In the recognition of the genus Eucelatoria provided by Sabrosky (1981) and Wood (1985) the wing vein R₄₊₅ is dorsally setose only at its base. The E. obumbrata species group described here differs from these generic definitions because specimens in this group have the wing vein R₄₊₅ dorsally setose from its base nearly to crossvein r-m. Although Wood (1985) already considered Machairomasicera carinata as belonging to Eucelatoria, and this species has the vein R₄₊₅ dorsally setose, Wood did not include this variation in the generic description of Eucelatoria because his revision was restricted to Central America, and M. carinata is known only from Ecuador. This trait appears to be a synapomorphy of the E. obumbrata species group, clearly distinguishing it from other Eucelatoria species. The presence of sex patches on ventral abdominal tergites 4 and 5 of males also serves to unite this group, however similar sexual patches have been observed in other Eucelatoria species (Stireman and Z.K. Burington, pers. obs.).

Lectotype male, by designation of Wood (1985: 100), labeled: “LECTOTYPE”, “♂”, “Omilteme,/ Guerrero,/ 8000 ft. [feet]/ July H. H. Smith.”, “Central America/ Pres. By F.D. Godman,/ O. Salvin/ 1903-172.”, “B.C.A. Dipt. II./ Hypostena obumbrata v.d.W”, “Euptilodegeeria obumbrata/ Det. CHTT”, “LECTOTYPE ♂/ Of Hypostena obumbrata Wulp./ Designated 1979/ D.M. Wood”, “Eucelatoria/ obumbrata (Wulp)/ det. D.J. Inclán/ & J.O. Stireman” (BNHM).

10 specimens examined. 2 males labeled: “Co-type”, “♂”, “Omilteme,/ Guerrero,/ 8000 ft. [feet]/ July H. H. Smith.”, “Central America/ Pres. By F.D. Godman,/ O. Salvin/ 1903-172.”, “B.C.A. Dipt. II./ Hypostena obumbrata v.d.W”, “PARALECTOTYPE/ Of Hypostena obumbrata Wulp./ Designated 1980/ D.M. Wood”, “ Cotype/ 23967 U.S.N.M.”, “USNM 2049536”, “Eucelatoria/ obumbrata (Wulp)/ det. D.J. Inclán/ & J.O. Stireman”, “DI81NM”, “DI82NM” (NMNH); 2 males, as above except without the last label, “DI79NM”, “DI78NM” [ 1 specimen with terminalia dissected] (NMNH); 1 male, as above except without the “Cotype/…” labeled and having one extra label “Euptilodegeeria obumbrata/ Det. CHTT”, “DI80NM” (NMNH); 1 male, same as above except without the last two labels and the paralectotype label was attached in 1979, “ DI105BM” (BNHM); 1 male, same as above except without the last two labels, the location label “Xucumanatlan [miss spelled Xocomanatlan]/ Guerrero/ 7000 ft./ July. H.H. Smith” and the paralectotype label was attached on 1979, “DI106BM” (BNHM); 1 male and 2 females, “Omilteme,/ Guerrero,/ 8000 ft. [feet]/ July H. H. Smith.”, “Central America/ Pres. By F.D. Godman,/ O. Salvin/ 1903-172.”, “Eucelatoria/ obumbrata (Wulp)/ det. D.J. Inclán/ & J.O. Stireman”, “DI109BM” [male with terminalia dissected], “DI108BM”, “DI107BM” (BNHM).

This species can be distinguished from E. flava sp. n. by the primarily black coloration of the abdomen, with yellow coloration being restricted to the sides of tergites 1+2, 3, and 4. This contrasts with the entirely yellow abdomen of E. flava. Eucelatoria obumbrata usually bears median discals on tergite 3 and/or tergite 4, but these are absent in E. flava. The terminalia are similar between these species, but differ in several subtle respects including: the basal section of sternite 5 is distinctly shorter and broader basally in E. obumbrata; the surstylus, in lateral view, is equal to the cercus in length or slightly longer, whereas in E. flava it is markedly longer. In posterior view, the lateral margins of the cerci are narrowed linearly until the apical cleft, whereas in E. flava they are abruptly constricted below the upper lobes; the pregonite of E. obumbrata is relatively rectilinear, whereas that of E. flava triangular in shape, with a relatively broad at base, and strong narrowing toward apex. Females differ from E. carinata in having yellow coloration laterally on tergites 1+2, 3, and 4 (all black in E. carinata), densely haired eyes, more sparsely bristled palpi, and silvery parafrontals (bronzy in E. carinata).

