Euphaea saola Phan & Hayashi, sp. nov.

(Figs 14d, 15a, 16e, 18a–b, 18g, 20a–d)

Euphaea guerini [nec. Rambur, 1842]: van Tol & Rozendaal (1995), p. 102 (Fig. 20) [Illustration of S9–10 of unspecified locality in Vietnam]; Karjalainen & Hämäläinen (2013), p. 202) [Photo of male from Lak Sao, Bolikhamxay Prov., Laos].

Holotype. ♂, A Luoi Nature Reserve, Thua Thien-Hue Prov., 18.IX.2015, Q.T. Phan and F. Hayashi leg. Deposited at Zoological Collection of Systematic Zoology Institute in Tokyo Metropolitan University, Tokyo, Japan (TMUZ). Male paratypes. 4♂, A Luoi Nature Reserve, Thua Thien-Hue Prov., 18.IX.2015, Q.T. Phan, F. Hayashi and H. Karube leg. (FHC).

Female paratype. 1♀, A Luoi Nature Reserve, Thua Thien-Hue Prov., 18.IX.2015, F. Hayashi leg. (FHC). Other materials examined. [Vietnam] 2♂, Quang Binh Prov., VI.2016, T. Kompier leg. (TKC) ; Quang Tri Prov., VI.2016, T. Kompier leg. (TKC); Thua Thien-Hue Prov., VI.2016, T. Kompier leg. (TKC); 3♂ 1♀, A Luoi Nature Reserve, Thua Thien-Hue Prov., 18.IX.2015, F. Hayashi leg. (FHC); 3♂, Dong Giang District, Quang Nam Prov., 26.V.2015, Q.T. Phan leg. (PQTC) ; 3♂ 1♀, Quang Nam Prov., 21.VI.2016, T. Kompier leg. (TKC); 1♂, Ba Na Nature Reserve, Da Nang city, 22.V.2017, Q.T. Phan leg. (PQTC) ; 4♂ 1♀, Chu Mom Ray National Park, Kon Tum Prov., 22.V.2017, Q.T. Phan leg. (PQTC) ; 10♂, Hon Ba Nature Reserve, Khanh Hoa Prov., 16.IV.2017, Q.T. Phan leg. (PQTC) ; 4♂, Bach Ma National Park, Thua Thien-Hue Prov., 28.VI.2017, Q.T. Phan leg. (PQTC) ; 8♂, Chu Yang Sin National Park, Dak Lak Prov., 30.IV.2017, Hoang Quang Duy leg. (PQTC) .

Other materials confirmed by field observations. [Vietnam] Some individuals, Bach Ma, Thua Thien-Hue Prov., 5–8.VIII.2016, T. Kompier.

Etymology. The specific name “ saola ” of this species is derived from the name of the bovid “Saola” ( Pseudoryx nghetinhensis Dung, Giao, Chinh, Tuoc, Arctander & MacKinnon, 1993). This is one of the world’s rarest large mammals, a forest-dwelling bovine found only in the Truong Son mountain range of Vietnam and Laos. The type locality of Euphaea saola sp. nov. is A Luoi Nature Reserve which is a part of the Saola Conservation Area, central Vietnam. The general distribution of the new species largely coincides with that of this extraordinary mammal.

Description of holotype. Head, prothorax, synthorax, and legs (Fig. 20a). Entirely black excluding some narrow yellow stripes along the border of mesepimeron and metepisterum and on lower margin of metepimeron.

Wings (Fig. 14d). Similar to those of E. guerini with most of FW area darkened, excluding the basal part of the wing (but covering all cells along the subcosta), and the apical one-sixth, although the apical margin of the FW is also darkened. HW are black with metallic blue covering a large part of their underside, and with metallic green on the upperside, as in E. guerini . FW has 28–29 Ax and 32–33 Px, and HW have 22–23 Ax and 35–37 Px. The cubital space has 2–3 crossveins in both wings.

Abdomen. Entirely black. Lateroventral margin of S3 and S7–8 with fine setae in addition to the tuft of long setae on the base of S9 like E. guerini (Fig. 15a). Dorsum of S10 raised into large carinal spine posteriorly and with a small hump near its anterior margin (Fig. 20b).

Genital ligula. With two thick flagella, perpendicular to terminal segment as in Figure 20c.

Anal appendages. Typical of the genus with cerci short and robust, paraprocts are very short, slightly curved upward (Fig. 20b).

Measurements (in mm). HW 29; abdomen (incl. appendages) 37.

Variation in paratype males. Four paratypes show little morphological variation, excluding size; 27.5–29.5 mm in HW length and 36–38 mm in abdomen including appendages.

