Leptocera dicrofulva, Buck & Marshall, 2009

Buck, Matthias & Marshall, Stephen A., 2009, Revision of New World Leptocera Olivier (Diptera, Sphaeroceridae), Zootaxa 2039 (1), pp. 1-139 : 100-102

Leptocera fulva species group

Species included. L. dicrofulva sp.n., L. fulva (Malloch) , L. insularum sp.n., L. prolixofulva sp.n., L. rhadinofulva sp.n.

Description. Body length 1.8–2.5 mm. Body brown, the following yellow to dirty yellowish brown ( Figs. 230 , 3 ): at least anterior half of frons, face, gena, antenna (dorsal surface sometimes darker), palpus, sutures of thorax, legs except most of mid coxa. Thorax sometimes with obscure, orange-yellow postpronotal lobes, illdefined dorsocentral stripes in at most anterior third of mesoscutum (fading posteriorly) and lateral spots in front of transverse suture. Wing ( Fig. 10 ) greyish hyaline with slight yellowish tinge. Halter white, stem whitish brown. Lower orbital bristle short, 0.5–0.6x as long as upper one ( Fig. 3 ). No additional setulae on orbit behind upper orbital bristle. Palpus slender. Arista long-pubescent. Mesonotum thinly pruinose and subshining excluding velvety brown disc of scutellum ( Fig. 9 ). Chaetotaxy of mesoscutum more reduced than in other species groups ( Figs. 9 , 230 ): 3–4 dorsocentral bristles, fourth one from behind, if differentiated, only slightly longer than surrounding hairs; acrostichals completely uniform, short and hair-like except for enlarged prescutellar pair. Fore tarsus with apical tarsomeres slightly wider in male than in female. Mid tibia with lowermost bristle of proximal posterodorsal series short, 0.5–0.6x as long as lowermost bristle of anterodorsal row; bristle above distal dorsal short, shorter than corresponding bristle above distal anterodorsal; posteroapical bristles unequal, ventral one about twice as long as dorsal one, extending about 0.7–0.8x length of distance towards base of ventrobasal metatarsal bristle. Abdominal sternites, especially of male, with conspicuous bluish-green pruinosity. Male sternites 3 and 4 with erect hairs that are more or less recurved.

Male terminalia: Sternite 5 (e.g., Fig. 242 ) with field of enlarged microtrichia posteromedially, desclerotized near hind margin; hind margin with a row of enlarged black scales (scales in mid section much shorter than lateral ones). Sternite 8 completely fused with epandrium. Epandrium dark brown, shield-like (wide and shallow), on each side with a fan-like cluster of long bristles above lower margin. Cercus yellow, slender and sparsely haired (e.g., Fig. 240 ), in some species divided into dorsal and ventral arms (e.g., Fig. 233 ). Anterior section of surstylus flat (lacking distinct ventral lobe), with one long bristle posteriorly, otherwise only with short bristles except in L. dicrofulva sp. n. and L. insularum sp. n. Anterior process of anterior section of surstylus rounded, apical portion bare (devoid of microtrichia), anterior margin finely crenulate, posterior margin with a series 3–4 of short bristles. Posterior section of surstylus elongate, sometimes club-shaped (expanded distally), apical half with one long, curved bristle on inner margin (depending on species either inserted near apex or more or less removed from apex). Apex of surstylus either with stout (sometimes blunt-tipped) or with slender bristles. Postgonite characteristic ( Figs. 267, 268, 271 ), without conspicuous bend, lacking posterobasal notch.

Female terminalia: Sternite 7 modified (e.g., Fig. 245 ), usually with posteromedian field of enlarged microtrichia and with posteromedian projection (except L. dicrofulva sp.n.). Sternite 8 relatively uniform, trapezoid with narrow, apically rounded posterolateral flaps. Tergite 10 and cerci completely fused to each other, with one pair of long bristles and several shorter hairs. Spermathecae spherical (e.g., Fig. 237 ), with short spicules at base, surface finely striate.

