taxonID	type	description	language	source
9709E54DFF82FFB84A2DFDB1FB33BEC8.taxon	type_taxon	Type species † Palaeopsole weiterschani Caruso & Wichard, 2011.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF82FFB84A2DFDB1FB33BEC8.taxon	diagnosis	Emended diagnosis Tergum 9 with one posteromedial spine; sternum 9 extended caudally forming rounded subgenital plate which undergirds sternum 10, basally with vesicle; lateral projections of tergum 10 ending caudad in a more or less concave margin; subanal lobes variable in shape and length; cerci short and unsegmented, apex variably modified; epiproct upturned and hook-shaped, basal cushion variably modified.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF82FFBF4A4EFC6FFC0EBEE9.taxon	description	urn: lsid: zoobank. org: act: 18 C 09 F 91 - CCDA- 44 F 6 - 9 B 37 - 94 B 2143 CE 78 D Figs 1 – 3	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF82FFBF4A4EFC6FFC0EBEE9.taxon	diagnosis	Diagnosis Epiproct slender (wider in P. weiterschani); paraprocts sharp (rounded in P. weiterschani); cerci without humps (with humps in P. weiterschani); lateral projections of tergum 10 obtuse (pointed in P. weiterschani); ra-rp reaching RP after fork point (at fork point in P. weiterschani).	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF82FFBF4A4EFC6FFC0EBEE9.taxon	etymology	Etymology The specific epithet refers to the spine-shaped epiproct of the holotype.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF82FFBF4A4EFC6FFC0EBEE9.taxon	materials_examined	Type material Holotype (Fig. 1 A – B) LITHUANIA • ♂; Lithuanian amber, Eocene, Bartonian to Priabonian, ca 34 – 38 Ma; beach collected; CZT-PLE-BA 6, ICJUST.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF82FFBF4A4EFC6FFC0EBEE9.taxon	description	Description Male BODY. Slender (Fig. 1 C – D), length (excluding antennae) ca 3.0 mm. Macropterous; generally dark brown. HEAD. Dark and rounded, much wider than pronotum (Fig. 1 C). Triocellate; compound eyes large and protruded. Antennae filiform and dark brown, preserved segments almost equal with body length, with about 29 segments plus scapus and pedicellus, each segment covered with short bristles. Maxillary palp four-segmented, basal segment shortest, apical three segments subequal in size. Labial palp extremely short. THORAX. Pronotum rectangular and dark brown, much longer than its width (Fig. 1 C). Mesothorax and metathorax darkly sclerotized, much wider than prothorax. Legs generally brown (Fig. 1 C – D); tibia thinner and slightly longer than femur, ventroapically with two giant spurs. Tarsus with three segments; first and third segments subequal in length, second segment shortest. WINGS. Forewings length ca 4.0 mm (Fig. 1 C – D). In forewings, ScP reaches RA before ra-rp; RP originated from near base of RA, forked before ra-rp and at near half length of the wing; M forked before the fork of RP; Cu basally forked to CuA and CuP; area between M and CuA with six crossveins in left forewing and seven crossveins in right forewing; area between CuA and CuP with ten crossveins in left forewing and seven in right forewing; AA 1 curved, AA 2 forked. Hind wings rolled, veins invisible. ABDOMEN. Short, near ⅓ of body length (Fig. 1 C – D). Terga 1 – 8 generally pale. Terga 9 – 10 sclerotized laterally and membranous medially (Fig. 2 A – D). Posterior margin of tergum 9 projected with pale long spine, length of spine near half of tergum 9. Central area of tergum 10 generally pale, without obvious sclerite; lateral parts of tergum 10 rounded and unmodified, without projections. Epiproct hook-shaped with sharp apex, abruptly curved upwards; basal cushion of epiproct broad and wide, laterally with two bilobed plates. Paraprocts (subanal lobes) long, visible apical half semielliptical with sharp apex. Sternum 9 sclerotized, apically with distinct subgenital plate as wide as long and rounded apically, basally with oval vesicle (ventral lobe), which with length 1.5 × as long as its width (Fig. 3 A – B). Cerci short and near cylindrical, apical half strongly sclerotized, hemispherical in shape.