Two New Species of Mesochorista (Insecta, Mecoptera, Permochoristidae) from the Guadalupian Yinping Formation of Chaohu, Eastern China ^†

Simple Summary

The megadiverse Permian mecopteran family Permochoristidae is well recorded worldwide and plays an important role in understanding the origin of the crown group of Mecoptera. However, fossil records from China remain scarce. Herein, we describe and illustrate two new species of Mesochorista from the Guadalupian Yinping Formation: Mesochorista tillyardi Lian and Huang, sp. nov., and Mesochorista yinpingensis Lian and Huang, sp. nov. In addition, we discuss Permochorista and Mesochorista and support that Permochorista should be considered a junior synonym of Mesochorista. These new fossils extend the known distribution of Mesochorista and improve our understanding of its diversity.

Abstract

Permochoristidae is a megadiverse mecopteran group that has mainly been reported from Russia and Australia, whereas records from China remain scarce. In this report, two new species of Mesochorista are described and illustrated from the Guadalupian Yinping Formation, Eastern China. Mesochorista tillyardi Lian and Huang, sp. nov. is characterized by the forewing covered with dense oval spots, and Sc₁ closely approximal to R₁ and connected by a short sc-r crossvein. Mesochorista yinpingensis Lian and Huang, sp. nov. is characterized by the forewing covered with dense irregularly colored patches, Sc₁ devoid of expanded area, and M with only five branches. Based on a detailed discussion of the type species and other co-occurring species of Mesochorista and Permochorista, in light of the new insights into Sc₃, we support that Permochorista is a junior synonym of Mesochorista.

1. Introduction

Mecoptera are one of the oldest holometabolous insect orders that can be dated back to the early Permian [1]. Recent Mecoptera exist as a relict lineage comprising only ca. 800 species [2,3]. In contrast, fossil mecopterans were diverse and constituted a significant component of various Paleozoic and Mesozoic entomofaunas [4,5]. Mecopterans are commonly referred to by different vernacular names based on their morphological, ecological, and ethological traits. For example, species with enlarged and upward-curved male genitalia, resembling a scorpion’s tail, are called “scorpionflies” (e.g., Panorpoidea Latreille, 1805), species that hang from vegetation using their forelegs while capturing prey are known as “hangingflies” (Bittacidae Handlirsch, 1906, Cimbrophlebiidae Willmann, 1977), those with forceps-like male genitalia reminiscent of earwigs are referred to as “earwigflies” (Meropeidae Handlirsch, 1906), and species adapted to cold environments and often found on snow surfaces are termed “snow scorpionflies” (Boreidae Latreille, 1816).

Mecoptera reached their first peak in species diversity during the Middle to Late Permian, with fossil records reported from Africa, Australia, Brazil, China, India, North America, and Russia [6,7,8,9,10,11,12,13,14,15]. The family Permochoristidae Tillyard, 1917 was the dominant mecopteran group during Permian; however, their diversity declined significantly after the onset of the Triassic and only survived as a relict lineage into the Jurassic, with the latest record being from the Early Jurassic [16,17]. The classification systems of Permochoristidae essentially rely on wing venation. The most common character of this diverse family is the six-branched M (M₂ and M₄ with a fork), while the other venational characters display a fairly high disparity. Based mainly on the branches of Sc and Rs, Permochoristidae was divided into four subfamilies: Permochoristinae Tillyard, 1917, Agetopanorpinae Carpenter, 1930, Sylvopanorpinae Novokshonov, 1997, and Pseudonannochoristinae Novokshonov, 1994. The Permochoristinae, which represents one of the most diverse mecopteran subfamilies, is characterized by its Sc possessing one or two anterior veinlets and Rs forking into four branches.

Over the past years, we have reported several Permian mecopterans from the Guadalupian Yinping Formation [15,18,19], including two permochoristid species: Permeca chaohuensis Lian, Cai and Huang, 2022 (Permochoristinae), and Chaohuchorista liaoi Lian, Cai and Huang, 2022 (Pseudonannochoristinae). However, records of Permochoristidae from China are still scarce compared with their high diversity in other deposits worldwide. In this report, two new species of Mesochorista, 1916 are described and illustrated from the Yinping Formation, which represent the first record of Mesochorista from the Permian of China.

