning ornated or decorated), referring to the impressive color patterns of this new species.

Comparative notes.

Chinemesa ornata sp. n. and C. feminata are known only from the apterous female. However, these two species are not conspecific because the new species possesses completely different body size and colouration. The anterior lobe of the pronotum is nearly as long as the head in C. ornata sp. n. but much longer in C. feminata.

Based on our phylogenetic results, C. ornata sp. n. is closely related to C. weilingfengi sp. n. (see below). It is distinguished from the latter by the longer anterior lobe of the pronotum which is subequal in length of the head, and the reddish femorotibial articulations of mid and hind legs. In C. weilingfengi sp. n., the anterior lobe of the pronotum is distinctly shorter than the head, the femorotibial articulations of mid and hind legs are whitish, and the extreme base of the meso- and metatibiae is dark brown. The COX1 genetic distance between C. ornata sp. n. and C. weilingfengi sp. n. is 13.6%, falling within the range of interspecific distances among the sampled Chinemesa species (11.6%–22.8%), indicating that they should be treated as distinct species.

Chinemesa pulchella sp. n.

https://zoobank.org/196F6BF7-DC6C-4147-A129-CD9531A27AC4

Figures 4, 5

Chinese vernacular name: 秀丽钟蚊猎蝽

Type material.

Holotype: ♂, CHINA, Xizang, Nyingchi, Medog, Damu Tw. [达木乡], 1420 m, 11.vi.2017, Chufei Tang (CAU). Paratype: 1♂, CHINA, Xizang, Nyingchi, Medog, Damu Tw. [达木乡], 1814 m, 22.vi.2017, Chufei Tang (CAU).

Figure 4.

Habitus and morphological details of Chinemesa pulchella sp. n.: A Macropterous male, holotype, dorsal view; B macropterous male, holotype, lateral view; C macropterous male, holotype, ventral view; D foreleg of macropterous female, ventral view. Scale bar 2 mm (A–C), 1.5 mm (D).

Figure 5.

Male genitalia of Chinemesa pulchella sp. n.: A Pygophore, dorsal view; B pygophore, lateral view; C pygophore, caudal view; D paramere, dorsal view; E paramere, lateral view; F phallus, dorsal view; G phallus, lateral view; H phallus, ventral view. Scale bar 0.5 mm.

Diagnosis.

Body medium-sized, 11–12 mm; head bicolorous, blackish anterior lobe and reddish posterior lobe (Fig. 4A, B); anterior lobe of pronotum slightly shorter than head (Fig. 4A, B); posterior lobe of pronotum with one pair of submedian, oblique, yellowish-brown stripes in basal half (Fig. 4A); procoxa with one median light-colored annulus (Fig. 4D); profemur with three light-colored annuli (Fig. 4D); meso- and metafemora with two indistinct, pale brown annuli and two broad, dark brown annuli in apical half, and one apical whitish annulus; hemelytron with indistinct reticulate patterns (Fig. 4A); connexivum bicolorous (Fig. 4B, C); abdomen ventrally with light-colored spots on both sides (Fig. 4B, C); phallosoma with paired lateral sclerites and one pair of dorsolateral lobes near apex (Fig. 5F–H).

Description.

