Amerikeroplatus dimorphicus, Fitzgerald, 2019

Fitzgerald, Scott J., 2019, A curious new genus of Keroplatini (Diptera: Keroplatidae) from Guatemala, Zootaxa 4586 (2), pp. 383-390 : 384-388

Amerikeroplatus dimorphicus n. sp.

Figs. 1–8

Diagnosis. The presence of r-m (Figs. 4a–b) (or a very short radiomedial fusion (R S + M) (Fig. 4c)), absence of R 2+3, and long CuP reaching the wing margin will distinguish A. dimorphicus from all other species of Keroplatini . See also generic diagnosis above.

Description. Male ( Figs. 1 , 3–7 ). Body length: approx. 6.0–8.0 [7.0] mm (n=4). Head. Light brown with short black setae on posterior half. Three ocelli in a triangular position on black diamond-shaped area. Lateral ocelli larger than median ocellus and less than their diameter distant from the eye margin. Median ocellus distinctly smaller and placed at the anterior end of a sagittal furrow between lateral ocelli. Compound eye bare. Antennae about 2.7 times as long as head, light brown. Scape and pedicel light brown with black setae, slightly laterally compressed and enlarged ventrally. Fourteen cylindrical antennal flagellomeres about as broad as long except basal flagellomere with short narrow basal neck, light brown with black setae dorsally and light brown pubescence elsewhere ( Fig. 3 ). Face bare, white with black rectangular area just above clypeus. Clypeus beige, broadly triangular with dark setae. Mouthparts strongly reduced. Palpi black, setose, with one porrect segment bearing a white circular sensory area apically. A small (about the size of the adjacent palpal segment) oval setose sclerite medial to the palpi, but projecting more ventrally, is presumably the labellum. Thorax. Thorax dark brown. Dorsum matte with four bare areas separated by four irregular longitudinal rows of short black setae; a narrow acrostichal row, two dorsocentral rows, and two broad lateral alar rows. Scutellum dark brown (light brown ventrally) with black setae dorsally and along posterior edge; without any differentiated long, strong setae. Anepisternum, katepisternum (preepisternum 2), anepimeron, laterotergite, and mediotergite, dark brown, bare. Laterotergite strongly convex. Anepimeron reaching ventrally between katepisternum and laterotergite. Antepronotum and proepisternum dark brown with black setae. Prosternum bare. Anterior spiracle and membranous area around it beige with black setae posteriorly. Halter dark brown. Legs. Coxae dark brown. Coxa 1 setose primarily anteriorly and on apical half of posterior surface, laterally sparse. Coxa 2 setose on apical 2/3 of anterior surface, sparse laterally, and a few apical setae posteroapically. Coxa 3 setose primarily on apical 2/3 of lateral surface with some posteriorly. Remainder of legs clothed with short black dense irregular microsetae not forming distinct rows. Distinct macrosetae absent. Femora dark brown, tibia mostly dark brown with paler beige areas (especially ventrally), tarsi beige. Apex of fore tibia very slightly expanded, but without tibial organ. Tibial spurs 1:2:2 with inner and outer spur of mid and hind legs roughly subequal in length and slightly longer than apical diameter of tibia. Ratio of basitarsus to tibia of fore, mid, and hind legs respectively: 1:1.3, 1:1.7, 1:1.7. Basal half of tarsal claws with ventral comb of 4–5 fine, dense, teeth. Pulvilli and small pulvilliform empodium present. Wings. (Fig. 4). 5.5–6.0 [6.0] mm (n=4), without distinct markings, light brown fumose, becoming darker costally, covered with microsetae, macrosetae absent. Veins brown, all with dorsal setae except Sc, crossveins, and distal half of CuP bare. Sc long, ending just before half way point between base Rs and termination R 1. C ending near apex of wing half way between R 4+5 and M 1. Basal cell well developed, not reduced. R 2+3 absent. Crossvein r-m usually present (Figs. 4a–b), but when absent, either very short radiomedial fusion (R S +M) present (Fig. 4c), or bm-cu, base Rs, R 4+5, and stem of M all meeting at a central point forming a clean “X.” Stem of M relatively long, but distinctly shorter than M 1, M 2 fork. Crossvein bm-cu oblique. Posterior fork branching near base of wing. CuA distinctly down-curved toward wing margin. CuP reaching wing edge in most specimens, but sometimes terminating just shy of wing edge. Abdomen. Brown with dense dark setae, distinctly bent ventrally toward apex. Terminalia. ( Figs. 5– 7 ). Tergite nine about 1/3 broader than long with broad, deep v-shaped emargination on posterior edge ( Fig. 5 ). Cerci fleshy, flap-like, with dense, fine hairs, visible dorsally at posteromedian edge of and just ventral to tergite 9 ( Fig. 5 ). In ventral view gonocoxites medially divided longitudinally, gonostylus horn-like ( Fig. 6 ). In posterior view, gonostylus horn-like, slightly curved, sinuate, tapered to a rounded point apically ( Fig. 7 ). In strict lateral view, gonostylus mostly obscured, but in posterolateral view, gonostylus dorsally directed, tapering towards apex, outer surface evenly curved with gonotstylus thickest medially, inner surface mostly flat though slightly curved anteriorly near apex. Aedeagal complex not anteriorly elongated into segment 7, at most slightly protruding into segment 8.

