Leptomorphus sevciki Kaspřák & Borkent, 2017

Kaspřák, David, Borkent, Christopher J. & Wahab, Rodzay Abdul, 2017, Leptomorphus sevciki sp. nov., a remarkable new wasp-mimicking fungus gnat from Brunei (Diptera: Mycetophilidae), Acta Entomologica Musei Nationalis Pragae 57 (1), pp. 195-203 : 197-200

Leptomorphus sevciki Kaspřák & Borkent sp. nov.

Type material. HOLOTYPE: J, BRUNEI: Ulu Temburong National Park, Kuala Belalong Field Studies Centre , primary forest, 4°33′07.5″N 115°09′26.8″E, 14.i.2014, J. Ševčík and D. Kaspřák leg., ex pupa (coll. UBD, in ethanol). Specimen voucher number JSS25a-LS1 . PARATYPES: BRUNEI: Ulu Temburong National Park, Kuala Belalong Field Studies Centre , primary forest, 4°33′07.5″N 115°09′26.8″E, 8–20.i.2014, ex pupa, J (JSS25c-LS2) and ♀ (JSS25e- - LS3 ) (coll. UBD, in ethanol) ; 3 JJ (pinned, JSS25- LS4 , JSS25- LS5 , JSS25- LS6 ), 1 ♀ (pinned, JSS25- LS7 ) and 1 ♀ (in ethanol, JSS25f-LS8) (coll. JSL-UOC) ; 1 J (JSS25- LS9 ) and 1 ♀ (JSS25- LS10 ) (coll. CSCA, pinned) ; and 1 J (JSS25- LS11 ) (coll. NMPC, pinned) .

Immature material not included in type series: BRUNEI: Ulu Temburong National Park, Kuala Belalong Field Studies Centre, primary forest, 4°33′07.5″N 115°09′26.8″E, 8–20.i.2014, 2 L and 2 P (coll. JSL-UOC, in ethanol).

Diagnosis. The only extant species of Leptomorphus with the following combination of characters: male antennae covered in long setae (unique in the genus); yellow V-shaped marking on the dorsal side of dark brown scutum; katepisternum yellow and brown; metakatepisternum partially dark brown; abdominal segments swelling towards the apex of terminalia. Sternite 9 with medioventral lobe and a pair of lateroventral lobes bearing four dark megasetae apically. Description. Male. Body length 14.3 mm. General colouration dark brown and dark yellow, yellow-orange and brown striped abdomen ( Fig. 1, 3 ).

Head. Dark brown, light brown laterally with many long setae. Ocelli yellow, in a straight line. Face yellow. Flagellomeres dark brown, densely covered with long, fine, dark brown setae ( Fig. 5 ). Basal part of first flagellomere yellow. Scape and pedicel yellow, setae on at least the anterior surface. Face and clypeus covered with many long setae. Clypeus and palpus light brown.

Thorax. Mostly dark brown. Scutum dark brown with dorsal yellow V-shape marking, covered with fine hairs, several long light setae along margin ( Fig. 6 ). Scutellum light brown, with many short setae. Antepronotum, proepisternum, anepisternum, anepimeron and laterotergite dark brown. Proepisternum covered with light setae. Paratergite light to dark brown. Laterotergite with several long setae. Anepisternum and anepimeron bare. Katepisternum anterior dark brown and posterior yellow, bare. Metakatepisternum partially dark brown, bare. Mediotergite yellow, bare. Margin of anterior and posterior spiracles yellow with yellow trichia. Haltere: stem yellow, knob dark brown.

Wing ( Fig. 7 ). Hyaline, membrane densely covered with irregularly arranged macrotrichia. Cell among base of R 1, crossvein r-m and M bare, sector between veins M and CuA bare except apically. Apical shading dark brown but fading towards apex and posterior margin (pale brown apical wing shading not reaching to wing tip), running from anterior to posterior wing margin, beginning halfway along R 5. Medial macula small, only around Rs. Costa ending at tip of R 5. Sc short, ending in costa beyond base of r-m. Vein sc-r ending beyond Rs. Vein R 4 absent. Vein R 5 slightly concave for entire length. Crossvein r-m relatively long (twice as long as radial sector). Apex of crossvein r-m lighter than base. Apices of M and CuA veins clearly reaching wing margin. Point of furcation of CuA and M 4 well before crossvein r-m. CuP thick, slightly shorter than A

1

. A

1

distinct.

