Raphidioptera Navás, 1916

Lu, Xiumei, Zhang, Weiwei, Wang, Bo, Engel, Michael S. & Liu, Xingyue, 2020, A new and diverse paleofauna of the extinct snakefly family Baissopteridae from the mid-Cretaceous of Myanmar (Raphidioptera), Organisms Diversity & Evolution (New York, N. Y.) 20 (4), pp. 565-595 : 567-588

publication ID	https://doi.org/ 10.1007/s13127-020-00455-y
persistent identifier	https://treatment.plazi.org/id/03C5283A-FF97-FF90-F08A-F8B5FD89A082
treatment provided by	Felipe
scientific name	Raphidioptera Navás, 1916
status

Treatment

Order Raphidioptera Navás, 1916 View in CoL View at ENA

Suborder Raphidiomorpha Engel, 2002

Family Baissopteridae Martynova, 1961 View in CoL

Diagnosis: This family is characterized by the following characters: (1) ocelli present; (2) RA veinlet within pterostigma usually present; (3) forewing M with stem usually shorter than doi 1; (4) forewing M and CuA diverging at angle of> 40°; (5) venation enriched, especially crossvenation, forming at least three radial cells in forewing and four radial cells in hind wing, at least two discal cells in both fore- and hind wings, usually four or more discoidal cells in both fore- and hind wings; (6) male gonocoxites IX paired and shell-like; (7) male gonapophyses IX reduced.

Remarks: The familial diagnostic characters were previously revised by Makarkin and Archibald (2014). This family is generally defined by the enriched venation, which was considered to be secondary and possibly a familial autapomorphy by Makarkin and Archibald (2014). Exceptionally, in some small-sized baissopterids, as described herein (e.g., Allobaissoptera oligophlebia gen. et sp. nov.), the wing venation is much sparser than in species of Baissoptera , but similar in number to some mesoraphidiids, such as Cretoinocellia cellulosa Ponomarenko, 1988 . However, we found two additional characters that are useful to distinguish baissopterids from such mesoraphidiids. First, the stem of forewing M is usually shorter than doi 1 and diverged with CuA at an angle> 40° in Baissopteridae . The combination of these two characters is present in all Burmese amber baissopterids as well as most baissopterids from other deposits (see Willmann 1994; Lyu et al. 2017a). In Mesoraphidiidae , the forewing M has its stem usually as long as or longer than doi 1 and diverged with CuA at an angle ~ 30°. Second, there are numerous forewing doi in medium- to large-sized baissopterids; otherwise, two or three forewing doi are present but not triangularly arranged, and two forewing dc and three forewing m are present in small-sized baissopterids. In Mesoraphidiidae , there are three forewing doi triangularly arranged, which is a typical feature of this family, while in some minute mesoraphidiids with one or two forewing doi, the number of forewing discal and medial cells are also decreased to one or two. Based on the revised familial diagnosis present above, the baissopterid affinity of Cretoraphidiopsis bontsaganensis ( Ponomarenko 1988) from the Lower Cretaceous of Mongolia is suspect because the configuration of the proximal part of forewing M is identical to that in Mesoraphidiidae (see Ponomarenko 1988: Fig. 6 View Fig ). However, the number and arrangement of forewing doi are baissopterid-like in this species. If truly a baissopterid as other traits suggest, then the condition of the forewing M is either a secondary reversal to a putatively plesiomorphic condition or perhaps this species is sister to the remainder of the family. Only a future phylogenetic analysis will determine which scenario is accurate. It is also notable that the configuration of the forewing M stem is greatly differed among the species of Cretoraphidia Ponomarenko, 1993 from the Lower Cretaceous of Russia. In Cretoraphidia certa Ponomarenko, 1993 (the type species of the genus), the forewing M has an extremely long stem, while in C. macrocella Ponomarenko, 1993 and C. reticulata Ponomarenko, 1993 , this vein is short or very short, respectively (see Ponomarenko 1993: Figs. 7 View Fig , 8 View Fig , 9 View Fig , 10 View Fig , and 11). The accuracy of the original drawings as well as the baissopterid affinity of these species needs further consideration once the primary types are re-examined. Besides the wing character, the shell-like male gonocoxite IX is present in all of the currently described species with male genitalia preserved. Interestingly, this feature is quite similar to that in the extant snakefly family Inocelliidae . The shell-like male gonocoxite IX is known to be a reliable character to distinguish Inocelliidae from the other extant family, Raphidiidae ( Aspöck et al. 1991) . However, whether this character can be used to distinguish Baissopteridae from Mesoraphidiidae is still unclear.

Genus Baissoptera Martynova, 1961 View in CoL ( Figs. 1 View Fig , 2 View Fig , 3 View Fig , 4 View Fig , 5 View Fig , 6 View Fig , and 7; Figs. S1–S View Fig 2 View Fig )

Synonyms: Cratoraphidia Martins-Neto and Nel, 1992: 426 . Type species: Cratoraphidia pulchra Martins-Neto and Nel, 1992 View in CoL , by original designation. Synonymy by Engel (2002).

Rudiraphidia Ren, 1997: 175 . Type species: Baissoptera liaoningensis Ren, 1994 View in CoL , by original designation. Synonymy by Engel (2002).

Type species: Baissoptera martinsoni Martynova, 1961 .

Revised diagnosis: Medium- to large-sized (forewing length ~ 10.0–28.0 mm); head nearly rectangular, about twice as long as wide, with vertex slightly longer than compound eye (diameter of compound eye about one-half head length). Tarsomere III simple, symmetrically bilobed, or asymmetrically bilobed. Forewing long elliptical, ~ 3.0–4.0× as long as wide; ScP terminating into costal margin posteriad midpoint of wing; pterostigma ~ 3.5–8.0× as long as wide, closed by a crossvein proximally, mostly with one RA veinlet incorporated; MA originating at or close to initial branching point of MP; three or more radial cells, three or more discal cells, and five or more discoidal cells present; three cua-cup crossveins present. Hind wing with four or more radial cells, three or more discal cells, and five or more discoidal cells; stem of MA proximally fused with MP or R (“fusion with R ” described mostly in compression fossils, in which the true fusing condition is actually hard to discern); three mp-cua crossveins, 1mp-cua connecting to stem of MP at or slightly proximad its midpoint, distinctly inclined or slightly vertical to MP; CuA simple or distally forked. Male gonocoxite IX shell-like, but varied in length and width.

Baissoptera burmana sp. nov. ( Figs. 1 View Fig and 3a, b View Fig ; Figs. S1– S View Fig 2 View Fig )

Diagnosis: Tarsomere III asymmetrically bilobed, with a long and a short lobe; a dark marking present on apex in both fore- and hind wings; forewing MA with stem separating at initial branching point of MP; nine forewing doi and 13 hind wing doi present.