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF82FFBF4A4EFC6FFC0EBEE9.taxon	discussion	Remarks The slightly rolled wings, absence of the X-pattern of crossveins at the cord, and the unsegmented cerci collectively assign † P. spinosa sp. nov. to the family Leuctridae. The species’ small and simple epiproct excludes its affiliation with the subfamily Megaleuctrinae (Zwick 2000). Its high morphological similarity to the extant genus Rhopalopsole Klapálek, 1912 suggests that it belongs to the subfamily Leuctrinae. The presence of a posteromedial spine on abdominal tergum 9, combined with its Eocene origin, confirms † P. spinosa as a member of the extinct genus † Palaeopsole Caruso & Wichard, 2011. The original definition of † Palaeopsole was based solely on the type species, † P. weiterschani, and several characters of † P. spinosa do not align with the type. Notably, the two long, triangular paraprocts of † P. spinosa resemble those in Leuctra, in which males have two slender median specilla adapted for sperm transfer (Pardo & Zwick 1993; Zwick 2000). The apical half of the cercus in † P. spinosa is strongly sclerotized into a distinct hemisphere, a feature absent in all known Leuctridae, including its only congener, † P. weiterschani.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF85FFBF4A40FBE8FC77B99A.taxon	type_taxon	Type species Nemoura decepta (Frison, 1942).	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF85FFB24A5BFAA0FB43BF9A.taxon	description	urn: lsid: zoobank. org: act: 1850 D 232 - C 1 D 5 - 4 A 84 - B 1 C 3 - F 9 EE 6017 FD 40 Figs 4 – 7	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF85FFB24A5BFAA0FB43BF9A.taxon	diagnosis	Diagnosis Vein ra-rp joining anterior branch of RP after fork point in both forewing and hind wings, without typical ‘ X-pattern’ at cord. Posterior margin of abdominal sternum 7 membranous, extended backwards. Median sclerite on female abdominal sternum 8 subtriangular basally, apical half bilobed, each lobe slender, extending along lateral margin of sternum 8 ’ s anteromedial indentation.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF85FFB24A5BFAA0FB43BF9A.taxon	etymology	Etymology The specific epithet refers to the bilobed median sclerite on abdominal sternum 8.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF85FFB24A5BFAA0FB43BF9A.taxon	materials_examined	Type material Holotype LITHUANIA • ♀; Lithuanian amber, Eocene, Bartonian to Priabonian, ca 34 – 38 Ma; beach collected; CZT-PLE-BA 1, ICJUST.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF85FFB24A5BFAA0FB43BF9A.taxon	description	Description Female WINGS. In forewing (Fig. 4 A – B), terminal costal crossvein c-r joining RA near ra-rp; ScP reaching RA before ra-rp; RP forked; ra-rp joining anterior branch of RP, distal to RP fork point; CuA and CuP unforked. In hind wings (Figs 4 A – B, 5 A – B), terminal costal crossvein c-r joining RA shortly distal to a-rp; ScP reaching RA before ra-rp; RP forked; ra-rp joining anterior branch of RP, distal to RP fork point; CuA and CuP unforked; AA 1 simple; AA 2 with at least five branches. TERMINALIA. Posterior margin of abdominal sternum 7 membranous, extended backwards (Figs 6 A – B, 7 A). Sternum 8 deeply indented anteromedially, posterior half folded, notched near posteromedial margin; median sclerite subtriangular basally, apical half bilobed, each lobe slender, extending along lateral margin of sternum 8 ’ s anteromedial indentation. Sternum 9 darkly sclerotized, slightly shorter than sternum 8, posteromedial margin slightly extended. Sternum 10 darkly sclerotized, near half length of sternum 9, posterior margin unmodified. Paraprocts subtriangular, with rounded corners. Cerci weakly sclerotized, 2 × as long as wide; apex rounded.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF85FFB24A5BFAA0FB43BF9A.taxon	discussion	Remarks † Podmosta biloba sp. nov. is easily distinguished from the five extant species of Podmosta (Fig. 7) by its uniquely shaped median sclerite on the female abdominal sternum 8 (Frison 1936; Ricker 1952; Baumann 1975; Chen 2018 a; Grubbs & Baumann 2023). It differs from † P. attenuata in the structure of the ra-rp vein, which joins the anterior branch of RP after the fork point in both the forewing and hindwing, resulting in the absence of the typical X-pattern in the cord area. In contrast, in † P. attenuata, the ra-rp vein joins RP before the fork point in both wings, forming the characteristic X venation pattern found in extant species of Podmosta (Frison 1936; Caruso & Wichard 2010; Grubbs & Baumann 2023).	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF89FFB34A54FAB2FC10B8EC.taxon	type_taxon	Type species Isoperla bilineata (Say, 1823).	