Leptocera parallelipennis, Buck & Marshall, 2009

Buck, Matthias & Marshall, Stephen A., 2009, Revision of New World Leptocera Olivier (Diptera, Sphaeroceridae), Zootaxa 2039 (1), pp. 1-139 : 61-62

Leptocera cultellipennis subgroup

Species included. L. cultellipennis (Enderlein) , L. duplicata Richards , L. ellipsipennis Richards , L. parallelipennis sp.n.

Description. Orbit without additional setulae behind level of upper orbital bristle. Arista short- to medium-pubescent (as in Figs. 4, 5 ). Palpus slender. Scutum with two pairs of greatly enlarged presutural acrostichals ( Fig. 109 : ac). Wing usually greatly reduced, extending slightly beyond level of tip of scutellum ( Figs. 11–15 ; except in L. duplicata ), strongly infuscated. R 4+5 only slightly curved forward in the macropterous L. duplicata . Fore tarsus not sexually dimorphic. Main bristles of mid tibia unusually long and strong ( Fig. 17 ), with four proximal posterodorsal bristles (instead of the usual 2–3), lowermost bristle shifted distally (very slightly so in L. cultellipennis ), inserted at or just below middle of tibia. Micropterous species differ from L. duplicata as follows: Knob of halter reduced. Syntergite 1+2 lacking the usual pale anterobasal area (only visible when abdomen is cleared). Bristles at posterior margin of tergites 2–5 enlarged.

Male terminalia: Sternite 5 with small pale area in front of posteromedial field of microtrichia; hind margin lacking enlarged scales (e.g., Fig. 113 ; except in L. ellipsipennis ). Epandrium with few long bristles ventrally. Posterior section of surstylus without process at base.

Female terminalia: Spermatheca elongate with dilated apical portion (e.g., Fig. 115 ).

Biogeography. This group of species is endemic to Robinson Crusoe I. (Juan Fernández Is., Chile).

Phylogeny. The L. cultellipennis subgroup is clearly monophyletic as evidenced by the autapomorphic mid tibia chaetotaxy (lowermost bristle of proximal posterodorsal series shifted distally) and two pairs of greatly enlarged acrostichal bristles. The lack of orbital setulae behind the upper orbital bristle is probably also apomorphic (reversal to ancestral state), since the closest relatives of this species group on the South American mainland all have such setulae.

Figures

FIGURE 109. Leptocera parallelipennis sp.n., holotype male (Juan Fernández Is.). ac—enlarged acrostichal bristles, dc—dorsocentral bristles, m—marginal bristles, phu—posthumeral bristle.

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 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 110–116. Leptocera cultellipennis (Juan Fernández Is.). Male terminalia (phallus and postgonites omitted): (110) lateral; (111) posterior; (112) ventral; (113) sternite 5. Female terminalia: (114) dorsal; (115) spermathecae; (116) ventral. lp—lamellate process of cercus.