Taxonomic notes on the genus Orthobrachia Warren, with description of a new species from China and Thailand (Lepidoptera, Geometridae)

Abstract All seven members of the genus Orthobrachia Warren, 1895 are recorded, with description of a new species from Sichuan Province, China and N. Thailand, including Orthobrachia latifasciata (Moore, 1888) and Orthobrachia flavidior (Hampson, 1898) from northern India, Nepal and China, Orthobrachia tenebrosa Yazaki, 1992 from Nepal and India, Orthobrachia owadai Yazaki, 1992 from India, Orthobrachia simpliciata Yazaki, 2002 from China, and Orthobrachia maoershanensis Huang, Xin & Wang, 2003 from South China. A key to the Orthobrachia species is provided, along with a distributional map of all nominal species. The type specimens of the new species are deposited in Hunan Agricultural University (China), South China Agricultural University (China) and Zoological Research Museum Alexander Koenig (Germany).

Recently, some geometrid moths were collected at Longcanggou Town, Yingjing County, Sichuan Province, among them one species of the genus Orthobrachia which was confirmed as new to science and will be described herein. Surprisingly, one additional specimen of this species was discovered among material from N. Thailand in the ZFMK collection.
In the present paper, seven species from the Oriental Region are treated, and the adults and the genitalia are illustrated. Diagnostic generic characters of adults are proposed, and a key to all species is provided, based on external features. A distributional map of all Orthobrachia species is presented.

Material and methods
Adults of the new species were collected by light trap. The types of previously described species, deposited in the Natural History Museum, London, UK (BMNH) and in the National Science Museum, Tokyo, Japan (NSMT), were examined. Other specimens examined in this study are deposited in South China Agricultural University (SCAU), Hunan Agricultural University (HUNAU), China and Zoological Research Museum Alexander Koenig, Bonn, Germany (ZFMK).
The methods for examining the genitalia and taking the photographs are as described in Wang et al. (2015). Morphological terminology in descriptions follows Kristensen (2003). Type specimens of the new species described here are deposited in HUNAU, SCAU and ZFMK. Thorax. Hind leg tibia not dilated, without scent-brush. Index of spurs 0-2-4. Forewings without fovea; common stalk of veins R 2 -R 5 arising at large distance from the upper corner of the cell (= origin of M 1 ) in forewing, very close to the origin of vein R 1 which anastomoses with Sc. In hindwing vein Rs also at large distance from M 1 . Abdomen with tergites and sternites weak, membranous, only tergites 1 and 2 and sternites 1+2 may be slightly sclerotized. Sternite 3 without setal comb. Tympanal organs rather large, globular, without laciniae. Characters indicating Orthobrachia to be a distinct genus are found in the male genitalia: Elongated, spined or densely setose lobes arising from dorsal margin of sacculus near its base are present in all species of Orthobrachia, but are not found in other genera of Baptini. The valves are elongated, more or less parallel-sided, with rounded apex, curved upward in all species except O. simpliciata, with a broad, immaculate zone with one or two processes of different shape; valve lamina with an elongated field of setae; gnathos weak, only lateral arms present; juxta a broad, oval, somewhat elongate plate, ventrally angled and with v-shaped incision distally; aedeagus with bulbous caudal end, curved or straight, with one or two large cornuti on vesica, in two species with a bunch of external cornuti or a long row of small cornuti.

Taxonomy
The female genitalia also indicate the distinctness of Orthobrachia, though their characters separate two species-groups: 1) the latifasciata-group, also containing fla-vidior, tenebrosa and owadai: their genitalia are characterized by a well sclerotized antrum with distal and/or lateral processes, continued into a long, sclerotized band that reaches deeply into the bursa copulatrix. Signum a large, ring-like structure without dentation; 2) the simpliciata-group with semicircular lamellae antevaginales, without long sclerotized bands and with a stellate signum. O. simpliciata exhibits the most plesiomorphic characters in the female, but also in the male genitalia.
Host-plant. Unknown. Distribution. Oriental Region. The distributional map of all the known species is provided in Figure 1.
