Leptocera ellipsipennis Richards, 1955

Buck, Matthias & Marshall, Stephen A., 2009, Revision of New World Leptocera Olivier (Diptera, Sphaeroceridae), Zootaxa 2039 (1), pp. 1-139 : 66-68

Leptocera ellipsipennis Richards, 1955

( Figs. 11–12 , 19 , 124–130 , 143 )

Leptocera (Leptocera) ellipsipennis Richards, 1955: 76 (holotype ♂, IESC, apparently lost).

Leptocera ellipsipennis .— Roháček et al., 2001: 152 (World catalog).

Taxonomy. This species has been confused with L. parallelipennis sp.n. since its description by Richards (1955). The material examined by Richards (collected by G. Kuschel in 1951–5) apparently included 9 ♂♂ and 8 ♀♀ ( IESC, BMNH, USNM). Among these were only 3 ♂♂ and 1 ♀ of the species Richards described as L. ellipsipennis , the other specimens are L. parallelipennis sp.n. Richards recognised the difference in wing venation between both species but misinterpreted it as sexual dimorphism. His description of the male wing refers to L. ellipsipennis ( Richards, 1955: Fig. 2 ), his female wing is L. parallelipennis sp.n. (l.c.: Fig. 3 ). Unfortunately, the holotype appears to be lost which leaves some doubt as to the identity of L. ellipsipennis . Considering that the holotype is a male we assume it is conspecific with the male wing described and photographed by Richards (taken from the paratype ♂ mentioned below and examined by us).

Description. Body length 2.3–4.0 mm. A brown species, frons, inner surface of pedicel, notopleural callus and postalar callus paler, more reddish. Scutum with five dorsocentral bristles (anterior one small). Third dorsocentral bristle from behind in the usual position: its socket distinctly behind line connecting sockets of presutural supra-alar and presutural intra-alar bristles. Wing strongly infuscated, wedge-shaped, showing all major wing veins of typical Limosininae ( Figs. 11, 12 ). Third costal sector usually shorter than second. Vein M connected to R 4+5 by a more or less developed crossvein r-m (sometimes obliterated and M and R 4+5 touching each other), the point of connection between the two always well basad of apex of discal cell. Discal cell with pointed apex, usually appendiculate. Mid tibia with bristle above distal dorsal bristle longer than corresponding bristle above distal anterodorsal, 0.4–0.6x as long as distal anterodorsal; posteroapical bristles short, ventral one usually longer than dorsal one ( Fig. 19 ).

Male terminalia ( Figs. 124–127 ): Sternite 5 with microtrichose posteromedial area of moderate size, hind margin with ca. 4 strong, enlarged scales. Surstylus with anterior process of anterior section rounded apically and with small, dark, acute anterior point; ventral lobe relatively short and high, ventral margin slightly convex, with relatively long bristles, the long posterior bristle not on a prominence. Posterior section of surstylus with two strong bristles close to apex, both with fine tips (outer one shorter and less tapered), inner margin broadly desclerotized, transparent and membranous; bristles of posterior surface more numerous than in other species. Cercus with a finger-like, microtrichose ventromedial process, continued dorsally by a transparent, membranous area (requires careful observation). Postgonite with very wide posterobasal notch, shank slender ( Fig. 143 ).

Female terminalia ( Figs. 128–130 ): Tergite 7 dark, relatively long, strongly convex, pruinose except for slightly shining, narrow hind margin and median stripe in posterior half of tergite; enlarged paramedian bristles long, strong and convergent (not cruciate). Sternite 7 dark, with shining, paler (reddish) hind margin. Tergite 10 + cerci very short, with few short hairs. Sternite 8 with deep emarginations on each side of posteromedial lobe. Spermathecae elongate, dilated apical portion with bumpy surface.

Type material. Holotype ♂ ( IESC, apparently lost): CHILE, Masatierra [= Robinson Crusoe I.], Plazoleta del Yunque, 200 m, 9.1.195 2, G. Kuschel . Paratype ♂ ( IESC): Masatierra, Yunque, 915 m, 10.ii.1952, P.G. Kuschel (right wing removed and mounted by O.W. Richards, not examined). Note: All other paratypes (♀ allotype plus 1 ♂, 2 ♀♀; IESC, BMNH) are misidentified L. parallelipennis sp.n., and are listed under that species. The IESC has an additional 2 ♂♂ of L. ellipsipennis and 2 ♂♂, 2 ♀♀ of L. parallelipennis sp.n. labelled as paratypes of L. ellipsipennis (red, printed label “ PARATYPE ”). These are not true paratypes because they were not mentioned by Richards (1955). Richards indicated paratype (allotype) status only on his white, hand-written determination labels and did not attach additional red paratype (allotype) labels.