Description: Holotype CAU-BA-XF-20001. Female. Body (head largely not preserved) length 15.4 mm; pronotum length 4.4 mm, width 0.9 mm; mesothorax length 1.4 mm, width 2.7 mm; metathorax length 1.3 mm, width 2.6 mm; forewing length 14.6 mm, width 4.1 mm; hind wing length 13.5 mm, width 4.0 mm; abdomen length 6.3 mm.

Body dark brown. Prothorax slender. Legs slender, densely setose; tarsomere III asymmetrically bilobed, with an elongate narrow lobe and a short narrow lobe; pretarsal claws with proximal half broad, distally forked into a subtriangular projection.

Forewing: Long elliptical, ~ 3.0× as long as wide; costal space broadened at proximal 1/3, with nine crossveins; ScP terminating into costal margin at distal 2/5 of wing; five simple RA veinlets present; pterostigma long, ~ 3.5× as long as wide, uniformly colored, closed by a crossvein proximally, distally ending at second veinlet of RA, with a slightly sinuate RA veinlet incorporated; five radial crossveins present, five radial cells gradually shortened, r 1 strongly narrowed and elongate; RP forked slightly proximad its midpoint, with five pectinate branches, most of them simple except posterior-most one forked marginally; four rp-ma crossveins, forming four discal cells; MA with stem originating at branching point between MP 1 and MP 2; MA deeply forked at its proximal 1/3, with two marginally forked branches; five ma-mp crossveins, forming five medial cells; MP deeply forked, with nine short terminal branches and nine discoidal cells arranged in three series; CuA and CuP simple; three cua-cup crossveins present; A1 and A2 forked.

Hind wing: Slightly shorter than but almost as wide as forewing; costal space narrow, with seven crossveins preserved; ScP terminating into costal margin at distal 1/3 of wing; four RA veinlets, with third one forked; pterostigma similar to that of forewing but slightly paler and starting closer to termination of ScP; a distinctly curved RA veinlet present within pterostigma; six radial crossveins present, r 3 longest; RP forked slightly proximad its midpoint, with five pectinate branches, most of them simple except posterior-most one forked marginally; five rp-ma crossveins, forming five discal cells; MA with stem originating from base of MP stem, long and sinuate; MA initially branching at its proximal 1/3, with two marginally forked branches; five ma-mp crossveins, forming five medial cells; MP deeply forked, with eight short terminal branches and 13 discoidal cells arranged in three series; five mp-cua crossveins, with 1mp-cua slightly vertical to stem of MP; CuA and CuP simple; three cua-cup crossveins present; A1 with four pectinate branches; A2 simple.

Genitalia largely not preserved.

Paratype EMTG BU-002258 ( Fig. S1 View Fig A-C). Adult with sex unknown. Head and prothorax entirely lacking. Meso- and metathorax, and abdomen partially preserved. Tarsomere III in hind leg asymmetrically bilobed as in holotype. Wings partially preserved; right fore- and hind wings with distal markings partly preserved; venation largely similar to that in holotype.

Paratype EMTG BU-002190 ( Fig. S1 View Fig D-E). Adult with sex unknown. Only head, thorax, and basal parts of right fore- and hind wings preserved. Head nearly rectangular, length 3.0 mm, width 1.5 mm, with clypeus + labrum 0.5 mm long, vertex 1.0 mm long; compound eye length 1.1 mm, width 0.5 mm; ocelli present; antennae with more than 60 flagellomeres. Prothorax much narrower than head, but much wider on proximal half, 3.0 mm long, 1.0 mm wide; mesoplus metathorax 4.2 mm long. Tarsomere III in all preserved legs asymmetrically bilobed.

Paratype EMTG BU-002104 ( Fig. S2 View Fig ). Male pupa. Exarate. Body length 14.0 mm; head nearly rectangular, length 3.2 mm, width 1.1 mm, with vertex 1.1 mm long; compound eye length 1.0 mm, width 0.5 mm; prothorax length 1.9 mm, width 0.8 mm; tarsomere 3 asymmetrically bilobed. Genitalia with a pair of gonocoxites IX and ectoproct discernible; gonocoxite IX subtriangular, slightly longer than wide, with a spinous apex.

Type material: Holotype: CAU-BA-XF-20001: Amber piece with a nearly complete adult female of Baissoptera burmana sp. nov., with apical part of head not preserved. Paratype: EMTG BU-002190: Amber piece with an adult of B. burmana sp. nov., with head and thorax preserved. Paratype: EMTG BU-002258: Amber piece with an incomplete adult of B. burmana sp. nov., with wings partly preserved. Paratype: EMTG BU-002104: Amber piece with a pupa of B. burmana sp. nov.

Etymology: The specific epithet “ burmana ” (meaning, “ Burma ”) refers to the occurrence of the new species in Myanmar. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:D490D7F7-ECF7-4E42-884D-9635E2FCEA7D .

Remarks: The new species has a distinct dark marking on the apex of both fore- and hind wings, and this feature is only shared by another Burmese amber species of Baissoptera , i.e., B. maculata sp. nov. (see below). However, the new species differs from B. maculata sp. nov. by the asymmetrically bilobed tarsomere III, the broader wings, the stem of MA in forewing originating from the branching point between MP 1 and MP 2, and the presence of more discoidal cells in both fore- and hind wings. In B. maculata sp. nov., tarsomere III is symmetrically bilobed, the wings are apparently narrower than that of B. burmana sp. nov., the stem of forewing MA originates from MP 1 (slightly distad branching point between MP 1 and MP 2), and there are only five discoidal cells in both fore- and hind wings.

Baissoptera maculata sp. nov. ( Figs. 2 View Fig and 3c, d View Fig )

Diagnosis: Tarsomere III symmetrically bilobed, with a pair of ovoid lobes; a dark marking present on apex of both fore- and hind wings; forewing MA with stem originating slightly distad initial branching point of MP; five doi present in both fore- and hind wings.

Description: Holotype NIGP163570. Male. Body length 13.9 mm; head length 2.3 mm, width 1.3 mm, with clypeus + labrum 0.5 mm long, vertex 1.1 mm long; compound eye length 0.8 mm, width 0.5 mm; antenna (partly preserved) length 5.3 mm; occiput length 0.1 mm; pronotum length 2.6 mm, width 0.8 mm; meso- plus metathorax length 2.2 mm; forewing length 11.9 mm, width 3.1 mm; hind wing length 10.8 mm, width 2.9 mm; abdomen length 6.7 mm.

Body blackish brown; head nearly rectangular, with vertex nearly as long as compound eye; occiput short; clypeus anteriorly truncate; compound eyes ovoid; ocelli present; antennae with about 70 flagellomeres.

Prothorax slender, slightly longer than head; meso- plus metathorax almost as long as prothorax. Legs short, slender, densely setose; tarsomere III symmetrically bilobed, with a pair of ovoid lobes; pretarsal claw forked at distal 1/3 into acutely tapering tooth.

