Oxyporus (Oxyporus) procerus Kraatz, 1879

Tokareva, Alexandra, Solodovnikov, Alexey & Konstantinov, Fedor, 2020, Immature stages and biology of the enigmatic oxyporine rove beetles, with new data on Oxyporus larvae from the Russian Far East (Coleoptera: Staphylinidae), Acta Entomologica Musei Nationalis Pragae 60 (1), pp. 245-268 : 255-257

Oxyporus (Oxyporus) procerus Kraatz, 1879 ( Figs 2 , 28–44 )

Material examined. 13 third instar larvae ( NHMD): RUSSIA: PRIMOR- SKY TERRITORY: Arboretum of the Gornotaezhnaya Station FEB RAS, 43.6945498°N, 132.1520375°E, 10.ix.2018, from Pleurotus sp., A. Tokareva leg. 13 third instar larvae were reared by A. Tokareva (rearing R 13) from second instar larvae collected in the fungus.

DNA barcoding. 1 third instar larva ( NHMD 620700: GenBank Accession No.: MN 508940 ) and one associated adult ( NHMD 620701: GenBank Accession No: MN 508941 ).

Diagnosis. Oxyporus procerus larva differs from any other described Oxyporus larvae including O. maxillosus and O. (P.) melanocephalus by the following characters: thoracic tergite I with six anterior setae (A1–A6); color pattern with brownish yellow head capsule and yellow tergites; body twice or more times as big as that described for other Oxyporus larvae. Larva of O. procerus further differs from that of O. maxillosus by the following characters: three membrane setae on each side before thoracic tergite I (M1–M3); six anterior setae (A1–A6) and six posterior setae (P1–P6) on each side of thoracic tergite I, five lateral setae (L1–L5) on each side of thoracic tergite II). Description. Head capsule brownish yellow, thoracic and abdominal tergites yellow; body length 16.8–20.9 mm; head length 1.9–2.1 mm; head width 1.9–2.05 mm; n = 13.

Head. Oval to slightly drop-shaped ( Figs 28, 29 ). Nasale with two pairs of setae of medium length (Ll1, Ld1) on dorsal surface and four short setae on anterior margin (Lm1, Lm2). Frontal setae arranged in vertical rows Fd1–Fd3 and Fl1–Fl4. Occipital group consists of microsetae P1–P4 and one campaniform sensillum. Epicranial setae arranged in rows on each side: Ed1–Ed3, El1–El4, T1–T3, L1–L3, V1. Head capsule with 52 setae in total. Campaniform sensilla present on head capsule as follows: Fc1–Fc4, Ec1, Ec2, Pc, Lc. Antennomere I with two campaniform sensilla dorsally (Ic1, Ic2) in basal portion and two ventrally (Ic3, Ic4) in apical portion ( Fig. 29 ). Antennomere II with one campaniform sensillum dorsally, three setae near apex, tubercle-like (SA1) and narrow conical (SA2) sensory appendages ventrally at apex.Antennomere III with three apical setae and superior group of small sensilla consisting of one thickened membranous solenidium (IIIs3), two narrow spiny solenidia (IIIs1–IIIs2), and one microseta (IIIams) ( Figs 34 , 41 ). Mandibles with two setae on outer side. Maxillae as in general description. Maxillary palpi with palpifer as in general description. Labium as in general description; prementum with two setae and campaniform sensilla Pv1, Pv2, Pc; labial palpi with one campaniform sensillum on each palpomere.

Thorax. Membrane anterior to pronotum with three pairs of microsetae M1, M2, M3 ( Fig. 20 ). Pronotum tergite with anterior, discoidal, lateral, and posterior rows A1–A6, D1–D3, L1–L6 and P1–P6. Membrane anterior to mesonotum with four pairs of microsetae M1, M2, M3, M4. Mesonotum with anterior, lateral, and posterior A1–A6, L1–L5, P1–P6 setae. Metanotum with setation almost as on mesonotum, except six lateral setae on each side (L1–L6) ( Fig 35 ).