Redescribed from 11 males (including the lectotype and 4 paralectotypes), and 2 females, unless otherwise noted as “N”.

Length: males, 6.2–7.1 mm (x = 6.8 mm); females, 6.1–7.0 mm (x = 6.5 mm).

Head (Fig. 2): Parafacial covered with dull silver to slightly bronze pruinescence in male, silvery in female. Fronto-orbital fig and vertex black in ground color, covered with silver pruinescence (appearing grayish or brownish from certain angles), usually with a faint golden or bronzy pruinescence. Frontal vitta usually entirely black, sometimes fading to dark-brown toward antenna. Pedicel black and first flagellomere black, covered with fine microtrichia, and appearing grayish. Arista long, with minute setae, black with brown on basal 1/3 or less, thickened only on basal 1/4 or less. Eye densely haired, with long ommatrichia. Eye 0.85–0.90 head height in male, 0.85 in female. Vertex width, at its narrowest point, 0.17–0.22 head width in male, 0.24–0.25 in female. Length of first flagellomere 0.38–0.58 head height in male, 0.40–0.42 in female. Width of first flagellomere 2.57–3.80 parafacial width at its narrowest point in male, 2.0–3.33 in female. Pedicel length 0.25–0.36 length of first flagellomere in male, 0.33–0.36 in female. Fronto-orbital fig with 8–11 medioclinate frontal setae in male, 5–6 in female; 2 reclinate inner orbital setae in both sexes; female with 2 proclinate outer orbital setae, male without outer orbitals. The outer vertical seta varied from scarcely to moderate differentiated from the row of postocular setae in both sexes. Ocellar setae well-developed, proclinate. Parafacial bare and extremely narrow with the narrowest point equal to or narrower than the basal width of the palpus in both sexes. Facial ridge with hairs on basal 2/5 or less (occasionally higher, but if so, short and hairlike above lowest third), and lower margin of face descending to the level of vibrissa. Subvibrissal ridge short, usually with 1 or 2 setae; postgena narrow, with a distinct but small genal dilation. Posteroventral part of the head with the majority of setae fine and white-yellowish and posterodorsal part of the head without black setae behind the postocular row. Palpus yellowish; sparsely to moderately bristled; almost uniform in width, but sometimes slightly broadened at the apex.

Figure 2. 

Male of E. obumbrata (Wulp). Full body from lateral (a) and dorsal (b) view and head from lateral (c) and frontal view (d).

Thorax (Fig. 2a, b): Shiny black in ground color; presutural scutum with thin white pruinescence, postsutural scutum with much sparser pruinescence revealing underlying black ground color. In dorsal view, only the presutural scutum appears grayish; whereas in lateral view the postsutural scutum appears grayish as well. Faint white pruinose stripes on presutural scutum leaving 4 black vittae; the inner 2 vittae longer and thinner, almost 1/2 the width of each of the outer 2 vittae. Prosternum with several hair-like setae. Postpronotum usually with 3 setae in a line. Proepisternum bare. Katepisternum with 3 setae. Scutum setae highly variable, with 2 or 3 presutural acrostichal setae; postsutural acrostichal setae varied from 1 to 3; 2 or 3 presutural dorsocentral setae; 2 or 3 postsutural dorsocentral setae; 1 presutural intra-alar seta, occasionally with 1 or 2 additional small seta; 2 to 4 postsutural intra-alar setae; 3 postsutural supra-alar setae, rarely 2. The first postsutural supra-alar seta is small or rarely absent. Scutellum with 3 pairs of setae: basal bristles of moderate length, short, usually divergent or parallel lateral bristles, long, divergent subapicals and without apical setae.