Forewing: Long elliptical, ~ 3.5× as long as wide; costal space broadened at proximal 1/3, with seven crossveins; ScP terminating into costal margin slightly distad midpoint of wing; four simple RA veinlets present; pterostigma ~ 5.0× as long as wide, uniformly colored, closed by a crossvein proximally, distally terminating at second veinlet of RA, with a slightly curved RA veinlet incorporated; five radial crossveins present, five radial cells gradually shortened, r 1 elongate and broadened distad; RP forked proximad its midpoint, with four simple branches; four rp-ma crossveins, forming four discal cells; MA with stem originated at MP 1, slightly distad initial branching point of MP; MA deeply forked at its proximal 2/5, with MA 1 marginally forked and MA 2 simple; four ma-mp crossveins, forming four medial cells; MP deeply forked, with five terminal branches and five discoidal cells arranged in two series; CuA and CuP simple; three cua-cup crossveins present; A1 and A2 bifurcate.

Hind wing: Slightly shorter and narrower than forewing; costal space narrow, with six crossveins preserved; ScP terminating into costal margin slightly distad midpoint of wing; four simple RA veinlets present; pterostigma similar to that of forewing but slightly narrower, a strongly inclined but slightly curved RA veinlet present within pterostigma; six radial crossveins present, r 3 longest; RP forked slightly proximad its midpoint, with four branches, most of them simple except posterior-most one forked marginally; four rp-ma crossveins, forming four discal cells; MA with stem originating from base of MP stem, elongate and distinctly sinuate; MA initially branched slightly proximad its midpoint, with two marginally forked branches; four ma-mp crossveins, forming four medial cells; MP deeply forked, with eight terminal branches and five discoidal cells arranged in three series; three mp-cua crossveins, with 1mp-cua nearly vertical to stem of MP; CuA simple; CuP with a marginal fork; three cua-cup crossveins present; A1 with four pectinate simple branches; A2 simple.

Terminalia visible in lateral and ventral views; tergum IX broad, ventrally fused with sternum IX; gonocoxites IX paired, slenderly shell-like, nearly as long as tergum IX plus ectoproct, much longer than wide, with apex slightly curved dorsad in lateral view; ectoproct large, nearly as long as tergum IX, slightly protruding posterodorsad, with trichobothria present along posterior margin.

Type material: Holotype: NIGP163570: Amber piece with a complete adult male of Baissoptera maculata sp. nov.

Etymology: The specific epithet “ maculata ” refers to the presence of a distinct marking on apices of both fore- and hind wings in the new species. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:FA5F16F8-23A6-4B88-B70E-40818DF44576 .

Baissoptera monopoda sp. nov. ( Figs. 4 View Fig and 7a, b View Fig )

Diagnosis: Tarsomere III not bilobed; pterostigma bicolored in both fore- and hind wings; forewing MA with stem separating at initial branching point of MP; seven doi present in both fore- and hind wings.

Description: Holotype NIGP163571. Sex unknown. Mesoplus metathorax length 2.6 mm; forewing length 13.4 mm, width 3.4 mm; hind wing length 12.1 mm, width 3.3 mm; abdomen length 5.6 mm.

Body blackish brown. Head not preserved.

Pronotum partly preserved, slender. Meso- and metathorax robust. Legs slender, densely setose; tarsomere III not bilobed; pretarsal claws forked at distal 1/3 into an acutely tapering tooth.

Forewing: Narrowly elongate, ~ 4.0× as long as wide; costal space narrow, slightly broadened at proximal 1/3, with six crossveins; ScP terminating into costal margin at distal 2/5 of wing; pterostigma long, ~ 8.0× as long as wide, bicolored, with part distad incorporated RA veinlet much darker, closed by a crossvein proximally, distally ending at second veinlet of RA, with a straight but inclined RA veinlet incorporated; four radial crossveins, four radial cells gradually shortened, r 1 longest, r 2 broadest; RP forked proximad its midpoint, with four simple branches; four rp-ma crossveins, forming four discal cells; MA with stem originating at branching point of MP 1 and MP 2; MA deeply forked at its proximal 1/3, MP 1 forked slightly distad its midpoint, MP 2 deeply forked at its proximal 1/3, branching of MP 1 much shorter than branching of MP 2; four ma-mp crossveins, forming four medial cells; MP deeply forked, with six terminal branches and seven discoidal cells arranged in two series; CuA and CuP simple; three cua-cup crossveins present; A1 with three simple branches; A2 bifurcate.

Hind wing: Slightly shorter than but almost as wide as forewing; costal space narrow, with five crossveins preserved; ScP terminating into costal margin at distal 2/5 of wing; four simple RA veinlets present; pterostigma similar that of forewing, but with a short and slightly curved RA veinlet incorporated; five radial crossveins present, r 3 longest; RP forked proximad its midpoint, with four simple branches; four rp-ma crossveins, forming four discal cells; MA with stem originated from base of MP stem, long and sinuated; branching condition of MA similar to that of forewing; four ma-mp crossveins, forming four medial cells; MP deeply forked, with six terminal branches and seven discoidal cells arranged in two series; three mp-cua crossveins, with 1mp-cua distinctly inclined to stem of MP; CuA and CuP simple; three cua-cup crossveins present; A1 with five pectinate simple branches; A2 simple.

Genitalia not preserved.

Type material: Holotype: NIGP163571: Amber piece with an incomplete adult of Baissoptera monopoda sp. nov., with head, apical parts of prothorax, and forewing not preserved.

Etymology: From the Greek “ mono -” (single) and “- podus ” (leg), in reference to the unpaired tarsomere III in the new species. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:65528BCB-6345-4523-858D-CC179EB14237 .

Remarks: The new species mostly resembles B. wangi sp. nov. in having a similar wing shape, bicolored pterostigma, and forewing MA stem originating from the initial branching of MP. However, the new species can be distinguished from B. wangi sp. nov. and other species of Baissoptera by the unpaired tarsomere III. In addition, the venation of B. wangi sp. nov. is relatively reduced by comparison to that of the present new species, with only five doi in both fore- and hind wings (see below).

Baissoptera pankowskiorum sp. nov. ( Figs. 5 View Fig and 7c, d View Fig )

Diagnosis: Tarsomere III symmetrically bilobed, with a pair of short lobes; forewing MA with stem originating slightly distad initial branching point of MP; hind wing MA with stem nearly half length of r 1; five doi present in both fore- and hind wings.

Description: Holotype SEMC F000385 (Bu-131). Female. Body length 14.7 mm; head length 3.1 mm, width 1.8 mm; compound eye length 0.8 mm; pronotum length 3.2 mm, width 1.5 mm; forewing length 11.7 mm, width 3.6 mm; ovipositor length 4.7 mm (beyond abdominal apex).

Body dark brown; head nearly rectangular, with vertex slightly longer than compound eye; occiput short; compound eyes ovoid; ocelli present; antenna with at least 75 flagellomeres.

Prothorax elongate, slightly longer than head; meso- plus metathorax slightly shorter than pronotum. Legs short, slen- der, densely setose; tarsomere III symmetrically bilobed, with a pair of short lobes.