Key to the species of the genus Orthobrachia (based on wing pattern and colouration) Diagnosis. This species can be recognized and distinguished from the other Orthobrachia species based on external features. Main diagnostic characters are the strongly waved antemedial and postmedial lines in forewing, the white or slightly greyish-white medial bands and the large, dark brown apical patch with concave posterior border in hind wing (see also key to species). In addition the genitalia of both sexes exhibit distinctive characters: valva with a large, dorsal saccular lobe, formed like a heterocercal fish-tail in a lateral view, broadly oval in dorsal view. Compared to flavidior, the uncus is more slender, and the shorter and broader valva of the latter has a large basal lobe instead of the hook-like costal process just beyond the middle of the valva. The aedeagus of latifasciata is long and slender, with one stout cornutus, that of flavidior is shorter and rather stout, with two cornuti. The female genitalia are distinctive, with three long spines distally on the antrum, while flavidior has two short distal and two long proximal spines laterally on antrum. A second similar species is owadai, also having a white median band in hind wing (diagnosis given under owadai).
Material examined. INDIA: 1♂, Lectotype of Stegania latifasciata Moore, designated by Yazaki (1992), labeled "Type/ Stegania latifasciata Moore, Type/1621 Darjeeling/ Moore Coll. 94-106/ Geometridae genitalia slide No. 7925 ♂", BMNH;  Diagnosis. This species is very similar to O. latifasciata, but is generally smaller and can be distinguished by external features and characters of the genitalia: the postmedial line of forewing is almost straight or just slightly curved inward from costa to tornus, the clear white medial bands of hind wing are narrowly bordered dark grey outside, but a large, dark apical patch is absent; the uncus is broader and a little shorter than in latifasciata; the valva is shorter and broader and has a large, roundish, sclerotized lobe at base of the costa and lacks a median, hook-like costal process found in latifasciata. The basal saccular process is much larger and longer and arises more distally. A second saccular lobe is missing. The aedeagus is rather stout, with a round apex, which is bluntly pointed in latifasciata. The cornuti, consisting of a pair of stout spines situated on a diverticulum of the vesica, are somewhat longer than in latifasciata. In the female genitalia, the antrum is well sclerotized, nearly quadrate, with two pairs of processes, longer at caudal and shorter at distal margin, while in latifasciata it bears three longer distal spines.
Material examined. INDIA: 1♀, Lectotype of Orthobrachia latifasciata ab. flavidior Warren, designated by Yazaki (1992) Remarks. This species was firstly described by Warren (1896) as latifasciata ab. flavidior, which is nomenclaturally unavailable. Hampson (1898) raised the name to a species-group rank, stating, "The Khasi form has the dark markings of forewing reduced, and the white band of hindwing broader." -The "latifasciata"-male from Zhejiang figured in Seitz 4, Suppl. on plate 22, line g, is misidentified and in fact a male of flavidior. It is preserved in coll. ZFMK and could be checked by D.S. Yazaki, 1992 Figs 3B, 4D, 5D
Diagnosis. This species can be distinguished from other Orthobrachia species, especially from the very similar female of latifasciata, based predominantly on the following characters: In the forewing, the postmedial line is situated more distally and less deeply waved. In the hindwing, the postmedial line is shaded distally with brown, more broadly than in flavidior, but much less than in latifasciata. In the latter the whole apical one-third is dark brown, with a rounded posterior border. In the male genitalia, the valva has a large triangular, distally rounded costal process just before the middle, a second, smaller one at the base of the valva and the saccular lobes are shorter and broader, roundish, curved basad. The aedeagus is slender with a bunch of short spines externally near apex, the vesica bears two cornuti situated one after another on a large diverticulum (looking like one large cornutus in our Fig. 4D). In the female genitalia, a large lamella postvaginalis is absent and the antrum bears only two spines distally, pointing laterally. Longitudinal sclerotized band and round, ring-like signum are uniting owadai with the three species mentioned before.  Diagnosis. This species is similar to O. latifasciata, O. flavidior and O. owadai, especially similar to latifasciata, which has very similar transverse lines and also a large, dark brown apical patch in the hindwing, but can be distinguished easily from all three species by the dark brown medial area of the hindwing which are white or greyish-white in the other three. Moreover, the postmedian line is situated more distally. In the forewing, the broader median area is more strongly suffused with greyish-brown (see also key to species). In the male genitalia, length and width of the uncus are intermediate between latifasciata and flavidior. The valva bears a small triangular, apically rounded costal process arising from beyond the middle, and the saccular lobe is longer, extending more dorsally beyond dorsal margin of the valva, compared to flavidior. The aedeagus is more slenderly built and shorter, two cornuti are present on vesica, but smaller in size. There is no external bunch of spines like in owadai. The female genitalia are very similar to those of latifasciata, but the antrum is smaller, with the lateral pair of spines of equal length of the central one. In latifasciata, the lateral spines are longer. Biology. The adults are flying in September and October in high elevations between 2500 and 2800 m.
