Mesosmicrips sunae Lyubarsky et Perkovsky 2023, sp.n.
Creators: name: Lyubarsky, Georgy Yu.
name: Shaw, Josh Jenkins
name: Vasilenko, Dmitry V.
name: Perkovsky, Evgeny E.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Smicripidae
Mesosmicrips
Mesosmicrips sunae

description: Mesosmicrips sunae Lyubarsky et Perkovsky sp.n.   
https://zoobank.org/ urn:lsid:zoobank.org:act: 16F93EF8-70A1-4EA1-BA6E-8A759B32AB38  
Figs.1-2  
 Holotype: (BFU (A)-0002, BFU). Syninclusions: in the amber piece with the holotype of the nitidulid species Phenolia (Palaeoronia) haoranae Kirejtshuk and Jenkins Shaw, 2023 and other syninclusions mentioned in the description of the latter species.   
 Etymology. Species named for Haoran Sun, the PhD student at the Natural History Museum of Denmark and Beijing Forestry University, who kindly provided the specimen for the study.   
 Diagnosis. The new species is distinguished by the following combination of characters: 1) the pronotum slightly elongate, 1.1 times as longer than wide; 2) short grooves of pronotum on posterior fourth of pronotum absent; 3) posterolateral angles of pronotum obtuse; 4) protibiae parallel-sided in distal quarter, length of protibia is 5 times greater than its width (in the type species, the tibiae are evenly expanded towards the apex, the length of the tibia is 3.3 times greater than the width); 5) elytra exposing only two apical tergites, elongate, 1.75 as long as wide combined (M. cretacea: elytra leave not only the two apical tergites open, another one is at least half open, 1.5 as long as combined wide).   
 Body surface glabrous, with fine microsculpture on dorsal head, pronotum and elytra. In extant and extinct species of the genus Smicrips, the surface is weakly shiny and densely punctured. Apparently, this is a feature diagnostic for the genus Mesosmicrips.   
 Description. Body small, elongate, 1.15 mm long (from apex of mandibles to abdominal apex), parallel-sided, flattened; uniformly brownish. Male. Body surface glabrous, with fine microsculpture on dorsal surfaces of head, pronotum and elytra.   
Head large (Fig. 1A, 2A), 0.25 mm long and 0.235 mm wide, very slightly narrowed posterior to eyes (Fig. 2A), head at eyes not wider than the maximum width of the pronotum. Eye small, rounded, laterally convex (Fig. 2A). Temples long, as long as eye’s diameter. Frontoclypeal suture distinctly impressed, deeply U-shaped. Antenna more or less short; with 11 antennomeres (Fig. 1A), antennal length nearly equals the distance between base of scapus and posterior margin of pronotum; antennomeres (A) 1 and 2 dilated, A1 longest, twice longer than wide; A2 slightly narrower and half long as A1; A3-A8 small, distinctly narrower than A2, A3 longer its width, A4-A8 almost in same length and width; A9-A11 form a capitate club, it is only two times longer its width, A9 about 1.8 times the width of A8; A10 slightly longer and wider than A9; A11 strongly narrower than A10, widest across middle. Antennal insertions exposed from above, positioned near base of labrum (Fig. 2C). Labrum prominent, with slightly rounded apex (Fig. 2C). Mandibles slightly exposed from beneath frons and labrum, robust, broadly triangular; mandibular apex is acutely angulate sharp (Figs. 1A, 2A, 2C). Mentum large, strongly transverse; apical margin W-shaped. Gular sutures not developed (Fig. 2A). Ventral side of head with microsculpture (Fig. 2A). Vertex is damaged in the middle.  
 Pronotum 0.27 mm long and 0.24 mm wide (Fig. 1A), sides slightly narrowed posteriorly, each side with ca. 20 small, indistinct teeth (Fig. 1A). Posterior tooth on lateral margin (near the hind angle) is evidently larger than others (Fig. 2C). Anterolateral angles obtuse; posterolateral angles obtuse; posterior margin simple, nearly straight. Surface with same microsculpture as those on head (Fig. 1A). Short grooves on posterior fourth of pronotum absent (Fig. 1A). Basal pits and grooves absent. Prosternum long (Fig. 2A); prosternal process long, extending beyond posterior margins of procoxae, apex truncate, concave medially, expanded apically (Fig. 2A). Procoxal cavity externally broadly open behind, strongly transverse. Mesoventrite short (Fig. 1B, 2A). Mesocoxae slightly transverse, moderately separated, open laterally. Metaventrite elongate, longer than prosternum, slightly convex, without both median line and paracoxal line before metacoxae; posterior margin of metaventrite with rectangular notch. Metacoxae transverse (Fig. 1B), widely separated. Femoral (submetacoxal) line absent. Femur robust, more or less fusiform. Tibia slightly widened towards apex (Fig. 2B, 2C); with long setae apically, with two apical spurs. Protibia parallel-sided in distal quarter, 5 times as long as wide. Tarsal formula 5-5-5; tarsomeres (T) 1-4 short; T1-3 broad, tarsomeres 1 not wider than 2 nd; T4 very small; T5 very elongate, two times longer than basal four tarsomeres combined. Pretarsal claw long, simple.   
Scutellar shield subtrapezoid, truncated on the apex. Elytra short, 0.48 mm long and 0.26 mm wide, subparallel-sided, 1.75 as long as wide combined, elytra truncated (exposing apical abdominal segments), lateral margin rounded; surface glabrous, with fine microsculpture. Elytral epipleura narrow, incomplete. Hind wings present.  
Abdomen with five ventrites (V); V1 elongate, equals to V2-V4 combined; V2-V4 almost in same length; V5 very long, nearly as long (16:18) as preceding four combined. Genitalia not visible.  
 Remarks   
 The specimen studied here can be placed in the family Smicripidae based on the following characters: 1) head not narrowed behind eyes. 2) antennae 11-segmented, with a 3-segmented, broad club. 3) frontoclypeal suture distinctly impressed and curved. 4) labial palps 2-segmented. 5) elytra truncate, exposing two abdominal tergites. 6) abdomen with five ventrites, caudal ventrite equal in length to preceding four combined (Price 2002). The beetle belongs to the genus Mesosmicrips based on the following characters: head elongated and not subtriangular, eyes located at midlength of head and scutellar shield subtrapezoid (see Kirejtshuk 2017).   
 Smicrips fudalai has the tarsal formula is 5-5-5 (our observation), with a very small 4 th tarsomere, well seen only at 730x magnification. A very small 4 th tarsomere was also observed in the two known species of Mesosmicrips as well. In the diagnosis of the family Smicripidae a new character can be introduced: the tarsal formula 5-5-5, since both included genera are characterized by the identical tarsal formula. The study of Mesosmicrips sunae sp.n. confirmed this combination of characters: five-segmented tarsi were also observed in this taxon.
description: Published as part of Lyubarsky, Georgy Yu., Shaw, Josh Jenkins, Vasilenko, Dmitry V. & Perkovsky, Evgeny E., 2023, A second species of Mesosmicrips Kirejtshuk, 2017 (Coleoptera: Smicripidae) from Kachin amber, pp. 94-100 in Ecologica Montenegrina 70 on pages 95-98, DOI: 10.37828/em.2023.70.11, http://zenodo.org/record/13248119