Female ( Figs. 2 , 8 ). Essentially as in male with the following exceptions/additions: Body 5.0– 8.5 mm (n=3), wing 5.5–7.5 mm (n=2). Setae of antennal flagellomeres not limited to dorsal surface. Thorax orange except metepimeron and metepisternum dark brown. Setation as in male, black. Ratio of basitarsus to tibia of fore, mid, and hind legs: 1:1.3, 1:1.8, 1:1.9. Female terminalia somewhat retracted into segment 7; in lateral view, cerci not visible in dried specimens, but partly visible in macerated specimens. In lateral view, cerci broader than long, roughly rectangular, apically truncate, sternite 8 broadly rounded. In posterior view, sternite 8 medially divided, cerci fleshy with fine hairs ( Fig. 8 ).

Etymology. The specific epithet is derived from the word dimorphic (Greek di - (two), morphe (form), + suffix – ikos) as the species shows distinct sexual dimorphism with bright orange females and dark brown males.

Type material. Holotype : Male ( Fig. 1 ), point-pinned [CNCI], GUATEMALA: Guatemala, Puerta Parada , 1850 m alt. 5–12 October 2013, J.C. Schuster [white label] / HOLOTYPE, Amerikeroplatus dimorphicus Fitzgerald [red label], terminalia dissected. Paratypes: same as holotype except: 2 females [1 UVGC, 1 SFC], 19– 26 October 2013 , Bosque ciprés; 1 male [ JSL-UOC], 8–15 August 2015 ; 2 males [ SFC], 17–21 August 2013 ; 1 female [ SFC], 15–22 August 2015 ; 4 males, 1 female [1 UVGC, 4 SFC], 24–31 August 2013 ; 1 male [ SFC], 31 August–7 September ; 1 male [ CNCI], 21–28 September 2013 ; 1 female [ SFC], 12–19 October 2013 ; 1 male [ SFC] 15–22 December 2012 , Bosque ciprés.

Figures

FIGURE 1. Amerikeroplatus dimorphicus n. sp., holotype male, habitus. Scale bar = ca. 1.0 mm.

FIGURES 2–3. Amerikeroplatus dimorphicus n. sp., 2. Female, lateral. 3. Male (holotype) head and anterior thorax, lateral. Scale bar = ca. 1.0 mm.

FIGURES 5–8. Amerikeroplatus dimorphicus n. sp., male and female terminalia. Figs. 5–8. Male [holotype] terminalia. 5. Dorsal. 6. Ventral. 7. Posterior. 8. Female terminalia, posterior view. Abbreviations: aed, aedeagal complex; cer, cerci; gc, gonocoxite; gs, gonostylus; S7, sternite 7; S8, sternite 8; T7, tergite 7; T9, tergite 9. Scale bar = ca. 0.25 mm.