Systenus fuscus, Ramos-Pastrana & Merchan-Vargas & Soares, 2024

Ramos-Pastrana, Yardany, Merchan-Vargas, Geraldine Lucia & Soares, Matheus M. M., 2024, First record of the genus Systenus Loew (Diptera: Dolichopodidae) from Colombia, with description of four new species, Zootaxa 5514 (3), pp. 257-272 : 263-265

Systenus fuscus sp. nov.

( Figs 3 , 7 )

Diagnosis. Antenna entirely brown, postpedicel mostly triangular, abruptly narrowed at apical 1/3, about 3.5X as long as basal width ( Fig. 3B ). Metepimeron brown ( Fig. 3A ). Legs brown, except apex of all coxae, all trochanters, base and apex of all femora, all tibiae, It 1–4, basal 1/4 of IIt 1 and basal 1/2 of IIIt 1 yellow ( Fig. 3A ). Wing hyaline ( Fig. 3D ). Surstylus longer than epandrial capsule and as long as cercus, somewhat rectangular at basal 2/3 and with a ventral indentation at apical 1/3 and slightly curved ventrally at apex, and with 1 long digitiform process curved posteriorly at basal 1/3 ( Fig. 3F ).

Description. Male ( Fig. 3 ). Body length: 1.8 mm; wing 1.6 mm. Head ( Fig. 3A, B ). Similar to S. bickeli sp. nov. except as noted: Antenna entirely brown, postpedicel mostly triangular, abruptly narrowed at apical 1/3, about 3.5X as long as basal height; arista short, about 1/2 as long as postpedicel. One row of postocular setae, uppermost five black, remaining setae pale brown. Thorax ( Fig. 3A, C ). Mostly metallic light green with weak bluish reflections, thorax wholly covered by dense silvery pruinosity. Metepimeron brown. Legs ( Fig. 3A ). Brown, except apex of all coxae, all trochanters, base and apex of all femora, all tibiae, It 1–4, basal 1/4 of IIt 1 and basal 1/2 of IIIt 1 yellow. Leg I. Podomere ratios: 45, 44, 22/10/8/6/5. Anterior surface of coxa I covered by short vestiture of yellow setae, 4 long yellow setae at apical edge. Femur I clothed by short vestiture of brown setae. Leg II. Podomere ratios: 50, 55, 30/18/13/9/5. Anterior surface of coxa II covered by short vestiture of yellow setae, longer at apical 1/2. Femur II mostly clothed by short vestiture of black setae, except ventral surface with pale setae. Tibia II with 1 posterodorsal setae at basal 1/4, and crown of setae at apex: 1 anterodorsal, 1 dorsal, 1 posterior and 1 ventral. Leg. III. Podomere ratios: 60, 65, 20/18/16/11/7. Lateral surface of coxa III with 1 strong yellow seta near middle. Femur III clothed with short vestiture of brown setae at dorsal surface, anterior surface of basal 1/2 clothed by pale setae and posterior surface mostly bare. Tibia III with row of strong setae dorsally, starting at basal 1/4 and ending at apical 3/4. Wing ( Fig. 3D ). Hyaline, veins pale brown. Crossvein dm ending at basal 4.5/8; R 2+3 nearly straight; R 4+5 and M 1 slightly bowed at apical 6/8 and ending parallel at apex. Abdomen ( Fig. 3A, E ). Mostly metallic green, covered by short vestiture of black setae, tergite 1 with long setae at posterior margin, tergites 3–4 with brown central band, tergites 5–7 entirely brown, tergite 7 brown, long and setose, sternite 8 brown. Hypopygium ( Fig. 3F ). Surstylus longer than epandrial capsule and as long as cercus, somewhat rectangular at basal 2/3, with ventral indentation at apical 1/3 and slightly curved ventrally at apex, with 1 long digitiform process curved posteriorly at basal 1/3, a few short setae at ventral edge of basal 2/3 and 1 ribbon-like seta at apex. Epandrial lobe about 1/2 as wide as surstylus at widest point, gradually narrowed and hook-shaped at apex, strongly curved ventrally, with 1 long seta at middle of ventral edge. Cercus yellow, with rounded swollen base, thin medially and apically, clearly longer than epandrial capsule, about as long as surstylus and covered by long yellow setae.

Female. Unknown.

Type material. HOLOTYPE ♂, labelled: “ COLOMBIA, Caquetá, Caquetá, Paujil, Vda. [Vereda] San Pedro, Fca. [Finca] Buenos Aires , 01º33’00’’N / 75º14’27’’W, 283 m, 26.X–9.XI.2016 / Trampa Malaise en Bosque (Dosel),

Y. Ramos-Pastrana Leg. ” ( LEUA) (photographed specimen). Holotype condition: good, right It 3–5 broken off, abdomen dissected and stored in microvial with glycerin.

Distribution. Colombia (Caquetá: Paujil) ( Fig. 7 ).

Remarks. The new species is similar to S. eboritibia Bickel , S. nigriatus Naglis and S. tenorio Bickel by the postpedicel triangular and wholly dark brown and femora mostly dark brown. It can be differentiated from S. eboritibia by the yellow tibia III and the ventral edge of the surstylus nearly straight at basal half (tibia III white and ventral edge of surstylus with basal lobular process in S. eboritibia ). It can be distinguished from S. nigriatus also by the lobular ventral process present on the surstylus on the latter species ( Naglis 2000, fig. 1b) and from S. tenorio by the arista-like stylus apical (arista-like stylus subapical in S. tenorio ).

Etymology. From the Latin ‘ fuscus ’ (= brown), referring to the color of antenna and femora of the new species.

Figures

FIGURE 3. Systenus fuscus sp. nov., holotype male (before dissection). A. Habitus, lateral view; B. Head, lateral view; C. Thorax, dorsal view; D. Left wing; E. Abdomen, dorsal view; F. Hypopygium, left lateral view.

FIGURE 7. Geographical records of Systenus Loew in Colombia. S. beatae Naglis, 2000; S. bickeli sp. nov.; S. colombiensis sp. nov.; S. flaviatus Naglis, 2000; S. fuscus sp. nov.; S. grossus sp. nov.; S. maculipennis Bickel, 2015; S. naranjensis Bickel, 2015 and S. parkeri Bickel, 2015.