Leptomorphus chaseni Edwards

Borkent, Christopher J. & Wheeler, Terry A., 2012, Systematics and Phylogeny of Leptomorphus Curtis (Diptera: Mycetophilidae) 3549, Zootaxa 3549, pp. 1-117 : 23-24

7. Leptomorphus chaseni Edwards

( Figures 7, 48, 137, 150, 152)

Leptomorphus chaseni Edwards, 1933a: 229 .

Leptomorphus (Gymnoscutum) chaseni: Matile, 1977: 145 .

References: Colless & Liepa 1973: 454 (catalogue); Matile 1977: 141,145 (subgeneric placement); Papp & Ševčík 2011: 139 (notes on identity).

DIAGNOSIS: The only extant species of Leptomorphus with the following combination of characters: Laterotergite and anepisternum brown; wing without apical spot ( Fig. 48); vein sc-r joining R within its own length of origin of Rs; segments 3–5 of abdomen noticeably swollen relative to other segments. Male unknown.

This species can be distinguished from the other Oriental and eastern Palaearctic species in this manuscript, based on the dark brown colour of the katepisternum and metepisternum ( Fig. 7, both completely yellow in L. babai ( Fig. 2), L. ornatus ( Fig. 30) and L. titiwangsensis ( Fig. 38); metepisternum light brown in L. tabatius ( Fig. 35) and half brown/ half yellow in L. tagbanua ( Fig. 40)). The lack of adequate description by Papp & Ševčík (2011) makes it difficult to distinguish this species from theirs, especially as L. chaseni is known only from the female.

DESCRIPTION: Female. ( Fig. 7) Head: Yellow, circular in anterior view. Antenna with basal flagellomeres lighter brown, darkening apically; scape yellow, with black setae in single apical row extending from dorsum laterally into thick patch covering apicoventral process, basal third and entire medial surface bare, anterobasal patch of setulae absent; pedicel yellow, with 3–4 large bristles, several setae on apicodorsal margin, none ventrally; flagellomere 1 with tapered base yellow remainder brown; flagellomere 6 1.0X as long as broad. Clypeus yellow, square; bristles on clypeus brown, 2–3 strong bristles on ventral margin directed ventrally, remaining setae directed medioventrally, clypeus 1.5X as long as face. Face yellow; shape a slightly wider than tall triangle; bare. Frons yellow; bare, frontal furrow running full distance from dorsal margin towards ventral margin, frontal cleft more than 1X diameter of median ocellus anterior of median ocellus. Palpus with segments 1–4 yellow, segment 5 brown; segment 1 hidden behind eye, segments increasing in length, segment 5 1.3X length of segment 4 with central half thinner than base and apex, segment 3 spherical with apicolateral depressed patch of fine yellow setae partially encircled by strong dark setae. Labellum yellow. Eye with very few, short inter-ommatidial setulae scattered on surface. Occiput yellow with appressed, anteriorly directed setae. Ocelli with median slightly in front of laterals, space between ocelli less than diameter of laterals, lateral ocelli 2X their own diameter from eye margin, ocellar triangle dark brown/black. Thorax: Length 1.23 mm (n = 1). Dark brown. Scutum dark brown; surface of scutum bare; acrostichal setae absent; dorsocentral setae present as fine setae for most of length; multiple rows of lateral setae present; patch of setae on scutum at wing base present. Scutellum yellow; without large bristles but few small bristles. Prescutum brown. Mediotergite dark brown with 10 bristles on posterolateral corners, few medially. Laterotergite brown; anterior margin of laterotergite abutting katepisternum. Anepimeron brown. Anepisternum brown. Katepisternum brown. Antepronotum and proepisternum brown. Margin of anterior and posterior spiracles yellow with yellow trichia. Metepisternum brown. Anapleural suture with anterior portion slightly curved dorsally. Halter with basal 1/3 of stem ivory, apical portion and knob dark brown. Legs: principally yellow; extreme anteroapical corner yellow on all femora. Tibia with covering of yellow macrotrichia, tibial spurs yellow, foretibial spur length 2X apical thickness of foretibia, midtibia with faint, fragmented, dorsal, bare patch of even thickness along its length, shortest midtibial spur subequal to length of longest, longest midtibial spur 4X apical thickness of midtibia, shortest hind tibial spur subequal to length of longest, longest hind tibial spur 3.5X apical thickness of hind tibia. Foreleg first tarsomere 1.7X length of foretibia. Wing ( Fig. 48): Length 5.3 mm (n = 1). Hyaline; apical macula absent; medial macula absent. Macrotrichia in all cells. Setae on basal posterior margin of wing (along base of cell a) alternating long, short. Calypter with a few short setae. Vein sc-r present, apical end joining R within its own length prior to origin of Rs. R 4 absent. R 5 straight, slight posterior turn near tip. M 1 reaching apex before R 5, apices of M veins fading before wing margin. M 4 -CuA fork arising at same level as r-m. A 2 absent. Abdomen: Abdominal segments 3–5 swollen relative to other segments; tergites 3–5 with anterior 1/3 yellow, remainder dark brown/black. Cercus yellow.

Male. Unknown.

Immatures. Unknown.

BIOLOGY: Unknown.

DISTRIBUTION: Northern Borneo [Kenokok, Mt Kinabalu] ( Fig. 137), 1000 masl.

DISCUSSION: It is quite possible that one of the three species described from northern Borneo by Papp & Ševčík (2011) is a synonym of L. chaseni , as it is only known from the female. As discussed below in the phylogeny section, the placement of Leptomorphus species in subgenera ( Matile 1977) is not supported by our phylogenetic results. This species is therefore removed from the subgenus Gymnoscutum and placed solely in Leptomorphus .

MATERIAL EXAMINED: Holotype: adult female, pinned on double mount, labelled “[ Circular label with red edge] HOLO-/ TYPE; B.N. BORNEO/ Mt. Kinabalu,/ Kenok,/ 3,300 ft. / 26 th. Apr. 1929./ [underside of label] H.M. Pendlebury / coll./ F.M.S. Museums.; [underside of label] Pres. by/ F.M.S. Museum / B.M. 1930–510; HOLOTYPE / Leptomorphus / chaseni/ Edwards/ det. J.E. Chainey, 1996.; [underside of label] BMNH (E) #/ 257836” [ BMNH].