New stem-dictyopteran insects from the Pennsylvanian deposits at Mazon Creek and Sosnowiec (Insecta: Polyneoptera)

ABSTRACT Polyneopteran clade of insects is very diverse and has a remarkable fossil history starting in the Late Palaeozoic. Representatives of Dictyoptera comprise roaches, termites and mantids and their stem group relatives like the common Palaeozoic and Mesozoic roachoids, a group well known for its problematic taxonomy. In this study, two new taxa are described based on forewing venation well displaying convexity or concavity of the veins due to preservation in spherosideritic concretions. A new paoliid, Stephanopsis testai sp. nov. (Blattinopsidae), from Moscovian deposits at Mazon Creek (Illinois, U.S.A.), supplements Stephanopsis mirandus found at the same locality, which mainly differs in the branching patterns of MP and anal veins. A new stem dictyopteran, Sosnowiecia dareki gen. nov. et sp. nov. (?Mesorthopteridae), from Langsettian deposits at Sosnowiec-Klimontów (Lower Silesia, Poland) is problematic in terms of taxonomy as it has a mosaic of characters characteristic of Paoliida, Eoblattida and Grylloblattida, but retains affinities with roachoid insects, such as Miroblatta sp. Hence, these two new species increase the diversity of Carboniferous polyneopteran insects, but reveals the problem of depending only on alar characters in taxonomy. LSID urn:lsid:zoobank.org:pub:49299826-0F1E-4892-8D88-82FBDCC192BF


Introduction
Dictyoptera is a well-supported clade of polynepteran insects comprising crown groups of Mantodea (mantids) and Blattodea (cockroaches and termites) with long evolutionary histories and stem group relatives in the Late Palaeozoic and Mesozoic strata (Legendre et al. 2015;Wipfler et al. 2019).These include particularly well-known roachoids, the females of which had very long ovipositors (Grimaldi and Engel 2005;Hörnig et al. 2018).Although these insects were very abundant and diverse in Late Palaeozoic ecosystems, their systematics is unsatisfactory mainly due to large intraspecific variability in wing venation, which is frequently used as characters for their classification.On the other hand, the alar characters of the stem group of Dictyoptera, such as Paoliida, are not so variable at the intraspecific level and therefore more suitable for taxonomy (Prokop et al. 2014).Paoliida currently consists of three families, Paoliidae, Blattinopsidae and Anthracoptilidae, but the position of some others remains uncertain (Guan et la. 2016).
In this paper two new Pennsylvanian taxa of stem-Dictyoptera are designated: Stephanopsis testai sp.nov.(Blattinopsidae) from Mazon Creek in Illinois, U.S.A and Sosnowiecia dareki gen.et sp.nov.(?Mesorthopteridae) from Sosnowiec-Klimontów in Lower Silesia, Poland.In addition, problems with the classification of Palaeozoic polyneopteran insects are discussed.
The specimens were observed in a dry state using a Nikon SMZ 745T stereomicroscope.Line drawings of venation were made using a Zeiss SteREO Discovery.V20 with camera lucida attachment.Habitus drawing of S. dareki gen.nov.et sp.nov.was done by a scientific illustrator, Zuzana Čadová (Liberec, Czech Republic).Photographs of fossil specimens in a dry state were taken with a Canon EOS 550D digital camera equipped with either a MP-E 65 mm or EF-S 60 mm macro-lens.Original photographs were processed using the image-editing software Adobe Photoshop CS and some were processed using the stacking software Helicon Focus.
Both type specimens are housed in the institutional collections of The Field Museum of Natural History (Chicago, U.S.A.) and the Natural History Museum of the Institute of Systematics and Evolution of Animals PAS (Cracow, Poland).

Diagnosis
Area between C and ScP twice as wide as the area between ScP and RA.First branches of RP and MP at the same level of about half of the length of the wing.RP posteriorly pectinated with five primary branches.Two rows of cells between CuA and CuP below the arculus.PCu vein well developed.Anal veins simple.

Description
Based on forewing venation.Wing very well preserved with numerous cross veins and noticeable reticular pattern with two rows of large irregular cells in cubital and partially in medial area.Wing length about 23.9 mm, and maximum width 9 mm.Noticeable short weakly sigmoidal ScA ending at the costal margin 3.7 mm from the wing base.ScP with numerous anterior and slightly oblique veinlets, ending at the costal margin two-thirds along the length of the wing.Area between C and ScP wide (1.8 mm), about twice the width at the widest part of the area between ScP and RA.RA apparently convex, slightly sigmoidal and simple.RP emerging from RA 8.7 mm from the base of the wing, regularly posteriorly pectinated with five main branches and several sigmoidal anterior terminal shoots that reach the apical margin of the wing.MP with three branches, with the first at the same level as the first branch of RP, around half of the length of the wing.CuA with five primary posterior branches.Branches of RP, MP and CuA run parallel and form a regular pattern distally with veinlets between adjoining branches about 3 mm in length.Strong oblique cross vein mp-cua (arculus) present between MP and CuA.CuP simple and distally nearly straight.Convex PCu running parallel to CuP (sensu Schubnel et al. 2020).Three simple anal veins discernible.