Forewing: Long elliptical, ~ 3.0× as long as wide; costal space slightly broadened at proximal 1/3, with eight crossveins; ScP terminating into costal margin slightly distad midpoint of wing; four simple RA veinlets present; pterostigma ~ 4.0× as long as wide, uniformly colored, closed by a crossvein proximally, distally ended at second veinlet of RA, with a long, strongly inclined and slightly sinuate RA veinlet incorporated; four radial crossveins present, r 2 nearly as long as r 1 but much broader than r 1, r 3 and r 4 much shorter; RP forked slightly proximad its midpoint, with four simple branches; four rp-ma crossveins, forming four discal cells; MA with stem originating at MP 1, slightly distad initial branching point of MP; MA deeply forked at its proximal 1/3, MP 1 forked at its distal 1/3; MP 2 deeply forked at its midpoint, branching of MP 1 slightly shorter than branching of MP 2; four ma-mp crossveins, forming four medial cells; MP deeply forked, with six terminal branches and five discoidal cells arranged in two series; CuA and CuP simple; three cua-cup crossveins present; A1 and A2 respectively bifurcate.

Hind wing: Distal part not preserved; costal space narrow, proximally with five costal crossveins; MA with stem originated from R, short and nearly straight, nearly half length of r 1; MP deeply forked, with six terminal branches and five discoidal cells arranged in two series; three mp-cua crossveins, with 1mp-cua distinctly sinuated and inclined to stem of MP.

Genitalia visible in dorsal view; ovipositor (incomplete as preserved) robust, straight, length beyond abdominal apex (as preserved), with numerous, minute setae.

Type material: Holotype: SEMC F000385 (Bu-131): Amber piece with a complete adult female of Baissoptera pankowskiorum sp. nov.

Etymology: The new species is named in honor of the Mark Pankowski family for their commendatory support of paleoentomological research. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:3745890B-3CA4-40E2-BC17-12AFFE7B50BD .

Remarks: The new species can be distinguished from the other species of Baissoptera by having the combination of three gradate series of crossveins in the RP and MA field and five doi in the forewing. These two characters do not co-exist in the other species of Baissoptera . Moreover, the stem of hind wing MA is very short, nearly one-half length of r 1 in the new species, while it is as long as or slightly longer than hind wing r 1 in the other species of Baissoptera in which the hind wing is preserved.

Baissoptera wangi sp. nov. ( Figs. 6 View Fig and 7e, f View Fig )

Diagnosis: Tarsomere III symmetrically bilobed, with a pair of ovoid lobes; pterostigma bicolored in both fore- and hind wings; forewing MA with stem originating at initial branching point of MP; five doi present in both fore- and hind wings; gonocoxites IX much wider than long.

Description: Holotype CAU-BA-WN-20001. Male. Body length 12.1 mm; head length 2.4 mm, width 1.1 mm, with clypeus + labrum 0.8 mm long, vertex 0.9 mm long; compound eye length 0.8 mm, width 0.3 mm; antenna length 5.9 mm; occiput length 0.3 mm; pronotum length 2.0 mm, width 1.1 mm; meso- plus metathorax length 2.3 mm; forewing length 11.0 mm, width 2.9 mm; hind wing length 10.7 mm, width 2.6 mm; abdomen length 5.0 mm.

Body blackish brown; head nearly rectangular, with vertex slightly longer than compound eye; occiput short; compound eyes ovoid; antenna with about 70 flagellomeres.

Prothorax stout, as long as head; meso- plus metathorax almost as long as prothorax. Legs slender, densely setose; tarsomere III symmetrically bilobed, with a pair of ovoid lobes; pretarsal claws forked at distal 1/3 into an acutely tapering tooth.

Forewing: Narrowly elongate, ~ 4.0× as long as wide; costal space narrow, slightly broadened at proximal 2/5, with seven crossveins; ScP terminating into costal margin at distal 2/5 of wing; pterostigma ~ 5.0× as long as wide, bicolored (area distad incorporated RA veinlet much darker), closed by a crossvein proximally, distally ending at second veinlet of RA, with a sinuate RA veinlet incorporated; three radial crossveins present, three radial cells gradually shortened, r 1 slenderly elongate; RP forked at its midpoint, with three simple branches; three rp-ma crossveins, forming three discal cells; MA with stem originated at initial branching point of MP; MA deeply forked at its proximal 1/3, MA 1 simple, MA 2 deeply forked at its midpoint; three ma-mp crossveins, forming three medial cells; MP deeply forked, with five terminal branches and five discoidal cells; CuA and CuP simple; three cua-cup crossveins present; A1 and A2 bifurcate.

Hind wing: Slightly shorter and narrower than forewing; costal space quite narrow, with three crossveins preserved; ScP terminating into costal margin at distal 2/5 of wing; pterostigma similar to that of forewing, but starting closer to termination of ScP, a sinuate RA veinlet present within pterostigma; four radial crossveins present, r 3 longest; RP forked at its midpoint, with three simple branches; three rp-ma crossveins, forming three discal cells; MA with stem basally damaged, elongate and slightly sinuate; MA initially branching proximad its midpoint, MA 1 simple, MA 2 deeply forked at its midpoint; three ma-mp crossveins, forming three medial cells; MP deeply forked, with five terminal branches and five discoidal cells; three mp-cua crossveins, with 1mp-cua distinctly inclined to stem of MP; CuA and CuP simple; two cua-cup crossveins present; A1 with four pectinate simple branches; A2 simple.

Terminalia visible in lateral view: Tergum IX short; gonocoxites IX paired, shell-like, much wider than long; ectoproct nearly as long as tergum IX.

Type material: Holotype: CAU-BA-WN-20001: Amber piece with a complete adult male of Baissoptera wangi sp. nov.

Etymology: The specific epithet honors Mr. Ning Wang, who kindly provided the specimen of the new species for our research. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:86156883-AE84-4F2F-9CAE-B303FF1F65C1 .

Genus Burmobaissoptera gen. nov. ( Figs. 8 View Fig and 9 View Fig )

Type species: Burmobaissoptera jiaxiaoae sp. nov.

Diagnosis: Medium-sized (female forewing length ~ 12.0 mm); head rectangular, with vertex almost as long as compound eye (diameter of compound eye about one-half head length). Tarsomere III symmetrically bilobed. Forewing long elliptical, ~ 3.0× as long as wide, with distal half distinctly broadened; ScP terminating into costal margin slightly proximad wing midpoint; pterostigma extremely long and distinctly broadened distad, ~ 15.0× as long as wide; starting slightly distad termination of ScP, diffuse proximally, no RA veinlet incorporated; MA with stem originating at initial branching point of MP; four radial cells, three discal cells, and three discoidal cells present; two cua-cup crossveins present. Hind wing with five radial cells, three discal cells, and three discoidal cells; stem of MA originating at diverging point between R and M; two mp-cua crossveins, 1mp-cua connecting to stem of MP at its base, strongly inclined to MP and slightly sinuate; CuA distally bifurcate.

