Burmeumastax lexiae Husemann, Schall, Uchida & Kotthoff, 2025, sp. nov.
Creators: name: Husemann, Martin
name: Schall, Ole-Kristian Odin
name: Uchida, Kei
name: Kotthoff, Ulrich
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Orthoptera
Eumastacidae
Burmeumastax
Burmeumastax lexiae

description: Burmeumastax lexiae sp. nov.
Figs 3, 4
Holotype. —
Male; possibly nymph. Deposited in the amber collection of the LIB (GPIH 07011), Leibniz Institute for the Analysis of Biodiversity Change, Hamburg, Germany.
Etymology. —
The species is named after Lexi Husemann, the daughter of the first author of the study.
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 old, and the amber from Tanai is ca. 99 My old.
Diagnosis. —
Same as for genus, since this is the only species.
Description. —
Body long and slender, about seven times as long as high. Body length (tip of head to tip of abdomen) 7.53 mm; 1.03 mm high (measured right in front of metathoracic leg).
Head. — Twice as high as wide and twice as high as body height. Top of head capsule to bottom tip of mouth parts, 2.05 mm; 1.03 mm width at widest point (eye level). Fastigium not elongated. Eyes large, ellipsoid, and laterally protruding from head. Eyes take up almost half the head height and are about twice as high as wide. Eye top to bottom 0.87 mm long, 0.45 mm wide. Distance from bottom of the eye to bottom of the head, 1.2 mm. Interocular distance (measured at top of head), 0.32 mm. Antennae missing except antennal bud, which is 0.32 mm long and reminiscent of a pinecone with scales closed. Antennal bud located right in front of the bottom of the eyes. Lower face slightly oblique in profile with mouthparts forming a cone or almost triangular shape. Right maxillary palpus 7 - segmented, 0.87 mm long in total.
Thorax. — Thoracic height 1.06 mm, of which 0.58 mm is covered by the pronotum. Pronotum 1.31 mm long dorso-laterally, slightly shorter at 1.12 mm ventro-laterally. Pronotum saddle-like, covering the thorax with distinct elevation. Pronotum marked by two distinct grooves on its dorsal surface, one smooth anteriorly, second sharp posteriorly.
Wings. — Brachypterous. Short wing buds can be seen sticking out from under the posterior margin of the pronotum. Wing buds ca. 0.42 mm long.
Legs. — Prothoracic leg: only preserved up to femur. Long and slender. Preserved part 1.64 mm long. Mesothoracic leg: only preserved up to femur. Long and slender. Preserved part 2.36 mm long. Metathoracic leg: femur very long, length / width ratio 4.2 mm / 0.77 mm = 5.5; thinning distally. Tibia thinning further along its length of more than 4 mm (metatibia not fully preserved) until it shares a width similar to pro- and mesofemur. Dorsal margin of metafemur on proximal half with spaced short fine hairs, which are replaced by small spines on distal half. Spines continuing along the dorsal margin of metatibia and getting larger distally (0.03 mm – 0.12 mm). Dislocated object in bottom left area probably left metatibia: 4.04 mm long (including three spines at distal end; these spines may be the apical spines of the metatibia).
Abdomen. — Abdomen with a distinct hump at the position of metathoracic legs. Last abdominal tergite made up of five to seven individual plates that cover the dorsal part of the genitalia like a ring. Dorsal (= middle) plate setulose. Supra-anal plate elongate, triangular. Sub-genital plate bulbous with central fold apically and lateral cercus-like lobes. Real cercus slender, ca. 0.47 mm long. Sub-genital plate and cercus setulose.
Remarks. —
Based on the short wing buds and the small body size, Burmeumastax lexiae may be a nymph. This is further supported by the abdomen not being curved upwards, as is the case in several male Eumastacoidea, for example Paralethus insolitus Rowell and Perez-Gelabert, 2006 or Episactus tristani Rehn & Rehn, 1934. However, in other species, such as Teicophrys robertsi (Rehn & Rehn, 1939), the male abdomen is straight.
description: Published as part of Husemann, Martin, Schall, Ole-Kristian Odin, Uchida, Kei & Kotthoff, Ulrich, 2025, The first Cretaceous Eumastacoidea (Orthoptera, Caelifera) from Burmese amber, pp. 151-157 in Journal of Orthoptera Research 34 (1) on pages 151-157, DOI: 10.3897/jor.34.134361