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF89FFB74AA7FA4AFAF9BFB9.taxon	description	urn: lsid: zoobank. org: act: 0 FE 85367 - E 3 C 5 - 46 C 2 - 92 F 8 - 3 FF 11976 E 76 E Figs 8 – 11	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF89FFB74AA7FA4AFAF9BFB9.taxon	diagnosis	Diagnosis Head generally pale brown, with a light M-shaped pattern. Pronotum narrower than head, width ca 1.5 × as long as length, with angled corners, anterior margin convex, posterior margin almost straight, lateral margins slightly oblique; median suture distinct, lateral areas rugose. Macropterous. In forewing, ScP reaching RA before ra-rp; RP with two branches; CuA with two branches; AA 1 simple, AA 2 forked. In hind wing, ScP reaching RA before ra-rp; RP with two branches. Tibia with moderate apical spurs. Abdominal terga 1 – 8 unmodified. Tergum 9 with a subquadrate patch of short stout sensilla basiconica medially. Tergum 10 complete, with depressed, membranous, posteromedial area, anterior and lateral areas of the membrane surrounded by short stout sensilla basiconica similar to those on tergum 9. Paraprocts darkly sclerotized, upcurved, narrow, pointed apically. Sternum 7 with posteromedian extension. Vesicle of sternum 8 absent. Sternum 9 greatly expanded backwards into hood exceeding basal cercal segment, posterolateral margins forming oblique ridges. Cerci slightly shorter than abdomen.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF89FFB74AA7FA4AFAF9BFB9.taxon	etymology	Etymology The new species is named after Lithuania, where the piece of amber was obtained.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF89FFB74AA7FA4AFAF9BFB9.taxon	materials_examined	Type material Holotype LITHUANIA • ♂; Lithuanian amber, Eocene, Bartonian to Priabonian, ca 34 – 38 Ma; beach collected; CZT-PLE-BA 9, ICJUST.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF89FFB74AA7FA4AFAF9BFB9.taxon	description	Description Male BODY. Length (from anterior of head to posterior of abdomen) ca 9.5 mm. Body mostly pale brown (Fig. 8 A – B). HEAD. Generally pale brown, anteriorly with light M-shaped pattern (Fig. 9 A). Triocellate, anterior ocellus near half in size of posterior ones. Compound eyes large and rounded. Antennae slender, generally dark brown, subequal in length to abdomen. Maxillary palps slender, five-segmented with strongly shortened apical segment; labial palps much shorter, three-segmented with slightly shortened apical segment (Fig. 9 A – B). THORAX. Pronotum narrower than head (Fig. 9 A), width ca 1.5 × as long as length, with angled corners, anterior margin convex, posterior margin almost straight, lateral margins slightly oblique; median suture distinct, lateral areas rugose. Macropterous; wings hyaline, veins brown (Fig. 8 A – B). Forewings length ca 8.0 mm, hindwings length ca 6.5 mm. In forewing, ScP reaching RA before ra-rp; RP with two branches; CuA with two branches; AA 1 simple, AA 2 forked. In hind wing, ScP reaching RA before ra-rp; RP with two branches; anal area large and folded. Legs mostly brown, darker at joints of femur and tibia; tibia with moderate apical spurs. ABDOMEN. Abdominal segments mostly dark brown. Terga 1 – 8 unmodified. Tergum 9 with subquadrate patch of short stout sensilla basiconica medially (Fig. 10 A – C). Tergum 10 complete, with elliptical, depressed, membranous, posteromedial area, anterior and lateral areas of membrane surrounded by short stout sensilla basiconica similar to those on tergum 9. Paraprocts darkly sclerotized, upcurved, narrow, pointed apically. Sternum 7 with short but wide posteromedian extension (Fig. 11 A – B). Vesicle of sternum 8 less developed, indistinguishable from sternum. Sternum 9 greatly expanded backwards into hairy, rounded hood exceeding basal cercal segment; posterolateral margins of sternum 9 forming oblique ridges. Cerci slender, preserved parts slightly shorter than abdomen, basal segments pale, apical segments dark.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
9709E54DFF89FFB74AA7FA4AFAF9BFB9.taxon	discussion	Remarks Compared with † Isoperla succinica Hagen, 1856, whose holotype is lost and whose status has been treated as incertae sedis (Caruso & Wichard 2010; Jouault et al. 2021), † I. lituana sp. nov. can be distinguished by the 8 th cercomere, which is more than 2 × as long as broad (vs barely 2 × as long as wide in † I. succinica), and by the absence of a median cleft in tergum 10 (vs presence of a cleft in † I. succinica) (Jouault et al. 2021). The new species can also be differentiated from † I. baltica by several features, including: the forewing with ScP reaching RA before ra-rp (vs after ra-rp), CuA with two branches (vs three branches), abdominal sterna 9 and 10 with patches of sensilla basiconica (vs lacking sensilla basiconica), and an elongated sternum 9 that exceeds the basal cercal segment (vs not exceeding the basal cercal segment) (Jouault et al. 2021). In addition to these distinguishing traits, † I. lituana differs from extant species by its unique combination of characters, as outlined in the diagnosis.	en	Chen, Zhi-Teng (2025): Three new stoneflies (Insecta: Plecoptera) from Eocene Baltic amber. European Journal of Taxonomy 1026: 107-122, DOI: 10.5852/ejt.2025.1026.3107, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3107/13863
