Oxyporus (Pseudoxyporus) melanocephalus Kirshenblat, 1938

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 : 257-259

Oxyporus (Pseudoxyporus) melanocephalus Kirshenblat, 1938

( Figs 3, 5, 6 , 45–62 )

Material examined. 10 third instar larvae ( NHMD): RUSSIA: PRI- MORSKY TERRITORY: Arboretum of the Gornotaezhnaya Station FEB RAS, 43.6945498°N, 132.1520375°E, 11.ix.2018, from Pholiota sp., A. Tokareva leg. 10 third instar larvae were reared by A. Tokareva (rearing R 13) from eggs to third instar larvae collected in the fungus.

DNA bardcoding. 1 third instar larva ( NHMD 620698: GenBank Accession No.: MN 508939 ) and one associated adult ( NHMD 620699: GenBank Accession No: MN 508938 ).

Diagnosis. Larva of O. melanocephalus differs from other described Oxyporus larvae by the following set of chaetotaxy characters: two D setae on thoracic tergite I, three A and three P setae on thoracic tergite II, three A, five L, and three P on thoracic tergite III. It differs from larvae of both O. procerus and O. maxillosus by two lateral (Lc1–Lc2) and one ventral campaniform sensilla (Vc) on each side of head capsule; dorsal c. s. on mala located between two lateral setae above medial seta and under palpifer (compare Fig. 52 with Figs 14 , 31 ); five anterior (A1–A5), two discoidal (D1–D2), and five lateral setae (L1–L5) on each side of thoracic tergite I; three anterior setae (A1–A3), three posterior setae (P1–P3) on each side of thoracic tergite II; three membrane setae (M1–M3) on each side before thoracic tergite III; three anterior setae (A1–A3), five lateral setae (L1–L5), three posterior setae (P1–P3) on each side of thoracic tergite III; two anterior setae (A1–A2), five lateral setae (L1–L5), three posterior setae (P1–P3) on each side of abdominal tergite I.

Description. Tergites pale yellow, head capsule yellow. Third instar body length: 9.6–12.6 mm; head length: 1.1–1.3 mm; head width: 1.2–1.4 mm; n = 10.

Head. Oval ( Figs 45–46 ). Nasale with two pairs of setae of average length (Ll1, Ld1). Frontal setae 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: Fc1–Fc5, Ec1, Ec2, Pc, Lc1, Lc2, Vc. 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) ( Fig. 47 ). 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; labial apex distinct, ligula-like, with two setae and half- -ring of microtrichia ventrally on hypopharyngeal part; prementum with two setae and campaniform sensilla, Pv1, Pv2, Pc; labial palpus with one campaniform sensillum on each palpomere ( Figs 47–52 ).

Thorax. Membrane anterior to pronotum with three pairs of microsetae M1, M2, M3 ( Figs 53 , 58 ). Pronotum tergite with anterior, discoidal, lateral and posterior rows A1–A5, D1–D2, L1–L5 and P1–P6. Membrane anterior to mesonotum with four pairs of microsetae M1, M2, M3, M4. Mesonotum with anterior, lateral, and posterior (A1– A3, L1–L5, P1–P3) setae. Metanotum with setation as on mesonotum ( Fig. 53 ).

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 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 neighbouring 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. 56 ).

Abdomen. Membrane anterior to abdominal tergite I with three pairs of setae (M2–M4). Abdominal tergite I with anterior, lateral, and posterior rows (A 1–A2, L1–L5, P1–P3). 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 22 setae ( Figs 54, 55 ).

Development. The life cycle takes 22–23 days from eggs to prepupa in the laboratory. Duration of the pupa is unknown. Observed host fungi for larvae. Strophariaceae : Pholiota sp.

Biology observations. We observed only one breed associated with one female. That female did not build a chamber but instead laid every egg separately deep between fungal gills ( Fig. 66 ). No subsocial behavior was observed. Hatched larvae start feeding by boring thin tunnels behind the hymenophore. Because of that, and since the female made no big holes in the fungal cap, the populated fruit body looked intact externally.

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 45–52. Third instar larva of Oxyporus (P.) melanocephalus Kirschenblatt, 1938, head morphology. 45 – head, dorsal view; 46 – head, ventral view; 47 – antenna, dorsal view; 48 – mandible, dorsal view; 49 – maxilla, dorsal view; 50 – labium, dorsal view; 51 – labium, lateral view; 52 – maxilla, ventral view.

Figs 53–56. Third instar larva of Oxyporus (P.) melanocephalus Kirschenblatt, 1938, selected body tergites. 53 – thoracic tergites I–III; 54 – abdominal tergite I; 55 – abdominal apex, dorsal view; 56 – mesothoracic leg, posterior view.

Figs 57–62. Scanning electron micrographs of larva of Oxyporus (P.) melanocephalus Kirschenblatt, 1938. 57 – head, lateral; 58 – intersegmental membrane, M1, M2 microsetae of thoracic tergite I; 59 – pore-like structure between P1–P2 pronotal setae, campaniform sensilla missing between setae; 60 – pore-like structure, magnified; 61 – pore-like structure between P1–P2 pronotal setae; 62 – pore-like structure between P1–P2 mesonotal setae.

Figs 7–14. Third instar larva of Oxyporus maxillosus Fabricius, 1775, head morphology. 7 – head, dorsal view; 8 – head, ventral view; 9 – antenna, dorsal view; 10 – mandible, dorsal view; 11 – maxilla, dorsal view; 12 – labium, dorsal view; 13 – labium, lateral view; 14 – maxilla, 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 63–66. Habitat and rearing of Far East Oxyporus species. 63 – aspen-maple forest with lime-trees in a lowland of the Arboretum of the Gornotaezhnaya Station, locality of Oxyporus (P.) melanocephalus. 64 – oak forest on a hill of the Arboretum of the Gornotaezhnaya Station, locality of Oxyporus maxillosus. 65 – rearing box with the sand layer, the leaf litter and a fruit body of Laetiporus sulphureus. 66 – an egg of Oxyporus (Pseudoxyporus) melanocephalus Kirschenblatt, 1938 nested between the gills of Pholiota sp.