Longitermes, JOUAULT, ENGEL,, 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 : 610-612

LONGITERMES PULCHER JOUAULT, ENGEL, LEGENDRE, & NEL SP. NOV.

( FIGS 1 , 2 )

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. org/ urn:lsid:zoobank.org:act:6327861A-3757-4810-BEED-9800D20146C2

Material: Holotype, IGR.BU-052, preserved in an ovoid piece of amber measuring 18 × 12 × 2 mm, housed in the amber collection of the Geological Department and Museum (IGR), Rennes, France.

Locality and horizon: Noije Bum Hill, Hukawng Valley, Kachin State, Myanmar; Upper Albian to Lower Cenomanian, ‘Mid’-Cretaceous.

Etymology: The specific epithet is from the Latin adjective pulcher , beautiful.

Diagnosis: As for the genus (vide supra).

Description: Imago specimen. Body c. 7.34 mm long (as preserved and measured from tip of labrum to abdominal apex). Head elongate, c. 1.44 mm long (measured from posterior margin to tip of labrum) and c. 0.82 mm wide excluding compound eyes (measured beyond eyes), trapezoidal in dorsal view, prognathous, sides slightly convex, postclypeus c. 0.11 mm long, anteclypeus c. 0.11 mm long, labrum lobe-shape, sides nearly parallel, slightly narrower basally, apical margin nearly straight, with few setae; mandibles triangular shaped, c. 0.20 mm high, covered by labrum; left mandible apical tooth elongate, sharp; three marginal teeth, LM 1 small, LM 1 -LM 2 interdental space small, v-shaped, LM 2 elongate, forming broad cutting edge, LM 2 -LM 3 separated by a notch, LM 3 bend toward base of mandible (general aspect similar to left imago mandible of Hodotermopsis ); right mandible with long, sharp apical tooth, and at least one marginal tooth of similar shape and length; buccal pieces: glossa with two visible segments, paraglossa with three segments, length from base to apex (in mm) 0.05, 0.06, 0.1; lacinial incisor with two teeth; five maxillary palpomeres visible, length from base to apex (in mm): 0.06, 0.05, 0.08, 0.09, 0.12; three labial palpomeres present, total length as preserved c. 0.21 mm; compound eyes, c. 0.37 mm long, ovoid, situated laterally near head midlength, and separated from posterior head margin by more than their length; ocelli absent; fontanelle absent; antennae moniliform with 14 antennomeres. Pronotum c. 0.54 mm long and c. 1.0 mm wide, nearly flat with anterior margin concave, anterior corners arched, sides broadly convex and posterior margin convex with a medial indentation, posterior corners broadly arched.

Legs robust; profemur medially swollen, c. 0.63 mm long, protibia c. 0.37 mm long, protarsus c. 0.22 mm long; protibia with three spurs f1, f2, f3; mesofemur medially swollen c. 0.63 mm long, mesotibia c. 0.42 mm long, mesotarsus c. 0.22 mm long; mesotibia with four observable spurs m1, m2, m3, m4; metafemur c. 0.51 mm long, metatibia c. 0.52 mm long, with two observable spurs h1, h2, mesotarsus c. 0.25 mm long; all tarsi pentamerous, with arolium. Forewing scale c. 0.80 mm long and 0.54 mm wide (measured distally), RP with additional tertiary branches joining costal margin; median (M) weak, closer to cubitus (Cu) than to radial sector (RP), with five branches terminating at lower margin; CuA with six primary and secondary branches extending to lower margin; anal vein absent. Hindwing (folded or damage): humeral suture weak, barely visible; wing venation apparently similar to forewing except anal vein present.

Abdomen at least 4.0 mm long (damaged during the fossilization process) with at least ten observable segments; abdominal segments apparently slightly wider near midlength. Cerci multi-merous c. 0.16 mm long, five(?) cercomeres (sometimes fused so not clearly countable).

Colour: Not preserved.