Etymology: From “ Burma ” (meaning “ Myanmar ”) and Baissoptera (the type genus of Baissopteridae ), in reference to the occurrence of the new genus from the mid-Cretaceous amber of Myanmar. Gender: Feminine. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:E560CDB1-F254-4F8B-92A5-9C28EE01CBCB .

Remarks: The baissopterid affiliation of the new genus is based on the presence of a short M stem, which is diverged with CuA stem at angle of> 40° in the forewing, and the moderately rich venation. However, it differs from the other genera of Baissopteridae by the ScP terminating into costal margin proximad wing midpoint, the presence of a greatly elongate pterostigma with diffuse base, and the lack of a pterostigmal RA veinlet. In the other genera of Baissopteridae , the ScP terminates into the costal margin at or distad wing midpoint; the pterostigma is relatively short, closed by a crossvein proximally; and a pterostigmal RA veinlet is present in most genera.

Burmobaissoptera jiaxiaoae sp. nov. ( Figs. 8 View Fig and 9 View Fig )

Diagnosis: Same as for the genus (see above).

Description: Holotype CAM BA-0016. Female. Body length 13.3 mm; head length 2.6 mm, width 1.2 mm, with clypeus + labrum 0.5 mm, vertex length 1.0 mm; compound eye length 1.0 mm, width 0.5 mm; pronotum length 1.6 mm, width 0.7 mm; meso- plus metathorax length 2.6 mm; forewing length 11.8 mm, width 3.5 mm; hind wing length 11.4 mm, width 3.4 mm; abdomen length 6.4 mm; ovipositor length 6.3 mm, width 0.2 mm.

Body dark brown; head rectangular, with vertex almost as long as compound eye; occiput short; compound eyes ovoid; ocelli present.

Prothorax almost as long as head; meso- plus metathorax slightly longer than prothorax. Legs slender, densely setose; tarsomere III symmetrically bilobed, with a pair of ovoid lobes; pretarsal claws forked at distal 1/3 into an acutely tapering tooth.

Forewing: Long elliptical, ~ 3.0× as long as wide, with distal half distinctly broadened; costal space narrow, with seven crossveins; ScP terminating into costal margin slightly proximad wing midpoint; three simple RA veinlets present; pterostigma greatly elongate and distinctly broadened distad, ~ 15.0× as long as wide, uniformly colored, proximally diffuse, starting slightly distad termination of ScP, distally ending at first veinlet of RA, no RA veinlet incorporated; four radial crossveins present, r 1 longest, r 2 broadest and as long as r 3, r 4 shortest and narrowest; RP forked at its proximal 1/3, with four simple branches; three rp-ma crossveins, forming three discal cells; MA with stem originating at initial branching point of MP; MA deeply forked at its proximal 1/3, with two simple branches; three ma-mp crossveins, forming three medial cells; MP deeply forked, with four terminal branches and a series of three discoidal cells; CuA bifurcate, CuP simple; two cua-cup crossveins present; A1 bifurcate; A2 simple.

Hind wing: Slightly shorter than forewing, proximal half much narrower than forewing, but distal half distinctly broadened; costal space quite narrow, with five crossveins preserved; ScP terminating into costal margin proximad wing midpoint; three simple RA veinlets; pterostigma similar to that of forewing; five radial crossveins present, r 1 shortest, r 3 longest and broadest, r 4 almost as long as r 3; RP forked slightly distad its proximal 1/3, with three simple branches; three rp-ma crossveins, forming three discal cells; MA with stem originating at diverging point between R and M, slightly longer than r 1; MA initially branching at its proximal 1/3, with two simple branches; three ma-mp crossveins, forming three medial cells; MP deeply forked, with five terminal branches and a series of three discoidal cells; two mp-cua crossveins, with 1mp-cua connecting to base of MP, distinctly inclined to MP stem, and slightly sinuate; CuA distally bifurcate; CuP simple; one cua-cup crossvein present; A1 bifurcate; A2 simple.

Terminalia visible in ventral and lateral views; tergum VII almost as long as combined length of terga VIII+IX and ectoproct; sternum VII broad, slightly longer than tergum VII, with posterior margin convex; no sclerotized subgenitale discernible; tergum IX nearly one-half length of tergum VIII, distinctly narrowed ventrad; ectoproct slightly shorter than tergum IX; ovipositor long and stout; a pair of ovoid gonostyli IX present at tip of ovipositor.

Type material: Holotype: CAM BA-0016: Amber piece preserved with a nearly complete adult female of Burmobaissoptera jiaxiaoae gen. et sp. nov., with left wings largely not preserved.

Etymology: The specific epithet honors Mrs. Xiao Jia, who kindly provided the specimen of the new species for our research. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:EDAFE551-EB59-4075-A75F-946C099E5D23 .

Genus Allobaissoptera gen. nov. ( Figs. 10 View Fig and 12a–c View Fig )

Type species: Allobaissoptera oligophlebia sp. nov.

Diagnosis: Small-sized (male forewing length ~ 6.0 mm); head narrowly rectangular, with vertex slightly longer than compound eye (diameter of compound eye about one-half head length). Tarsomere III symmetrically bilobed, with a pair of narrow lobes. Forewing narrow, ~ 3.5× as long as wide; ScP terminating into costal margin at midpoint of wing; pterostigma long, ~ 6.0× as long as wide, closed by a crossvein proximally, without RA veinlet incorporated; RA distally bifurcate; RP and MA each with two branches, branching of RP half-length of branching of MA; MA with stem separating from MP distinctly distad branching point between MP 1 and MP 2; three radial cells, two discal cells, and two discoidal cells present. Hind wing with four radial cells, two discal cells, and two discoidal cells; stem of MA proximally fused with MP, medially with a short crossvein connecting to MP 1; CuA distally bifurcate. Male gonocoxite IX slightly longer than wide, strongly produced posteriad.

Etymology: From the Greek “ allos ” (meaning “different”) and Baissoptera (the type genus of Baissopteridae ), in reference to the unusual reduction of wing venation in the new genus compared with other baissopterids. Gender: Feminine. The name is registered with ZooBank LSID: LSID urn:lsid:zoobank.org:act:E1D1AD4F-EE92-4E1A-8D2A-3C3EF92F095E .

Remarks: The new genus is placed in Baissopteridae based on the presence of a short M stem, which is diverged with CuA stem at angle of> 40° in the forewing. However, it differs from the other genera of Baissopteridae by the presence of only two doi and the RP branching nearly one-half length of the MA branching in both fore- and hind wings. This new genus mostly resembles Electrobaissoptera gen. nov. in having similar relatively smaller body size, and the generally reduced wing venation, but can be distinguished from the latter genus by the termination of ScP at the wing midlength, the absence of a RA veinlet within the pterostigma, and the aforementioned unique generic features.

Allobaissoptera oligophlebia sp. nov. ( Figs. 10 View Fig and 12a–c View Fig )

Diagnosis: Same as for the genus (see above).