Legs. Tarsungulus with two spine-shaped, short setae. Tibiotarsus with five spine-shaped, short setae on dorsal side, two setae on lateral side, and three setae on ventral side, nine setae in total. Femur with three setae on ventral side, two on lateral side, three on dorsal side, eight setae in total. Trochanter with three setae near Tr–Fe joint of which medial seta twice as long as each neighbour seta, two setae more medially, one short thin seta near coxal joint on each lateral side, and one short thin seta near Cx–Tr joint dorsally, in total eight setae. Coxa with 18 setae, including several basal microsetae ( Fig. 38 ).

Abdomen. Membrane anterior to abdominal tergite I with three pairs of setae (M2–M4) and one pls. Abdominal tergite I with anterior, lateral, and posterior rows: A1–A3, L1–L4, P1–P5. Last abdominal tergite with two pairs of setae on dorsal side and three setae on each lateral side on posterior angles. Urogomphi as in generic description. Pygopod with asymmetrically arranged 16–18 setae ( Figs 36 , 37 ).

Development. The life cycle duration was observed only from the third instar which took 5 days until the prepupal stage.

Observed host fungi for larvae. Pleurotaceae : Pleurotus sp.

Observed host fungi for adults. Pleurotaceae : Pleurotus sp., Fomitopsidaceae : Laetiporus sulphureus (Bull.) Murrill.

Biology observations. According to our observations single females were often found with O. maxillosus feeding on Laetiporus sulphureus but no larvae of Oxyporus were ever found in this fungal species. Mature third instar larvae turn pink and migrate for pupation in soil. According to observations by S. A. Shabalin (pers. comm.), this species (adults and larvae) usually feeds on different Pleurotus species on fallen lime trees (Tilia sp.) and alder trees (Alnus sp.) along small streams and thus can be found mostly in September or later.

Figures

Figs 1–6. Third instar larvae and adults of Oxyporus spp. general view.1 – imago of O. maxillosus Fabricius, 1775, dorsal view; 2 – imago of O. procerus Kraatz, 1879, dorsal view; 3 – imago of O. (P.) melanocephalus Kirschenblatt, 1938, dorsal view; 4 – larva of O. maxillosus, lateral view; 5 – larva of O. (P.) melanocephalus, lateral view; 6 – larva of O. (P.) melanocephalus, head and thorax in ventral view.

Figs 28–34. Third instar larva of Oxyporus procerus Kraatz, 1879, head morphology. 28 – head, dorsal view; 29 – head, ventral view; 30 – mandible, dorsal view; 31 – maxilla, ventral view; 32 – maxilla, dorsal view; 33 – labium, dorsal view; 34 – antenna, dorsal view.

Figs 35–36. Third instar larva of Oxyporus procerus Kraatz, 1879, selected body tergites. 35 – thoracic tergites I–III; 36 – abdominal tergite I.

Figs 37–38. Third instar larva of Oxyporus procerus Kraatz, 1879, apex of abdomen, mesothoracic leg. 37 – apex of abdomen, dorsal view; 38 – mesothoracic leg, posterior view.

Figs 39–44. Scanning electron micrographs of larva of Oxyporus procerus Kraatz, 1879. 39 – campaniform sensilla and setae of nasale; 40 – posterior epicranial group of sensilla; 41 – antennomeres II and III, apical sensorial complex; 42 – premental group of sensilla; 43 – campaniform sensillum, segment II of maxillary palpus; 44 – thoracic tergite I, lateral view.

Figs 19–27. Scanning electron micrographs of larva of Oxyporus maxillosus Fabricius, 1775. 19 – cervical intersegmental membrane with microsetae M2, M3; 20 – M1 microseta, magnified; 21 – M3 microseta, magnified; 22 – posterior epicranial group of sensilla; 23 – posterior epicranial campaniform sensillum; 24 – ventral sensilla, head capsule; 25, 26 – campaniform sensilla missing between mesonotal setae; 27 – epipharynx with median furrow, hypopharynx with microtrichia.