The piece of amber containing the specimen derives from the deposits of the Hukawng Valley, Kachin State, Northern Myanmar. The specimen is permanently deposited in a well-established, public museum, in full compliance with the international Palaeoentomological Society Statement (Haug et al. 2020). We align with the content of Haug et al. (2020) regarding the controversy surrounding the ethics of Burmese amber research in relation to the Myanmar armed conflict. We also acknowledge the clarifying publications, such as Peretti (2020), which address misinterpretations of this controversy.

The specimen is housed at the Geominer Museum of the Instituto Geológico y Minero de España, Consejo Superior de Investigaciones Científicas (IGME, CSIC) in Madrid. The specimen was examined with an Olympus BX53 compound microscope equipped with a digital camera. The nomenclature of the hemipteran venation and morphology characteristics used here is based on the interpretations of Schuh and Slater (1995) and Cassis and Schuh (2010).

Plates were edited and processed using Adobe Photoshop. The specimen was drawn using a drawing tube Olympus U-DA attached to the Olympus BX53 microscope. The figures were composed with Photoshop CC2018. The model of the hemipteran was performed with Light-Wave 3D computer graphics program (NewTek) and the live reconstruction scene was performed using Adobe Photoshop (art by José Antonio Peñas).

A total of 49 characters were examined (File S1). The selection of morphological characters was according to the following previous works by Henry (1997), Schuh et al. (2009), Du et al. (2016) and Cassis et al. (2023). However, we excluded some characters for the present cladistic analysis for the following reasons:

Internal morphology. The presence of microchromosome, sex chromosome, number of salivary gland lobes and gastric caeca on mid gut were not considered because they are not preserved/observed in fossil taxa.

Nymph morphology. We exclude characters associated with morphology of nymphs because the immature stages are unknown in the fossil record.

Feeding habits and lifestyle. We exclude these characters because we consider that there is no evidence to accurately characterize the feeding type for most of the taxa in our matrix. In addition, for example, although a high percentage of Miridae are host-plant specific, there is evidence that many species feed on both plant and animal materials.

We choose a pentatomorph species (Malcus sp.) as our external group taxon so as not to bias the choice of fossil taxa to families included in the Cimicomorpha. The 10 ingroup terminal taxa include two fossil taxa and eight extant taxa. All terminal taxa are identified to species level. The matrix was generated in Mesquite software (version 3.5, see http://www.mesquiteproject.org) and all the characters are unordered and of equal weight, and missing data were scored as unknown. The data matrix and the complete list of taxa used in the phylogenetic analysis are provided in File S1.

The phylogenetic analysis was based on the parsimony criterion, conducted in TNT (version 1.5, see https://www.lillo.org.ar/phylogeny/tnt; Goloboff and Catalano 2016). Runs were conducted using the following commands: Maximum trees to keep (hold) = 10000; Number of replications (mult*N) = 100. Bremer support values (Bremer 1994) were calculated as measures of branch support using the following command sequence in TNT: commandline: calculate support [bremer, build (0)]. All characters were analysed as unordered and under equal weights (EW). The data matrix and tree file were transferred to Winclada (version 1.00.08, see www.lillo.org.ar/phylogeny/winclada; Nixon 2002) to produce graphical depiction of the tree.

Order Hemiptera Linnaeus, 1758

Suborder Heteroptera Latreille, 1810

Infraorder Cimicomorpha Leston, Pendergrast and Southwood, 1954

Family Thaumastocoridae Kirkaldy, 1908

Subfamily Thaumastocorinae Kirkaldy, 1908

The phylogenetic analysis was based on the parsimony criterion, conducted in TNT. Analysis of the character matrix yielded two most parsimonious trees, length = 77, CI = 0.740, RI = 0.740, the strict consensus tree is shown in Figure 4; character data are plotted on the tree using fast optimization with Bremer support values and > 50% resampling support bootstrap (Fig. 4). The phylogenetic analysis includes a single clade, Malcus sp., which represents the outgroup taxon that displays characters typical for Trichophora and Pentatomomorpha groups, namely: long and narrow bucculae that extend to half the length of the head (character 4-1); presence of pulvillus (character 35-1); and abdominal trichobothria on each sternum (character 41-1).