2. Materials and Methods

The studied specimens were collected from black shale of the lower part of the Yinping Formation near Houdong Village, Chaohu City, Anhui Province (see detailed map in Lian et al. [15]: Figure 1). The Yinping Formation is considered to be Guadalupian in age (see detailed discussions in Lian et al. [18]).

Some specimens were carefully prepared using a sharp knife. Photographs were captured by a digital camera attached to a Zeiss Discovery V20 microscope, and scanning electron microscopy (SEM) images were obtained with a Hitachi SU 3500 scanning electron microscope, operating with an accelerating voltage of 25 kV and a pressure of 60 Pa. Line drawings were made using Adobe Illustrator 2019 graphic software (San Jose, CA, USA). All specimens are housed in the Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing, China.

The venation terminology primarily follows the scheme proposed by Minet et al. [20] and partly follows Bashkuev and Sukatsheva [21].

3. Systematic Paleontology

Order Mecoptera Packard, 1886

Family Permochoristidae Tillyard, 1917

Subfamily Permochoristinae Tillyard, 1917

Genus Mesochorista Tillyard, 1916

 

Revised diagnosis. Forewings ca. 6–11 mm long; Sc with one (Sc₂) or two anterior veinlets (Sc₂ and Sc₃), Sc₃ usually faint or absent; Rs with four branches, Rs₁₊₂ generally more than twice as long as Rs₃₊₄; M usually with six branches (sometimes five).

Remarks. Mesochorista is a derived permochoristid group showing a trend toward venational simplification. It commonly remains a forked M₂, a plesiomorphic character; while it also shares some derived characters, such as a simplified Sc (Sc₂ and Sc₃ shortened and weakened), and Rs (with Rs₄ unbranched). In some species, M₂ is single, a condition characteristic of more derived crown-group Mecoptera since the Mesozoic.

 

Mesochorista tillyardi Lian and Huang, sp. nov.

(Figure 1, Figure 2 and Figure 3A–H; LSID urn:lsid:zoobank.org:act:1BC155B9-8599-44EF-919F-975620B45DCF)

Etymology. The specific name honors R. J. Tillyard, a distinguished pioneer in the study of fossil Mecoptera.

Type locality and horizon. Yinping Mountain, Chaohu City, Anhui Province, China; Yinping Formation (Capitanian).

Diagnosis. Forewings densely ornamented with rounded and oval-colored spots; costal area greatly expanded at apex of Sc₁; Rs₁₊₂ twice as long as Rs₃₊₄. Hindwings with short, single-branched Sc; Rs and M both four-branched.

Material. Holotype, NIGP205288a–c (Figure 1A–C), specimen broken into three pieces. NIGP205288a (Figure 1A) preserves two hindwings and one forewing attached into the body; another isolated forewing preserved at 2 cm away. NIGP205288b (Figure 1B) preserves the body and two hindwings. NIGP205288c (Figure 1C) preserves a single forewing, representing the counterpart of the isolated forewing in NIGP205288a.

Paratypes, NIGP205289, NIGP205290a, b (part and counterpart), NIGP205291a, b, NIGP205292a, b, NIGP205293a, b, and NIGP205294a, b, each representing a complete forewing; NIGP205295 a, b (part and counterpart), a hindwing missing a small part of wing base; NIGP205296, a forewing lacking apex, middle part distorted and missing; NIGP205297 and NIGP208853, incomplete forewings.

Description. Holotype, NIGP205288, female; thorax and head structures poorly preserved. I–VII abdominal segments with clear boundary; I–IV subequal in length, width slowly tapering posteriorly; VI and VII equal in length, half as long as segment V; segment II–IV each with a sclerotized drum-shaped tergite, the other segments indistinct; one hind leg preserved, trochanter drum-shaped; femur robust, 1.7 mm long, 0.2 mm wide; tibia much thinner than femur, partially preserved.

