The first larva of the cucujiform superfamily Cleroidea from the Mesozoic and its ecological implications (Coleoptera) Author Kolibac, Jiri https://orcid.org/0000-0001-8178-7084 Moravian museum, Department of Entomology, Hviezdoslavova 29 a, 62700 Brno, Czechia jkolibac@mzm.cz Author Rosova, Katerina Charles University, Faculty of Science, Department of Zoology, Vinicna 7, 12800 Prague 2, Czechia Author Prazak, Jan Simon https://orcid.org/0000-0001-7438-2548 Charles University, Faculty of Science, Department of Zoology, Vinicna 7, 12800 Prague 2, Czechia & Museum of Eastern Bohemia in Hradec Kralove, Eliscino nabrezi 465, 500 03 Hradec Kralove 3, Czechia Author Hammel, Joerg U. https://orcid.org/0000-0002-6744-6811 Institute of Materials Physics, Helmholtz-Zentrum Hereon, Max-Planck-Strasse 1, 21502 Geesthacht, Germany Author Prokop, Jakub Charles University, Faculty of Science, Department of Zoology, Vinicna 7, 12800 Prague 2, Czechia text Arthropod Systematics & amp; Phylogeny 2023 2023-03-15 81 289 301 http://dx.doi.org/10.3897/asp.81.e98418 journal article http://dx.doi.org/10.3897/asp.81.e98418 1864-8312-81-289 8EE85535FA17418BB1BA6929C4EC7F34 B6D463D417985EFD924A2E9864DF1F05 Cretorhadalus constantini Kolibac & Prokop gen. et sp. nov. Figs 1 , 2 , 5 Type material. Holotype PrFUK 20 preserved in a polished, transparent yellow piece of amber (18.1 x 9.9 x 3.6 mm); deposited in the collection of Charles University, Faculty of Science, Department of Zoology, Prague. Type stratum. Lowermost Cenomanian (Upper Cretaceous); age based on U-Pb dating of zircon crystals from the volcaniclastic matrix ( Shi et al. 2012 ). Type locality. Hukawng Valley, Kachin State, northern Myanmar. Description. Body length from clypeus to the last abdominal segment (excluding urogomphi) 2.41 mm. For other measurements see Table 3 . Table 3. Measurements of some body parts of Cretorhadalus constantini gen. et sp. nov. (in millimetres).

Body part	Measurements
Body length from clypeus, excl. urogomphi	2.41
Body length from clypeus, incl. urogomphi	2.59
Head capsule anterior, max. width	0.36
Head capsule base, width	0.28
Head capsule, max. length	0.34
Antenna, length incl. connecting membrane	0.22
Antennomeres 1+2+3, length	0.03+0.04+0.05
Prothorax, width	0.42
Prothorax, length	0.31
Mesothorax, width	0.47
Mesothorax, length	0.22
Metathorax, width	0.52
Metathorax, length	0.24
Metafemur, length	0.16
Metatibia, length	0.14
Urogomphi, approx. circumference	0.21

Body habitus and pubescence (Fig. 1A, B ): Body elongate, whitish, sclerotized parts brown. Head capsule, urogomphi and dorsal part of abdominal segment IX heavily sclerotized, dark brown (urogomphi lighter than tergite IX); prosternum, protergum and mesotergum with sclerotized brown plates; metathorax and abdomen up to segment VIII whitish. Cranium with long sparse pubescence dispersed irregularly (c. 50-60 setae on dorsal side and c. 20 setae on ventral side); dorsum of thoracic segments with c. 10-15 long setae; legs with few long setae; abdominal segments I-VIII with dorsally about 2-4 long and laterally about 5 setae; sides of abdominal segments IX-X with dense and long pubescence, urogomphi also with long setae. Ventral sides of thoracic and abdominal segments with shorter and sparser pubescence. - Head : Cranium approximately as wide as long, lateral sides weakly rounded (convex), its anterior margin wider than base (Table 1 ; Figs 1C , 4C ); five stemmata occur on each side with the formula 2+3 (two posterior and three anterior) (Fig. 2C ); frontal arms distinctly Y-shaped, with branches curved at half their length and divergent (Fig. 4C ); median endocarina absent (Fig. 1C ); frontoclypeal suture present (Fig. 1A, C ); gular sutures widely separated, subparallel, virtually extending to anterior part of cranium (Fig. 5 ); hypostomal rods absent; paragular sclerites absent. Gular region membranous and pale, its middle part nearly reaching midpoint of cranium so that the maxillolabial complex reaches slightly beyond half of cranium; head capsule is ventrally open, without bridge along anterior margin (Figs 1D , 5 ). - Antennae (Figs 1D ; 2B, D ): 3-segmented, 1st antennomere shorter than 2nd, the latter obliquely truncated and shorter than 3rd; sensory appendix relatively short and stout, triangular, not extending behind one quarter of 3rd antennomere, which is relatively slender and long, with long seta on apex. - Mandible (Figs 1D , 2A ): bidentate (Fig. 2A ), that is with two apical teeth situated side by side; other mandibular structures not visible in fossil. - Maxilla (Figs 2D , 5 ): mala small, triangular, with at least 3 thick long setae along outer margin; pedunculate seta not observed; palpi 3-segmented, 1st and 2nd palpomeres equal in length, terminal palpomere coniform and longer than 1 or 2; cardo and stipes distinctly separated; cardo narrow and transverse, much smaller than stipes (Fig. 5 ). - Labium (Figs 1A , 2A , 5 ): ligula small, pale, membranous, ciliate, rounded; palpi 2-segmented, terminal palpomere cylindrical, about twice as long as basal palpomere; prementum in single part (not divided); border of postmentum not conspicuous. - Labrum (Figs 1C , 2E , 5 ): free; anterior margin wide and convex, with about 6 long setae (Fig. 5 ); other details not visible. - Thorax (Fig. 1A, B, C ): protergum heavily sclerotized and pigmented, with single large tergal plate longitudinally divided by medial suture; mesotergum with pair of small but distinctly pigmented and sclerotized tergites; structure of metatergum the same as that of mesotergum, but sclerites slightly smaller (Fig. 1C ). Ventral part of pro-, meso- and metathorax without distinctly pigmented sclerites. - Legs (Fig. 1B, C ): Coxae projecting; trochanters rather triangular; femora longer than tibiae; tarsunguli without visible setae. - Abdomen : segments I-VIII membranous, their terga without sclerites (tergites) or pigmented plates (Figs 1A , 2E ); segment IX with single tergite (not transversely divided into two parts) bearing a pair of slender hooked urogomphi (Fig. 2E ); median process or glandular openings on or between urogomphi not visible, but it is possible that a pair of membranous appendages are present approximately at the centre of tergite IX; urogomphi without large tubercles, relatively slender, conspicuously turned upwards, well-developed (Fig. 1E ; cf. Fig. 3B, D ). Etymology. The specific epithet honours Robert Constantin (Saint Lo , France), the eminent specialist of beetles in the melyrid lineage and leading authority on their larvae.