Distribution. Nepal, NE. India Remarks. The female from Sikkim, designated as paratype by Yazaki (1992), is the only female known so far. We figure its genitalia here, provided by Mr. K. Yazaki.
Diagnosis. This species is characterized in appearance by rather long antennal rami in the male, less yellowish (rather creamy white) wings, especially in the distal third of the hindwing, somewhat ill-defined transverse fasciae, and in the hindwing-pattern consisting of an incomplete postmedial line only. In the male genitalia the valva is simple, almost not curved dorsad at apex and any costal ornamentation, such as  (Hampson, 1898) C O. tenebrosa Yazaki, 1992, paratype D O. owadai Yazaki, 1992 small processes, present in latifasciata and tenebrosa, or the large dorsal expansions in flavidior and owadai, are absent. The saccular process is small and situated close to the base of valva. The aedeagus is unique in having a large row of small cornuti on vesica, together with a terminal, stronger and straight cornutus. Female genitalia are very different compared to latifasciata, flavidior, tenebrosa and owadai ("latifasciata-group"). The distinctive differences unite simpliciata with maoershanensis and hirowatarii (the simpliciata-group): with an arcuate, narrow lamella antevaginalis instead of a spined antrum, without long sclerotized bands and with an asymmetric, stellate signum. O. simpliciata exhibits the most plesiomorphic characters in the female, but also in the male genitalia.
Biology. The species was flying in spring at the type-locality.

Distribution. China (Taiwan).
Remarks. This species is endemic to Taiwan.
Diagnosis. The species is externally very similar to the new species described below, to O. simpliciata and also to O. tenebrosa, but can be distinguished from all by the following characters: The antemedial and postmedial lines of the forewing are distinctly waved in tenebrosa, in maoershanensis almost straight, only the postmedial is slightly curved inward near costa of forewing, straight in the new species. From O. simpliciata, it can easily be separated mainly by the differences in the hind wing pattern described above. Further distinguishing features see next species. The male genitalia of all three species have clear specific characters, the female genitalia as well, the latter uniting simpliciata, maoershanensis and hirowatarii sp. n. by a number of characters shared. Diagnosis. This new species is externally very similar to O. maoershanensis but can be distinguished by the dark-brown ante-and postmedial lines, which are stronger and straight in hirowatarii, more delicate and the postmedial line curved inwards near costa in maoershanensis. The tornal dark brown patch is broader and shorter in the latter, reaching up to the middle of the medial band; the narrower patch of hirowatarii is longer and reaches almost back to the antemedial line. In the hind wing, the narrow, almost black postmedial line is almost straight between apex and tornus in hirowatarii, while it is evenly curved between anterior and posterior margin distinctly basad of apex and tornus in maoershanensis. The valve in the male genitalia is longer and narrower with two processes near the base in hirowatarii, a multi-dentate costal process and an arm-shaped, angled, apically densely setose saccular process. The costal process in maoershanensis is short and apically rounded, the saccular process thumblike, with shorter setae at tip. In addition, the latter has a broad, basal costal process, similar to that found in flavidior. The aedeagus is short, stout, with two cornuti in maoershanensis, while hirowatarii has a longer, narrow aedeagus with a bunch of external spines at the border between shaft and vesica. The female genitalia are also clearly separable, though both (and simpliciata, too) have a similar, asymmetric, stellate signum (very small in simpliciata). Hirowatarii has a large, rather quadrate, strongly sclerotized antrum, with a transverse, semicircular, broad lamella antevaginalis distally, decorated with a pair of lateral spines. In maoershanensis, the