Taxonomy. The species of this group are practically identical externally. Fortunately, the most important distinguishing characters of the male and female terminalia can usually be seen without dissection (but with high magnification). Diagnostic are shape and chaetotaxy of the posterior section of the surstylus and cercus in the male, and shape of sternite 7 and chaetotaxy of tergite 10 + cerci in the female.

Biogeography. The L. fulva group is restricted to tropical areas of the Neotropical region (including Caribbean Islands) and adjacent areas (southern Florida). In South America it ranges as far south as northern Argentina.

Phylogeny. This species group is undoubtedly monophyletic as evidenced by the shortened lower orbital bristle, characteristic male cercus, surstylus and postgonite, as well as the field of enlarged posteromedial microtrichia of female sternite 7.

Biology and habitat. Adults are rarely attracted to dung or carrion but are frequently collected in malaise traps, flight intercept traps or by aerial sweeps. Three species have been collected at lights ( L. dicrofulva sp.n., L. fulva , L. rhadinofulva sp.n.). The larvae probably develop in decaying vegetation or in the soil. Mostly distributed in lowlands (usually below 1,500 m), occasionally up to 2,100 m.

Figures

FIGURES 230–231. Leptocera fulva, males (Costa Rica).

FIGURES 2–6. Leptocera heads and antennae. Heads of (2) L. argentinica sp.n. (Argentina); (3) L. fulva (Costa Rica). Arista and first flagellomeres of (4) L. aequilimbata (Peru); (5) L. neocurvinervis (Chile); (6) L. caenosa (U.S.A.). ad s—additional setulae on orbit, l or—lower orbital bristle, u or—upper orbital bristle.

FIGURES 10–15. Leptocera wings: (10) L. fulva (Belize); (11–12) L. ellipsipennis, showing variation (Juan Fernández Is.); (13) L. cultellipennis (Juan Fernández Is.); (14) L. parallelipennis sp.n., normal wing venation (Juan Fernández Is.); (15) ditto, aberrant venation. Scale bar 0.1 mm. Cs—costal sector.

FIGURES 7–9. Leptocera thoraces: (7) L. cymatonota sp.n. (Guatemala); (8) L. hexadike sp.n. (Costa Rica); (9) L. fulva (Belize). ad sc—additional scutellar bristles.

FIGURES 239–245. Leptocera fulva (Belize, except 244: U.S.A.). Male terminalia (phallus and postgonites omitted): (239) lateral, cercus omitted; (240) posterior; (241) ventral, cerci omitted; (242) sternite 5. Female terminalia: (243) dorsal; (244) spermathecae; (245) ventral. ce—cercus.

FIGURES 232–238. Leptocera dicrofulva sp.n. (232–235: Ecuador, 236–238: Brazil). Male terminalia (phallus and postgonites omitted): (232) lateral; (233) posterior, arms of left cercus omitted; (234) ventral; (235) sternite 5. Female terminalia: (236) dorsal; (237) spermathecae; (238) ventral. aps—anterior process of anterior section of surstylus, ce—cercus, cda—dorsal arm of cercus, cva—ventral arm of cercus, ep—epandrium, fm—field of dense microtrichia, ha—hypandrial apodeme, hy—hypandrium, pa—phallapodeme, pss—posterior section of surstylus, S—sternite, sc—enlarged scales, se—subepandrial sclerite, T—tergite (female tergite 8 divided into two halves), vls—ventral lobe of anterior section of surstylus.

FIGURES 267–272. Postgonites and aedeagal complex of Leptocera fulva group. Postgonites of (267) L. dicrofulva sp.n. (Ecuador), (268) L. prolixofulva sp.n. (Venezuela). Aedeagal complex of L. fulva (Belize): (269) posterior; (270) anterior; (271) lateral; (272) dorsal. bcp—basal connection between postgonites, bp—basiphallus, dp—distiphallus, ea—ejaculatory apodeme, pa—phallapodeme, pg—postgonites.