Description: Holotype NIGP 163572. Male. Body length 6.6 mm; head length 1.0 mm, with clypeus + labrum 0.1 mm long, vertex 0.5 mm long; compound eye length 0.5 mm; antenna length 3.3 mm; pronotum length 1.6 mm; meso- plus metathorax length 1.5 mm; forewing length 5.9 mm, width wing. f Mid leg. g Male genitalia, lateral view. h Drawing of male genitalia, lateral view. Scale bar = 1.0 mm

1.6 mm; hind wing (proximal part not preserved) length 5.4 mm; abdomen length 3.0 mm.

Body dark brown; head narrowly rectangular, with vertex slightly longer than compound eye; occiput short; compound eyes ovoid; ocelli present; antenna with ca. 50 flagellomeres.

Prothorax slightly longer than head; legs slender, densely setose; tarsomere III symmetrically bilobed, with a pair of narrow lobes; pretarsal claw tiny, distally forked.

Wings transparent. Forewing: Narrow, ~ 3.7× as long as wide; costal space narrow, with five crossveins; ScP terminating into costal margin at midpoint of wing; two simple RA veinlets present; pterostigma long, ~ 6.0× as long as wide, uniformly colored, closed by a crossvein proximally, distally ending at anterior veinlet of RA, RA veinlet within pterostigma absent; three radial crossveins present, three radial cells gradually shortened; RP forked distad its midpoint, with two simple branches; two rp-ma crossveins, forming two discal cells; MA with stem originating from MP 1, distinctly distad branching point between MP 1 and MP 2, MA forked slightly proximad its midpoint, with two simple branches, length of branching of MA nearly twice as long as branching of RP; three ma-mp crossveins, forming three medial cells; MP deeply forked, with four short terminal branches and two discoidal cells; CuA distally forked, with two simple branches; CuP simple; two cua-cup crossveins present; A1 and A2 simple.

Hind wing: Much narrower than forewing; costal space with four crossveins preserved; ScP terminating into costal margin at midpoint of wing; two simple RA veinlets present; pterostigma similar to that of forewing but slightly paler and starting more distad termination of ScP, RA veinlet within pterostigma absent; four radial crossveins present, r 3 longest; RP forked at its distal 1/4, with two simple branches; two rp-ma crossveins, forming two discal cells; MA with stem originating from base of MP stem, long, sinuate; MA forked at its midpoint, with two simple branches, branching of MA twice as long as branching of RP; four ma-mp crossveins, with 1ma-mp crossvein connecting MA stem and MP 1, four medial cells present; MP deeply forked, with four short terminal branches and two discoidal cells; two mp-cua crossveins, with 1mp-cua nearly vertical to stem of MP; CuA distally bifurcate; incomplete CuP simple; one cua-cup crossvein; anal region not preserved.

Terminalia visible in lateral view; tergum IX broad; gonocoxites IX paired, shell-like, much longer than wide, distinctly produced posteriad, with apex slightly bent dorsad; ectoproct slightly shorter than tergum IX.

Type material: Holotype: NIGP163572: Amber piece with a nearly complete adult male of Allobaissoptera oligophlebia gen. et sp. nov.

Etymology: From the Greek “ oligos ” (few) and “ phlebos ” (vein), in reference to the reduced venation of the new species. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:C047362A-B3C8-47C5-8B39-73735801A15E .

Genus Electrobaissoptera gen. nov. ( Figs. 11 View Fig and 12d, e View Fig )

Type species: Electrobaissoptera burmanica sp. nov.

Diagnosis: Small-sized (female forewing length ~ 7.0 mm); head narrowly rectangular, about twice as long as wide, with vertex almost as long as compound eye (diameter of compound eye about one-fourth head length). Tarsomere III symmetrically bilobed, with a pair of slender lobes. Forewing long elliptical, ~ 3.5× as long as wide; ScP terminating into costal margin slightly distad wing midpoint; pterostigma ~ 5.0× as long as wide, closed by a crossvein proximally, with one RA veinlet incorporated; MA with stem originating at MP 1, distinctly distad initial branching point of MP; three radial cells, two discal cells, and three discoidal cells present; two cua-cup crossveins present. Hind wing with five radial cell, two discal cells, and three discoidal cells; stem of MA proximally fused with MP; doi 1 with a short veinlet (an incomplete ma-mp crossvein) directed toward stem of MA; three mp-cua crossveins, 1mp-cua short and straight, almost vertical to MP; CuA distally bifurcate.

Etymology: From the Greek “ elektron ” (meaning “amber”) and Baissoptera (the type genus of Baissopteridae ), in reference to the discovery of the new genus from amber. Gender: Feminine. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:E92040C0-F05C-41D2-B97A-1749FFC440B6 .

Remarks: The new genus is similar to Allobaissoptera gen. nov. as both are small-sized baissopterids. It is also notable that there is a crossvein between the stem of hind wing MA and the MP 1 (or doi 1) in these two genera, although it is incomplete in both hind wings in the holotype of the type species of Electrobaissoptera gen. nov. Whether it is an aberrant development needs to be clarified when more specimens of Electrobaissoptera gen. nov. are available. Refer to the comparison between these two genera in the Remarks of Allobaissoptera gen. nov. (see above).

Electrobaissoptera burmanica sp. nov. ( Figs. 11 View Fig and 12d, e View Fig )

Diagnosis: Same as for the genus (see above).

Description: Holotype CAM BA-0017. Female. Body length 11.6 mm; head length 1.2 mm, width 0.5 mm, with clypeus + labrum 0.3 mm long, vertex 0.7 mm long; compound eye length 0.3 mm, width 0.1 mm; antenna length 1.1 mm; pronotum length 1.7 mm, width 0.2 mm; meso- plus metathorax length 1.3 mm; forewing length 6.7 mm, width 1.9 mm; hind wing length 6.3 mm, width 1.8 mm; abdomen length 3.2 mm; ovipositor length 4.4 mm, width 0.1 mm.

Body dark brown; head narrowly rectangular, with vertex slightly longer than compound eye; occiput short; compound eyes ovoid; ocelli present.

Prothorax slenderly elongate, slightly longer than head; meso- plus metathorax as long as prothorax. Legs slender, densely setose; tarsomere III symmetrically bilobed, with a pair of slender lobes; pretarsal claws forked at distal 1/3 into an acutely tapering tooth.

Forewing: Long elliptical, ~ 3.5 times as long as wide; costal space broadened at proximal 1/3, with five simple crossveins; ScP terminating into costal margin slightly distad wing midpoint; four simple RA veinlets present; pterostigma ~ 5.0× as long as wide, uniformly colored, closed by a crossvein proximally, distally ending at second veinlet of RA, with a straight but distinctly inclined RA veinlet incorporated; three radial crossveins present, three radial cells gradually shortened, r 1 longest, r 2 broadest; RP forked proximad its midpoint, with two simple branches; two rp-ma crossveins, forming two discal cells; MA with stem originating at MP 1, distinctly distad initial branching point of MP; MA deeply forked proximad its midpoint, with two simple branches, length of branching of MA as long as branching of RP; three ma-mp crossveins, forming three medial cells; MP deeply forked, with three terminal branches and a series of three discoidal cells; CuA marginally forked; CuP simple; two cua-cup crossveins present; A1 and A2 simple.

