Larval features illuminating adult taxonomy? Case study in the European cardinal beetle species of the genus Pyrochroa (Coleoptera: Pyrochroidae: Pyrochroinae) Author Molfini, Marco 0000-0003-0508-0751 Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Roma, Italy. & andrea. digiulio @ uniroma 3. it; https: // orcid. org / 0000 - 0003 - 0508 - 0751 & marcoalberto. bologna @ uniroma 3. it; https: // orcid. org / 0000 - 0003 - 2498 - 8917 Author Giulio, Andrea Di 0000-0003-0508-0751 Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Roma, Italy. & andrea. digiulio @ uniroma 3. it; https: // orcid. org / 0000 - 0003 - 0508 - 0751 & marcoalberto. bologna @ uniroma 3. it; https: // orcid. org / 0000 - 0003 - 2498 - 8917 Author Mancini, Emiliano Department of Biology and Biotechnology “ Charles Darwin ”, Sapienza University, Viale dell’Università 32, 00185 Roma, Italy. & emiliano. mancini @ uniroma 1. it Author Bologna, Marco A. 0000-0003-0508-0751 Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Roma, Italy. & andrea. digiulio @ uniroma 3. it; https: // orcid. org / 0000 - 0003 - 0508 - 0751 & marcoalberto. bologna @ uniroma 3. it; https: // orcid. org / 0000 - 0003 - 2498 - 8917 text Zootaxa 2021 2021-05-04 4966 3 337 348 journal article 6520 10.11646/zootaxa.4966.3.5 3dabef90-bc57-460b-9221-e290cfd837d2 1175-5326 4736738 4159E660-EA53-48E2-9724-DDB48DB6FC43 Pyrochroa serraticornis (Scopoli) ( Figs 1B , 2B, D, F , 3E–H , 4B, D , 5B ) Diagnosis. The most diagnostic characters are structures associated with the highly sclerotized urogomphal plate: lateral lobes acute rounded; sclerotized conical teeth between lateral lobes and the straight parallel urogomphi; urogomphal lip flat, ventrally to the single urogomphal pit with parallel rugulae. Other diagnostic characters vs . P. coccinea are shown in Table 1 . Description of mature larva. Body length about 2.4 cm (from mesal labral apex to apices of urogomphi) and maximum width about 3.8 mm (across widest portion of urite VIII) ( Fig. 1B ). Body orthosomatic with sides subparallel, moderately sclerotized except much of cephalic capsule, mandibles, and urogomphal plate more heavily sclerotized; body vestiture consisting of short to moderately elongate, scattered setae. Thoracic and abdominal tergites II–VII and IX lacking parabasal ridges; abdominal tergites I and VIII with weakly formed parabasal ridge ( Figs 1B , 4B ). Head and body from light yellowish to darker, melanisation much darker in areas of heavy sclerotization such as mandibles, urogomphi, urogomphal lip and urogomphal pit. FIGURE 2. Details of cranium: A—cranium of Pyrochroa coccinea , dorsal view; B—cranium of P. serraticornis , dorsal view; C—cranium of P. coccinea , ventral view; D—cranium of P. serraticornis , ventral view; E—right maxilla of P. coccinea , ventral view; F—right maxilla of P. serraticornis , ventral view. Scale bars: A–D = 1.5 mm; E–F = 0.5 mm. Head. Prognathous, flattened, exserted from prothorax, about 3.3 mm width ( Figs 2B, D ). Epicranial suture lyriform with stem short, frontal arms complete nearly to antennal insertions, endocarinae absent ( Fig. 2B ). Free, symmetrical trilobate labrum with scattered slender setae ( Fig. 2B ). Two pair of stemmata on each lateral side, parallel with antennal insertions. Antennal insertions fully exposed; antennae moderately long, stout, 3-segmented; antennomere I quite straight, narrower in the middle area, wider apically; sensorium of II small, drop-shaped; antennomere III narrower than I–II, about 2/3 the length of II, acutely rounded apically; setae well distributed on all the surface of antennomers. Mouthparts retracted ( Figs 2B, D ). Mandibles heavily sclerotized, movable, asymmetrical, molar area of mandibles well developed; left mandible bigger, bearing a prominent, hooked inwards, molar tooth, apex sub-securiforme with one small subapical expansion; inner surface bearing two longitudinal depressions so as to make it appear tridentate from a ventral view ( Fig. 3F, G ); apex of right mandible securiforme, inner surface concave so as to make it appear bidentate from a ventral view ( Figs 3E, H ). Maxillae ( Fig. 2F ) each with 1-segmented cardo which is diagonally folded upward upon itself toward the stipes and thus appearing 2- segmented; a well-developed, undivided, pad-like maxillary articulating area; ventral surface of stipes bearing few scattered spiniform