A new species of Elcanidae (Orthoptera, Elcanoidea), Parelcana pulchmacula sp. nov., is described based on four new specimens from the Middle Jurassic Jiulongshan Formation of northeastern China. The new species differs from all other known Archelcaninae species by its combination of wing-venation characters. This new finding improves our knowledge of variation on wing venation in elcanid insects and constitutes the first record of Elcanidae from the Daohugou fossil bed (Yanliao Biota) of northeastern China.

Archelcaninae, Inner Mongolia, Middle Jurassic, Parelcana, systematic paleontology, Yanliao Biota

The extinct family Elcanidae is a cryptic group of Orthoptera insects due to their complex anatomical features. The caeliferan-like wing venation, characteristic of this family, groups them close to Caelifera in cladistic analyses (Béthoux and Nel 2002). However, Elcanidae also shares a long, filiform antennae and exerted ovipositors with the suborder Ensifera. The presence of these contrasting anatomical features makes the systematic position of Elcanidae unclear.

The Elcanidae existed from the Upper Triassic to the Cretaceous in Eurasia and America (Handlirsch 1906; Sharov 1968; Martins-Neto 1991; Gorochov et al. 2006; Poinar et al. 2007; Peñalver and Grimaldi 2010; Fang et al. 2015; Fang et al. 2018a, Fang et al. 2018b; Heads et al. 2018; Tian et al. 2019). So far 50 species in 16 genera have been described from compression fossils and ambers. These species have been divided into two subfamilies, the Archelcaninae and the Elcaninae, based on taxonomic characters (Gorochov et al. 2006). Elcanids evolved a unique character among orthopterans, i.e., the presence of various spurs on the distal part of the metatibia. These structures might have been associated with an improved capability to swim (Tian et al. 2019).

The Jurassic elcanids are well known from the UK (Handlirsch 1906; Whalley 1985), Germany (Handlirsch 1906; Ansorge 1996), Kazakhstan (Sharov 1968), and Kyrgyzstan (Sharov 1968). In China, two specimens have been reported, one from the Guangxi Province (from Early Jurassic), and one from the Hebei Province (from Middle Jurassic). Both were attributed to Elcana reticulata (Handlirsch, 1939), based on existing highly fragmented forewing sample specimens (Handlirsch 1939; Hong 1983; Lin 1986). Other Orthoptera are commonly discovered from the Daohugou fossil bed, at the widely known and profuse fossil assemblages of Yanliao Biota, northeastern China. Numerous species discovered from this fossil bed have been described, including ensiferans and caeliferans (Ren and Meng 2006; Ren et al. 2010, 2019; Gu et al. 2009, 2011, 2012, 2016; Wang et al. 2017). In this report we describe a new species of Elcanidae, Parelcana pulchmacula sp. nov., from the Daohugou fossil bed. The new species is erected based on four isolated but well-preserved forewings, providing new insights into the complex wing-venation patterns of elcanids.

Geological setting

The specimens described here were collected in the Daohugou Bed, located along the boundaries of the provinces of Hebei, Liaoning and Inner Mongolia (Fig. 1). The Daohugou Bed has been previously assigned to the Middle Jurassic Jiulongshan Formation (Ren et al. 2002, 2010, 2019). The Mesozoic section of the Daohugou Bed is mainly composed of tuffaceous conglomerates, tuffaceous siltstones, tuffaceous mudstones, tuffaceous shales, and volcanic breccias. Isotopic radiometric dating of rock samples from the Daohugou area enabled assessment of the age of the Jiulongshan Formation at circa 168–164 million years (Chen et al. 2004; He et al. 2004; Liu et al. 2006; Yang and Li 2008; Chang et al. 2014). This indicates that the age of the Jiulongshan Formation falls within the Bathonian–Callovian boundary interval (Xu et al. 2016).

Figure 1. 

Location map for Parelcana pulchmacula sp. nov.

The wing specimens were examined with a Nikon SMZ 25 microscope, and photographed with a Nikon DS-Ri 2 digital camera system. Line drawings were prepared using Adobe Illustrator CC 17.0.0 and Adobe Photoshop CC 14.0 graphics software. The measurements were taken using Adobe Illustrator. The lengths of wings were measured from the apex to the visible base of the wing; the widths of wings refer to the maximum width of the wing. The specimens are deposited in the Key Lab of Insect Evolution & Environmental Changes, Capital Normal University (CNU), Beijing, China.