Legs entirely black. Tarsal claws longer than 5th tarsomere in male and shorter than 5th tarsomere in female. Mid tibia with 1 anterodorsal seta, 2 posterodorsal setae, and 1 ventral seta. Hind tibia with anterodorsal setae uneven in length and not closely spaced; 2 well-developed posterodorsal setae, rarely with 1 additional shorter seta; 2 well-developed anteroventral setae. Upper and lower calypteres brownish-yellowish. Wing varied from light to dark fumose on cells sc, r₁, r₂₊₃, and sometimes on r₄₊₅. Females with nearly hyaline wings. Wing vein R₄₊₅ dorsally setose from its base nearly to crossvein r-m, and R₁ bare, rarely only with 1 or 2 setae. Vein M smoothly curved at bend and ending at wing margin, separately from vein R₄₊₅.

Abdomen (Figs 2a, b; 3a, b): Mostly black with yellow laterally on tg1+2 to tg4. Transverse bands of sparse white pruinosity on basal 1/3 to 2/3 of tergites 3 to 5, more noticeable medially on the black areas of the abdomen. Mid-dorsal depression of tg1+2 only extending approximately half way to hind margin. One pair of median marginal setae on tg1+2 and tg3; a row of median marginals on tg4 and tg5; 1 pair of lateral marginal setae on tg1+2 and tg3; median discal setae present on tg3, usually also on tg4 in males, but absent in females. Males with dense patches of very short setae (sex patches; Cerretti et al. 2014a) present on the ventral surface of tg4 and tg5 (Fig. 3). Sternites completely overlapped by tergites. Females with spine-like setae on ventral margins of tg4 making two irregular rows of short, stout, curved and closely set of 7–10 spines per each row, which are concentrated in the distal 2/3 of the tergite (Figure 4a).

Figure 3. 

Lateral view of the male abdomen of E. obumbrata (Wulp) (a) showing the sexual patches on tergites 4 and 5 (b).

Figure 4. 

Female terminalia of E. obumbrata (Wulp). Spine-like setae on the ventral margins of tergite 4 (a) and tergite 7 and sternite 7 modified into a piercer, below the piercer is sternite 6 (b).

Male terminalia (N = 2, Figs 5, 6): Sternite 5 with median cleft smoothly V-shaped; inner margin somewhat projecting, with minute setae; internal margins of the apical lobes slightly convex anteriorly; apical lobe slightly rounded apically with small scattered, setae (Fig. 5). The basal section of st5 distinctly longer than the length of the apical lobes. Hypandrial arms separated. Pregonite slightly curved anteriorly and tapered to a narrow rounded tip. Postgonite well developed, parallel sided and strongly curved anteriorly, with rounded apex. Epiphallus reduced. Surstylus with small hairs on the outer surface. Surstylus, in lateral view, slightly narrowed toward the apex, and ending in a broad rounded point. Surstylus and cercus subequal in length, or surstyli slightly longer. Cercus, in lateral view, slightly curved along its anterior and posterior margins, ending in a rounded apex (Fig. 5). In posterior view, cerci narrowed linearly from upper lobes to apical cleft and then constricted on apical 1/3; upper lobe and medial section subequal in length, upper lobe longer than the apical cleft; apical cleft weakly defined (Fig. 5). Distiphallus divided at base into long, thin sclerite posteriorly and broader winged and sclerotized portion anteriorly, the latter studded with small dentate structures.

Figure 5. 

Lateral (a) and posterior view (b) of the male terminalia and sternite 5 (c) of E. obumbrata (Wulp).

Figure 6. 

Lateral view of the hypandrial complex (a) and distiphallus (b) of E. obumbrata (Wulp).

Female terminalia (Fig. 4): Tergite 6 laterally reduced in size. Tergite 7 fused with the sternite 7 and modified into a strong piercing ovipositor that is curved downward and anteriorly. Sternite 6 small, with hairs on its posterior margin. Cerci strongly reduced.

Specimens of E. obumbrata have been collected in southwestern Mexico (Fig. 1) at high altitudes of about 2000 m. All of the specimens were collected in July.