Remarks: Longitermes pulcher is unique among Cretaceous termites, with an unprecedented combination of diagnostic characters making it close to the family Archotermopsidae , as treated in Jiang et al. (2021), i.e. encompassing Archotermopsis , Hodotermopsis and Zootermopsis . Here we follow the new system of Wang et al. (2022: table 1), which recently resolved paraphyly of Archotermopsidae by elevating Hodotermopsinae to family rank. In fact, L. pulcher shares with Archotermopsidae and Hodotermopsidae the lack of a fontanelle; a Y-shaped ecdysial line present; large compound eyes; ocelli absent; pronotum faintly arched, slightly wider than head; left mandible with an apical tooth and three marginal teeth. Legs: five tarsomeres (some cryptic); tibial spur formula 3-4-2; arolium present. Cerci with five(?) cercomeres. Forewing: costal margin flat to faintly arched; humeral suture well defined, almost straight; Sc, RA, RP sclerotized, RP with the main branch bending to apex of wing, five to six secondary branches and additional tertiary branches joining costal margin; M weak, with secondary branches terminating at lower margin; Cu with primary and secondary branches extending to lower margin; anal vein absent. The wing venation with the radial field encompassing most of the wing apex and the shape of the left mandibular teeth, nearly similar to that of Hodotermopsis , strengthen the taxonomic placement. However, the phylogenetic position of the new genus is hard to ascertain and it may be a stem representative of Hodotermopsidae or of Archotermopsidae (sensu Wang et al., 2022) . Since the new specimen differs from the genera Archotermopsis and Zootermopsis ( Archotermopsidae sensu Wang et al., 2022 ), at least based on its mandibular shape with LM 2 elongate and forming a broad cutting edge (vs. sharp and not forming a cutting edge in the aforementioned genera) ( Krishna et al., 2013), and resembles more the genus Hodotermopsis in its wing venation and mandibular configuration, we presume that Longitermes is probably a stem-Hodotermopsidae (sensu Wang et al., 2022). Hodotermopsis differs from the new specimen in possessing small eyes, while they are large in Longitermes , but also in having numerous antennomeres (at least 23), while the new specimen only possesses 14 (the antenna might not be complete but the number of antennomeres seems to be lower than in Hodotermopsis ) ( Krishna et al., 2013). Recently, several families were erected based on Cretaceous specimens from Kachin amber (e.g. Melqartitermitidae and Mylacrotermitidae) but our specimen cannot be placed in any of them ( Jiang et al., 2021). Its broad radial field precludes affinities with the Melqartitermitidae and the presence of a welldefined forewing basal suture demarcating the scale precludes affinities with Mylacrotermitidae ( Jiang et al., 2021). Similarly, the new specimen differs from representatives of the family Krishnatermitidae , at least, because of its forewing with PCu straight (vs. arched in Krishnatermes ), RP encompassing the wing apex (variable in Krishnatermes ) and its hindwing with a defined scale (vs. absent in Krishnatermes ). However, the habitus of Longitermes and Krishnatermes are at first sight similar, which, if not symplesiomorphic, may indicate a proximity between the two genera and a hypothetical proximity of Krishnatermes with the Teletisoptera.

Figures

Figure 1. Longitermes pulcher gen. et sp. nov., holotype IGR.BU-052. Photograph of habitus. Scale bar: 1 mm.

Figure 2. Longitermes pulcher gen. et sp. nov., holotype IGR.BU-052. Detailed photographs.A, head; B, mandibles; C, apical part of left foreleg; D, mesotibia; E, metatibia; F, metatibia; G, forewing. la, left apical tooth; lc, lacinia; lci, lacinial incisor; LM1-LM3, left marginal teeth (number corresponding); Lp, labial palp; Mp, maxillary palp; pgl, paraglossa; CuA, anterior cubitus; M, media; PCu, postcubitus; RA, anterior radius; RP, posterior radius; Sc, subcosta. Scale bars: 0.5 mm (A, B, C, D, G); 0.25 mm (E, F).