According to the present results, the first node includes the families of Cimicomorpha (node 1; Fig. 4) supported by the following six synapomorphies: base of antenna rising below the level of eye (character 10-1); costal fracture present (character 27-1); cuneus present (character 28-1); m-cu crossvein of hindwing absent (character 29-1); ovipositor plate-like to reduced (character 44-1) and a vestigial or absent spermatheca (character 45-1). The reduced dorsal arolium on the pretarsus, the labium inserted on the anterior surface of the head, the presence of 1–3 closed cells on the forewing membrane, a plate-like to reduced ovipositor and the spermatheca transformed into a vermiform gland were used by Schuh et al. (2009) to support the monophyly of Cimicomorpha. Based on the above, the new taxon is confidently placed within Cimicomorpha. Additionally, Reduvioidea Latreille, 1807 and Microphysidae Dohrn, 1859 are monophyletic, as supported by several synapomorphies (e.g., presence of trichobothria on the antennal pedicel (character 11-1) and presence of Brindley’s gland in the metathorax (character 17-1)).

As expected based on previous work (Cassis et al. 2023), our analysis recovers Miridae Hahn, 1833 as sister to the Thaumastocoridae + Tingidae Laporte, 1833 with 52% symmetric resampling support (node 2; Fig. 4) with three uncontradicted characters (mandibular plates enlarged (character 3-1); absence of ocelli (character 7-1); distal sector of R+M in hind wing (character 30-0)) and two contradicted (veins of the corium reduced (character 21-1); entire sternite VII (character 40-2)) synapomorphies. The Thaumastocoridae + Tingidae sister-group relationship is supported by a 95% resampling value (node 3: Fig. 4) and the following nine synapomorphies (seven uncontradicted and two contradicted, respectively): lateral head (character 2-1); antennal segment I short (character 12-0); metathoracic scent-gland without evaporatorium and peritreme (character 16-0); costal area explanate and not areolate (character 22-1); hemelytral membrane without veins or cells (character 23-1); presence of areolate hemelytra (character 25-1); cuneus present (character 28-0); two-segmented tarsi (character 33-1); and absence of a dorsal arolium (character 36-1). Tingidae monophyly is supported with 100% resampling support with eight characters (e.g., presence of pronotal carina (character 14-1); costal area explanate and areolate (character 22-2); areolate texture of hemelytral membrane (character 26-1)).

Popovocoris punctatusnov. sp. is nested within Thaumastocoridae (node 4; Fig. 4). The monophyly of this family (Thaumastocorinae + Xylastodorinae sister-group relationship) is well supported by a 96% resampling value and the following synapomorphies (four uncontradicted and three contradicted, respectively): presence of ocelli (character 7-0); absence of costal fracture (character 27-0); coxal shape globose (character 38-1); symmetrical parameres (character 42-2); fused dorsolateral and medial abdominal tergites (character 46-1); opening of pygophore lateral (character 47-1); and pygophore tubiform (character 48-1). Xylastodorinae monophyly is supported by a 67% resampling values and two uncontradicted synapomorphies: body ovoid (character 0-2); and obsolete parameres (character 42-3). However, Popovocoris punctatusnov. sp. is recovered as a sister-group of Thaumastocorinae supported by a 52% value (Fig. 4) supported by the stylate eyes (character 6-1). On the other hand, the monophyly of Thaumastocorinae is well supported by a 94% resampling value, due to three contradicted synapomorphies (Fig. 4), which are: presence of tibial appendix (character 32-1); lateral articulation of the metacoxae (character 37-0) and development of claval commissure (character 24-0). The new species shows the following synapomorphies: absence of mandibular plates (character 3-0); base of antennal arising below level of eye (character 10-0); and one-segmented tarsi (character 33-2).

The cladistic analysis performed by Schuh et al. (2009), which had a more extensive taxon sampling and included both morphological and molecular characters, concluded that the asymmetrical male genitalia found in the Thaumastocoridae is supporting the monophyly of the family. Our analysis coincides with some characteristics recovered by the recent phylogenetic analysis of Cassis et al. (2023), where the monophyly of the family is well supported (with Thaumastocorinae and Xylastodorinae as sister-group) on the basis of a large number of characters which are: dorsalised mandibular plates; fused dorsolateral and medial abdominal tergites; absence of abdominal spiracle 1; pygophore tubiform; lateralised articulation of pygophore; absence of female external genitalia; and hemelytra with short setiferous punctures. The absence of veins on the forewing membrane in our taxon and in thaumastocorids is a distinctive feature, but it is also present in species of the Tingidae (Cassis et al. 2023) that are commonly treated as the sister-group to the Thaumastocoridae (e.g., Schuh et al. 2009, Cassis et al. 2023). While our findings align with some previously described morphological characteristics, others were not observable due to the lack of preserved females and the limited observation of morphological structures in the analyzed fossil male specimen.

