Rhithrogeniella ornata Ulmer, 1939

Braasch, Dietrich & Boonsoong, Boonsatien, 2010, A contribution to the Heptageniidae (Insecta, Ephemeroptera) of Thailand and Malaysia, Zootaxa 2610, pp. 1-26 : 23-24

Rhithrogeniella ornata Ulmer, 1939

Material examined. 5 SI males, Malaysia, Gombak River, Research-Station Senckenbergmuseum Frankfurt am Main, 16.– 20.08.2007, leg. D. Kovac, det. Braasch.

Diagnosis. The longer male subimagos of Rhithrogeniella ornata (5.5-7.0 mm) can be separated from R. tonkinensis Soldán & Braasch, 1986 by: a pair of brown paramedian bands, and median streak cleft on terga II–VIII ( Ulmer 1939: p. 577, Fig. 170), posterior margins of terga with broad darker rim, contiguous to the bands; figure mark on tergum VIII residuary, consisting merely of two median streaks of half tergum length and a cross-streak medio-distally; and terga IX–X light. In contrast to R. ornata from Java and Sumatra ( Ulmer 1939), the median streak in the specimens from Malaysia is only faintly cleft and their pattern of tergum V is somewhat blurred or extinguished. The apices of penis are bluntly pointed, and the medial portion of posterior margin of subgenital plate is slightly concave. Ulmer (1939) illustrated the male (p. 577, Fig. 165–168) and described the female (text only) of R. ornata ; the larva of this species remains unknown.

In the smaller male subimagos of R. tonkinensis (4.1–4.7 mm) throu-going paramedian bands on terga II– VI, on V and VI shortened, median streaks on terga lacking, terga VII–X are light; apices of penis lobes broadly rounded; posterior margin of subgenital plate straight (Soldán & Braasch 1986: p.209, Fig. 19–20). Larvae, and larvae and imagos of R. tonkinensis are respectively figured in Soldán & Braasch (1986: p. 205, Figs. 1–8, p. 207, Figs. 9–12) and Braasch (1990: p.11, fig. 17.1–4).

Discussion. The new findings in Malaysia only presented subimago males. Therefore comparison was made along corresponding figures in Soldán and Braasch (1986) and Ulmer (1939). Now, Rhithrogeniella ornata is known from Java, Sumatra and continental West-Malaysia, whereas R. tonkinensis is found in China, Thailand and Vietnam ( Braasch 1990, Ulmer 1939, You et al. 1983). We have already previously pointed out ( Braasch & Boonsoong 2009) that R. tonkinensis is probably identical with ‘ Afronurus’ sangangensis ( You et al. 1982: p. 62, Figs. 1–13), but we had no opportunity to confirm this by comparing Chinese material.