Genus Elaphropeza Macquart, 1827

Elaphropeza Macquart, 1827: 86

(type-species: Tachydromia ephippiata Fallén, 1815, by monotypy).

Ctenodrapetis Bezzi, 1904: 351 (as subgenus of Drapetis) (type-species: Drapetis (Ctenodrapetis) ciliatocosta Bezzi, 1904 by subsequent designation in Melander 1928: 309).

The genus Elaphropeza can be distinguished from other genera of the Drapetidini by the following combination of characters: occiput convex, antennae not upturned, postpedicel conical, its ventral margin as straight as dorsal margin, stylus apical, anepisternum bare, wing with shortened cell br, abdominal tergites may bear squamiform setae, intersegmental modifications present between tergites 3–5 or 4–5. For a detailed diagnosis and the general morphology we refer to Grootaert & Shamshev (2012).

Key to male Elaphropeza from mangroves in Hong Kong

The present key is limited to the species occurring in mangroves in Hong Kong and their siblings in Singapore and Taiwan, modified after Grootaert & Shamshev (2012). All species belong to the E. ephippiata group in having the proepisternum bare just above the fore coxa (lacking a long upturned bristle) and the abdominal tergite 3 with unmodified setae, lacking squamiform setae.

All species here are yellow with an entirely yellow scutum without spots, with yellow or black occiput and hind tibia with a single anterodorsal bristle near the middle. Wings hyaline or uniformly infuscate.

For black species or those with hind tibia without prominent bristles or with an apical curved spine, or scutum with a colour pattern or wing with a pattern, check Grootaert & Shamshev (2012, 2015) for Oriental species or Yang et al. (2005, 2006) for China and Wang et al. (2012) for Taiwan.

1. Occiput black..................................................................................................................................... 2

– Occiput yellow (Taiwan, Hong Kong)................................................ E. xanthocephala Bezzi, 1912

2. Hind tibia with long pointed apical projection. Scutellum and metanotum brown. Acrostichal bristles lacking on prescutellar depression. Haltere yellow (Taiwan, Hong Kong)......................................... ................................................................................................................... E. calcarifera Bezzi, 1907

– Hind tibia with short, rounded apical projection. Different combination of characters .................... 3

3. Scutellum entirely yellow.................................................................................................................. 4

– Scutellum largely brown or black (in E. riatanae there is a variation of colouration from entirely yellow to entirely brown to black scutellum, but metanotum is always black)............................... 10

4. Acrostichal bristles extending to base of scutellum. Haltere darkened............................................. 5

– Acrostichal bristles lacking on prescutellar depression. Haltere yellow ........................................... 6

5. Postpedicel about 6.0 × longer than wide, stylus about 0.7× length of postpedicel. Right epandrial lamella with only two pale blunt spines. Tip of fused part of cerci long, with short bristles. Metanotum reddish-yellow (Singapore) .............................................. E. asiophila Shamshev & Grootaert, 2007

– Postpedicel about 4.6 × as long as wide, stylus nearly as long as postpedicel (0.86 ×). Tip of right epandrial lamella with 3 black blunt spines; fused part of fused cerci shorter, with long bristles (Fig. 7 A–B). Metanotum rather orange-yellow (Hong Kong) ............................ E. guenardi sp. nov.

6. Fore tibia and tarsus, mid and hind tarsomere 5 brownish (legs sometimes entirely yellow in E. furcatella sp. nov). Abdominal tergite 4 and 5 with or without squamiform setae....................... 7

– Legs with only tarsomere 5 brown. Abdominal tergite 4 with slightly flattened setae, tergite 5 with squamiform setae ............................................................................................................................... 8

7. Abdominal tergites 4 and 5 with squamiform setae. Male: cerci broadly fused, forked, right epandrial lamella truncate apically, lacking spines (Singapore)............. E. furca Shamshev & Grootaert, 2007

– Abdominal tergites 4 and 5 without squamiform setae. Male: tip of right epandrial lamella forked (Fig. 5A), tip of cercus truncate, but pointed at the left side (Fig. 5B). Legs entirely yellow, sometimes fore and mid tibiae and tarsi dusky yellow, not brown. .................................... E. furcatella sp. nov.

8. Male: right epandrial lamella with unmodified setation, lacking spines (Fig. 11F) (Singapore) ........ .................................................................................................. E. lowi Grootaert & Shamshev, 2012

– Male: right epandrial lamella with three apical black spines or a single subapical spine at the inside.................................................................................................................................................. 9

9. Tip of right epandrial lamella broadened, with three black spines apically (Fig. 11E) (Malaysia, Singapore)...................................................................... E. malayensis Shamshev & Grootaert, 2007

– Tip of right epandrial lamella not broadened and bearing a single spinule at the inside (Fig. 11B) ........................................................................................................ E. hongshulin sp. nov.

10. Scutellum brown medially (Taiwan).......................................................... E. marginalis Bezzi, 1912

– Scutellum entirely brown or black....................................................................................................11

11. Legs with fore tibia and tarsus wholly brown, hind femur near apex above brownish (Singapore, Hong Kong) ....................................................................... E. riatanae Shamshev & Grootaert, 2007

– Legs with only tarsomere 5 brown to black..................................................................................... 12

12. Acrostichal bristles biserial near middle of scutum, lacking on prescutellar depression ................ 13

– Acrostichal and dorsocentral bristles multiserial............................................................................. 14

13. Larger (about 2.5 mm). Left surstylus with a shallow notch apically (Grootaert & Shamshev 2012: fig. 155) (Singapore)......................................................... E. feminata Shamshev & Grootaert, 2007

– Large (about 1.7 to 2.3 mm). Left surstylus with a deep notch on dorsal border (Fig. 9C) (Hong Kong) ......................................................................................................... E. hongkongensis sp. nov.

14. Hind tibia with long, pointed apical projection; two long prescutellars (Taiwan, Hong Kong).......... ................................................................................................................... E. calcarifera Bezzi, 1907

– Hind tibia with small, rounded apical projection; one long prescutellar bristle (Taiwan)................... ..................................................................................................................... E. melanura Bezzi, 1912