Forewings elongate, 6.3 mm long, 2.0 mm wide (L/W = 3.2) (Figure 3B), apex narrowly convex, covered with dense rounded and oval pigmented spots, interspersed with larger patches, colored markings denser along wing margin and posterior basal region; Sc initially parallel to costa, distally forked into two branches, costal area expanded along Sc₁, a short crossvein connecting Sc₁ and R₁ at narrowest area; Sc₂ and Sc₃ crossvein-like, origin of Sc₂ at level of Rs fork, and Sc₃ at level of origin of Rs; R₁ single-branched, curving down after entering pigmented, elongated pterostigma; pterostigma fused with adjacent colored markings; Rs with four branches, Rs₁₊₂ 2.1 × length of Rs₃₊₄, two crossveins connecting Rs and M; M with six branches, M₁₊₂ 4 × length of M₃₊₄, M₄ longer than its branches, one crossvein between M₁ and M₂, another between M₁₊₂ and M₃; crossvein m-cua connecting fork of M₃₊₄ and CuA; Rs fork slightly distal to M fork; CuA single, curved apically, M₅ very short, or M, M₅, CuA, and CuA base meeting at one point, forming a “X”; CuP single, smoothly curved at apex; crossvein cua-cup transverse in one wing, obliquely inclined in the other wing; three anal veins detected: A₁ straight, A₂ undulate, A₃ short and straight; one crossvein connecting bases of A₁ and A₂.

Hindwings smaller and rounder than forewings, devoid of colored markings, 4.4 mm long, 1.7 mm wide (L/W = 2.4); Sc single and short, terminating at the same level as Rs fork; R₁ distally forked into two branches, covered by pigmented lentoid pterostigma; Rs with four branches; one crossvein between Rs₂ and Rs₃; Rs₁₊₂ 1.6 × length of Rs₃₊₄; M with four branches; M₁₊₂ 2 × length of M₃₊₄; one crossvein between M₁₊₂ and end of Rs₃₊₄; crossvein m-cua connecting mid M₄ and CuA; Rs fork proximal to M fork; CuA and CuP single; CuA fused with M stem for long distance; one anal vein present; other details not preserved.

• Paratypes, NIGP205289 (Figure 2A and Figure 3D), 5.5 mm long, 2.0 mm wide (L/W = 2.8), humeral vein present; Sc₃ present; Rs₁₊₂ 2.2 × length of Rs₃₊₄; M₁₊₂ 5.3 × length of M₃₊₄, M₄ shorter than M_4a and M_4b; one crossvein between Rs₂ and Rs₃, and between Rs₃ and Rs₄, two crossveins between Rs and M, crossvein m-cua connecting basal M₄ and CuA; NIGP205290 (Figure 2B and Figure 3E), 5.5 mm long, 2.0 mm wide (L/W = 2.8), Sc₃ undetected, crossvein sc₁-r₁ moderately long, Rs₁₊₂ 2.2 × length of Rs₃₊₄, M₁₊₂ 5.0 × length of M₃₊₄, three crossveins connecting Rs and M, crossvein m-cua connecting basal M₄ and CuA; NIGP205291 (Figure 3F), 6.4 mm long, 2.0 mm wide (L/W = 3.2), wing relatively elongated, Sc₂ relatively long, Sc₃ undetected, Rs₁₊₂ 2.6 × length of Rs₃₊₄, M₁₊₂ 5.4 × length of M₃₊₄, M₂ relatively short, M₄ shorter than M_4a, one crossvein connecting Rs₃ and Rs₄, crossvein m-cua connecting basal M₄ and CuA; NIGP205292 (Figure 3G), 5.4 mm long, 1.9 mm wide (L/W = 2.8), Sc₂ relatively short, Sc₃ at level of Rs origin, Rs₁₊₂ 2.5 × length of Rs₃₊₄, M₁₊₂ 5.6 × length of M₃₊₄, M₄ stem longer than M_4a and M_4b, sc₁-r₁ moderately short, one crossvein between Rs₁ and Rs₂, and mid Rs₃ and Rs₄, m-cua connected basal M₄ and CuA; NIGP205293 (Figure 3H), 4.8 mm long, 2.0 mm wide (L/W = 2.8), Sc₁ moderately short, Sc₂ very short, Sc₃ undetected, costal area narrow, Rs₁₊₂ 1.7 × length of Rs₃₊₄, M₁₊₂ 3.0 × length of M₃₊₄, M₂ fork rounded; NIGP205294, 5.0 mm long (as preserved), 1.8 mm wide, Sc moderately short, Sc₃ undetected, Rs₁₊₂ 2.1 × length of Rs₃₊₄, M₁₊₂ 5.0 × length of M₃₊₄, M₄ longer than M_4a and M_4b, sc₁-r₁ short, one crossvein connecting Rs₃ and Rs₄, two crossveins connecting Rs and M, m-cua connecting basal M₄ and CuA; NIGP205295 (Figure 3C), 4.2 mm long, 1.6 mm wide, hindwing, R_1a forming the boundary of pterostigma basal; Rs₁₊₂ 2.0 × length of Rs₃₊₄, M₁₊₂ 2.7 × length of M₃₊₄, two straight anal veins present; NIGP205296, 4.9 mm long (as preserved), 1.7 mm wide, wing deformed in middle part, Sc₃ proximal to origin of Rs.