Macropterous male (Fig. 4A–C): Colouration: Generally blackish-brown. Anterior lobe of head with one pair of triangular, whitish-yellow spots behind antennal insertions (Fig. 4A); posterior lobe reddish-brown (Fig. 4A, B); apex and lateral margins of anteclypeus yellowish-brown; labrum whitish-yellow. Extreme apex of antennal scape whitish. Labium with base and apex of visible segment III yellowish-brown (Fig. 4B). Anterior lobe of pronotum tinged with brown along midline (Fig. 4A); posterior lobe with one pair of submedian, oblique, yellowish-brown stripes in anterior half (Fig. 4A). Procoxa with broad, pale brown annulus at midpoint (Fig. 4D); profemur dark brown to blackish-brown, with two whitish-yellow annuli at midportion and one small whitish-yellow spot subbasally (Fig. 4D); protibia with narrow whitish-yellow annulus at midpoint (Fig. 4D); protarsus brown (Fig. 4D). Mid and hind legs yellowish-brown; meso- and metafemora each with one indistinct, narrow, whitish-yellow annulus at base, two indistinct, pale brown annuli and two broad, dark brown annuli in apical half, apically broadly whitish; mesotibia with two broad, dark brown annuli in basal third, basally broadly whitish. Hemelytron brown, with indistinct reticulate patterns (Fig. 4A); veins partially yellowish-brown. Abdomen dark brown to blackish-brown; connexival segments III–VII yellowish-brown in basal half (Fig. 4B, C); sternite III with one small yellowish-brown spot posteriorly on both sides (Fig. 4B, C); sternites IV–VI each with two small yellowish-brown spots on both sides (Fig. 4B, C). — Vestiture: Body surface smooth, strongly polished, covered with dense, very short, decumbent to suberect pubescence and sparse, long, erect pubescence. Posterior lobe of pronotum transversely wrinkled. Meso- and metapleura gently wrinkled. Profemur with several long, erect, strong setae ventrally; protibia with short, erect, strong setae ventrally. — Structure: Head (Fig. 4A–C) elongate oval, 1.1 times as long as width across eyes; width across eyes 2.15 times as broad as interocular space. Eye (Fig. 4A–C) medium-sized, remote from dorsal and ventral margins of head in lateral view. Labium (Fig. 4B, C) with visible segments I and II subequal in length; visible segment III 1.65–1.75 times as long as visible segment I. Pronotum (Fig. 4A, B) 1.35 times as long as width across humeral angles; anterior lobe 0.9 times as long as head, with shallow longitudinal furrow along midline; posterior lobe bell-like, with shallow, triangular, median impression on disc, humeral angles rounded and slightly elevated, posterior margin gently concave. Scutellum (Fig. 4A, B) semicircular, with erect spine-like process. Metanotum with short spine-like process; meso- and metasterna (Fig. 4C) with longitudinal carina along midline. Foreleg (Fig. 4D) robust; procoxa 0.9 times as long as pronotum; profemur gently curved, 14.5 times as long as its maximum width, twice as long as procoxa; posteroventral series composed of nine long spines and many smaller ones inserted on distinct basal processes, and of some small, denticle-like spines apically; protibia 0.8 times as long as profemur, armed ventrally with two irregular rows of small denticles. Mesotibia 1.55 times as long as mesofemur. Hemelytron (Fig. 4A) narrow at proximal portion and widest at subapical portion; M basad of subbasal cell less than half of length of Cu; subbasal cell acuminate. Abdomen (Fig. 4B, C) elongate, 3.5–3.6 times as long as its maximum width. Male genitalia: pygophore (Fig. 5A–C) oblong, with narrow transverse bridge and wide, flattened, deeply incised apical projection; paramere (Fig. 4D, E) short, curved, with subacute apex; phallus as shown in Fig. 5F–H; articulatory apparatus thick, with basal plate arms widely separated; phallosoma membranous, with one pair of narrow lateral sclerites and one pair of dorsolateral lobes near apex; struts long and slender, apically widened and flattened; endosoma tube-like. — Measurements: [in mm, ♂ (n = 2)]. Length of body: to apex of hemelytron 12.00, to apex of abdomen 11.00–11.30; length of head 1.10–1.30; length of anteocular region 0.50; length of postocular region 0.40; width across eyes 1.05–1.10; interocular space 0.50; length of antennal segments 6.20, ? (missing), ? (missing), ? (missing); length of visible labial segments 0.40–0.45, 0.40–0.45, 0.70–0.75; length of anterior pronotal lobe 1.05–1.10; length of posterior pronotal lobe 1.15–1.40; maximum width of anterior pronotal lobe 0.80–0.90; maximum width of posterior pronotal lobe 1.70–1.80; length of procoxa, femur, tibia, tarsus 2.10, 4.30–4.40, 3.40, 0.50; maximum width of profemur 0.30; length of mesofemur, tibia, tarsus 6.30, 9.70, 0.50; length of metafemur, tibia, tarsus 9.50, ? (missing), ? (missing); length of hemelytron 7.90; length of abdomen 6.10–6.50; maximum width of abdomen 1.75–1.80.