Holotype male, labeled: “ ECUADOR, Napo [Province]/ 7 km. s. [South] Baeza/ 20-25.II.79/ G. &M. Wood 2000m”, “HOLOTYPE/ Eucelatoria/ flava/ Inclán & Stireman [red label]”, “DI244CA [specimen ID]” (CNC).

Paratype, 1 male: “DI12CA” (CNC). As above, except the identification type label reads “PARATYPE/ Eucelatoria/ flava/ Inclán & Stireman [yellow label]”.

From the Latin flava, meaning yellow, in reference to the yellow abdomen that distinguishes this species from its close related species, E. obumbrata.

This species is morphologically very similar to E. carinata and E. obumbrata, but can be easily separated by the abdominal coloration. Eucelatoria flava sp. n. has a yellow abdomen, which contrasts with the abdomen of E. carinata that is entirely black and E. obumbrata that is primarily black, with yellow coloration confined to the sides of styntergite 1+2, and tergites 3 and 4. Additionally, median discal setae are lacking on tergites 3 and 4 in males of this species where they are present on tergites 3 and/or 4 in males of E. obumbrata. The eyes of this species are sparsely and short-haired, contrasting with the densely and long-haired eyes of E. obumbrata and from the sparsely, but long-haired eyes of E. carinata.

Described from 2 males, unless otherwise noted as “N”.

Length: 6.6–6.7 mm.

As described for E. obumbrata except for:

Head (Fig. 7): Eye sparsely haired. Eye 0.88 head height. Vertex width, at its narrowest point, 0.18–0.20 head width. Length of first flagellomere 0.41 head height. Width of first flagellomere 3.0–3.6 parafacial width at its narrowest point. Pedicel length 0.32–0.36 length of first flagellomere. Fronto-orbital fig with 7–9 medioclinate frontal setae, 2 reclinate inner orbital setae in both sexes, male without outer orbitals. The outer vertical seta barely to undifferentiated from the row of postocular setae. Facial ridge with hairs on basal 1/3 or less. Posterodorsal part of the head only with a few black setae behind the postocular row.

Figure 7. 

Male of E. flava sp. n. Full body from lateral (a) and dorsal (b) view and head from lateral (c) and frontal view (d).

Thorax (Fig. 7a, b): Scutum with 2 or 3 presutural acrostichal setae; postsutural acrostichal setae varied from 1 to 2; 2 presutural dorsocentral setae; 3 postsutural dorsocentral setae; 2 presutural intra-alar seta; 4 postsutural intra-alar setae; 1 presutural supra-alar seta, with 1 additional small seta; 3 postsutural supra-alar setae. The first postsutural supra-alar seta is small.

Wing varied from light to dark fumose on cells c, sc, r₁, r₂₊₃, and r₄₊₅. Wing vein R₄₊₅ dorsally setose from its base until nearly the crossvein r-m, and R₁ bare.

Abdomen (Figs 7a, b; 8): Fully yellow, sometimes the tg5 appearing dark yellowish. Transverse bands of sparse white pruinosity scarcely visible to naked eye. Median discal setae absent on tg3 to tg5. Sexual patches of relatively dense hairs present on the ventral surface of tg4 and tg5, hardly noticeable to naked eye.

Figure 8. 

Lateral view of the male abdomen of E. flava sp. n. (a) showing the sexual patches on tergites 4 and 5 (b).

Male terminalia (N = 1, Figs 9, 10): The basal section of the st5 distinctly longer than the length of the apical lobes, and the internal sides of the apical lobes almost linear (Fig. 9c). Basal half of hypandrium not strongly bent, in line with more apical portion. Surstylus, in lateral view, slightly narrowed toward the apex ending in a broad rounded apex. Surstylus distinctly longer than cercus. Cercus, in lateral view, nearly straight along anterior and posterior margins, ending in rounded apex (Fig. 9a). In posterior view, cerci abruptly constricted below upper lobes and narrowed on apical 1/3; upper lobe slightly shorter than medial section, but longer than the apical cleft; apical cleft weakly defined (Fig. 9b). Pregonite somewhat triangular in shape, relatively broad at base, narrowing toward apex. Postgonite slightly narrower than in E. obumbrata, and narrowed slightly towards apices, distinctly curved anteriorly, with rounded apex.