Type material
Holotype TVT 4023 (originally in Thomas V. Testa coll., currently deposited in FMNH), positive (B) and negative imprint (A) of nearly complete forewing preserved in siderite nodule.

Discussion
This fossil wing clearly belongs to Blattinopsidae (Paoliida) because ScP ends on the costal margin with exception in Avionblattinopsis Quispe et al., 2021, stem of R sigmoidal, RP pectinated with high number of posterior branches and slightly, but not extensively extends the area between MP and CuA, which differentiates Blattinopsidae from Paoliidae (Prokop et al. 2014;Quispe et al. 2021).There is also a superficial resemblance in the venation with some Archaeorthoptera, but this group differs in a common stem for M + CuA and the fusion of CuA and CuP(a), which are missing in this fossil (Béthoux and Nel 2002).
The general pattern of venation S. testai sp.nov.resembles some other blattinopsid like species of the genus Glaphyrophlebia Handlirsch, 1906, but Glaphyrophlebia has a regular parallel pattern of R, M and CuA branches with many supplementary veins.For example, in Glaphyrophlebia wettinensis Fritsch, 1899 the first branch of RP and MP is at the same level and RP is posteriorly pectinated and has a similar number of branches (Hörnschmeyer and Stapf 2001).But there is a marked difference between S. testai sp.nov.and Glaphyrophlebia in that it lacks the typical vein-bow and has a distinctly narrower space between veins ScP and RA (Hörnschemeyer and Stapf 2001;Aristov et al. 2021;Aristov and Rasnitsyn 2022a).
The present forewing can be clearly assigned to the genus Stephanopsis Kukalová, 1958 as the width of the costal area (between C and ScP) is much wider than the area between ScP and RA (Hörnschemeyer and Stapf 2001).Stephanopsis testai sp.nov.clearly differs from Stephanopsis incerta Laurentiaux, 1950 and Stephanopsis elegans Schlechtendal in Handlirsch 1906 by the position of the first branch of RP being about half way along the wing, whereas in the latter species, the first branch of RP is about a third of the way along the length of the wing and more anterior to the first branch of MP.Moreover, S. elegans has a much longer ScP reaching far beyond two-thirds of the way along the length of the wing and in S. incerta there is a much finer reticular pattern between veins CuA and CuP.But as the preserved fossil of S. incerta is probably a hindwing (Kukalová 1958), an exact comparison is difficult.The venations of S. testai sp.nov.and S. mirandus (Richardson, 1956) are similar and they are described from the same locality.The vein RA has a similar sigmoidal shape, first branch of RP and MP occur at the same level of about half way along the length of the wing and the general branching pattern of RP is similar (Richardson 1956).However, MP has the same number of branches in both species, but their branching pattern is different in respect of topology.The most remarkable difference is the posterior branching of the anal veins in S. mirandus, whereas in S. testai sp.nov.they are clearly all simple.Hörnschmeyer and Stapf (2001) also consider the venation of Klebsiella extincta (Meunier, 1908) to be similar to that of the genus Stephanopsis (Meunier 1908).As the holotype of K. extincta was recently reviewed by Quispe et al. (2021), we compared both these species.The general pattern of veins is comparable, especially the primary branching of the main veins.However, a better developed medial area with six terminal branches instead of three as in S. testai sp.nov.and a less developed cubital area clearly distinguish these two species.Also, the regular pattern of terminal veinlets is absent in K. extincta.

Diagnosis
Based on forewing characters: RA and RP branch near the middle of the wing behind the first and second branches of M. Long stem of Cu.CuA posteriorly pectinated with four convex branches.Area between MP and CuA very narrow with one row of cells.Arculus (cross vein mp-cua) weakly developed.CuP terminally bifurcated.Area between CuA and CuP slightly enlarged with numerous irregular cells.

Diagnosis
By monotypy, that of the genus.

Description
Body preserved with arched mesonotum and both mesothoracic wings flexed and slightly open, partially preserved metathorax hidden under the anal areas of wings and four slender segments of abdomen (proximal part of abdomen hidden as well).Forewing incompletely preserved with about one-third of the distal part missing.Regular net of transverse veinlets or irregular cells, the socalled archedictyon, present.ScP slightly oblique, running parallel to stem of R and ending in distal third of the length of the wing.Costal area between anterior wing margin and ScP with a coarse network and two rows of cells.Costal area 1.4 mm wide without apparent widening near wing base; costal area about one and half times wider than the widest part of the area between ScP and RA.RA/RP bifurcation relatively distant, 13.9 mm from base of wing, which is approximately between one-third and half of the length of the wing.RA and RP simple in preserved basal parts of the wing.Stem of M/MP clearly concave and anteriorly pectinated with four visible branches.First division of MP is 3.3 mm from the bifurcation of RA and RP.Straight or oblique simple cross veins in area

Type material
Holotype MP ISEA I−F/MP/1488/22-08 (print and counter imprint of thorax with mesothoracic wings and partially preserved abdomen in sideritic concretion).