Figure 2. Paratypes of Mesochorista tillyardi Lian and Huang, sp. nov. (A) NIGP205289. (B) NIGP205290a. (C) NIGP205295a. Photographs were captured under vertical reflected light after being moistened with 75% alcohol. Scale bars = 1 mm in (A–C).

Figure 2. Paratypes of Mesochorista tillyardi Lian and Huang, sp. nov. (A) NIGP205289. (B) NIGP205290a. (C) NIGP205295a. Photographs were captured under vertical reflected light after being moistened with 75% alcohol. Scale bars = 1 mm in (A–C).

Other fragmentary specimens include NIGP205297 and NIGP208853.

Figure 3. Line drawings. (A–H) Mesochorista tillyardi Lian and Huang, sp. nov. (A) General habitus, NIGP205288a (holotype). (B) NIGP205288c (holotype), forewing. (C) NIGP205295, hindwing. (D) NIGP205289, forewing. (E) NIGP205290, forewing. (F) NIGP205291, forewing. (G) NIGP205292, forewing. (H) NIGP205293, forewing. (I) Mesochorista yinpingensis Lian and Huang, sp. nov., NIGP205298, forewing. Scale bar = 1 mm in (A–I).

Figure 3. Line drawings. (A–H) Mesochorista tillyardi Lian and Huang, sp. nov. (A) General habitus, NIGP205288a (holotype). (B) NIGP205288c (holotype), forewing. (C) NIGP205295, hindwing. (D) NIGP205289, forewing. (E) NIGP205290, forewing. (F) NIGP205291, forewing. (G) NIGP205292, forewing. (H) NIGP205293, forewing. (I) Mesochorista yinpingensis Lian and Huang, sp. nov., NIGP205298, forewing. Scale bar = 1 mm in (A–I).

Remarks. Mesochorista tillyardi Lian and Huang, sp. nov. represents the dominant Mesochorista species in Chaohu City, comprising 11 specimens that exhibit a stable venational pattern, with only minor variations present in the arrangement of crossveins and the relative position of some forks (such as Sc, Rs₁₊₂ and Rs₃₊₄, M₁₊₂ and M₃₊₄). Sc₃ is a very faint vein in this species, and its absence in some line drawings is due to non-observation, possibly as a result of preservation. Mesochorista tillyardi Lian and Huang, sp. nov. can be confidently placed to Permochoristinae by the presence of two to three Sc branches (one or two anterior veinlets), a four-branched Rs with Rs₁₊₂ much longer than Rs₃₊₄, and a six-branched M in which both M₂ and M₄ are bifurcated [22]. They can further be placed within the genus Mesochorista due to the costal space being narrow, and the presence of one or two crossvein-like Sc anterior veinlets (Sc₂ and Sc₃).

Mesochorista tillyardi Lian and Huang, sp. nov. is characterized by its forewings covered with dense pigmented spots interspersed with several colored patches, and by Sc₁ closely approximating R₁. This combination of characters readily differentiates it from other related species. It can be further distinguished from M. proavita (the type species of Mesochorista) by its smaller wing size (4.7–6.4 mm vs. preserved 10.5 mm), Rs₁₊₂ not strongly curved upwards, and a lower Rs₁₊₂/Rs₃₊₄ ratio (1.7–2.6 vs. 3.6) [23,24]; from M. conjunctiva by its Rs₁₊₂ not strongly curved upwards, and a lower Rs₁₊₂/Rs₃₊₄ ratio (1.7–2.6 vs. 3.8) [25]; from M. australica by its smaller wing size (4.7–6.4 mm vs. ca. 12 mm (preserved 8.0 mm)), M₄ fork sharp instead of rounded, and a higher M₁₊₂/M₃₊₄ ratio (4.6–5.4 vs. 2.9) [8]; from M. affinis by lacking strongly sinuate CuA apex [7]; from M. sinuata (Handlirsch, 1939) from the Lower Jurassic of Dobbertin, which represents the latest occurrence of Mesochorista, by its apical costal area expanded, R₁ curved near apex instead of sinuous, M₂ forked instead of single, and a long stem of M₄; from M. angustipennis by its smaller and broader wings (4.7–6.4 mm vs. at least 12.0 mm; L/W ratio = 2.8–3.2 vs. 3.9), and Sc₁₊₂ fork at same level as Rs fork instead of strongly proximal to Rs fork [6].