Burmese amber has yielded a significantly more diverse assemblage of Pentatomomorpha compared to the relatively limited representation of Cimicomorpha (Ross 2023). This amber has preserved various morphotypes of early Pentatomomorpha, some of which are unique to Burmese amber. Specifically, the extinct family Yuripopovinidae, known for its peculiar and heterogeneous taxa, has been extensively studied in Burmese amber, with several new genera and species described. The initial appearance of extant cimicomorphan families is documented between the Triassic and Jurassic periods, with Tingidae first occurring in the Triassic, followed by Nabidae (Cimicoidea) and Miridae (Miroidea) in the Jurassic (Carpenter 1992, Hou et al. 2012, Nicholson et al. 2015, Montagna et al. 2018). Some cimicomorphan families became well recorded during the Cretaceous period, as evidenced by members of Tingidae (Perrichot et al. 2006, Gould and Popov 2008). To date, Cretaceous amber has yielded thirteen species across seven genera of Tingidae (Montagna et al. 2018), contrasting with only two described species of Microphysidae (Aiba et al. 2025) and Nabidae (Ma et al. 2024). Therefore, the fossil record of Thaumastocoridae was, prior to this study, limited to four Cenozoic amber species. The specimen described herein therefore represents the first reliable Mesozoic record of the family (Figure 5).

The new genus exhibits characters of Thaumastocoridae based on the morphological characteristics mentioned above (Phylogenetic analysis), especially the asymmetrical genitalia. The presence of ocelli is universal in the Thaumastocoridae, also present in Popovocorisnov. gen., and these are in a postocular position. Pseudopulvilli are characteristic of the entire subfamily Xylastodorinae and are rejected as pulvilli (fleshy pretarsal structures) based on the attachment to both the unguitractor plate and base of claws sensu Schuh (Schuh 1976, van Doesburg et al. 2010). Pulvilli are present in other extant (e.g., Anthocoridae: Oriini) (Schuh et al. 1995) and fossil (e.g., †Thaumastotingis areolatus Heiss and Golub, 2015) cimicomorphans (Heiss and Popov 2002). Popovocoris punctatusnov. sp. is a close relative of the subfamily Thaumastocorinae (Fig. 4) based on the following characters: first labial segment short and dilated; metathoracic gland efferent system absent; and reduced tarsi (Cassis et al. 2023). All Thaumastocorinae species have greatly reduced tarsi, reminiscent of burrowing Cydnidae, with reduction in the thaumastocorines coupled with the presence of the fossula spongiosa = tibial appendix of Cassis et al. (2023) = lobate sensory appendage of Drake and Slater (1957) (e.g., in fig. 12F of Noack et al. 2011). The new fossil is characterised by one-segmented tarsi; however, it cannot be ruled out that it has a very reduced basal first tarsomere, like in extant Thaumastocoris species (e.g., T. peregrinus in Carpintero and Dellapé 2006). Compared to the diagnostic character matrix compiled for the four extant Thaumastocorinae genera (Table 1 in Noack et al. 2011), Popovocorisnov. gen. combines a mosaic of ancestral and derived states rather than aligning cleanly with any single genus. Its convex mandibular plates match the condition in Baclozygum, Onymocoris, and Wechina rather than the flat to strongly concave plates diagnostic of Thaumastocoris. Its weak pronotal constriction and moderate labium length likewise fall closer to the Onymocoris and Thaumastocoris condition than to the more strongly constricted, longer-labiate condition of Baclozygum and Wechina, while its non-conspicuous, fine tibial combs (6–7 setae) most resemble the reduced tibial dentition of Baclozygum rather than the thick, numerous teeth (3–20) typical of Thaumastocoris. On the other hand, the genus Popovocorisnov. gen. and Thaumastocoris share the characteristic of a dull-white hemelytral membrane with a narrow dark-brown margin along the corial border and the shape of the corium. The male genital capsule in P. punctatus opens to the left side as in Thaumastocoris australicus Kirkaldy, 1908. On the other hand, P. punctatusnov. sp. differs from other Thaumastocorinae by the presence of one segmented tarsi, an absence of distinctive mandibular plates, surface of abdominal tergites with depressions of varied sizes, ocelli placed on small tubercles and absence of a fossula spongiosa.