setae; galea and lacinia fused to form maxillary mala; mala bearing stout apical and adoral spiniform setae and a well-developed pointed uncus at apico-adoral margin; 3-segmented, filiform maxillary palpus, palpomere II about 1.2 times as long as I, palpomere III subequal in length to II, tapering distally, acutely rounded apically. Labium with mentum trapezoidal ( Fig. 2D ); submentum glabrous, shape elongate with sides shallowing sinuate basally, apical margin slightly more heavily sclerotized ( Fig. 2D ); ligula well developed, elongate, almost glabrous, bearing few setae hardly characterized from our samples; each labial palpus short, 2-segmented, palpomere I twice as long as II. Hypostomal rods ( Fig. 2D ) well developed, divergent; gular sutures separate ( Fig. 2D ). FIGURE 3. Mandibles of Pyrochroa coccinea (A–D) and Pyrochroa serraticornis (E–H): A, E—right mandible, ventral view; B, F—left mandible, ventral view; C, G—left mandible, inner view; D, H—right mandible, inner view. Scale bars: A–H: 0.5 mm. Thorax and Abdomen. Thorax flattened, segmentation well developed, sides of prothorax subparallel, meso- and metathorax rounded ( Fig. 1B ); cervicosternum divided into three plates ( Fig. 2D ). Legs well developed, moderately short, 5-segmented including tarsungulus, vestiture consisting of sparse, short setae.Abdomen flattened, sides slightly converging forward, moderately sclerotized, tergites I–VII subequal in length and width; tergite VIII approximately 2.8 as long as each other ( Fig. 1B ). Sternite VIII emarginate apically ( Fig. 4D ). Ventrolateral margins of abdominal laterotergite VIII emarginate, with lanceolate shape, ending with more sclerotized acute apex forming a lateral tooth visible even from dorsal view ( Figs 1B , 4D ). Tergite IX divided into four plates ( Fig. 4B ), hinged, capable of considerable dorso-longitudinal movement, extending ventrally, thus forming the urogomphal plate, widest basally where it forms well developed acute rounded lateral lobes ( Figs 4B, D ); surface of urogomphal plate bearing numerous, well-developed, callosities and several setigerous calli, in particular, long setae are associated with three pair of calli on the dorsolateral surfaces and one pair of calli at the base of urogomphi ( Fig. 4B ); a pair of well developed, highly sclerotized conical teeth between urogomphi and lateral lobes ( Figs 4B, D ); urogomphi heavily sclerotized, long, slender, straight, parallel, tapering and acuminate apically; ventral surface of urogomphal plate sharply excavate basally at articulation with sternites IX–X, excavation narrowing distally to bases of urogomphi and urogomphal lip forming a thin slot ( Fig. 4D ). Urogomphal plate possessing a heavily sclerotized urogomphal lip ventrally ( Figs 4B, D , 5B ), forming the ventral surface of the wide heavily sclerotized single urogomphal pit ( Fig. 5B ), which fills the space between the heavily sclerotized fixed urogomphi, and bear characteristic parallel rugulae. Sternite IX broadly transversely U-shaped ( Fig. 4D ), partially recessed into shallow emargination of sternite VIII, possessing continuous semicircular arch of approximately 32 well-developed asperities along anterior margin; ventrolateral margin heavily sclerotized forming an acute tooth slightly visible even in dorsal view ( Figs 1B , 4D ). Segment X reduced, transversely ovate, basal margin rounded, recessed into emarginations of sternite IX, visible ventrally ( Fig. 4D ). FIGURE 4. Details of abdomen: A—abdominal urites XIII–IX of Pyrochroa coccinea , dorsal view; B—abdominal urites XIII–IX of P. serraticornis , dorsal view; C—abdominal urites XIII–X of P. coccinea , ventral view; D—abdominal urites XIII–X of P. serraticornis , ventral view. Scale bars: A–D = 1 mm. FIGURE 5. Details of urogomphal plate: A—urogomphal plate of Pyrochroa coccinea , posterior view; B—urogomphal plate of P. serraticornis , posterior view. Scale bars: A–B = 1 mm. Spiracles. One pair of well-developed, ovate, thoracic spiracles situated ventrolaterally on laterotergite along anterior end of mesothorax. Paired, sub-ovate abdominal spiracles, subequal in size, located on dorsolateral margin of abdominal tergite I ( Fig. 1B ) and ventrolateral margins of abdominal laterotergites II–VII; paired spiracles of abdominal laterotergite VIII annular-ovate, located ventrolaterally at distal 1/3 of its length ( Fig. 4D ).