The hindwing somewhat resembles that of Mesochorista prospera, but its Sc is much shorter, and M with four branches instead of five branches [26]. It differs from the hindwings of M. wolbromae and M. sokolovensis by the shorter Sc, and broader costa space [26].

 

Mesochorista yinpingensis Lian and Huang, sp. nov.

(Figure 3I and Figure 4; SID urn:lsid:zoobank.org:act:2D63D30A-AB5B-4F62-A23B-2FFCABAE3A01)

Etymology. The species epithet is derived from Yinping Mountain, where the fossil was collected.

Type locality and horizon. Yinping Mountain, Chaohu City, Anhui Province, China; Yinping Formation (Capitanian).

Diagnosis. Forewing with dense, irregular pigmented patches; Sc₁ relatively long, distal to Rs₁₊₂ fork; M with five branches.

Material. Holotype, NIGP205298a, b, with part and counterpart. Two forewings, one hindwing overlapped with a forewing, and some blurry body structures are preserved; the venation of hindwing is partially identified.

Description. Forewing elongate and rounded, widest at wing 3/4 length, tapering basally, wing base narrow; forewing 5.0 mm long, 1.8 mm wide (L/W = 1.9); covered with dense irregular pigmented patches, pigmentation dominant over hyaline area; pterostigma pigmented, boundary unclear, overlying apical Sc; Sc parallel to costa, forked into two branches at mid wing, costal area along Sc₁ not expanded, Sc₂ short and oblique, Sc fork distal to Rs fork; Rs with four branches, Rs₁₊₂ 1.9 × length of Rs₃₊₄; M with five branches, M₁₊₂ 2.8 × length of M₃₊₄, M₄ fork small, M₄ slightly longer than M₃₊₄, M fork unsclerotized; Rs fork distinctly distal to M fork; CuA and CuP single, CuA base crossvein-like, M₅ short, CuA base and crossvein cua-cup transverse; three anal veins present, one oblique crossvein connecting the base of A₁ and A₂; one crossvein connecting Rs₂ and Rs₃, M₂ and M₃, and A₁ and A₂, respectively, two crossveins connecting Rs and M.

Remarks. The species M. yinpingensis Lian and Huang, sp. nov. can be assigned to the subfamily Permochoristinae based on the presence of one anterior veinlet on Sc, a four-branched Rs with Rs₁₊₂ significantly longer than Rs₃₊₄, and a five-branched M with a forked M₄.

Mesochorista yinpingensis sp. nov. differs from the co-occurred M. tillyardi Lian and Huang, sp. nov. by having its forewing widest closer to the apex, colored markings denser and in an irregular shape, Sc₁ longer, costal area along Sc₁ not expanded, lacking the crossvein between Sc₁ and R₁, and M with five branches instead of six. The presence of a five-branched M allows the new specimens to be readily distinguished from other related species. Among species with a five-branched M, the new species can be further differentiated as follows: it differs from the holotype of M. asiatica (Martynova, 1948) by its Sc fork distal to (rather than proximal to) Rs fork, R₁ apex smooth (vs. distinctly curved), Rs₁₊₂/Rs₃₊₄ ratio smaller (1.9 vs. 3.1), and Rs fork distinctly distal to M fork (vs. nearly aligned) [17,27]; from Yanorthophlebia hebeiensis Ren, 1995 (Mecoptera: incertae familiae) by having a smaller wing size (length 5.2 mm vs. 7.2 mm), Rs fork distinctly distal to M fork (vs. nearly at the same level), M₄ fork smaller, and CuA base transverse instead of horizontal [28,29].