Distribution.

China – Xizang: Medog (Fig. 8).

Etymology.

The specific epithet is derived from Latin pulchella (meaning beautiful), referring to the peculiar markings on the head, pronotum, and abdomen of this new species.

Comparative notes.

Chinemesa pulchella sp. n. can be distinguished from its other congeners by the remarkable color patterns first of all: body generally blackish (vs reddish-brown to dark brown in other species); head bicolorous, with anterior lobe blackish and posterior lobe reddish (vs head concolorous in other species); abdomen ventrally with whitish-yellow spots on both sides (vs lacking such spots in other species).

This new species is morphologically similar to C. chinensis and C. murudiana. These species share the medium body size, the relatively short anterior lobe of the pronotum (shorter than the head), and the bicolorous connexivum. The new species can be readily separated from the latter two species by: procoxa about half as long as profemur (vs much longer than half of length in C. murudiana); meso- and metafemora each with four alternating light and dark annuli, and one apical whitish annulus (vs with 15 alternating light and dark annuli in C. murudiana; mesofemur with two broad and one narrow light annuli, metafemur with six dark annuli and one apical whitish annulus in C. chinensis); hemelytron with indistinct reticulate patterns (vs with distinct reticulate patterns in C. murudiana); subbasal cell of hemelytron acuminate (vs broad in C. chinensis); pygophore oblong (vs elongate oval in C. chinensis); phallosoma with paired lateral sclerites near apex (vs without such sclerites in C. murudiana).

Chinemesa weilingfengi sp. n.

https://zoobank.org/FC6C691B-D1C9-433A-85A7-0D50CA161952

Figures 6, 7

Chinese vernacular name: 魏氏钟蚊猎蝽

Type material.

Holotype: ♂, CHINA, Yunnan, Xishuangbanna, Mengla, Wangtianshu [望天树], 19.xi.2022, Lingfeng Wei (CAU).

Figure 6.

Habitus and morphological details of Chinemesa weilingfengi sp. n.: A Macropterous male, holotype, dorsal view; B macropterous male, holotype, ventral view; C anterior part of body of macropterous male, dorsal view; D anterior part of body of macropterous male, lateral view; E foreleg of macropterous male, ventral view; F hemelytron of macropterous male, dorsal view. Scale bar 5 mm (A, B), 1.5 mm (C–F).

Figure 7.

Male genitalia of Chinemesa weilingfengi sp. n.: A Pygophore, dorsal view; B pygophore, lateral view; C pygophore, caudal view; D paramere, dorsal view; E paramere, lateral view; F phallus, dorsal view; G phallus, lateral view; H phallus, ventral view. Scale bar 1 mm.

Diagnosis.

Body small-sized, 9.5 mm; anterior lobe of pronotum distinctly shorter than head (Fig. 6C, D); posterior lobe of pronotum with one pair of submedian, oblique, yellowish-brown stripes, humeral angle yellowish-brown (Fig. 6C, D); profemur with two light-colored annuli and one subapical light-colored spot (Fig. 6E); meso- and metafemora with 15 and 17 alternating dark and light annuli, respectively (Fig. 6A, B); extreme base of meso- and metatibiae dark brown (Fig. 6A, B); hemelytron with distinct reticulate patterns (Fig. 6F); connexivum bicolorous (Fig. 6B); phallosoma with paired lateral sclerites near apex (Fig. 7F–H).

Description.

