Leptocera nigra, Olivier. Two, 1813

Buck, Matthias & Marshall, Stephen A., 2009, Revision of New World Leptocera Olivier (Diptera, Sphaeroceridae), Zootaxa 2039 (1), pp. 1-139 : 116-117

Leptocera nigra species group

Species included. Neotropical (apparently introduced): L. nigra Olivier. Two other species occur in the Old World and Australasia: L. salatigae (de Meijere) , L. sterniloba Roháček. (Note: we have examined numerous specimens of the latter two species from various countries throughout their range; DEBU, CNCI, ANIC, BPBM, CMNH).

Diagnosis. Body length 1.4–2.4 mm. Lower orbital bristle ca. 0.6x as long as upper one. Arista shortpubescent. Palpus slender. Mesoscutum with 4–5 dorsocentrals (anterior 1–2 very small). Acrostichals uniform except for slightly enlarged prescutellar pair. Wing relatively short, R 2+3 strongly curved up to C (cf. Roháček, 1982: Fig. 69 ; 1983: Fig. 3 ). Fore tarsus not sexually dimorphic. Mid tibia with lowermost bristle of proximal posterodorsal series short, ca. 0.6x as long as lowermost bristle of anterodorsal series; bristle above distal dorsal very short, almost hairlike, shorter than bristle above distal anterodorsal; posteroapical bristles greatly unequal: ventral one very long, almost half as long as mid basitarsus, dorsal one very short, extending at most slightly beyond tibial apex ( Fig. 29 ).

Male terminalia: Sternite 5 pale and deeply emarginate posteromedially but lacking field of dense microtrichia, emargination bordered on each side by densely spinulose or microtrichose lobe (e.g., Fig. 275 ). Sternite 8 separate from epandrium. Epandrium with sparse and short hairing, only with one longer bristle posteroventrally on each side. Surstylus highly characteristic: anterior section with anterior process reduced; posterior section very short (shorter than cercus), divided into 2–3 bristly lobes, lacking stout bristles. Cercus comma-shaped, with a few bristles on stout basal portion, very similar to L. fontinalis group. Postgonite lacking posterobasal notch (lateral view).

Female terminalia: Tergite 7 simple (neither lengthened nor conspicuously shortened, without enlarged paramedian bristles or shining areas). Sternite 7 simple. Sternite 8 characteristic (e.g., Fig. 278 ): broad rectangular (at least twice as wide as long), with posterior margin slightly shorter than anterior one and posterior corners acute; posteromedial lobe truncate, not very prominent. Tergite 10 and cerci completely fused, relatively large, with four hairs near base and several hairs (including one moderately enlarged pair) in distal third. Spermathecae elongate and cylindrical (e.g., Fig. 277 ), at least twice as long as wide, with rounded apex and striate surface structure, base with or without short, tubercles (not spicules).

Taxonomy. Species identification relies exclusively on the male and female terminalia.

Biogeography. This species group is widely distributed in the Old World and Australasia ( Roháček et al., 2001). One species ( L. nigra ) is newly recorded from Venezuela.

Phylogeny. The L. nigra group in the present sense was defined by Roháček (1983). This group is clearly monophyletic based on the characteristic surstylus structure (i.e., posterior section divided into 2–3 lobes, lacking stout bristles), lobate male sternite 5, shortened anterior orbital bristle (also found in the Neotropical L. fulva group), and greatly enlarged ventral posteroapical bristle (also found in some Oriental species such as L. nigrolimbata Duda ).

Biology and habitat. Only the larval habitat of L. nigra has been recorded. In Europe the species breeds in mud or wet soil with a high proportion of organic matter ( Papp, 1973b, 1976), decaying vegetation ( Buck, 1997: rotten wheat grains) and sewage filter beds ( Learner, 2000). Rearing records from other decaying substrates such as dung ( Skidmore, 1978) and vertebrate carrion ( Buck, 1997; Froese, 1992) are highly exceptional. In Europe adults seem to be most common in open habitats that provide a sufficient measure of moisture (meadows, forest clearings, gardens, marshy areas; always near water in arid areas).

Figures

FIGURES 69–75. Leptocera gongylotheca sp.n. (Argentina). Male terminalia (phallus and postgonites omitted): (69) lateral; (70) posterior; (71) ventral; (72) sternite 5. Female terminalia: (73) dorsal; (74) spermathecae; (75) ventral. cp—finger-like process of cercus, da—desclerotized area, proc—process at base of posterior section of surstylus, sa—shining area of tergite 7.

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 16–29. Leptocera mid tibiae and basitarsi. Mid tibia, dorsal: (16) L. neocurvinervis (Chile); (17) L. duplicata (Juan Fernández Is.). Apical half of mid tibia and basitarsus, posterior: (18) L. parallelipennis sp.n. (Juan Fernández Is.); (19) L. ellipsipennis (Juan Fernández Is.); (20) L. erythrocera (Honduras); (21) L. sphaerotheca sp.n. (Mexico); (22) L. plax sp.n. (Ecuador); (23) L. tapanti sp.n. (Costa Rica); (24) L. cymatonota sp.n. (Mexico); (25) L. parafinalis (Canada); (26) L. neofinalis sp.n. (Canada); (27) L. kanata sp.n. (Canada); (28) L. fontinalis (France); (29) L. nigra (South Africa). d ad—distal anterodorsal bristle, d d—distal dorsal bristle, d pa—dorsal posteroapical bristle, l ad—lowermost bristle of proximal anterodorsal series, l pd—lowermost bristle of proximal posterodorsal series, mv—midventral bristle, pa v—preapical ventral bristle, vb—ventrobasal bristle of basitarsus, v pa—ventral posteroapical bristle.

FIGURES 273–278. Leptocera nigra (273–275: Spain, 276–278: Venezuela). Male terminalia (phallus and postgonites omitted): (273) lateral; (274) posterior; (275) sternite 5. Female terminalia: (276) dorsal; (277) spermathecae; (278) sternites 7 and 8. ass—anterior section of surstylus, ce—cercus, cp—ventral process of cercus, ep—epandrium, fm—field of dense microtrichia, ha—hypandrial apodeme, pa—phallapodeme, pss—posterior section of surstylus, S—sternite, se—subepandrial sclerite, T—tergite (female tergite 8 divided into two halves).