The new species resembles species of Permeca Novokshonov, 1995, except for the arrangement of Sc₁. Besides, it differs from Permeca tatarica by its colored markings denser and not arranged in bands, Rs₁₊₂ fork deeper, M₂ single instead of with one small fork, M₄ fork small, and apical CuA rather straight instead of sinuous [30]; differs from Permeca chaohuensis Lian, Cai and Huang, 2022 from the same beds by its wing larger (5.0 mm long vs. less than 4.0 mm), the absence of a strong crossvein between Sc₁ and R₁, M₄ fork small, apical CuA rather straight instead of sinuous, and CuA base transverse instead of horizontal [19].

4. Discussion

The family Permochoristidae is a “wastebasket” taxon that includes the majority of Permian mecopterans, which exhibit highly diverse venational patterns. Over the past century, approximately 40 genera and around 200 species have, at various times, been assigned to this family [22,31,32]. A systematic revision of this megadiverse family would constitute an extensive undertaking far beyond the scope of this paper. The Family Permochoristidae was established based on two poorly preserved specimens from the Upper Permian Belmont insect bed, and Tillyard [8] designated specimen No. 24, lacking the costal area, as the holotype of Permochorista australica, the type species of the type genus of the family. Meanwhile, he described another species, Permochorista mitchelli, based on specimen No. 26, which consists of a preserved basal portion of a wing only, and he illustrated it with a line drawing showing the Sc vein with multiple veinlets, which may be incorrect. Sc with multiple branches is a primitive character which is not a character of Permochorista [22]. Moreover, some taxa previously illustrated by Tillyard as possessing multiple Sc branches have been proven otherwise upon reexamination. For example, reexaminations of Mesochorista proavita Tillyard, 1916 and Mesochorista anglicana (Tillyard 1933) revealed that neither species exhibits multiple veins along the costal and R₁ regions (Willmann [24]: Figure 2). Tillyard [7] described two additional, well-preserved species from the same locality, both showing only one short anterior veinlet (Sc₂) in the costal area. Later, many species with a similarly short anterior Sc veinlet were assigned to this genus [6].

Mesochorista was established based on a holotype specimen collected from the Middle Triassic of Denmark Hill, Queensland, Australia [23]. Initially, this species was misinterpreted as having three additional crossvein-like structures between Sc₂ and h. Willmann [24] corrected this interpretation, clarifying that there is only one vein (Sc₃) between Sc₂ and h, and provided further details on the crossveins in other regions of the wing. Mesochorista shares venational similarity with Permochorista, and they have been synonymized by Riek [31]. However, Novokshonov [22] argued that this synonymization is not sufficiently justified, based on his observation that one of the anterior crossveins (interpreted as the distal branch of Sc, possibly Sc₂) is inclined to a certain degree, while the other (the proximal veinlet, possibly Sc₃) appears nearly desclerotized or absent. Nonetheless, this distinction is insufficient to serve as a reliable diagnostic feature above the species level and is of limited practical utility in taxonomic application. Therefore, we follow the opinion of Riek and treat Permochorista as a junior synonym of Mesochorista. According to personal communication with Alexey Bashkuev, he also holds this view.

It is worth noting that Riek [31] considered Mesochorista to possess only two Sc branches (one anterior Sc veinlet). However, according to the reconstructed venation by Willmann [24], the type species of Mesochorista exhibits three Sc branches (two anterior Sc veinlets). Based on our examination of Mesochorista specimens from the Middle Triassic Tongchuan and Guadalupian Permian Yinping entomofaunas, Sc₃ are often extremely faint and may not be discernible due to poor preservation [33]. This suggests that it may have been overlooked in previously described species. Consequently, the presence or absence of Sc₃ is not regarded as a definitive diagnostic character of Mesochorista.

Previously, only two species of Mesochorista have been reported from China, both from the Middle Triassic Tongchuan entomofauna: M. conjunctiva (Guo and Hong, 2003), and M. tongchuanensis Lian, Cai and Huang, 2022. M. tillyardi Lian and Huang, sp. nov. share some venational similarities with M. tongchuanensis and M. conjunctiva, including a narrow costal area, an expanded Sc₁ approaching R₁, and a typically faint Sc₃, indicating a close phylogenetic relationship. It is worth noting that the new species from the Yinping entomofauna exhibit denser colored markings which are lacking in those from Tonchuan entomofauna, indicating that the colored pattern may be regionally distinctive.

These newly discovered fossils represent the first occurrence of Mesochorista with preserved body structures, thereby broadening our knowledge of its morphology. In addition, new discoveries extend the known geographical distribution of Mesochorista and enhance our understanding of its paleobiodiversity.