Macropterous male (Fig. 6A, B). Colouration: Generally dark brown. Head reddish-brown, with portion before antennal insertions darker (Fig. 6C, D); labrum pale brown. Antenna blackish-brown; extreme apex of scape and pedicel whitish-yellow. Labium with intersegmental portions yellowish-brown (Fig. 6D). Pronotum blackish-brown; dorsal surface of anterior lobe reddish-brown (Fig. 6C, D); posterior lobe with one pair of submedian, oblique, yellowish-brown stripes reaching posterior margin, humeral angle yellowish-brown (Fig. 6C, D). Meso- and metapleura and sterna blackish-brown. Procoxa and trochanter reddish-brown (Fig. 6E); profemur reddish-brown to blackish-brown, with two whitish-yellow annuli at midportion and one small whitish-yellow spot subapically (Fig. 6E); protibia blackish-brown (Fig. 6E); protarsus brown (Fig. 6E). Mid and hind legs yellowish-brown; meso- and metafemora each with four or five narrow dark brown annuli in basal half, three broad dark brown annuli and two narrow whitish-yellow annuli in apical half, apically broadly whitish (Fig. 6A, B); meso- and metatibiae each with two broad dark brown annuli in basal third, basally broadly whitish with extreme base dark brown (Fig. 6A, B). Hemelytron brown, with distinct reticulate patterns; veins yellowish-brown (Fig. 6F). Abdomen with connexival segments IV–VII yellowish-brown in basal half (Fig. 6B). — Vestiture: Body surface smooth, strongly polished, covered with dense, very short, decumbent to suberect pubescence and sparse, long, erect pubescence. Antennal scape densely covered with long erect setae about three times as long as diameter of segment. Posterior lobe of pronotum transversely wrinkled. Meso- and metapleura gently wrinkled. Profemur with several long, erect, strong setae ventrally; protibia with short, erect, strong setae ventrally. — Structure: Head (Fig. 6C, D) subfusiform, 1.3 times as long as width across eyes; width across eyes 2.4 times as broad as interocular space. Eye (Fig. 6C, D) large, reaching dorsal and ventral margins of head in lateral view. Antennal scape 1.05 times as long as pedicel, 5.3 times as long as head; basiflagellomere slightly shorter than distiflagellomere. Labium (Fig. 6D) with visible segment I 1.3 times as long as visible segment II; visible segment III 1.75 times as long as visible segment I. Pronotum (Fig. 6C, D) 1.5 times as long as width across humeral angles; anterior lobe 0.7 times as long as head, with shallow longitudinal furrow along midline; posterior lobe bell-like, with shallow, triangular, median impression on disc, humeral angles rounded and slightly elevated, posterior margin concave. Scutellum (Fig. 6C, D) semicircular, with erect spine-like process. Metanotum with short spine-like process; meso- and metasterna with longitudinal carina along midline. Foreleg (Fig. 6E) robust; procoxa 1.05 times as long as pronotum; profemur gently curved, 13 times as long as its maximum width, 1.7 times as long as procoxa; posteroventral series composed of eight long spines and many smaller ones inserted on distinct basal processes, and of some small, denticle-like spines apically; protibia 0.85 times as long as profemur, armed ventrally with two irregular rows of small denticles. Meso- and metatibiae 1.55 and 1.7 times as long as respective femur. Hemelytron (Fig. 6F) narrow at proximal portion and widest at subapical portion; M basad of subbasal cell about one-third as long as Cu; subbasal cell acuminate. Abdomen elongate, 4.4 times as long as its maximum width. Male genitalia: pygophore (Fig. 7A–C) oblong, with narrow transverse bridge and wide, flattened, weakly incised apical projection; paramere (Fig. 7D, E) short, curved, with obtuse apex; phallus as shown in Fig. 7F–H; articulatory apparatus thick, with basal plate arms widely separated; phallosoma membranous, with one pair of narrow lateral sclerites near apex; struts long and slender, apically widened and flattened. — Measurements [in mm, ♂ (n = 1)]. Length of body: to apex of hemelytron 9.10, to apex of abdomen 9.50; length of head 1.10; length of anteocular region 0.40; length of postocular region 0.25; width across eyes 0.85; interocular space 0.35; length of antennal segments 5.80, 5.50, 1.00, 1.50; length of visible labial segments 0.40, 0.30, 0.70; length of anterior pronotal lobe 0.80; length of posterior pronotal lobe 1.00; maximum width of anterior pronotal lobe 0.60; maximum width of posterior pronotal lobe 1.20; length of procoxa, femur, tibia, tarsus 1.90, 3.30, 2.80, 0.40; maximum width of profemur 0.25; length of mesofemur, tibia, tarsus 6.10, 9.50, 0.40; length of metafemur, tibia, tarsus 8.40, 14.60, 0.40; length of hemelytron 5.90; length of abdomen 5.30; maximum width of abdomen 1.20.