Further, the morphological characteristics of the studied fossil indicate morphological conservatism, spanning ~99 million years, with respect to somatic (e.g., flattened body, reduced tarsi and hemelytral veins) and genitalic (e.g., pygophore asymmetry) characters, suggesting that the evolution of asymmetrical genitalia in this family had already occurred in East Asia during the Late Cretaceous. The new genus also displays morphological traits not found in extant thaumastocorids, which indicate loss of morphological diversity over time in the thaumastocorid lineage. Morphological disparity between extinct and present-day heteropterans has also been documented in other taxa groups as well, such as the Tingiometrinae (Heiss and Golub 2015).

Most Xylastodorinae species, including the Neotropical and Southwest Pacific ones, are associated with the plant subfamily Arecoideae that is the most diverse for the family Arecaceae (palms) (Cassis et al. 2023). Extant Thaumastocoris has the broadest host range within the Thaumastocorinae (Cassis et al. 1999). Host plant associations are documented for 12 of the 14 species of Thaumastocoris (Noack et al. 2011). Eight plant families are recorded for Thaumastocoris, and most species in this genus are associated with Myrtaceae (myrtles). Thaumastocoris hackeri Drake and Slater, 1957 is recorded on species of the plant families Elaeocarpaceae, Cunoniaceae, and Rubiaceae, and Thaumastocoris roy Noack, Cassis and Rose, 2011 of the Malvaceae (Noack et al. 2011). A diverse selection of angiosperm flowers has been found in Burmese amber. However, the families Arecaceae and Myrtaceae have not yet been found in Burmese amber as fossils. Nevertheless, molecular clock estimates for the origins of the Arecaceae are around 96.6 million years ago (Ma) in the Late Cretaceous (Chen et al. 2022). While most Burmese angiosperms cannot be assigned to extant families, two have been assigned to the cosmopolitan families Lauraceae and Poaceae, while three others have affiliations with the Gondwanan families Cunoniaceae, Monimiaceae and Dilleniaceae (Grimaldi 2000). Therefore, these families, and especially the Monimiaceae, could have been the host plants for the new fossil species.

The origin of Burmese amber biota is a subject of ongoing debate, primarily revolving around the geological position of the Burma Terrane during amber formation and whether the bioinclusions are of Gondwanan or Southeast Asian (Laurasian) origin (Sevastjanova et al. 2016, Licht et al. 2020, Morley et al. 2021, Kundrata 2025). While a common hypothesis suggests the Burma Terrane was a northward-drifting isolated island, recent studies on Burmese amber biota offer conflicting evidence. Many discoveries point to Gondwanan affinities (Peris et al. 2016, Jarzembowski et al. 2017, Jouault and Nel 2020), particularly with Australian and Neotropical regions, leading some researchers to propose the Burma Terrane acted as a “biotic ferry” transporting species from Gondwana to the Northern Hemisphere (Wood and Wunderlich 2023) However, other studies indicate Laurasian relatives for some Burmese amber taxa, with some authors arguing that the presence of modern Australasian/Neotropical relatives in Cretaceous ambers from other regions does not necessarily imply a Gondwanan origin, but rather widespread Cretaceous forest distributions (Jouault 2021, Hinkelman 2022). Ultimately, it is becoming clear that Burmese amber contains lineages from both Gondwana and Laurasia (Kundrata et al. 2025), and the biogeographic affinities of any single taxon, including the new fossil described here, must be interpreted within this mixed-provenance context rather than in isolation.

The phylogenetic affinities of Popovocoris punctatusnov. sp. with Thaumastocorinae, a subfamily whose extant representatives are today restricted to the Southern Hemisphere (chiefly Australia and southern India), are consistent with the hypothesis of a Gondwanan biogeographic signal among certain Burmese amber lineages. However, given that Cretaceous Burmese amber demonstrably preserves both Gondwanan- and Laurasian-affiliated taxa, and that the fossil record of Thaumastocoridae outside Myanmar remains extremely sparse, we regard this pattern as suggestive rather than conclusive. We therefore favour an open interpretation: the present discovery adds a data point consistent with proposed Gondwanan connections for the Burmese amber biota, while the precise geographic origin and early dispersal history of Thaumastocoridae remain to be resolved with additional Cretaceous fossils and a time-calibrated molecular phylogeny.