Epeorus nguyenbaeorum Braasch and Boonsoong

Braasch, Dietrich & Boonsoong, Boonsatien, 2010, A contribution to the Heptageniidae (Insecta, Ephemeroptera) of Thailand and Malaysia, Zootaxa 2610, pp. 1-26 : 19-20

Epeorus nguyenbaeorum Braasch and Boonsoong sp. nov.

This species was figured by Nguyen and Bae (2004) as Epeorus hieroglyphicus Braasch & Soldán, 1984 , from Vietnam. Prof. Dr. Bae, being corresponding author, was informed by personal communication (Braasch, 15.IX.2004) about the misinterpretation of the species in question, of which he has given kindly acknowledgement (Bae, 30.IX.2004 personal communication). In honour of Dr. Van Vhin Nguyen as discoverer of the new species and Prof. Dr. Yoon Jae Bae as his adviser and co-author, we name the new species Epeorus nguyenbaeorum sp. nov.

Material: HOLOTYPE: Female La (Figs. 19–24), Vietnam, Ha Giang Prov., Vi Xuyen, Than Thuy, 08.XII.2000, leg. Nguyen. Described by Nguyen & Bae (2004a: p. 19–28, Figs. 19–24: head and pronotum (Fig. 19), foreleg, dorsal (Fig. 20); abdomen, dorsal (Fig. 21), gill I (Fig. 22), gill III (Fig. 23), gill VII (Fig. 24). PARATYPES: 2 La, same locality; 2 La, Ha Giang Prov., Vi Xuyen, Tay Con Linh. 09.XII.2000, leg. V.V. Nguyen.

Diagnosis: The head of E. nguyenbaeorum with its quadrangular shape and conspicuous pattern contrasts strikingly with that of E. hieroglyphicus , which has a rhomboid head with a central marking according to Braasch & Soldán (1984a: Fig. 22, p.112); marks of the pronotum occupy the anterior half in E. hieroglyphicus , whereas E. nguyenbaeorum has only an anteromedian brown mark. Contrary to E. hieroglyphicus , having a submedian row of oblique streaks along sterna, the new species is without any pattern. Microscopic structure of abdominal terga in E. nguyenbaeorum is quite different in showing hind margin fringes with relatively long setae alternating with short acute bristles ( Nguyen & Bae 2004a: p. 24, Fig. 21), lacking in E. hieroglyphicus , which has 2 submedian tubercles covered with 2 minute, spiny bristles and scattered with short hairs at the posterior margin of each tergum ( Braasch & Soldán 1984a: p. 112, Fig. 27). The gill set offers distinct differences in gill I being egg-shaped ( Nguyen & Bae 2004a: p. 24, Fig. 22) in the new species, but pear-shaped in true E. hieroglyphicus ( Braasch & Soldán 1984a: p.112, Fig. 28), and in gill VII being obovate, whereas that of E. hieroglyphicus is somewhat oblong and distally with an asymmetrically pointed tip; gill III is large and elliptical in both species.

Type deposition: HOLOTYPE: mature male La (Figs. 19–24 see above), in Department of Invertebrate Zoology, Faculty of Biology, Hanoi University of Science, Vietnam; PARATYPES: 1 La at the same place; 2 La in College of Life Science & Biotechnology, Korea University, Korea.