Distribution.

China – Yunnan: Mengla (Fig. 8).

Figure 8.

Known distribution of Chinemesa spp.

Etymology.

This new species is dedicated to Mr. Lingfeng Wei (Forest City Studio, Shanghai, China), the collector of the holotype of this rare species, for his kind support to our study of Reduviidae.

Comparative notes.

Chinemesa weilingfengi sp. n. is morphologically similar to C. murudiana in the similar color patterns of the mid and hind legs, the distinct reticular patterns on the hemelytron, and the bicolored connexivum. This new species can be easily distinguished from the latter by: body small-sized, 9.5 mm in length (vs 14 mm in C. murudiana); anterior lobe of pronotum distinctly shorter than head (vs slightly shorter than head in C. murudiana); extreme base of meso- and metatibiae dark brown (vs broadly whitish in C. murudiana); phallosoma with paired lateral sclerites near apex (vs without such sclerites in C. murudiana).

Key to species of Chinemesa modified after Chen et al. (2020a)

1	Macropterous male	2
1’	Apterous female	7
2	Anterior lobe of pronotum longer than head; hemelytron without reticulate patterns; connexivum unicolored	3
2’	Anterior lobe of pronotum shorter than head; hemelytron with distinct or indistinct reticulate patterns; connexivum bicolored	4
3	Body about 16.5 mm in length; profemur with four reddish-brown annuli; meso- and metafemora each with about nine reddish-brown annuli and one broad apical whitish annulus	Chinemesa poiana Wygodzinsky, 1966
3’	Body about 7.8 mm in length; profemur with two whitish annuli; mesofemur with one narrow subapical whitish annulus, metafemur with one broad apical whitish annulus	Chinemesa uniannulata Rédei, 2007
4	Head bicolored, with blackish anterior lobe and reddish posterior lobe; abdomen ventrally with distinct light-colored spots; phallosoma with one pair of dorsolateral lobes near apex	Chinemesa pulchella sp. n.
4’	Head unicolored, reddish-brown or dark brown; abdomen ventrally without light-colored spots; phallosoma without dorsolateral lobes near apex	5
5	Profemur twice as long as procoxa; mesofemur with one narrow subapical whitish annulus; hemelytron with indistinct reticulate patterns and broad basal cell	Chinemesa chinensis Chen, Li & Cai, 2020
5’	Profemur less than twice as long as procoxa; mesofemur with one broad apical whitish annulus; hemelytron with distinct reticulate patterns and acuminate basal cell	6
6	Body about 9.5 mm in length; anterior lobe of pronotum distinctly shorter than head; extreme base of meso- and metatibiae dark brown; phallosoma with paired lateral sclerites near apex	Chinemesa weilingfengi sp. n.
6’	Body about 14 mm in length; anterior lobe of pronotum slightly shorter than head; base of meso- and metafemora broadly whitish; phallosoma without paired lateral sclerites near apex	Chinemesa murudiana Wygodzinsky, 1966
7	Body about 17 mm in length; anterior lobe of pronotum distinctly longer than head; metafemur reddish-brown, with three light-colored annuli	Chinemesa feminata Wygodzinsky, 1966
7’	Body about 11.4 mm in length; anterior lobe of pronotum slightly shorter than head; metafemur yellowish-brown, with 17 alternating dark and light annuli	Chinemesa ornata sp. n.

