Naginipteryx pinna Schall, Heads & Husemann, 2025, sp. nov.

Naginipteryx pinna sp. nov. Figs 3, 4, 5 Etymology. Named after the latin word “ pinna ” (fin) because of the ventral appendages on the abdomen, reminding of the dorsal fin of some fish, for example male sea goldies or the threadfin butterflyfish. Locality and horizon. The specimen was included in amber found in Hkamti, Sagaing Division, Myanmar or Tanai, Kachin State Burma, Myanmar, two nearby amber mining locations. The amber from Hkamti is ca. 110 My and the amber from Tanai ca. 99 My old. Holotype. Female. Specimen part of the LIB-Hamburg collection; collection number GPIH 07232 (ex coll. Martin Husemann, coll. no. MH 0011). Diagnosis of species. As for genus (monotypic). Description. The specimen is well preserved, but most of the head and thorax are somewhat contorted due to internal damage of the amber structure. Measurements: Body-length 2.52 mm (head to abdominal apex). Pronotum length 0.62 mm, height 0.38 mm. Prothoracic leg: femur ca. 0.35 mm long. Tibia ca. 0.27 mm long. Tarsus ca. 0.25 mm long (including claws). Forewing ca. 0.79 mm long. Hindwing ca. 1.53 mm long. Mesothoracic leg: tibia 0.39 mm long, 0.25 mm wide (max width). Tarsus 0.35 mm long. Metathoracic leg: femur 1.36 mm long. Tibia 1.41 mm long, 0.09 mm wide. Tarsus 0.32 mm long. Subapical spurs ca. 0.05 mm long. Apical spurs 0.08 mm long. Cercus 0.19 mm long. Paraproctal lobes 0.3 mm long (not including hairs). Ovipositor (longest valve) 0.17 mm long. Head: Morphology uncertain due to internal damage in the amber. Thorax: Pronotum without elevation. Very deep laterally, covering the entire height of the thorax. Fore- and hindwings present. Venation undiscernible (lines seen on the wings are fissures in the amber, not actual veins). Hindwings just as long as abdomen. Legs: Prothoracic leg: Coxa big, about 2.5 × the width of femur with sparse hair. Trochanter halfway in width between coxa and femur. Femur with numerous hairs. Tibia with numerous hairs, too. Apically with four dactyls, the longest of which is 0.05 mm long. Tarsus damaged. Slender without hair and ending in two claws. Mesothoracic leg: only tibia and tarsus can be seen. Tibia with very distinct shape, looking like it is made up of two triangles, where the distal half is inserted into the bigger (both wider and thicker) proximal half. Greatly inflated. Apically with some hairs. Tarsus two-segmented, slender, no hair and with two claws. Metathoracic leg: femur apically with sparse hair. Tapering toward apex, only somewhat inflated. Tibial fin with serration. A pair of subapical and apical spurs. Apical spurs with four conspicuous hairs on ventral margin. Tarsus blunt with two rows ventrally, one metatibial fin serrated, the other with hair. Abdomen: Proximal to abdominal apex are three fin-like appendages of which the anterior two have singe hair inserted. Posterior fin probably lost the hair during preservation. More fins may be present but are covered by the metafemur. Cercus one-segmented, cylindrical in shape and setulose. Paraproctal lobes two-segmented, longer than cercus. Distal segment swollen, clavate in shape with distinct long hairs, especially on the apex of distal segment. Ovipositor visible, with narrower pointed end. Remarks. Based on the structure of the external genitalia (cercus one-segmented; paraproctal lobes longer than cercus, modified in shape and with distinct apical hair; ovipositor visible), the new species should be assigned to Ripipterygidae. However, this family is usually recognized by an uninflated mesotibia, too (Heads 2010). Some species from Burmese amber that were previously assigned to Ripipterygidae were noted to have an untypical mesotibia, for example Zhao, Xu, Cao, Jarzembowski, Fang and Xiao (2024) remarked in their description of Kallosripipteryx zhangi “ mesotibia slightly fusiform, not slender as typical of ripipterygids ”. In Naginipteryx pinna, this character is extremely pronounced, with an inflation of the mesotibia surpassing what is common for Tridactylidae (who are characterized by an inflation of the mesotibia) (compare for example Latedactylus longapedi Zheng, Cao & Gu, 2023 or Burmadactylus tenuicerci Fan, Gu & Cao, 2023). As suggested for Abaddonella nwarrngaal gen. et sp. nov. (see above), this strange combination of characters may indicate the presence of an ancestral lineage (or perhaps several ancestral lineages?) of Tridactyloidea in the Burmese amber forest that had not yet completed the evolutionary separation between Tridactylidae and Ripipterygidae.