Hind wing: Slightly shorter and narrower than forewing; costal space narrow, with five crossveins; ScP terminating into costal margin slightly proximad wing midpoint; four simple RA veinlets present; pterostigma similar to that of forewing; five radial crossveins present, r 3 longest and broadest, remaining radial cells almost in equal length; RP forked proximad its midpoint, with two simple branches; two rp-ma crossveins, forming two discal cells; MA with stem originating from base of MP stem, long and sinuate; MA forked at its midpoint, with two simple branches, branching of MA as long as branching of RP; four ma-mp crossveins, forming three medial cells; MP deeply forked, with four terminal branches and a series of three discoidal cells; doi 1 with a short veinlet (an incomplete ma-mp crossvein) directing toward stem of MA; three mp-cua crossveins, with 1mp-cua almost vertical to stem of MP; CuA distally forked; CuP simple; two cua-cup crossveins present; A1 and A2 simple.

Terminalia visible in lateral view, with distal part not preserved; sternum VII broad, with arcuate posterior margin in lateral view; tergum VIII slightly shorter than tergum VII; ovipositor long and stout; a pair of gonostylus IX present at tip of ovipositor.

Type material: Holotype: CAM BA-0017: Amber piece with a nearly complete adult female of Electrobaissoptera burmanica gen. et sp. nov.

Etymology: The specific epithet “ burmanica ” (meaning, “of Myanmar ”), in reference to the discovery of the new species from Myanmar. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:665BEF10-AB8B-4019-BE52-9971D094D7BE .

Genus Rhynchobaissoptera gen. nov. ( Figs. 13 View Fig and 15a, b)

Type species: Rhynchobaissoptera hui sp. nov.

gen. et sp. nov., holotype: CAM BA-0017. d Right forewing. e Right hind wing. Scale bar = 1.0 mm

Diagnosis: Medium-sized (male forewing length ~ 15.0 mm); clypeus distinctly elongate; vertex greatly elongate, together with occiput about twice as long as compound eye (diameter of compound eye about one-third head length). Tarsomere III symmetrically bilobed, with a pair of ovoid lobes; pretarsal claws simple. Wing long elliptical, ~ 5.0× as long as wide; ScP terminating into costal margin slightly distad wing midpoint; 1scp-ra crossvein absent; pterostigma ~ 4.0× as long as wide, closed by a crossvein proximally, with one RA veinlet incorporated; MA with stem originated at MP 1, slightly distad initial branching point of MP; three radial cells, three discal cells, and at least five discoidal cells present. Hind wing with three radial cells, two discal cells, and six discoidal cells present; stem of MA proximally fused with MP; three mp-cua crossveins, 1mp-cua straight and inclined to MP. Male gonocoxites IX shell-like, much wider than long.

Etymology: From the Greek “ rhyncho s” (meaning “snout”) and Baissoptera (the type genus of Baissopteridae ), in reference to the presence of elongate rostrum in the new genus. Gender: Feminine. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:F0F5536A-8306-4E91-A362-C10A17E20740 .

Remarks: The new genus differs from the other genera of Baissopteridae by the distinctly elongate vertex, the simple pretarsal claws, and the absence of forewing 1scp-ra crossvein. In the other baissopterid genera, the vertex is nearly as long as or much shorter than the compound eye, the pretarsal claws are forked subdistally, and the forewing 1scp-ra crossvein is present.

Rhynchobaissoptera hui sp. nov. ( Figs. 13 View Fig and 15a, b)

Diagnosis: Same as for the genus (see above).

Description: Holotype CAU-BA-HZ-20001. Male. Body length 16.0 mm; head length 2.7 mm, width 0.6 mm, with clypeus + labrum 0.9 mm, vertex 1.4 mm long; compound eye length 1.0 mm, width 0.4 mm; antenna length 9.5 mm; occiput length 0.6 mm; pronotum length 3.3 mm, width 0.8 mm; meso- plus metathorax length 3.0 mm; forewing length 15.2 mm, width 3.2 mm (posteriorly damaged, probably wider if complete); hind wing length 13.4 mm, width 3.2 mm; abdomen length 6.0 mm.

Body blackish brown; head slenderly elongate, slightly thinner than prothorax, with vertex plus occiput about twice as long as compound eye; occiput short; clypeus elongate, slightly shorter than compound eye; compound eyes ovoid; ocelli present; antenna with at least 60 flagellomeres.

Prothorax slenderly elongate, slightly longer than head; meso- plus metathorax slightly shorter than prothorax. Legs slender, densely setose; tarsomere III symmetrically bilobed, with a pair of ovoid lobes; pretarsal claws slender and simple.

Forewing: Long elliptical, ~ 5.0× as long as wide; costal space narrow, with eight crossveins; ScP terminating into costal margin slightly distad wing midpoint; 1scp-ra absent; three simple RA veinlets present; pterostigma short, ~ 4.0× as long as wide, uniformly colored, closed by a crossvein proximally, distally ending at second veinlet of RA, with a straight but distinctly inclined RA veinlet incorporated; three radial crossveins present, three radial cells gradually shortened, r 1 longest; RP forked proximad its midpoint, with five simple branches; three rp-ma crossveins, forming three discal cells; MA with stem originating at MP 1, slightly distad initial

Fig. 15 Wing venations of Baissopteridae . a, b Rhynchobaissoptera hui sp. nov., holotype: CAU-BA-HZ-20001. a Left forewing. b Right hind wing. c–e Stenobaissoptera xiai gen. et sp. nov., holotype: CAU-BA-XF-20002. c Left forewing. d Left hind wing. e Right hind wing. Scale bar = 2.0 mm

branching point of MP; MA deeply forked at its proximal 1/3, with two simple branches; four ma-mp crossveins, forming four medial cells; incomplete MP with two terminal branches and five discoidal cells.

Hind wing: Slightly shorter than forewing; costal space narrow, with nine crossveins; ScP terminating into costal margin slightly distad midpoint of wing; three simple RA veinlets present; pterostigma shorter than that of forewing, and starting distad 2scp-ra crossvein; a short but slightly curved RA veinlet present within pterostigma; three radial crossveins present, r 1 longest; RP branched at its midpoint, with four simple branches; two rp-ma crossveins, forming two discal cells; MA with stem originating from base of MP stem, long and slightly sinuate; MA forked slightly proximad its midpoint, with two simple branches; four ma-mp crossveins, forming four medial cells; MP deeply forked, with six terminal branches and six discoidal cells arranged in two series; three mp-cua crossveins, with 1mp-cua distinctly inclined; A2 simple.