4. Discussion

4.1. Mitochondrial gene rearrangements of Chinemesa and phylogenetic implication

Gene rearrangement has long been considered a key aspect of mitogenome evolution. Mitochondrial gene rearrangements can be classified in several ways: (i) by gene type, into major (protein-coding and/or rRNA genes) and minor rearrangements (tRNA genes); (ii) by whether the transcription direction changes, into translocations and inversions; and (iii) by the gene clusters involved, into local and remote rearrangements (Cameron et al. 2007). Different types of gene rearrangements can occur in combination, with some types being more prevalent than others (Dowton et al. 2009). At least 23 rearranged gene orders have been observed in Heteroptera, distributed across twelve different families (Chen et al. 2020b; Ye et al. 2021; Zhao et al. 2025). Reduviidae represents a “hot-spot group” of mitochondrial gene rearrangement in Heteroptera, with ten distinct types previously reported in the family (Ye et al. 2021; Du et al. 2023).

The mitogenomes of the four Chinemesa species reported here reveal two novel gene orders that differ from all known gene orders of Reduviidae (Fig. 1). In all four species, trnI and trnQ are translocated from their ancestral position between the control region and trnM to a new position between trnW and trnC. An additional loss of trnW occurs in C. pulchella sp. n. The translocation of trnI-trnQ and the loss of trnW can be explained using the tandem duplication-random loss (TDRL) model (Boore 2000; Wei et al. 2010). With a common TDRL process, the tandem duplication of trnI-trnQ-trnM-ND2-trnW generated an intermediate sequence (trnI-trnQ-trnM-ND2-trnW-trnI-trnQ-trnM-ND2-trnW), followed by the deletion of trnI and trnQ in the first copy and trnM, ND2 and trnW in the second copy, yielding the current gene order (Fig. 9A). The non-coding region (3–19 bp) between trnQ and trnC may represent a residual sequence of the gene deletion process. In the mitogenome of C. pulchella sp. n., trnW in the first copy is also deleted, leaving a 27-bp remnant between ND2 and trnI (Fig. 9B).

Figure 9.

The hypothetical process of gene rearrangements of Chinemesa spp. based on the TDRL model: A. the translocation of trnI and trnQ in Chinemesa spp.; B. the translocation of trnI and trnQ and loss of trnW in C. pulchella sp. n. Different types of genes are labeled with different color blocks: PCGs, blue; rearranged tRNAs, orange; unrearranged tRNAs, pink; control region (CR), brown; deleted genes, light grey; non-coding region (NCR), dark grey.

Including the two newly discovered gene rearrangements in this study, a total of twelve types of rearranged gene orders has been documented in Reduviidae (Fig. 1), all of which are minor rearrangements. The tRNA genes are observed to have the highest mobility, possibly due to their small size (Moritz and Brown 1987; Peng et al. 2025). Among these rearrangement cases, tRNA gene translocation involves at least seven genes, while gene duplication and gene loss occur in only three and two genes, respectively, indicating that tRNA gene translocation is the primary form of mitochondrial gene rearrangement in Reduviidae.

From an evolutionary perspective, gene rearrangements may represent potential molecular synapomorphies for specific lineages. For instance, the gene order trnQ-trnI, present in all known Aradidae mitogenomes, is regarded as a molecular synapomorphy of the family (Song et al. 2016). The transposition of trnT and trnP (trnP-trnT) is hypothesized as a potential molecular synapomorphy of the superfamily Pyrrhocoroidea (Liu et al. 2019; Men et al. 2019). However, previously reported gene rearrangements within Reduviidae were scattered across unrelated lineages and thus considered to have evolved independently (Ye et al. 2021). The newly discovered trnI-trnQ translocation exists in all sequenced Chinemesa mitogenomes, suggesting that this rearrangement event likely occurred at least in the most recent common ancestor of these species and was retained as a potential molecular synapomorphy during the subsequent evolution of the genus. The loss of trnW evolved independently in C. pulchella sp. n.