Discussion
The pattern of forewing venation of this fossil corresponds to that of polyneopteran insects and clearly differs from that of Archaeorthoptera in the absence of a basal division of CuP, absence of distal fusion of anterior branch of CuP with CuA and also lack of basal fusion of veins M with CuA (Béthoux and Nel 2002).There is a clear resemblance to 'blattoid' lines Dictyoptera (Blattodea + Mantodea) and especially Paollida, but not an exact match.The most remarkable characters shared with Paoliida are a long common stem of Cu in front of the bifurcation into CuA and CuP, M running closely parallel to R near base of wing and relatively broad area with irregular network of cross veins between CuA and CuP.On the other hand, a short weakly developed convex arculus between M/MP and CuA is not very distinct and there are no convex anterior branches of CuA, which are typical for roachoidlike or paoliid insects (e.g.Zhang et al. 2013;Prokop et al. 2014;Correia et al. 2019).Other typical features of Paoliidae are oblique anterior veinlets of ScP or a broad area between MP and CuA, which are not present in S. dareki gen.et sp.nov.(Prokop et al. 2014), but are present in some Blattinopsidae and also some Palaeozoic roachoids, like Miroblatta costalis Laurentiaux-Vieira & Laurentiaux, 1987(see Béthoux et al. 2011).However, the position of these insects remains uncertain, but they most probably belong to the stem group of Dictyoptera (Correia et al. 2019).
Possible affinities to Eoblattida, including Gryloblattida sensu Storozhenko (1997), are also apparent, but the concept of this rich group is still questionable as the type species, Eoblatta robusta (Brongniart, 1893), seems to belong to Archaeorthoptera (Schubnel et al. 2020).General arrangement of the main veins in the mid wing area, for example, resemble 'eoblattid' Permula lebachensis Schlechtendal, 1913, with the first branch of M close to that of the first branch of R and CuA posteriorly pectinated (Aristov 2015).However, in S. dareki the width of the costal area between ScP and C clearly narrows distally and there is a different pattern of cross veins.In contrast, sigmoidal CuA and the costal field narrows towards wing base and the wing tip differs in P. lebachensis Schlechtendal, 1913.Moreover, a large part of the wing is missing and thus an exact comparison is impossible.There is a most definite resemblance to Paridelia pusilla Sharov, 1961(see Aristov 2015).The R division in both taxa is located beyond the first third of the length of the wing and behind the first branch of M. Both veins RA and RP run simple for a long distance.They also share posteriorly pectinated CuA with four branches and anterior branches of ScP forming a cellular meshwork instead of simple oblique veinlets.But P. pussila differs from S. dareki in the more basal placement of the first CuA branch in relation to the first branch of M, CuP lacks a distal bifurcation and the branching pattern of M is different.Taxonomic placement of P. pussila has been changed several times.Initially it was placed in the family Ideliidae (Sharov 1961) and subsequently in Kortshakoliidae, which are both part of Grylloblattida (Storozhenko 1997(Storozhenko , 1998)).Later, Aristov (2015) transferred Paridelia to the family Mesorthopteridae within Eoblattida.However, due to uncertain position of Eoblattida, the placement of the family Mesorthopteridae must be re-examined.Another problem complicating a correct taxonomic placement arises from the uncertain relationships between extinct Grylloblattida and presumably crown group Grylloblattodea with Grylloblattidae (Storozhenko 2002;Cui et al. 2015).A mosaic of characters (particularly resembling Paoliida, Dictyoptera and Grylloblattida) and uncertain, probably very basal position (within Polyneoptera) of the most similar species P. pussila, lead us to consider S. dareki as a representative of a stem group of Dictyoptera with affinity to blattoids, but without an exact placement in currently described orders.This statement is congruent with the recent analysis supporting a relatively close phylogenetic relationship of extant Grylloblattodea and Dictyoptera (Wipfler et al. 2019).

Conclusion
In this study one new genus and two new species of polyneopteran insects are described based on the venation of their forewings.
Stephanopsis testai sp.nov. is based on well-preserved venation, which clearly placed it in Blattinopsidae (Paollida).Sosnowiecia dareki gen.nov.et sp.nov. is based on an incomplete forewing which has a combination of characters that prevents an accurate placement, but affinities with blattoids are clearly apparent.The situation is further complicated by the uncertain status of Grylloblattida, the stem group of Dictyoptera (like roachoids) and especially Eoblattida.In order to determine the Palaeozoic evolutionary history of Polyneoptera, a comprehensive phylogenetic study and clarification of the status of these high ranked taxa is needed.