Figure 9. 

Lateral (a) and posterior view (b) of the male terminalia and sternite 5 (c) of E. flava sp. n.

Figure 10. 

Lateral view of the hypandrial complex (a) and distiphallus (b) of E. flava sp. n.

The only two known specimens of E. flava sp. n. were collected in highland cloud forest at about 2000 m in altitude on the eastern slope of the Andes of Ecuador (Fig. 1). The two specimens were collected in February.

Holotype female, labeled: “Manchi Ecuador/7000 ft/22-XI” [no year, but given as 1910 in description], “CHT Townsend/ Collector”, “Below/ Manchi Ec/Nov 22”, “Type No. 22247/U.S.N.M.”, “Machairomasicera/carinata/♀ Det CHTT 1”, “Eucelatoria/ carinata (Townsend)/ det. D.J. Inclán/ & J.O. Stireman” (NMNH).

This species can be distinguished from E. flava sp. n. and E. obumbrata by the entirely black coloration of the abdomen, which contrasts with the entirely yellow abdomen of E. flava, and the yellow and black abdomen of E. obumbrata. It also differs from females of E. obumbrata in having sparsely haired eyes, more densely bristled palpi, strongly infuscated wing veins, and a bronze tinted parafacial (dull silver in known females of E. obumbrata).

Length: 6.7 mm.

As described for E. obumbrata except for:

Head (Fig. 11): Eye sparsely, but long-haired. Eye 0.83 head height. Vertex width, at its narrowest point 0.26 head width. Length of first flagellomere 0.44 head height. Width of first flagellomere 4.6 parafacial width at its narrowest point. Pedicel length 0.28 length of first flagellomere. Fronto-orbital fig with 4–6 medioclinate frontal setae. Facial ridge with hairs on basal 1/2, but short and fine above basal 1/3. Posterodorsal part of the head without black setae behind the postocular row.

Figure 11. 

Female of E. carinata (Townsend). Full body from lateral (a) and dorsal (b) view and head from lateral (c) and frontal view (d).

Thorax (Fig. 11a, b): Scutum with 3 presutural acrostichal setae and 3 postsutural acrostichal setae; 2 presutural dorsocentral setae and 3 postsutural dorsocentral setae; 1 presutural intra-alar seta, with 1 additional small seta; 3 postsutural intra-alar setae. The first postsutural supra-alar seta present but reduced in size.

Wing moderately fumose on anterior half around veins C, Sc, R₁ and R₄₊₅, light infuscation also present along veins M, CuA₁, and dm-cu. Wing vein R₄₊₅ dorsally setose from its base until nearly the crossvein r-m, and R₁ bare.

Abdomen (Fig. 11a, b): Entirely black in ground color with transverse bands of sparse white pruinosity on basal 1/3 of tergites 3 and 4, and 1/2 of tergite 5. Median discal setae absent.

The only known specimen of E. carinata was collected in Ecuador. The specimen was collected in the Andes Mountains at about 7000 ft (2100 m). The locality of the specimen reads “Below Manchi”, but it is unclear what this name refers to.

Myiodoriops marginalis Townsend, 1935.

Myiodoriops can be separated from other blondeliine genera (see discussion section below) using a combination of external characters and traits of the male terminalia including: 2 katepisternal bristles, 2 postpronotal setae (or, if a small inner seta is present, all three arranged in a line or broad arc), sparsely haired eyes, facial ridge with hairs on lower 1/3 or less, vein M ending in R₄₊₅ vein just before wing margin or in wing margin very close to R₄₊₅, lack of proclinate orbital setae in males, the mid-dorsal depression extending nearly to the hind margin of tg1+2, absence of a piercing structure in females, and short, spine-like setae on the anteriorly on the apex of the surstyli.