Terminalia visible in lateral view; tergum IX and sternum IX partly preserved; gonocoxites IX paired, shell-like, much wider than long, probably with some modifications on inner side (not clearly discernible); ectoproct slightly shorter than tergum IX, posteriorly exceeding apex of gonocoxites IX.

Type material: Holotype: CAU-BA-HZ-20001: Amber piece with a complete adult male of Rhynchoraphidia hui gen. et sp. nov.

Etymology: The specific epithet honors Mr. Zhengkun Hu, who kindly provided the specimen of the new species for our research. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:2BEF5735-A931-492F-8FDD-A552364C67C1 .

Genus Stenobaissoptera gen. nov. ( Figs. 14 View Fig and 15c–e; Fig. S3 View Fig )

Type species: Stenobaissoptera xiai sp. nov.

Diagnosis: Small-sized (male forewing length ~ 7.5 mm); head ovoid, with vertex nearly one-half length compound eye; compound eyes enlarged, greatly exophthalmic. Tarsomere III symmetrically bilobed, with a pair of slender lobes. Forewing long elliptical, ~ 4.0× as long as wide; ScP terminating into costal margin slightly distad wing midpoint; pterostigma ~ 6.0× as long as wide, closed by a crossvein proximally, with one RA veinlet incorporated; MA with stem originating at MP 1, slightly distad initial branching point of MP, and nearly vertical to RP + MA; three radial cells, two discal cells, and four discoidal cells present; two cua-cup crossveins present. Hind wing with four radial cells, two discal cells, and four discoidal cells; stem of MA fused with MP; three mp-cua crossveins, 1mp-cua short and straight, almost vertical to MP; CuA simple. Male gonocoxites IX shell-like, slightly longer than wide.

Etymology: From the Greek “ stenos ” (meaning, “slender”) and Baissoptera (the type genus of Baissopteridae ), in reference to the slender body shape of the new genus. Gender: Feminine. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:91A3F959-7660-4BFB-A8EA-C1FACE6AA9E1 .

Remarks: The new genus together with Allobaissoptera gen. nov. and Electrobaissoptera gen. nov. are among the small-sized baissopterids, with slightly reduced wing venations and tarsomere III with a pair of slender lobes. However, the new genus is distinguished from the other closely related genera by the greatly enlarged compound eyes in association with the distinctly shortened vertex, the forewing MA stem close to the initial branching point of MP, the presence of four doi in both fore- and hind wings, and the hind wing doi 1 without a crossvein connecting to stem of MA. In Allobaissoptera gen. nov. and Electrobaissoptera gen. nov., the vertex is nearly as long as compound eye, the forewing MA stem is far distad the initial branching point of MP, the fore- and hind wings both have two or three doi, and there is a crossvein connecting doi 1 and stem of hind wing MA.

Stenobaissoptera xiai sp. nov. ( Figs. 14 View Fig and 15c–e; Fig. S3 View Fig )

Diagnosis: Same as for the genus (see above).

Description: Holotype CAU-BA-XF-20002. Male. Body length 11.6 mm; head length 1.2 mm, with clypeus + labrum 0.4 mm long, vertex 0.2 mm long; compound eye length 0.5 mm; antenna length 4.0 mm; pronotum length 2.6 mm; meso- plus metathorax length 1.6 mm; forewing length 7.4 mm, width 1.9 mm; hind wing length 7.0 mm, width 1.8 mm; abdomen length 5.2 mm.

Body dark brown; head ovoid, with vertex slightly shorter than compound eye; occiput short; clypeus distinctly elongate; compound eyes ovoid, extremely enlarged; ocelli present; antenna with at least 60 flagellomeres.

Prothorax elongate, longer than head; meso- plus metathorax shorter than prothorax. Legs slender, densely setose; tarsomere III symmetrically bilobed, with a pair of slender lobes; pretarsal claws forked at proximal 1/3 into an acutely tapering tooth.

Forewing: Long elliptical, ~ 4.0× as long as wide; costal space narrow, with eight simple crossveins; ScP terminating into costal margin at midpoint of wing; at least two simple RA veinlets present; pterostigma ~ 6.0× as long as wide, uniformly colored, closed by a crossvein proximally, distally ending at a veinlet of RA, incorporated RA veinlet not visible; three radial crossveins, three radial cells gradually shortened, r 1 longest, r 2 broadest; RP forked at its midpoint, with three simple branches; two rp-ma crossveins, forming two discal cells; MA with stem originating at MP 1, slightly distad initial branching point of MP; MA deeply forked proximad its midpoint, with two simple branches; three ma-mp crossveins, forming three medial cells; MP deeply forked, with five terminal branches and four discoidal cells; CuA and CuP simple; three cua-cup crossveins present; A1 and A2 bifurcate.

Hind wing: Slightly shorter and narrower than forewing; costal space quite narrow, preserved part with three crossveins; ScP terminating into costal margin at wing midpoint; at least two simple RA veinlets present; pterostigma similar to that of forewing, except paler and longer; RA veinlet within pterostigma not visible; four radial crossveins present, r 1 longest, as long as r 3, r 2 shortest, r 3 broadest; RP similar to that of forewing; two rp-ma crossveins, forming two discal cells; MA with stem originating from base of MP, long and sinuate; MA similar to that of forewing; three ma-mp crossveins, forming three medial cells; MP deeply forked, with five terminal branches and four discoidal cells arranged in two series; three mp-cua crossveins, with 1mp-cua short and straight, almost vertical to MP stem; CuA and CuP simple.

Terminalia visible in lateral view: tergum VIII as long as sternum VIII; tergum IX as long as tergum VIII, greatly extended and narrowed ventrad; gonocoxites IX paired, shell-like, much longer than wide, obliquely directed dorsad; ectoproct slightly shorter than tergum IX, in lateral view slightly narrowed posteriad.

Paratype CAU-BA-WN-20002. Male. Body length 8.4 mm; head length 1.1 mm, width 0.3 mm, with clypeus + labrum 0.4 mm long, vertex 0.1 mm long; compound eye length 0.6 mm, width 0.3 mm; pronotum length 1.8 mm, width 0.3 mm; meso- plus metathorax length 1.6 mm; forewing length 5.9 mm, width 2.0 mm; abdomen length 3.7 mm. Pterostigma with a straight but distinctly inclined RA veinlet incorporated in both fore- and hind wings. Genitalia visible in abdominal view, with a pair of shell-like gonocoxites IX .

Type material: Holotype: CAU-BA-XF-20002: Amber piece with a complete adult male of Stenobaissoptera xiai gen. et sp. nov. Paratype: CAU-BA-WN-20002: Amber piece with an almost complete adult male of S. xiai gen. et sp. nov.

Etymology: The specific epithet honors Mr. Fangyuan Xia, who kindly provided the specimen (the holotype designated herein) of this new species for our research. The name is registered with ZooBank LSID: urn:lsid:zoobank.org:act:0028E777-5576-4AF7-87F2-52AB4F92593D .