Rioneta uluguruensis Johnson, 1975

Grebennikov, Vasily V., 2008, A featherwing beetle without wings: re-discovery and second species of Rioneta (Coleoptera: Ptiliidae) from the Uluguru Mountains, Tanzania, Zootaxa 1732, pp. 45-53 : 47

Rioneta uluguruensis Johnson, 1975

( Figs 1, 2 , 5–35 )

Diagnosis. Differs from R. inexpectata by markedly wider body ( Figs 1, 2 ).

Description. With the characters of the genus. Body length 1.10–1.13 mm (mean 1.12 mm, n=3), pronotal length 0.29–0.31 mm (mean 0.30 mm; n=3); pronotal width 0.58–0.62 (mean 0.60; n=3); ratio pronotal width/ length 1.93–1.98 (mean 1.96; n=3).

Material studied. Holotype (dry mounted on card, female) in the collection of the Musée Royal de l’Afrique Centrale, Tervuren [ MRAC]: “ Holotypus ” (printed on pink label); “ Tanzanie: Mts Uluguru/ Lukwangule Plateau/ alt. 2400–2600 m./ humus, 2–22/VII/71 ” (printed on white label); “Coll. Mus. Tervuren/ Mission Mts Uluguru/ L. Berger, N. Leleup/ J. Debecker V/ Viii/71 ” (printed on white label); “ Holotype female/ Rioneta / uluguruensis sp. n. / det. C. Johnson 1974” (written on white label). Paratype (dry mounted on card, male): similarly labelled. Additional material: 20 dry mounted, 10 mounted on Euparal microscope slides and about 100 stored in alcohol: “ Tanzania: Uluguru Mts., W slope between Tchenzema vil. and Lukwangule Plateau, H- 2200 m. Oct. 19–21, 2002, V. Grebennikov leg.” ( MRAC, Canadian National Collection of Insects, Arachnids, and Nematodes [ CNC]).

Figures

FIGURES 1 – 4. Habitus images of Rioneta beetles. 1 — R. uluguruensis, female, dorsal; 2 — R. uluguruensis, male, ventral; 3 — R. inexpectata sp. n., male, dorsal; 4 — R. inexpectata sp. n., female, ventral. Scale = 0.2 mm.

FIGURES 5 – 15. SEM images of Rioneta uluguruensis. 5 — habitus, ventral; 6 — head, ventral; 7 — left fore-tarsus, ventral; 8 — two apical antennomeres, arrow showing groups of sensillae, ventral; 9 — internal surface of meso- and metathorax with metendosternite, two arrows show internal part of lateral longitudinal keel on each side of metaventrite, dorsal; 10 — spermatheca and sperm pump, ventral; 11 — pretothorax and abdomen, arrow showing lateral longitudinal keel on left metaventrite, left elytron removed, fronto-lateral; 12 — pterothorax and abdomen, lateral, left elytron removed, three arrows showing spiracles I – III, respectively; 13 — internal surface of abdominal tergites V – X, double-pointed central arrow showing fused tergites VIII and IX, two lateral arrows showing remnants of internal apodemae of tergite IX, dorsal; 14 — abdominal apex, both elytra removed, dorsal, vertical double-pointed arrow showing fused tergites VIII and IX, horizontal arrows showing spiracles VIII – IV; 15 — right part of abdomen, right elytron removed, dorsal, oblique arrow showing posterior edge of terige VII without wing cleaning (= toiletry) device, vertical arrows showing spiracles VIII – III.

FIGURES 16 – 22. Rioneta uluguruensis, details of morphology. 16 — habitus, ventral, left legs omitted, aedeagus and metendosternite shown; 18 — head, dorsal, antennomeres 2 – 11 omitted; 18 — left fore-tarsus and tibia, ventral (separately shown enlarged bifurcate spine on apical part of tibia); 19 — right hind leg, ventral (separately shown enlarged tarsus with two visible apical tarsomeres); 20 — mouthparts (maxillae, mentum, and labium), ventral; 21 — right antenna, dorsal; 22 — clypeus, dorsal.

FIGURES 23 – 33. Rioneta uluguruensis, details of morphology. 23 — mesonotum, mesoscutellum, basal part of metascutellum, mesopleuron and basal part of metapleuron, elytra omitted, dorsal; 24 — pterothorax and abdomen, elytra omitted, dorsal; 25 — left metapleuron, lateral; 26 — apex of abdomen showing location of internal glands, dorsal (separately on the left showing right internal gland, enlarged); 27 — fused abdominal tergites VIII – IX and partly fused tergite X, dorsal; 28 — abdominal sternites VIII—IX, male, ventral; 29, 30 — spermatheca and sperm pump, partly oblique; 31, 32 — aedeagus with apex directed upwards, dorsal (31) and ventral (32); 33 — abdominal sternite IX, male, ventral.

FIGURES 34 – 36. 34, 35 — Rioneta uluguruensis, spermatheca, transparent light microscopy images, scale 0.05 mm; 36 — map of Eastern Arc Mountains with arrow showing Uluguru Mountains, the type locality and known area of distribution of both Rioneta species.