Myiodoriops is superficially similar to the E. obumbrata species group and to the genus Erythromelana in size, shape, and general appearance, which may explain the former grouping of these taxa into a single genus. However, it can be separated from these taxa using external morphological traits. It differs from the genus Eucelatoria generally in lacking the apomorphic piercing structure and associated short spines on ventral margins of abdominal tergites in females and absence of median discal setae on abdominal tergites 3 and 4, and it specifically lacks the apomorphic traits of the E. obumbrata group of R₄₊₅ bristled nearly to crossvein r-m and sex patches in the male. Myiodoriops can be separated from Erythromelana by having the vibrissa inserted slightly above the lower facial margin (subtended by one or more setae), vein M ending in R₄₊₅ vein or in wing margin very close to R₄₊₅, and the mid-dorsal depression extending nearly to the hind margin of tg1+2. Additionally, Myiodoriops has only 2 katepisternal setae, which differs from Eucelatoria and from most species of Erythromelana which have 3 (see Inclán and Stireman 2013). The male terminalia are also distinct from these other blondeliine taxa, particularly with respect to the surstylus, which is anteriorly curved and narrowed towards its tip with spine-like setae on the anterior side of its apex. Furthermore, males in this genus have the pregonite strongly curved anteriorly, which differs from the rectilinear one of Erythromelana.

The presence of short spines on the tip of the surstylus is reminiscent of Myiopharus (see Wood 1985; O’Hara 2007), which Myiodoriops resembles in a number of other respects. However, it appears distinct from the former genus in lacking proclinate orbital setae in the male, possessing bristles on the lower 1/3 of the facial ridge or less, an apparent lack of ommatrichia, three reclinate orbital setae in males, 2 postpronotal setae, or if 3, the innermost reduced in size and all 3 arranged in a broad arc, relatively short, stout surstylus and cercus, and a small and nearly pointed postgonite (see discussion section below).

Redescribed from 5 males (including the type M. marginalis) and 6 females.

Length: males, 5.1–5.8 mm (x = 5.42 mm); females, 3.9–5.1 mm (x = 4.54 mm).

Head: Parafacial covered with dull silver pruinescence. Fronto-orbital fig and vertex black in ground color, covered with silver pruinescence appearing grayish from certain angles, usually with faint sparsely golden pruinescence dorsally. Frontal vitta usually entirely black, sometimes fading to dark-brown toward antenna. Pedicel black and first flagellomere black, covered with fine microtrichia and appearing grayish. Arista long, with minute setae, black with brown on basal 1/3 or less, thickened on basal 1/4 or less. Fronto-orbital fig with 5–7 medioclinate frontal setae in male, 4–7 in female; 3 reclinate inner orbital setae in males, 2 in females; female with 2 proclinate outer orbital setae, male without outer orbitals. Vertex with one reclinate inner and usually one lateroclinate outer vertical seta, the latter often barely or undifferentiated from the row of postocular setae in both sexes. Inner orbital and vertical setae usually about twice the length of frontal setae. Ocellar setae well-developed, proclinate. Parafacial bare and narrow with the narrowest point about equal to the widest portion of the palpus in males; in females narrower, about the basal width of the palpus. Facial ridge with hairs on basal 1/3 or less, and lower margin of face descending slightly below the level of vibrissa. Subvibrissal ridge short, usually with 1 to 3 setae; postgena narrow, with a distinct but small genal dilation. Posteroventral part of the head with the majority of white-yellowish fine setae and posterodorsal part of the head with one row of black setae behind the postocular row. Palpus brownish to black in color, distinctly swollen apically, more markedly in females.

Thorax: Shiny black in ground color; presutural scutum with evident white pruinescence, postsutural scutum with much sparser pruinescence revealing underlying black ground color. In dorsal view, only the presutural scutum appears grayish; whereas in lateral view the postsutural scutum appears grayish as well. Faint white pruinose stripes on presutural scutum leaving 4 black vittae; the inner 2 vittae longer and thinner, almost 1/2 the width of each of the outer 2 vittae. Prosternum with several hair-like setae. Postpronotum with 2 or 3 setae, when 3, the inner most is reduced in size and together they form a broadly obtuse angle, ca. 130–150°. Proepisternum bare. Katepisternum with 2 setae. The first postsutural supra-alar seta smaller than the notopleural setae. Scutellum with 3 pairs of setae, without apical setae or with one small hair-like pair.