Description of paratype female. Head (Fig. 20d). Postclypeus, frons, antennae, and the dorsum of head matte black. Anteclypeus shining black. Labrum and base of mandibles dark yellow but margin and mid-dorsal part black. Genae dark yellow and this extends to the level of antennae.

Thorax (Fig. 16e). Anterior lobe of prothorax entirely black; middle and posterior lobes black with tiny orange spots; middle lobe raised into two large separately humps; distal margin of posterior lobe rounded, simple structurally (Fig. 18g). Synthorax black with narrow orange stripes as follows: mesepisternum has two separated narrow stripes on either side; mesepimeron entirely black; metepisternum and metepimeron both with two yellow stripes along distal and lower margins.

Legs. Black.

Wings. Hyaline tinted amber on proximal half of FW and complete HW. FW with 28–29 Ax and 31–32 Px, HW with 21 Ax and 29 Px. Cubital space with 1–3 crossveins in all wings.

Abdomen (Fig. 16e). Black with lateral yellow markings as follows: S1 with a large spot, S2–3 with a very narrow stripe, S4–5 with only tiny oval posterior spot, and S6–10 and ovipositor black.

Measurements (in mm). HW 29; abdomen (incl. appendages) 33.

Remarks. Euphaea saola sp. nov. is very similar to the population of E. guerini in Vietnam with similar wingcolor pattern of the male, but can be distinguished by more distinct dark apical margin and more distinct hyaline base in FW (Fig. 14d) compared to E. guerini (Fig. 14c). Abdominal segments S3 and S8 bear long setae in Euphaea saola (Fig. 15a), but very short setae in E. guerini (Fig. 15b). In Euphaea saola, the dorsum of S10 is raised in two places: there is a small hump in lateral view on the anterior part, but posteriorly it rises somewhat obliquely upward (Fig. 20b) forming a conspicuous carinal spine. S10 of Euphaea guerini lacks the anterior hump and the large posterior carinal spine rises strongly upwards, almost perpendicular to the abdomen (Fig. 20e). Cerci are short and robust, the posterior dorsal spine of S10 extending beyond their base posteriorly in lateral view in Euphaea saola (Fig. 20b), but cerci of E. guerini are narrower, petiolated at base, and the dorsal spine does not extend posteriorly of their base, so they are visible in dorsal view (Fig. 20e). Vesicle of Euphaea saola heartshaped, pointed at its posterior margin (Fig. 18a, b), but it is ax-shaped, with posterior margin rounded in E. guerini (Fig. 18c). The shape of the posterior lobe of the prothorax in females of Euphaea saola differs markedly from that of E. guerini by the smoothly rounded lateral edges and minor indentation of the posterior margin (Fig. 18g), while the lateral edges curve out and backwards in E. guerini, and the posterior margin is completely round centrally (Fig. 18h). In addition, (i) thorax black with very narrow stripes in E. saola (Fig. 16e), but stripes relatively broad in E. guerini (Fig. 16d); (ii) abdomen black with narrow yellow stripes on S1–3, tiny spots on S4–5, and entirely black on other segments in E. saola (Fig. 16e), but with stripes on S1–6 and a small yellow spot on S 9 in E. guerini (Fig. 16d); and (iii) wings entirely dark amber in E. saola, but hyaline with pale yellow color in E. guerini .

It is difficult to establish what published records/info of Euphaea guerini refer to E. saola . Van Tol & Rozendaal (1995) provided figures of the last abdominal segments and vesicle of Euphaea guerini from central Vietnam, but they did not specify the locality of each specimen. Figure 20 of ‘ Euphaea guerini ’ in van Tol & Rozendaal (1995) matches E. saola based on the resemblance of the dorsal prominence on S10, but their Fig. 21 of vesicle is similar to that of E. guerini (Fig. 18c) with apical margin rounded, not pointed as in E. saola (Fig. 18a, b). Hämäläinen (in litt.) also confirmed that ‘ Euphaea guerini ’ from Lak Sao, Bolikhamxay Prov., Laos by Karjalainen & Hämäläinen (2013) actually refers to E. saola . Similarly, earlier published records of ‘ Euphaea guerini ’ in Cambodia, central to southern Laos, and central Vietnam could likely include or refer to E. saola (e.g. Fig. 44, p. 31 in Phan et al. 2011).

Distribution. Vietnam (Ha Tinh [Hämäläinen in litt.], Quang Binh, Quang Tri, Thua Thien-Hue, Da Nang, Quang Nam, Quang Ngai [Hämäläinen in litt.], Dak Lak, Gia Lai, Kon Tum and Khanh Hoa [Hämäläinen in litt.] Provinces), Laos (Bolikhamxay Province) (Karjalainen & Hämäläinen 2013).