Wing-venation analyses followed the interpretation proposed by Béthoux and Nel (2001, 2002). Corresponding abbreviations used in taxonomical descriptions are as follows: CP, posterior costa; ScA, ScP, anterior and posterior subcosta, respectively; RA, RP, anterior and posterior radius, respectively; M, media; MA, MP, anterior, posterior media, respectively; CuA, CuP, anterior, posterior cubitus, respectively; CuPaα, the anterior branch of first posterior cubitus; CuPaβ, the posterior branch of first posterior cubitus; CuPb, the second posterior cubitus; AA1, first branch of anterior anal vein.

This new species can be assigned to Archelcaninae by its relatively wide area between RA and RP, and free distal part of CuPaβ, CuPb and AA1. Its simple ScA, the presence of 3 branches of M before RP fuses with MA1 and a very short CuA support assignment to the genus Parelcana. Parelcana pulchmacula sp. nov. shares with P. tenuis a short and vertical CuA, but differs from P. tenuis in its larger size, greater number of branches of ScP and RP, a long and S-shaped CuA+CuPaα, a wider area between CuPb and anals, and the coloration pattern of the forewing. The new species is notably different from P. anglicana in its greater number of branches of ScP, free and vertical CuA, wider area between CuA+CuPaα and anal region, and fusion pattern of CuA and CuPaα. Parelcana dubia was erected based on a fragmentary forewing. It differs from P. pulchmacula sp. nov. in having a wider area between RA and RP and the branching pattern of RP. Parelcana pulchmacula sp. nov. is also different from the other two known Chinese Jurassic elcanids. It is much larger than the specimen from the Early Jurassic with an estimated wing length of approximately 9.5 mm. The other specimen from the Middle Jurassic of Hebei was originally assigned to Elcana reticulata based on an isolated forewing with only the distal half. Most of the diagnostic characters were missing, making comparisons with the new species difficult. Based on the line drawing patterns described for the wing (see Hong 1983, fig. 28), it might be an elcanid, but its generic assignment is questionable.

Variation in forewing size and wing-venation pattern is common in fossil orthopterans and their relatives from the Palaeozoic to the Mesozoic (Prokop and Ren 2007; Gu et al. 2010, 2011, 2014; Béthoux et al. 2012), even between the left and right forewings of the same individual (Gu et al. 2009). For elcanids insects, the documentation on variation of wing venation is scarce since most of the species are described based on limited and often poorly preserved samples. We observed some variation of forewing venation within specimens of P. pulchmacula sp. nov.. The number of branches of ScP, RA and RP was not consistent (Fig. 2). Moreover, CuPaβ reaches the posterior wing margin distally to the end of ScP in CNU-ORT-NN2016041(Fig. 2A, B), but basally to the end of ScP in CNU-ORT-NN2016036 (Fig. 2G, H).

Based on the known data of wing venation of fossil orthopterans (Gu et al. 2010, 2011, 2014; Béthoux et al. 2012), the differences found in four P. pulchmacula sp. nov. specimens should be considered as variations within a species. The location of the fusion point of RP and MA1 is an important character usually used as a distinctive generic character of Elcaninae (Gorochov et al. 2006). In P. pulchmacula sp. nov., three of these fusion points show a clear pattern of M with 3 branches before RP is fused with MA1 (Fig. 3A–C). However in specimen CNU-ORT-NN2016042 (Fig. 3D), 2MA1 branches off at the level of RP when reaching MA1. Although this kind of difference always occurs between different species or genus, the integral similarity of wing venation between the four specimens of P. pulchmacula sp. nov. indicates that these specimens belong to the same species.

Figure 3. 

Details of the middle part of the forewings of Parelcana pulchmacula sp. nov., showing the variable location of the fusion point of RP and MA1 in the forewing. A CNU-ORT-NN2016035 B CNU-ORT-NN2016036 C holotype, CNU-ORT-NN2016041 D CNU-ORT-NN2016042. Scale bar: 0.5 mm.

We sincerely appreciate the critical and valuable comments from the editor and anonymous reviewers. We thank Dr Jose Marcelino from the Centre for Ecology, Evolution and Environmental Changes, University of the Azores, Portugal for improving our manuscript. This research is supported by grants from the National Natural Science Foundation of China (No. 41872020, 41688103, 31730087), the Program for Changjiang Scholars and Innovative Research Team at University (IRT-17R75) and the Project of High-level Teachers in Beijing Municipal Universities (No. IDHT20180518).