Legs entirely black. Tarsal claws longer than 5th tarsomere in male and shorter than 5th tarsomere in female. Mid tibia with 2 posterodorsal setae, and 1 ventral seta. Hind tibia with anterodorsal setae uneven in length and not closely spaced; 2 well-developed posterodorsal setae, rarely with 1 additional shorter seta; 2 anteroventral setae. Upper and lower calypters translucent yellow-brownish. Wing length nearly equal to body length. Wing usually hyaline, rarely light fumose on the anterior edge. Wing vein R₄₊₅ dorsally setose only at its base, and R₁ bare. Vein M smoothly curved at bend and ending in vein R₄₊₅ near the wing margin or separately in the margin closely approximated to vein R₄₊₅.

Abdomen: Mostly black with yellow laterally on tg1+2 to tg4 on males, fully black in females. Transverse bands of sparse white pruinosity usually on the anterior 1/4 of tg1+2 to tg5. Mid-dorsal depression of tg1+2 extending to marginal setae and nearly to hind margin. One pair of median marginal setae on tg1+2 and tg3; a row of median marginals on tg3 to tg5; 1 pair of lateral marginal setae on tg1+2 and tg5; discal setae absent in both sexes. Sternites completely overlapped by tergites.

Male terminalia: Sternite 5 with median cleft smoothly V-shaped; apical lobes narrowed to broad points at their apices. The anterior margin of st5 clearly concave. The basal section of st5 distinctly shorter than the length of the apical lobes. Hypandrial arms separated. Pregonite curved anteriorly and tapered to a narrow rounded tip. Postgonite distinctively curved anteriorly, with narrow, almost pointed apex. Epiphallus small, hidden between the pregonites. Surstylus, in lateral view, broad, anteriorly curved and narrowed toward the apex, considerably longer than cercus. Surstylus with several short spine-like setae on the anterior side of its apex. Cercus, in lateral view, broad, slightly concave along anterior margin and narrowed only on the posterior margin of the apex. In posterior view, the cerci with long rectilinear upper lobes, nearly as long as the medial section + apical cleft combined. Apices of cerci, in posterior view, with excavated inner margins. Lateral margins of cerci without a constriction towards the apical section; apical cleft well defined. Distiphallus divided at base into long and a broader sclerotized portion with a toothed margin anteriorly.

See the distribution of Myiodoriops marginalis below, except for four undescribed specimens (see discussion below) that were collected in Brazil, Peru and Argentina (Fig. 12). All known specimens were collected at lower elevations (< 200 m) except one specimen collected in Peru at 1600 m. Specimens have been collected from January until October, but most of the material was collected in January.

Figure 12. 

Known distributions of Myiodoriops species. M. marginalis Townsend is represented by red circles and M. spp. by green triangles.

The phylogenetic affinities of M. marginalis are unclear. As indicated in the diagnosis, there is little reason to believe that the species belongs with its former congeners in the genus Erythromelana or Eucelatoria, nor does it appear to be closely related to these taxa (see also Inclán and Stireman 2013). Myiodoriops marginalis is morphologically similar to the large and difficult genus Lixophaga, but it lacks the enlarged pair of bristles on sternite 5 characteristic of males of this genus (although it does have a number of smaller bristles; Fig. 14c) and the postpronotal bristles of M. marginalis, if three, are arranged in a line. It even more closely resembles members of Euthelyconychia in general appearance and chaetotaxy, sharing with this genus some features of the male genitalia as well (e.g. surstylar and postgonite shape), but the cerci are differently shaped and Euthelyconychia appears to lack surstylar spines. The possession of the unusual, anteriorly directed surstylar spines, suggests a close relationship with Myiopharus, and it is possible that M. marginalis represents a highly autapomorphic species of this genus, or of Euthelyconychia. Without detailed systematic study and analysis of these genera and the Blondeliini as a whole, which is beyond the scope of the present study, these possibilities cannot be confirmed or refuted. Therefore, we retain M. marginalis in its originally described genus.

