1. Introduction

In the mid-Cretaceous Burmese Amber, 47 extinct caddisfly (Trichoptera) species have been described to date, distributed among 17 genera and 11 families (Ross 2022). Of the 17 genera, five are extant genera that are still present 100 mill years later. 12 genera, however, are extinct, so far only found in Burmese amber, and contributing to the trichopteran biota in the mid-Cretaceous. Among the 11 families recorded, only three of them, Burmapsychidae, Cretapsychidae and Palleptoceridae, are recorded exclusively from Burmese amber.

The family Burmapsychidae belongs to the integripalpian superfamily Sericostomatoidea and can be distinguished from all extant and extinct families of the Trichoptera by the following combination of characters: adults without ocelli; antennae at least as long as forewings, often with modified flagellomeres; scape longer than the head, usually surrounded by brushes of long setae; maxillary palps 3-segmented based on strong apical stipes and a basal cardo; labial palps 3-segmented; terminal palpomeres of maxillary and labial palps not annulated and not flexible; forewing venation with apical forks II, III, and V, but apical forks I and IV absent, discoidal cell absent, and Cu2 ending on Cu1b or connected to Cu1b by a crossvein; hind wing venation with apical forks I, III, and V, discoidal cell absent, thyridial cell closed and long or absent; tibial spur formula 2/2/4. Two species are described: Burmapsyche comosa Wichard, Neumann, Müller, & Wang, 2018, and B. palpifurcata Wichard, Neumann, Müller, & Wang, 2018. A third species Burmapsyche wolframmeyi sp. nov., is described in this paper.

2. Material and methods

The amber material was collected by local people in the Hukawng valley of northern Myanmar (Myitkyina District of Kachin State) and dates from the middle Cretaceous (Cenomanian) period about 98.8 ± 0.6 Ma ago (Shi et al. 2012). The Burmese amber with the embedded Trichoptera inclusion was cut, face-grinded, and polished. Colour pictures and drawings were produced for the documentation of the specimen. The macroscope Leica M420 with Apozoom 1:6 was used in combination with a Canon EOS 80D, EOS 3.0 utility software, and the Zerene Stacker software. Measurements were made with the ocular micrometer of the Leica SApo microscope.

Abbreviations: The wing venation terminology: I = apical fork I, II = apical fork II, III = apical fork III, IV = apical fork IV, V = apical fork V, r-m = crossvein r-m, Sc = subcostal, R = radius, M = media, Cu1 = cubitus anterior, Cu2 = cubitus posterior, A = anal vein, TC = thyridial cell.

The head and male genitalia: scaly ap = scaly appendage, lab = labial palp, max = maxillary palp, cox = coxopodite, har = harpago, inf ap = inferior appendage, X ap = mesodorsal lobe of tergum X.

Fig. 1.

Burmapsyche wolframmeyi sp. nov. embedded in mid-Cretaceous Burmese amber, holotype, deposited in Systematic Entomology Collection of Hokkaido University Museum, Japan, SEHU: 54024.

3. Systematic palaeontology

Fig. 2.

Fore- and hind wing venations of Burmapsyche wolframmeyi sp. nov.; A – forewing: forks II, III, V; B – hind wing: forks I, III, V, and TC – thyridial cell.

Fig. 3.

Burmapsyche wolframmeyi sp. nov. A – Scapus, pedicellus, and basal parts of the left antenna. B – Three-segmented maxillary palps with stipes and cardo. C – Head region in left dorsolateral view. D – Drawing of male genital inferior appendages, ventral; cox = coxopodite (paired), har = harpago (paired), inf ap = inferior appendages (paired), x ap = apical processes of segment X. E – male genitalia with inferior appendages, ventral.

4. Discussion

The superfamily Sericostomatoidea is represented in the mid-Cretaceous Burmese amber with the three families Burmapsychidae, Cretapsychidae, and Helicopsychidae (Wichard 2021). Burmapsychidae and Cretapsychidae occur exclusively in Burmese amber, and comprises two and the six species in the genera Burmapsyche and Cretapsyche, respectively. These two families show a high agreement in the wing venations as forks II, III and V present and discoidal cell absent in forewings, and forks I, III, V present, fork II and the discoidal cell absent, and thyridial cell present in hind wings.

Otherwise, these two taxa can be differentiated by the forewings with thyridial cell absent (Burmapsyche) or closed and long (Cretapsyche), and Cu2 ending on Cu1b (Burmapsyche) or on crossvein from Cu1b to wing margin at arculus. The similarities in wing venation of these two taxa also reminder of the venation of the family Dysoneuridae from the Jurassic period and initially led to the misunderstanding of the affiliation of Burmapsyche and Cretapsyche by Wichard (2021).

Burmapsyche and Cretapsyche also differ clearly in the scapus and in the maxillary palps. In Burmapsyche the strong scapus is longer than the head, and in Cretapsyche scapus about as long as head. Burmapsyche has 3-segmented maxillary palps with terminal palpomere surrounded by brushes of long setae, whereas Cretapsyche maxillary palps are 5-segmented with second palpomere longest and the following three palpomeres becoming successively smaller (Wichard & Espeland 2022).

The family Helicopsychidae is represented in Burmese amber by the bizarre species Cretahelicopsyche liuyani, which bears unusual hair-fans lengthwise and bilaterally on the fore tibiae. This species furthermore bears also typical characteristics of the family Burmapsychidae with questionable forewing venation. Cretahelicopsyche liuyani was placed in the Helicopsychidae because the wing venation – so far as visible – was interpreted to be similar to that of the genus Rakiura (Wichard et al. 2018a), at a time when the family Burmapsychidae and its characteristics were not yet recognized. We hope to find another well-preserved specimen in amber that will clarify the family affiliation.