Elaphropeza riatanae Shamshev & Grootaert, 2007

Grootaert, Patrick, 2019, Species turnover between the northern and southern part of the South China Sea in the Elaphropeza Macquart mangrove fly communities of Hong Kong and Singapore (Insecta: Diptera: Hybotidae), European Journal of Taxonomy 554, pp. 1-27 : 19-21

Elaphropeza riatanae Shamshev & Grootaert, 2007

Figs 12–13

Elaphropeza riatanae Shamshev & Grootaert, 2007: 88 , figs 141–144; (type locality: Pulau Ubin, Chek Jawa, Singapore).

Elaphropeza riatanae – Grootaert & Shamshev 2012: 88 , new records.

Material examined

HONG KONG • 1 ♂; Tai Tan (28M1); 22.43857° N, 114.33327° E; C. Taylor and U. Chang leg.; 5–19 Dec. 2017; male genitalia as in holotype but fore tibiae not brown, tarsus brown; RBINS • 2 ♂♂; Sam A Chung (5 BM1 ); 22.50829° N, 114.27248°E; C.Taylor and U. Chang leg.; 11–27 Dec. 2017; 1 male has fore tibia and tarsus brown, mid tarsus as well; scutellum with only the margins brown while the second male has a black scutellum; RBINS • 3 ♂♂; Sam A Tsuen (5 AM1 ); 22.51534° N, 114.27121° E; C. Taylor and U. Chang leg.; 11–27 Dec. 2017; RBINS • 1 ♂; Tai Tan (28M1); 22.43857°N, 114.33327° E; C. Taylor and U. Chang leg.; 5–19 Dec. 2017; RBINS • 1 ♂; Yim Tin Tsai (45 AM1 ); 22.37576° N, 114.30160°E; C. Taylor and U. Chang leg.; 24 Nov. 2017; RBINS • 5 ♂♂, 1 ♀; Tai O (17 CM1 ); 22.25790°N, 113.86360°E; C. Taylor and U. Chang leg.; 20 Oct.–2 Nov. 2017; RBINS • 3 ♂♂, 1 ♀; Wong Chuk Wan (34M1); 22.39563° N, 114.28617° E; 5–19 Dec. 2017; muddy back mangrove; barcode references: HKC0000952 ♀, HKC0000956 ♂, HKC0000958 ♂, HKC0000960 ♂; RBINS • 1 ♂; Shui Hau (19M1); 22.21936°N, 113.91898° E; 1–14 Nov. 2017; sandy back mangrove; male terminalia figured ( Fig. 13 ); barcode reference JP1 E; RBINS • 1 ♂; Sam A Chung (5 BM1 ); 22.50829° N, 114.27248° E; C. Taylor and U. Chang leg.; 11–27 Dec. 2017; barcode reference JP1 H; RBINS • 1 ♀; Ho Chung (38 BM1 ); 22.35366°N, 114.25207° E; 4–18 Dec. 2017; muddy back mangrove; this female has a yellow scutellum; RBINS • 1 ♂; same collection data as for preceding; barcode reference HKC0000751; RBINS • 1 ♀; same collection data as for preceding; with black scutellum and the other dark body parts are also darker, fore tibia and tarsus, brownish patch on postalar callus, haltere dusky; barcode reference HKC0000747; RBINS • 1 ♂; Tai Tam (22M1); 22.24614° N, 114.22334°E; 9–23 Oct. 2017; sandy back mangrove; barcode reference HKC0000786; RBINS • 1 ♂; Sheung Pak Nai (10M1); 22.45197° N, 113.96253° E; 15 Nov.–1 Dec. 2017; sandy back mangrove; barcode reference HKC0001044; RBINS .

Description

Male ( Fig. 12 )

BODY. 1.5–1.6 mm long; wing 1.4–1.5 mm long.

HEAD. Occiput black, all setae pale yellow. Scape yellow, apical half of pedicel yellowish brown, postpedicel brown, but a little paler at base; postpedicel nearly 5.0 × as long as wide, stylus about as long as postpedicel. Ocellar bristles a little shorter that the verticals.

THORAX. Scutum orange yellow, scutellum brown and metanotum black; acrostichal and dorsocentral bristles multiserial, reaching the scutellum.

LEGS. Yellow with brownish pattern; fore tibia and tarsus and mid tarsus yellowish brown, in contrast to yellow femora. Mid tibia with brown ventral spinules in apical half, no apical spine. Hind tibia with one anterodorsal bristle near middle; tarsomere 1 yellow, with an irregular double row of brown spinules about as long as tarsomere is wide.

ABDOMEN. Tergites 2 and 3 brown at side, tergites 4 and 5 black, with squamiform setae, tergites 6 and 7 entirely black.

TERMINALIA ( Fig. 13 ). Black. Right epandrial lamella subtriangular ( Fig. 13B ), tip bent and elongate to right side ( Fig. 13A ). Cerci fused with a row of long bristles at base of fused part, tip elongate and bent to left, with a few short bristles apically. Left epandrial lamella fused with hypandrium, bearing a papillalike protuberance bearing a strong black bristle, with two long bristles at tip of hypandrium ( Fig. 13C ). Left surstylus triangular in lateral view ( Fig. 13D ), with a long protuberance at base elongate to right side and bearing there a few short, strong bristles.

Female

BODY. 1.5–1.6 mm long; wing 1.4–1.7 mm long.

Legs with identical colour pattern as in male. Ventral spinules on mid tibia less distinct than in male. Tergite 4 shorter than in male, with finer squamiform setae.

Remarks

The male terminalia of the Hong Kong specimens are similar to those of specimens from Singapore, though there are differences. The tip of the fused part of the cerci in Hong Kong males is more bent to the left and bearing at its tip a few short bristles. There are hardly any bent or short bristles on the tip of the cercus in the Singaporean specimens. The tip of the left surstylus in Hong Kong specimens seems to be more pointed than in the Singaporean specimens. Since there are no barcodes available for the Singaporean specimens to indicate that this variation is related to a large genetic distance, the specimens are considered conspecific. Elaphropeza riatanae is rare in Singapore, while very common in Hong Kong.

In the key to the Oriental species ( Grootaert & Shamshev 2012) of Elaphropeza it is stated that the scutellum is brown in this species. However, in Hong Kong there is a large variation in colour of the scutellum, from specimens with completely yellow scutellum, though generally the margin of the scutellum with the scutum is brown. Some specimens have the central area of the scutellum brown, while in others the scutellum is entirely black. The barcodes of these colour variations form a cluster of less than 1%. Thus, it is considered that all form a single species. Moreover, the populations are mixed. Specimens that are overall darker, with darker fore tibia and tarsus, generally have a darker scutellum.

Figures

Fig. 12. Elaphropeza riatanae Shamshev & Grootaert, 2007, ♂, habitus, RBINS (leg. C. Taylor and U. Chang; photo A. Samoh).

Fig. 13. Elaphropeza riatanae Shamshev & Grootaert, 2007, male terminalia (19M1), RBINS (leg. C. Taylor and U. Chang). A. Tip of right epandrial lamella. B. Right epandrial lamella. C. Epandrium dorsal view. D. Left surstylus. Scale bar: 0.1 mm.