Other material examined. CHILE. Reg. Aconcagua: 190 ♂♂, 144 ♀♀, Juan Fernández Is., Robinson Crusoe I., from the following localities: base of El Yunque , slopes of El Yunque , lower, upper and highest part of El Yunque trail, Plazoleta del Yunque , nr. Plazoleta del Yunque , above Plazoleta , lower and upper part of Plazoleta / El Yunque trail, Damajuana , Mirador de Selkirk , N and S side Mirador de Selkirk , quebrada on S side Mirador de Selkirk , Rabanal , Puerto Inglés , Puerto Francés, Villagra, various dates: 23–30.i.1992 and 1–12.i.1993, various habitats: open forest, fern forest, wet areas, mossy seep, creek, intermittent streambed, steep eroded slope, various methods: pan and dung traps, aspirated, Berlese, collected on dung, mule dung, moss, S.A. Marshall ( DEBU, IESC); 1 ♂, 1 ♀, “40.”, “ PARATYPE ” (mislabelled), no other data [probably collected by G. Kuschel on Robinson Crusoe I., 1951–5] ( BMNH) .

Distribution. Endemic to Robinson Crusoe I. (Juan Fernández Is., Chile).

Discussion. This species is superficially similar to L. parallelipennis sp.n. with which it has previously been confused, even though the two species have strikingly different male terminalia (sternite 5!) and differ in a number of more subtle external characters (see Discussion under L. parallelipennis sp.n.). Leptocera ellipsipennis is an interesting species because it retains several plesiomorphic characters that are absent in other species of the Juan Fernández clade but are found in a group of closely related species from the South American mainland ( L. aequilimbata , L. argentinica sp.n., L. gongylotheca sp.n., L. longilimbata sp.n., L. neocurvinervis , L. papallacta sp.n.): the third dorsocentral bristle from behind is in its usual position (shifted forward to a variable degree in other species of the L. cultellipennis subgroup), mid tibia with two posteroapical bristles (ventral one lost in other species of the L. cultellipennis subgroup), male sternite 5 with well developed enlarged scales on posterior margin (completely absent in other species of the L. cultellipennis subgroup, well developed in most South American species, small in L. aequilimbata ), male cercus with a microtrichose medial, finger-like process (absent in other species of the L. cultellipennis subgroup, present in most South American species except L. neocurvinervis ), and distal portion of spermathecae with bumpy surface (finely striate in other species of the L. cultellipennis subgroup, L. aequilimbata and L. neocurvinervis , bumpy in other South American species). Of these characters the first two are of special significance because the apomorphic state is unique within the L. caenosa group. It can therefore be hypothesized that L. ellipsipennis is the sister species to the remainder of the Juan Fernández endemics ( L. cultellipennis , L. duplicata , L. parallelipennis sp.n.). Interestingly, this also implies that flightlessness evolved at least two times in this island clade.

Figures

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 124–130. Leptocera ellipsipennis (Juan Fernández Is.). Male terminalia (phallus and postgonites omitted): (124) lateral; (125) posterior; (126) ventral; (127) sternite 5. Female terminalia: (128) dorsal; (129) spermathecae; (130) ventral. cp—finger-like process of cercus, sa—shining area of tergite 7.

FIGURES 138–146. Postgonites and aedeagal complex of Leptocera caenosa group. Postgonites of (138) L. aequilimbata (Argentina), (139) L. argentinica sp.n. (Argentina), (140) L. neocurvinervis (Chile), (141) L. erratica sp.n. (South Africa), (142) L. sphaerotheca sp.n. (U.S.A.), (143) L. ellipsipennis (Juan Fernández Is.), (144) L. parallelipennis sp.n. (Juan Fernández Is.), (145) L. cultellipennis (Juan Fernández Is.). Aedeagal complex of (146) L. duplicata (Juan Fernández Is.). bp—basiphallus, dp—distiphallus, ea—ejaculatory apodeme, pa—phallapodeme, pg—postgonites.

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.