Burmempheria densuschaetae Li, Wang & Yao, 2020

Hakim, Marina, Azar, Dany & Huang, Di-Ying, 2023, First record of fossil psocodeans in copula from mid-Cretaceous Burmese amber, Zootaxa 5396 (1), pp. 74-93 : 76-81

Burmempheria densuschaetae Li, Wang & Yao, 2020

(= Latempheria kachinensis Li, Wang & Yao, 2022 )

( Figs 1–4 )

Additional material. NIGP171865; one male (NIGP171865-a) and one female (NIGP171865-b) preserved in copula ( Fig. 1 ), syninclusions: one Collembola and some vegetal remains. The material is deposited at the Nanjing Institute of Geology and Palaeontology , Chinese Academy of Sciences, Nanjing, China .

Locality and horizon. Burmese Kachin amber (Burmite), from an amber mine located near Noije Bum Village, Tanai Township, Hukawng Valley, Myanmar; mid-Cretaceous.

Description. Head: relatively triangular in shape, with numerous spur-like setae covering vertex and frons; epicranial suture present, well pronounced at base of head capsule. Compound eyes globulous, half spheres in shape, flattened dorso-ventrally; ommatidia not setose. Three ocelli present, disposed in narrow inverted triangle at middle of vertex. Antennae ( Fig. 2A ) longer than body, scarcely setose; scape and pedicel elongate and 2–3× the width of flagellomeres, equal in length; 32 preserved flagellomeres, short and almost equal in length, with secondary annulations clear in basal segments and weak in distal segments. Postclypeus strongly bulged. Maxillary palpus four-segmented ( Fig. 2B ), with numerous long setae, second maxillary palpomere from base the longest, with short spur sensillum near base (not visible in female), two to three distinct long setae at apex of second and third palpomeres. Labial palpomeres not visible. Lacinia present, bicuspid, outer cusp with three visible apical denticles ( Fig. 2C ).

Thorax: Prothorax collar-like; mesothorax and metathorax well developed and triangular, mesothorax setose. Legs: femora setose; tibiae with two rows of spurs, very short and small in fore tibiae, but bigger and more pronounced in middle and hind tibiae, fore tibiae with two (sometimes one visible) longer apical spines, middle and hind tibiae with three longer apical spines; tarsi three-segmented, basal tarsomere the longest and bearing spurs, fore and middle tarsomeres about equal in length; claws sharply curved, with one strong preapical tooth, without pulvillus. Forewing ( Fig. 2G ; measurements are taken from male forewing) membranous, translucent; wing margin without setae; membrane setose in anal region; all veins except CuP setose with clear insertion marks, sometimes with two rows mostly with one row; stems R and M+CuA separating near wing base; Sc setose, well developed, strongly curving backwards and fusing with R 1; veinlet present between Sc and anterior wing margin, reaching margin; Sc’ directed forward, weakly curved; R 1 connected to Rs by short crossvein; Pt elongated and narrow, four-angled, transparent, not thickened; Rs and M fused for a length, 0.15 mm long; Rs forked into R 2+3 and R 4+5 at 1.13 mm from wing base, longer than stem Rs after separation from M; basi-radial cell elongated, five-angled; radial cell seven-angled, equal in length to basi-radial cell; M+CuA branching into stems M and CuA at 0.50 mm; M with three branches; M 3 emerging first at 0.93 mm, M 1 and M 2 splitting at 1.33 mm, fork M 1 +M 2 slightly longer than common stem M 1+2; fork of CuA at 0.69 mm; CuA 1 and CuA 2 long, sinusoidal, with length of CuA 2 about 2/3 length of CuA 1, forming elongated AP; AP free; CuP as thick as other veins, almost straight; A very faint; CuP and A meeting near wing margin and joining for a short length. Hind wing ( Fig. 2H ) membranous, translucent, without setae on membrane, wing margin or veins; Sc very short and faint; basi-radial cell present, four-angled; R 1 and Rs separating before fusion of Rs with M; Rs, M and A forked; CuA simple; CuP thin, simple.

Abdomen: dorsal side not clearly visible, covered by wings; individuals in copulation resulting in genitalia relatively hard to observe; female ovipositor with well-developed external valvulae, elongated and broad, membrane weakly undulated with very thin long setae, outer edges with some sclerotisation (?).

Measurements. Male. Head width 0.59 mm (compound eyes included), 0.40 mm (compound eyes excluded); compound eyes width 0.09 mm. Thorax length 0.53 mm; prothorax length 0.07 mm, mesothorax length 0.22 mm, width 0.40 mm; Fw length 1.81 mm, width 0.81 mm; Hw width 0.48 mm. Tarsi length: Ft1 0.15 mm, Ft2 0.05 mm, Ft3 0.06 mm; Mt1 0.16 mm, Mt2 0.05 mm, Mt3 0.06 mm; Ht1 0.29 mm, Ht2 0.06 mm, Ht3 0.05 mm.

