Mastotermes myanmarensis, Jouault & Engel & Fls & Legendre & Huang & Grandcolas & Nel, 2022

Jouault, Corentin, Engel, Michael S., Fls, Legendre, Frédéric, Huang, Diying, Grandcolas, Philippe & Nel, André, 2022, Incrementing and clarifying the diversity and early evolution of termites (Blattodea: Isoptera), Zoological Journal of the Linnean Society 196, pp. 608-629 : 620-621

MASTOTERMES MYANMARENSIS JOUAULT SP. NOV.

( FIGS 9 , 10 )

Z o o b a n k r e g i s t r a t i o n: h t t p: / / z o o b a n k. o r g / urn:lsid:zoobank.org:act:F5CF600D-2068-424E-B255-9F92051F952B

Material: Holotype, IGR.BU-054, preserved in an elongate, pale and ovoid piece of amber measuring 50 × 20 × 9 mm, housed in the amber collection of the Geological Department and Museum (IGR), Rennes, France.

Locality and horizon: Hkamti site, Hkamti District, Sagaing Region, Myanmar; Early Albian (c. 110 Mya), Early Cretaceous.

Etymology: The specific epithet refers to the country of origin of the amber piece, Myanmar, combining the country name with the Latin toponymic adjectival suffix, – ēnsis, meaning ‘from’.

Diagnosis: Imago. Wings membranous, long and broad, densely reticulate, with ‘cross-veins’ present; veins Sc, RA, RP and M more heavily sclerotized than CuA, reticulate veins obviously pigmented among radial and medial fields; forewing Sc with two main branches; R with two branches; width of radial field moderate, RA simple, RP with five main branches; medial field encompassing wing apex, M main vein closely parallel to RP main vein, with three main branches, first branch of M arising near apical-third of wing; CuA with five main branches, apical-most branch of CuA terminating into posterior margin and in apical-third of forewing length. Hindwing with large anal lobe; costal space wide; Sc simple, terminating on costal margin at basal-third of hindwing length; RA long, simple and terminating on costal margin before apical-third of hindwing length; RP with two main branches; medial field encompassing wing apex; M separating from RP near wing base, relatively closely parallel to RP, with three main branches, secondary branches present; CuA uniformly branching, terminating just posterior to wing apex.

Description: Imago. Wings membranous, reticulate veins present; forewing scale part missing, forewing preserved part at least 10.70 mm long and 4.62 mm wide, apex rounded, middle section of posterior slightly convex basally then convex; veins Sc, RA, RP and M more heavily sclerotized than CuA and A; forewing Sc short, bifurcate at suture, posterior branch with a faint subbranch at margin; RA with one branch; radial field width moderate, occupying about one-sixth area on average; RP with five branches, proximal branch fading apically before anterior wing margin; M closely parallel to RP, with three main branches; CuA with numerous posterior branches, apical-most branch of CuA terminating on posterior margin well proximal to apex, more proximal branches loosely pectinate, apicalmost of these branches terminating on margin near wing midlength.

Hindwing with large anal lobe, scale not preserved, 14.10 mm long and 6.0 mm wide with anal lobe and 5.16 mm wide without anal lobe; Sc longer than that of forewing; RA long, simple and terminating on costal margin before apical-third of hindwing length; RP with three branches, first branch originating just before point of contact between Sc and wing margin; M with four branches, separating from RP away from wing base, then closely parallel to RP, apical branch of M with a secondary branch; CuA with numerous posterior branches, some dichotomous, terminating posterior to wing apex.

Colour: Not preserved.

Remarks: Compared with the known ‘Mid’-Cretaceous fossil and the extant mastotermitids, M. myanmarensis stands out in having broadly rounded wings, wider intervals between the longitudinal veins (shared with M. monostichus Zhao et al., 2019 ), and a broad space above Sc on the hindwing. Additionally, the space occupied by Sc + RA + RP is extremely wide near the basal suture. Mastotermes myanmarensis has a hindwing with vein A1 without branches, while the extant M. darwiniensis has a vein A1 with numerous posterior branches (similar to M. monostichus ), and the anal veins in the anal lobe are all simple (vs. with some dichotomies in M. darwiniensis and M. monostichus ). Mastotermes myanmarensis can be differentiated from M. monostichus by the forewing with RA simple, M with only a reduced number of branches and the first dichotomy far from the wing base, CuA with more dichotomous branches; hindwing with a broad space above Sc, and the anal field with more branches. Mastotermes myanmarensis also differs from the extant M. darwiniensis by its temporal range (‘Mid’-Cretaceous vs. extant).

Figures

Figure 9. Mastotermes myanmarensis sp. nov., holotype IGR.BU-054. A, forewing; B, hindwing. Scale bars: 2 mm.

Figure 10. Mastotermes myanmarensis sp. nov., holotype IGR.BU-054. Line drawings with veins labelled (cross-veins omitted): A, forewing; B, hindwing. A1, first anal vein; CuA, anterior cubitus; M, media; PCu, postcubitus; RA, anterior radius; RP, posterior radius; Sc, subcosta. Scale bars: 2 mm.