Systenus

Bickel, Daniel J., 2015, The Costa Rican Systenus Loew (Diptera: Dolichopodidae): rich local sympatry in an otherwise rare genus, Zootaxa 4020 (1), pp. 169-182 : 171

Key to males of Systenus from Costa Rica

1 All femora yellow.................................................................................... 2

- At least one femur with some brown cuticle................................................................. 4

2 Cercus short, wide and subrectangular ( Figs 4 d, e); tibiae yellow with brownish vestiture; postpedicel basally subrectangular and yellow, and abruptly narrowed to elongate dark brown tapering point distally ( Fig. 4 c)............. S. parkeri sp. nov.

- Cercus elongate and digitiform ( Figs 1 d, f); tibia I white with ivory colored vestiture; postpedicel various.............. 3

3 Wing apex brown, and posterior membrane reduced near apex so vein M forms the posterior margin ( Fig. 1 e); CuAx ratio> 1.0................................................................................. S. maculipennis sp. nov.

- Wing hyaline, unmodified ( Fig. 1 c); CuAx ratio <0.7.................................... S. flavifemoratus sp. nov.

4 All femora with at least some brown cuticle; postpedicel elongate, triangular and tapering gradually.................. 5

- Femora I and II yellow, and only femur III with brown cuticle distally; postpedicel various.......................... 6

5 Both tibiae I and III with white cuticle and short ivory colored vestiture; tibia II yellow with brownish vestiture ( Fig. 4 a); cer- cus elongate and projecting well beyond surstylus ( Fig. 4 b).................................... S. eboritibia sp. nov.

- Tibia I only with white cuticle and ivory colored vestiture; tibia II yellow and tibia III brownish ( Fig. 1 a); cercus and short and digitiform, not extending beyond surstylus ( Fig. 1 b)............................................ S. tenorio sp. nov.

6 Vein M apically bent and forming sharp point on wing margin ( Fig. 3 a); tibia III entirely yellow; postpedicel gradually taper- ing; tibia and tarsus I with ivory colored vestiture; cercus flagellate with long setae ( Fig. 3 b)........ S. divericatus sp. nov.

- Vein M and R4+5 subparallel and wing margin entire; tibia III with some brown cuticle; other features various........... 7

7 Tibia I with normal short black vestiture; segment 7 (hypopygial peduncle) elongate, almost twice length of epandrium ( Fig. 3 c), cercus elongate and clavate with subapical field of strong pale setae ( Fig. 3 d).................... S. zurqui sp. nov.

- Tibia I with some ivory colored vestiture, segment 7 subequal in length to epandrium; cercus elongate with only short pale setae............................................................................................... 8

8 Tibia I only with ivory-colored vestiture on anterior face; tibia III with brown cuticle only on distal quarter ( Fig. 2 a), surstylus squarish with long dorsoapical projection ( Fig. 2 b).......................................... S. emusorum sp. nov.

- Femur, tibia and tarsus I almost entirely covered with short ivory-colored vestiture; tibia III with brown cuticle on basal quarter and distal quarter ( Fig. 2 c), surstylus elongate and curved ( Fig. 2 d)............................. S. naranjensis sp. nov.

Figures

FIGURE 1. Systenus tenorio sp. nov. (holotype): a. male habitus, left lateral (terminalia removed); b. hypopygium, left lateral. S. flavifemoratus sp. nov. (holotype): c. male habitus, right lateral; d. hypopygium, left lateral. S. maculipennis sp. nov.: e. male habitus, left lateral (terminalia removed); f. hypopygium, left lateral. Abbreviations: cer, cercus; epan, epandrium; hyp, hypandrium; ph, phallus; st, sternite; sur, surstylus; tg, tergite; 6, 7, 8, abdominal segments.

FIGURE 2. Systenus emusorum sp. nov. (holotype): a. male habitus, left lateral; b. hypopygium, left lateral. S. naranjensis sp. nov. (holotype): c. male habitus, left lateral; d. hypopygium, left lateral; e. male head, anterior.

FIGURE 3. Systenus divericatus sp. nov. (holotype): a. male habitus, left lateral; b. hypopygium, left lateral. S. zurqui sp. nov.: c. male habitus, left lateral; d. hypopygium, left lateral.

FIGURE 4. Systenus eboritibia sp. nov. (holotype): a. male habitus, left lateral; b. hypopygium, left lateral. S. parkeri sp. nov.: c. male habitus, left lateral; d. hypopygium, left lateral; e. male postabdomen, right lateral.