4.2. Diversity and distribution of Chinemesa

For a long time, Chinemesa was considered endemic to Borneo (Wygodzinsky 1966; Maldonado-Capriles 1990; Rédei 2007). Chen et al. (2020a) described the first species of Chinemesa from the mainland of Asia, extending the generic distribution range to the northern tropical boundary, and suggesting the possibility of finding new species elsewhere in the Oriental Region. The three new species described herein, all from southern China, further expand our understanding of the diversity of Chinemesa in the Asian mainland, and extend the northern limit of the generic distribution to the edge of the Oriental Region at approximately 29.5°N.

Males of Chinemesa possess fully developed wings, and specimens of at least two species (C. pulchella sp. n. and C. uniannulata) were collected using Malaise traps, indicating the flight capability of the males. However, all known females of this genus are apterous, suggesting that geographical isolation may act as an important driving force for the diversification of Chinemesa. Judging from the present distribution of Chinemesa, there are still large gaps in the Indochinese Peninsula and the Malay Peninsula, where further species are expected to be discovered. Future study should also focus on the natural history of Chinemesa species to better understand the role of habitat partition in the speciation of this genus.

5. Funding

This work was supported by grants from the National Natural Science Foundation of China (Nos. 32400373, 32120103006), the China Postdoctoral Science Foundation (No. 2025M773789), the China Scholarship Council (No. 202106350082), and the 2115 Talent Development Program of China Agricultural University.

6. Declarations

Conflict of interests. The authors declare that they have no conflict of interests.

Data availability statement. The molecular data newly generated in this study have been deposited in GenBank with accession numbers listed in Table S3.

7. Acknowledgements

We sincerely appreciate Chufei Tang and Lingfeng Wei for providing us specimens used in the present study. We are very grateful to Michael D. Webb, Valérie A. Lemaître (NHMUK), Charlotte Hartong and Luc Willemse (RMNH) for their kind help during our examination of Reduviidae specimens under their care. We thank Tadashi Ishikawa and an anonymous reviewer for their valuable comments on the manuscript, and Christiane Weirauch for her editorial work.

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Supplementary materials

Supplementary material 1

Tables S1–S6

Chen Z, Li H, Cai W (2026)

Data type: .xlsx

Explanation notes: Table S1. Information of specimens used for morphological comparison. — Table S2. Molecular sampling information of the present study. — Table S3. Molecular data used in the present study. The newly generated sequences are outlined in bold. — Table S4. The best-fitting partitioning scheme for the PCGRNA matrix. — Table S5. The best-fitting partitioning scheme for the PCG12RNA matrix. — Table S6. The K2P genetic divergences among the sampled Chinemesa specimens based on the standard COX1 barcoding region.

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

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Supplementary material 2

Figures S1–S4

Chen Z, Li H, Cai W (2026)

Data type: .zip

Explanation notes: Figure S1. Phylogenetic tree of Reduviidae inferred from the Bayesian inference (BI) analysis based on the PCGRNA dataset. Support values on nodes indicate PP. — Figure S2. Phylogenetic tree of Reduviidae inferred from the maximum-likelihood (ML) analysis based on the PCGRNA dataset. Support values on nodes indicate SH-aLRT (left) and UFBoot2 (right). — Figure S3. Phylogenetic tree of Reduviidae inferred from the Bayesian inference (BI) analysis based on the PCG12RNA dataset. Support values on nodes indicate PP. — Figure S4. Phylogenetic tree of Reduviidae inferred from the maximum-likelihood (ML) analysis based on the PCG12RNA dataset. Support values on nodes indicate SH-aLRT (left) and UFBoot2 (right).

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

Download file (241.34 kb)