Leptomorphus gracilis Matile

Borkent, Christopher J. & Wheeler, Terry A., 2012, Systematics and Phylogeny of Leptomorphus Curtis (Diptera: Mycetophilidae) 3549, Zootaxa 3549, pp. 1-117 : 36-37

16. Leptomorphus gracilis Matile

( Figures 18, 57, 106, 135, 150, 153)

Leptomorphus (Gymnoscutum) gracilis Matile, 1977: 151 .

Leptomorphus (Gymnoscutum) elegans Matile, 1997: 144 . new synonym.

Leptomorphus (Gymnoscutum) lepidus Matile, 1997: 145 . new synonym.

References: Crosskey 1980: 1221 (catalogue appendix); Matile 1997: 147–149 (figures, new records, morphological variation, key).

DIAGNOSIS: The only extant species of Leptomorphus with the following combination of characters: laterotergite, anepisternum and anepimeron yellow; scutellum brown; male genitalia with posterolateral projection (tg evg) of tergite 9 either square or with slightly acute angle on medial corner, gonostylus with shortest lobe rounded ( Fig. 106).

This species can be distinguished from most other Afrotropical species by the brown scutellum and lack of small setae covering the scutum (except along dorsocentral lines). It can be separated from L. crosskeyi by the smaller width of the posteromedial concavity of tergite 9 and lack of a thin point on the medial corner of the tergal evagination and from L. obscurus by the almost square posterior margin of the tergal evaginations ( Fig. 106).

DESCRIPTION: Male. ( Fig. 18) Head: yellow, with some brown lateral spots, circular in anterior view. Antenna brown; scape light brown/dark yellow, with brown 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 present; pedicel light brown, with 2 large bristles, several setae on apicodorsal margin, a number of fine setae on apicoventral margin; flagellomere 1 completely brown/ dark brown; flagellomere 6 1.6X as long as broad. Clypeus yellow to light brown, dorsoventrally elongate oval; bristles on clypeus brown, 4–6 strong bristles on ventral margin directed ventrally, remaining setae directed medioventrally, clypeus 2X as long as face. Face yellow to light brown; shape a just longer than wide triangle, with few bristles ventrolaterally. Frons yellow, sometimes with a thin line of brown dorsally; with few bristles medioventrally, frontal furrow running full distance from dorsal margin towards ventral margin, frontal cleft just anterior of median ocellus. Palpus with segments 1–2 yellow, remainder brown; segment 1 hidden behind eye, segments increasing in length, segment 5 2X length of segment 4 with central half thinner than base and apex, segment 3 with apicolateral patch of fine yellow setae encircled by strong dark setae. Labellum yellow. Eye with inter-ommatidial setulae absent. Occiput yellow with dorsolateral brown spots, with appressed, anteriorly directed setae. Ocelli in a straight line, space between ocelli less than diameter of laterals, lateral ocelli 2X their own diameter from eye margin, ocellar triangle dark brown/ black with electric blue green specks. Thorax: Length 1.12 mm (0.98–1.23 mm, n = 3). Brown or dark brown dorsally, yellow laterally. Scutum dark brown/black with blue-green specks, pair of yellow mediolateral and posterolateral spots; 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 brown; with 4–10 large bristles. Prescutum yellow. Mediotergite brown/dark brown with 6–8 bristles on posterolateral corners, with anteromedial patch of small setae. Laterotergite yellow; anterior margin of laterotergite not reaching katepisternum. Anepimeron yellow. Anepisternum yellow. Katepisternum yellow. Antepronotum and proepisternum yellow. Margin of anterior and posterior spiracles yellow with brown trichia. Metepisternum yellow. 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 dark brown on all femora; tarsi brown. Midfemur without apical spine-like process. Tibia with covering of brown macrotrichia, foretibia without comb of short setae along length of anteroventral surface, tibial spurs brown, foretibial spur length 2.5X apical thickness of foretibia, midtibia with strong, dorsal, bare patch of even thickness for 3/4 of its length, placed basally, shortest midtibial spur 0.75X length of longest, longest midtibial spur 4.5X 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 1.8X length of foretibia. Wing ( Fig. 57): Length 5.1 mm (4.8 – 5.4 mm, n = 3). Hyaline; apical macula absent; medial macula absent. Macrotrichia in all cells, though absent from posterobasal margin of cell a. 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 before or after 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 near margin but reaching wing margin. M 4 -CuA fork arising apically of origin of r-m. A 2 faintly present as crease. Abdomen: Tergite and sternite 1 yellow with posteromedial dark brown square or band, remaining tergites and sternites principally dark brown, 2–5 with anterior 1/3 yellow, 6 with anterior 2/3 yellow, 7 yellow or light brown, sometimes with posterior brown band. Tergite 8 smaller than all other abdominal sclerites, with 4–8 bristles on each apicolateral corner. Genitalia ( Fig. 106): light brown. Sternite 9 sclerotized, rounded diamond shape, 1/3 the width of genitalia at widest point, overlapping medial margin of gonocoxite. Tergite 9 longer than wide, with lateral margins slightly rounded and tapering apically into lateral ~squared off lobes with medial U-shaped indentation, two ventrally extending spines at base of posterior lobe. Gonocoxite placed basally on T9, medial margin not reaching medial line, bearing gonostylus apically. Gonostylus with two lobes both with rounded tip, dorsal lobe with broad base, ventral lobe 2X length but half the width of dorsal, gonocoxite III fused to dorsolateral margin. Aedeagus 2/3 length of T9, gradual tapering towards apex, apodemes 1/4 total length. Parameres a simple taper, apodemes ~3/4 length of parameres.

Female. Unknown.

Immatures. Unknown.

BIOLOGY: Unknown.

DISTRIBUTION: Central African Republic and Gabon ( Fig. 135), 200–520 masl.

DISCUSSION: Examination of the holotype specimens of Leptomorphus elegans and L. lepidus showed no significant differences between these species and L. gracilis . Leptomorphus elegans and L. lepidus are therefore considered new synonyms of L. gracilis . 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 male, pinned on double mount minuten, genitalia in glass vial on pin, labelled “[Blue label] REP. CENTRAFRIC./ LA MABOKE/ 29.VIII.1967 / L. MATILE rec.; [Red label] HOLOTYPE; Leptomorphus / (Afroleptomorphus)/ gracilis n. sp. ♂ ht/ L. Matile det. 1974; HOLOTYPE ♂ / Leptomorphus gracilis / Matile / Det. C.J. Borkent, 2012” [MNHN].

Other material: GABON, Makokou M’Passa , Bale Affl., 7–16.v.1979, J. Legrand (1♂, MNHN, HT of L. elegans ); same except 21–28.v.1979, (1♂, MNHN, HT of L. lepidus ) .