The genus description is based primarily on the specimens available for the known species M. marginalis. However, we found four specimens from Peru, Brazil and Argentina that belong to this genus, but they appear represent one or more undescribed species near M. marginalis. We have included these specimens in the genus description to cover all the generic variability, but we did not describe these specimens given the limited material and their poor condition. Additionally, of these four specimens, three are females and each is from a different locality. These four specimens exhibit slight differences in external morphology (e.g., parafacial width and abdominal coloration), but it is unclear if these differences represent intraspecific variation, male-female dimorphism, or actual differences between species. Therefore, we leave these specimens undescribed until additional material is available that can be used to help establish their identity.

Holotype male labeled: “HOLO-/TYPE”, “Type [red label]”, “Pariká/ Ruhununí/ B. Guiana/ Jan. 1934 [hand written]”, “Mycos/ 4401 [hand written]”, “Press. By/ J.G. Myers/ B.M. 1940-24” “Myiodoriops/ marginalis TT [hand written]/ DetCHTT ♂”, “Myiodoriops/ marginalis Townsend/ det. D.J. Inclán/ & J.O. Stireman” (BNHM).

Seven specimens examined. 1 male labeled: “St. Augustine,/ Trinidad, BWI./ 1. 24. 60”, “Myiodoriops/ marginalis [hand written]”, “DI240CA” (CNC). 1 male labeled: “St. Augustine,/ Trinidad, BWI./ JAN 8 1960”, “F. D. Bennett/ Collector”, “X P. (77)/ near/ Myiodoriops [hand written]”, “Myiodoriops/ marginalis Townsend/ det. D.J. Inclán/ & J.O. Stireman”, “DI241CA” (CNC). 1 male labeled: “PIARCO/ Trinidad, BWI./ OCT. 29. 1953.”, “Collector/ F. J. Simmonds”, “77 [hand written]”, “Myiodoriops/ n. sp. ♂ [hand written]”, “Myiodoriops/ marginalis Townsend/ det. D.J. Inclán/ & J.O. Stireman”, “DI243CA” (CNC). 1 female labeled, same as previous except by “OCT. 29. 1953”, without sp. ID, “DI74CA” CNC. 1 male labeled: “W. ARIMA/ TRINIDAD/ 26-8-1964”, “Myiodoriops/ marginalis Townsend/ det. D.J. Inclán/ & J.O. Stireman”, “DI73CA” (CNC). 1 female labeled: “St. Augustine,/ Trinidad, BWI./ II. 17. 60”, “Myiodoriops/ marginalis Townsend/ det. D.J. Inclán/ & J.O. Stireman”, “DI39CA” (CNC). 1 female labeled: same as previous except by “II. 28. 60”, “DI236CA” (CNC).

See diagnostic section for the genus Myiodoriops.

Redescribed from 5 males (including the type M. marginalis) and 3 females.

Length: males, 5.1–5.8 mm (x = 5.42 mm); females, 3.9–4.53 mm (x = 4.21 mm).

As described for the genus except:

Head (Fig. 13): Eye sparsely haired, ommatrichia short, about as long as 2–3 eye facets. Eye 0.85–0.87 head height in male, 0.83–0.88 in female. Vertex width 0.20–0.22 head width in male, 0.24–0.27 in female. Width of frontal vitta 0.25–0.30 vertex width in male, 0.28–0.43 in female. Length of first flagellomere 0.38–0.46 head height in male, 0.39–0.45 in female. Pedicel length 0.31–0.37 length of first flagellomere in male, 0.28–0.36 in female.

Figure 13. 

Male of M. marginalis Townsend. Full body from lateral (a) and dorsal (b) view and head from lateral (c) and frontal view (d).

Figure 14. 

Lateral (a) and posterior view (b) of the male terminalia and sternite 5 (c) of M. marginalis Townsend.

Figure 15. 

Lateral view of the hypandrial complex (a) and distiphallus (b) of M. marginalis Townsend.

Specimens of M. marginalis have been collected only from Guyana in northern South America, and from the southern Caribbean islands of Trinidad and Tobago (Fig. 12). All collections are from lowland tropical forest. Adults have been collected mainly in January, but also in February, August and October.