Leptocera plax Buck, 2009

Buck, Matthias & Marshall, Stephen A., 2009, Revision of New World Leptocera Olivier (Diptera, Sphaeroceridae), Zootaxa 2039 (1), pp. 1-139 : 121-123

Leptocera plax Buck , new species

( Figs. 22 , 280–286 , 297–301 )

Description. Body length 2.1–4.0 mm. Prosternum with (1–)2(–3) setulae on a small, brown plate on each side of midline. Pattern of scutum distinct: posterolateral areas (lateral of dorsocentral lines and posterior to presutural intra-alar bristle) with conspicuous blue (instead of colourless) reflections. Scutellum distinctly velvety. Mid tibia with dorsal posteroapical bristle only ( Fig. 22 ), ventral posteroapical not differentiated (indistinguishable from surrounding hairs).

Male terminalia ( Figs. 280–283 ): Sternite 5 with long, pale bristles near hind margin, and 8–10 strong, black marginal scales; lateral scales about twice as long/strong as medial ones; the pale field in front of scales small, with small black teeth that are similar to the marginal scales but smaller. Sternite 8 tightly joined but completely separate from epandrium. Epandrium on each side with one row of long bristles above ventral margin; the bristles above this row very sparse and short (except those along hind margin). Perianal field not narrowed ventrally, with U- shaped outline. Anterior section of surstylus with anterior process very broad and completely rounded apically (no anterior point); ventral lobe broad and horizontal (nearly linear in lateral view), with a row of strong lateral bristles in anterior half, posteriorly with three strong bristles whose sockets form a triangle (ventral view). Posterior section of surstylus with basal portion forming a roughly triangular, horizontal plate whose posterior margin is curved up like a lip towards epandrium and bears an irregular row of strong bristles; ventral portion narrow and finger-like, directed ventrally, apically bearing one small bristle and three setulae. Cercus fairly large, bearing long bristles similar to those of posterior section of surstylus, with a long, finger-like process originating from its dorsomedial margin; process asetose, with roughened surface. Subepandrial sclerite as in Fig. 297 . Aedeagal complex as in Figs. 298–301 .

Female terminalia ( Figs. 284–286 ): Sternite 7 slightly produced posteromedially, its posterior edge shining and paler. Fused tergite 10 + cerci rectangular with rounded corners.

Type material. Holotype ♂ ( ROME) and 5 ♂♂, 7 ♀♀ paratypes ( DEBU; ROME): ECUADOR, Prov. Napo, Baeza, 1,500 m, 16–19.v.1987, wet montane rain forest, malaise, Coote & Brown. Other paratypes: ECUADOR. Prov. Napo: 2 ♂♂, 2 ♀♀, Baeza, 1,550 m, 15–19.v.1987, wet montane rain forest/pasture, malaise, Coote & Brown ( ROME); 1 ♂, 2 ♀♀, Baeza, 1,700 m, 16–19.v.1987, wet montane forest/pasture nr. small creek, malaise, Coote & Brown ( ROME); 1 ♀, Baeza, 5.iii.1979, S.A. Marshall ( DEBU); Baeza, 2,000 m, 1 ♀, 1.iii.1979, 1 ♀, 1–10.iii.1979, S.A. Marshall ( DEBU); 8 ♂♂, 5 ♀♀, El Chaco , 2,000 m, 15–23.ii.1983, malaise, Masner & Sharkey ( DEBU, QCAZ); 4 ♂♂, 4 ♀♀, 4.8 km W El Chaco, 0°18'22"S, 1,750 m, 77°50'38"W, 7.xi.1999, S.A. Marshall ( DEBU, QCAZ); 3 ♂♂, 7 ♀♀, 5 km N El Chaco, 15.ii.1983, malaise and wet net, M.J. Sharkey ( DEBU, QCAZ); 1 ♂, 1 ♀, 4.2 km S Cosanga, pipeline trail, 2,200 m, 0°37'19"S, 77°50'01"W, 7.xi.1999, S.A. Marshall ( DEBU); 5 ♀♀, 2.5 km W Cosanga, 2,150 m, 0°35'24"S, 77°53'19"W, 5–7.xi.1999, dung/pans, S.A. Marshall ( DEBU, QCAZ); 1 ♀, SierrAzul Lodge, 14 km W Cosanga, 2,200 m, 0°40'55"S, 77°56'09"W, 5.xi.1999, S.A. Marshall ( DEBU).

Etymology. The species name is a noun in apposition and refers to the flat, plateau-like ventral lobe of the anterior section of the surstylus (Gr. plax : plate, tablet).

Distribution. Presently known only from a small area of the Andean foothills in Napo Province, Ecuador, at elevations between 1,500 and 2,200 m.

Discussion. This is the only species of this group known from South America. It differs in a number of ways from the two Central American species, notably by the absence of the ventral posteroapical midtibial bristle, armature of male sternite 5 (resembling the teeth of a predator’s jaw), the separate sternite 8 (not fused to epandrium), slender medial process of male cercus and other less conspicuous details of the male and female terminalia.

Figures

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 280–286. Leptocera plax sp.n. (Ecuador). Male terminalia (phallus and postgonites omitted): (280) lateral; (281) posterior; (282) ventral; (283) sternite 5. Female terminalia: (284) dorsal; (285) spermathecae; (286) ventral. aps—anterior process of anterior section of surstylus; ce—cercus; cp—finger-like process of cercus; ep—epandrium; ha—hypandrial apodeme; hy—hypandrium; pa—phallapodeme; pssb—posterior section of surstylus, basal part; pssc—ditto, connection between basal and distal part; pssd—ditto, distal part; 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 297–304. Aedeagal complex and subepandrial sclerite of Leptocera plax group. Leptocera plax sp.n. (Ecuador): (297) subepandrial sclerite and posterior section of surstylus, posterior; (298) aedeagal complex, lateral; (299) ditto, dorsal; (300) ditto, posterior; (301) ditto, anterior. Leptocera tapanti sp.n. (Costa Rica), aedeagal complex: (302) lateral; (303) dorsal; (304) anterior. bcp—basal connection between postgonites, bp—basiphallus, dp—distiphallus, ea—ejaculatory apodeme, pa—phallapodeme, pg—postgonites, pss—posterior section of surstylus, se—subepandrial sclerite.