Legs. Coxae principally yellow, forecoxa dark brown and hind coxa with anterior dark brown mark. All trochanters brown. Femora yellow, dark long setae laterally, hind femur brownish, dense setulae and dark brown mark beginning one third of length of hind femur and reaching beyond midpoint. Fore tibia yellow with basal brown mark, dense row of anteroventral bristles absent. Mid tibia entirely dark brown with irregular rows of short dark bristles. Hind tibia yellow with basal dark brown mark longer than fore tibia basal mark. Tarsi dark brown. First and second hind tarsomeres yellowish to light brown with dark brown apex.

Abdomen. Tergites principally dark brown, tergites 1–6 with anterior third light brown. Tergites 7–8 dark brown. Sternites brown. Posterior 4 segments of abdomen noticeably swollen relative to other segments ( Fig. 3 ).

Terminalia (Figs 9–12). Light brown, apex of gonostyli and medioventral lobe of sternite 9 darker. Sternite 9 sclerotized, medially covered with long setae, with medioventral lobe and a pair of lateroventral lobes, dark brown suture mediobasally. Medioventral lobe bare, as long as sternite 9, covering cerci, with two rounded processes bent ventrally and apical dark blunt bristles. Lateroventral lobe with bumpy margin, with several long setae and four dark apical megasetae. Tergite 9 sclerotized, densely covered with short setae and V-shaped indentation on the apex, bare transparent tapering part of base. Gonostyli bare, except lateral margin with long setae, dark blunt bristles on medial margin of apex, lateral rounded process and medial hooked process. Apex of gonostylus dark, tapering towards apex. Cerci and hypoproct covered with short trichia and long apical setae. Parameres strongly hooked at apex.

Female ( Figs 2, 4 ). Similar to male with following differences: antennal setae short, hind femur lighter with brown mark only anteriorly, genitalia lighter. Tergite 9 yellow, with long setae. Tergite 10 yellow, row of several long and shorter setae on posterior margin. Cerci brown, setose. Gonopore 9 brown. Gonocoxite 8 posteriorly brown and setose ( Fig. 8 ).

DNA sequences. DNA sequences taken from the holotype and one male paratype are deposited in the GenBank database, with following GB accession numbers: JSS25a-LS1 (holotype): 12S: MF045798 , 16S: MF045800 , COI: MF045803 , cytB: MF045805 , 28S: n/a ; JSS25c- LS2 (paratype): 12S: MF045799 , 16S: MF045801 , COI: MF045804 , cytB: MF045806 , 28S: MF045802 .

Etymology. This species is named after Jan Ševčík, a specialist on Diptera associated with fungi and supervisor of David Kaspřák’s Ph.D. study, who was the first to spot the specimens of the new species in Ulu Temburong National Park.

Biology. The larvae and pupae of the new species were found on the underside of a log over a small brook. The larvae spun a silk sheet over the surface of an unidentified wood encrusting fungus ( Fig. 13 , Video: https://youtu.be/89HN2255ZOs). The pupae were hanging from a singly anchored 3–5 cm long yellowish thread, bearing a drop of brownish liquid ( Fig. 14 , Video: https://youtu.be/89HN2255ZOs). The behaviour of the flying adults and their colouration were reminiscent of wasps or ichneumonids (Hymenoptera).

Figures

Figs 1–4. Leptomorphus sevciki sp. nov.: 1 – male (Photo: J. Ševčík); 2 – female (Photo: J. Ševčík); 3 – male, habitus; 4 – female, habitus.

Figs 5–8. 5–7 – Leptomorphus sevciki sp. nov., male: 5 – antennae; 6 – thorax, V-shape mark; 7 – wing; 8 – female, genitalia, lateral view.

Figs 13–15. 13 – The larvae of Leptomorphus sevciki sp. nov. on the surface of an unidentified wood encrusting fungus growing on a log in a rainforest in Brunei. 14 – The pupae of L. sevciki sp. nov., on the underside of a log in a rainforest in Brunei. 15 – The fallen tree over a pathway with hanging pupae in Ulu Temburong National Park in Brunei. (Photos: J. Ševčík).