Hukawngichthyurus maha, Hsiao & Li & Ren & Pang, 2021

Hsiao, Yun, Li, Yun, Ren, Dong & Pang, Hong, 2021, Morphological phylogenetics provide new insights into the classification and evolution of fossil soldier beetles from Mid-Cretaceous Burmese amber (Coleoptera: Cantharidae), Zoological Journal of the Linnean Society 193, pp. 1271-1293 : 1284-1285

† HUKAWNGICHTHYURUS MAHA SP. NOV.

( FIGS 7–8 )

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 3F289BBE-89FF-414D-965C-691C8E06EC 3F.

Type material: Holotype: Male ; no. YL-COL00001; earliest Cenomanian , Hukawng Valley , northern Myanmar; deposited in the Museum of Biology , School of Life Sciences , Sun Yat-sen University, Guangzhou, China.

Diagnosis: It can be distinguished from its congener by the head with distinct setae ( Fig. 8A, B ) (without setae in H. kyawkhaingwini ); thick scape and enlarged antennomere 3–6 ( Fig. 8C ) (scape thin and elongate and antennomere 3–5 stout, only slightly enlarged in H. kyawkhaingwini ); apical tergite moderately developed, with obtuse apex ( Fig. 8E ) (strongly developed,with acute apex in H.kyawkhaingwini );tibial spurs present ( Fig. 8G ) (absent in H. kyawkhaingwini ).

Description: Male. Body 3.0 mm long, 1.0 mm wide, parallel-sided, densely and finely pubescent, with pubescence distinct in head. Body yellowish brown, with dark brown elytra ( Fig. 7 ). Head ( Fig. 8A, B ) 0.5 mm long, 0.5 mm wide. Vertex finely wrinkled and with setae, slightly convex, slightly narrowed behind the eyes. Eyes large, hemispherically prominent, with fine facets, interocular distance 2.2 times maximum eye diameter. Anterior margin of clypeus somewhat concave, frontoclypeal suture absent. Labrum subquadrate, membranous, exposed. Gular sutures close, nearly confluent. Mandibles elongate, strongly curved at apical fourth, with a tooth on inflexed outer margin. Apical segment of maxillary palpi flattened, elongate, securiform, with apex straight-truncated; apical labial palpomere triangular. Antennae ( Fig. 8C ) filiform, with central antennomeres enlarged, 11-segmented, extending to half of elytral length; scape thick, widened apically; pedicel short, stout, moniliform; antennomere 3–6 stout, enlarged, subequal in length, longer than pedicel; antennomeres 7–11 filiform; relative lengths of antennomeres 3–11: 1.0:1.2:1.2:1.2:1.2:1.1:1.1:1.1:1.2. Pronotum ( Fig. 8D ) 0.4 mm long, 0.6 mm wide, transverse. Anterior margin slightly arcuate, posterior margin slightly concave, lateral margins narrowed apically in anterior half; disc irregular, with a large depression anteriorly. Scutellum narrowed apically, truncate at apex. Elytra ( Figs 7A , 8D ) 2.5 mm long, 0.8 mm wide, subparallelsided, somewhat narrowed before the middle, rounded at apex; elytra smooth; hindwing well-developed, exposed beyond elytra. Abdomen ( Fig. 7B ) weakly sclerotized, with eight ventrites; first six segments broad, as wide as elytra; last two segments ( Fig. 8E, F ) narrower, apical tergite ( Fig. 8E ) distinctly furcate, ventrite 7 ( Fig. 8F ) with apical margin straight, ventrite 8 tapered apically, forming narrow, elongate process. Aedeagus ( Fig. 8F ) partially exposed, with pair of slender ventral processes, curved outwards. Legs ( Fig. 8G ) short; profemur length 0.9 mm, mesofemur 0.9 mm, and metafemur 0.9 mm; tibiae slender, nearly straight, with pair of tibial spurs, protibia length 0.7 mm, mesotibia 0.7 mm, and metatibia 0.8 mm; tarsal formula 5-5-5; tarsomeres 1–3 simple, tarsomere 1 as long as combined length of tarsomere 2 and 3; tarsomere 4 bilobed; claws simple, with minute dent at base.

Etymology: The specific epithet is derived from m ā h ā, ‘great or noble’ in Sanskrit, referring to the discovery of this species being a great contribution to the palaeontology of Cantharidae . It is a noun in apposition.

Remarks: This species is closely related to H. kyawkhaingwini with which it shares the small body size, the head shape with the small rostrum, the apical maxillary palpomere with straight-truncated apex, the filiform antennae with the short, stout and moniliform pedicel and the stout central antennomeres, the transverse pronotum, with large depression on the disc anteriorly, the smooth and distinctly shortened elytra, with largely exposed caudal segments and hindwings and the furcate caudal segment. Considering that only four minute differences are identified between H. kyawkhaingwini and H. maha , we place it in the genus Hukawngichthyurus , rather than propose a new genus.

Figures

Figure 7. Habitus of Hukawngichthyurus maha: A, dorsal view; B, ventral-lateral view. Scale bars: 0.5 mm.

Figure 8. Details of body parts of Hukawngichthyurus maha: A, head, ventral-lateral view; B, ditto, dorsal view; C, antenna indicated by a black arrow; D, pronotum and elytra; E, apical tergite; F, caudal segments, with the process of aedeagus indicated by a black arrow; G, tarsus of left mid leg, with the tibial spurs indicated by a black arrow. Scale bars: 0.2 mm (A, B, E, F, G); 0.5 mm (C, D).