Female. Head length 0.33 mm, width 0.51 mm (compound eyes included), 0.33 mm (compound eyes excluded); compound eyes length 0.16 mm, width 0.08 mm. Thorax length 0.46 mm; prothorax length 0.04 mm, mesothorax length 0.25 mm, width 0.32 mm; Fw length 1.50 mm, width 0.66 mm. Tarsi length: Ht1 0.27 mm, Ht2 0.05 mm, Ht3 0.04 mm.

Additional description. Two individuals are encapsulated within the amber piece, preserved in copula. The female appears distinctly smaller in size than the male. The individuals are positioned along the same axis, their bodies forming a 180º angle. They are facing opposite directions, with their heads oriented away from each other and their abdomens in direct contact at the terminalia. The female’s external valvulae, which compose the ovipositor, are clearly visible on top of the male aedeagus from dorsal view ( Fig. 3B , red arrow)—visible through transparency from ventral view ( Fig. 3D , red arrow). The aedeagus is protruding from the male’s body and inserted into the female. At the base, the ejaculatory duct is surrounded by rounded lumps, possibly seminal vesicles. One structure ( Fig. 3D , blue arrow) is noticeably different in texture compared to the others with a very bumpy and granulated surface, possibly one of the testes; a nearby similar structure is visible as a cross-section and might be the matching pair ( Fig. 3D , green arrow). In ventral view of the male abdomen, an elongated membranous structure, strongly resembling the typical psocodean male hypandrium, is partially visible in the distal section of the abdomen, just before the externalised internal structures—it could not be captured in the photographs but it is clearly observed with an optical microscope).

Remarks. It is noteworthy that the forewing fork M 1 +M 2 is distinctly shorter than the common stem M 1+ 2 in specimen CNU-PSO-MA2015001 (holotype of Latempheria kachinensis ); whereas, the forewing fork M 1 +M 2 is slightly longer, almost equal to the common stem M 1+2, with a slightly less convex shape in specimen CNU-PSO-MA2019001 (holotype of Burmempheria densuschaetae ). However, in Latempheria kachinensis , these wing venation features are only observed clearly in one forewing—the second wing being twisted apically ( Li et al., 2022: fig. 2A–C), thus we cannot confidently confirm this trait as a consistent and reliable diagnostic character instead of an intraspecific morphological variation or simply a teratism in the individual. Consequently, we tentatively synonymise the two taxa until further discoveries indicating the legitimacy of two distinct species. We also note the likely presence of a conical sensillum basally on the second maxillary palpomere, and the occasional three apical spines on the tibiae (clearly visible on one middle leg) in both specimens.

In specimen NIGP171865-a, an obvious teratism in wing venation is observed in one hind wing in which R 1 is free and does not reach wing margin. It is then followed by another vein reemerging from Rs before the fork R 2+3 +R 4+5, and reaching wing margin.

We note the following differences between the individuals of NIGP171865 and the holotype material CNU-PSO-MA2019001: the forewing fork M 1 +M 2 is usually slightly longer than common stem M 1+2; middle and hind tibiae with three clear apical spines (uncertain in CNU-PSO-MA2019001, but always at least two, and sometimes three). Since the reliability of the two characters remains vague, we tentatively assign the new individuals to Burmempheria densuschaetae , and refrain from establishing a new species unless further discoveries can support it.

The specimen NIGP171865-b has the external valvulae with slightly undulated edges and very fine long setae. Both specimens CNU-PSO-MA2019001 and CNU-PSO-MA2015001 were identified as female with well-developed V 3, fused together basally and without setae. Upon investigation, another interpretation is possible as the two specimens could actually be males (refer to discussion section below).

Figures

FIGURE 1. Burmempheria densuschaetae, NIGP171865, male (right side) and female (left side) in copula. A, Habitus in dorsal view. B, Habitus in ventral view. Scale bars = 0.5 mm.

FIGURE 2. Burmempheria densuschaetae, under green fluorescence. A, Antenna. B, Maxillary palpomere (red arrow: spur sensillum). C, Lacinia. D, Hind tibial spurs. E, Tibial apical spines. F, Claws. G, Forewing. H, Hind wing. Scale bars = 0.2 mm for A, G, H, 0.1 mm for B, 0.05 mm for D, 0.02 mm for C, E, F.

FIGURE 3. Burmempheria densuschaetae. A, Details of genitalia in copula, in ventral view. B, Female external valves (pointed by red arrow), in dorsal view. C, D, Confocal imagery showing details of genitalia in copula, in ventral view (red arrow: external valves; blue and green arrows: testes?). Scale bars = 0.5 mm for A, 0.2 mm for C, D, 0.1 mm for B.

FIGURE 4. Burmempheria densuschaetae, hand drawings of female individual. A, Forewing. B, Hind wing. Scale bars= 0.2 mm.