quadrate part is absent, the semicircular part more delicate and the spines smaller. Moreover, maoershanensis has a much longer, fluted ductus bursae and the bursa is smaller (in our Fig. 5G with a damage on the left side). Description. ♂ Expanse 27-30 mm, length of forewing 13-15 mm. Head. Antenna bipectinate to three-fourths, rami arising from the proximal one third of flagellomers, apical 15-16 segments not pectinated. Frons narrow, smoothscaled, lower half with yellow, upper half with greyish-brown scales. Vertex with larger, creamy white scales. Palps narrow, short, scaled light greyish-brown. Thorax. Patagia greyish-brown, tegulae creamy white, thorax subdorsally with two longitudinal, dark brown lines (which are continued on the abdomen). Forewing ground colour creamy white, with transverse striation of dark brown and orange, scales of the same colours also accompany the veins. There is a dark brown patch at tornus, extended along posterior margin, reaching almost the antemedial line. The latter line strong, dark brown, straight, shortly curved basad and broadening near costa; postmedial line straight from tornus to 1/4 of costal margin; there is a small, semicircular loop between veins R 5 and M 1 at termen (also present in maoershanensis and simpliciata); cilia dark brown at posterior half of termen, creamy white between the dark end of the veins in anterior half. Hindwing rounded; ground colour similar to forewing, with broad, greyish-brown medial area. Thin blackish-brown postmedial line straight between tornus and apex, discal cell with a small black spot. Cilia brown, apart from those in the spaces M 1 -M 3, M 3 -CuA 1 and CuA 1 -CuA 2 which are creamy white.
♀ Expanse 30-34 mm, length of forewing 14-16 mm, antenna filiform. The ground colour of the wings and the pattern elements are very similar to the male.
Male genitalia: Uncus rather broad and short, beak-shaped. Gnathos consisting of weak, flattened lateral arms only, not fused in the middle. Valva long and narrow, with the distal end of costa projecting above the valve surface. Costa with a large, multidentate process just basally of the middle, and saccular process with a narrow basal arm and a broader, globular, apically densely setose distal parts. Juxta a large, broad, somewhat elongated plate. Saccus broad and rounded, flattened at base. Aedeagus slender with a bunch of well-developed cornuti, arising externally at the border between shaft and vesical, the latter without cornuti.
Female genitalia: Papillae anales elongate, apophyses long; a. anteriores about 3/5 the length of a. posteriores; lamella antevaginalis well sclerotized, semicircular, with a pair of spines bilaterally, united with a large, nearly quadrate, well sclerotized antrum; bursa copulatrix thinly membranous, pear-shaped (not clearly visible in our figure), distal part sclerotized, fluted, containing a wrinkled band; ductus bursae very short; signum rounded, margins and internal surface covered with spines.
Holotype Biology. The adults fly in August in Sichuan, in January in Thailand, at elevations between 1400 and 1700 m. The host of larvae is unknown.
Remarks. This new species was collected at a small village in the forest, with a light-trap inside a house, with artificial vegetation around it. Therefore the habitat seems to be quite different from that of other Orthobrachia species. E. g., O. maoershanensis originates from environment with natural vegetation in the core zone of the Nature Reserve.

Conclusions and discussion
The systematic relationship of the genus Orthobrachia has been questioned for a long time, as explained in the introduction chapter. We are convinced that it is a member of the tribe Baptini (sensu Holloway (1994)) indicated by the following characters: 1) vein R 2 in the forewing arising from a common stalk with R 3 -R 5 ; 2) fovea in forewing absent; 3) transverse comb of setae on sternite 3 absent; 4) valves elongate, more or less parallel-sided, rounded at apex, with a broad, immaculate costal zone, often with a marginal process or angle, an elongate field of setae, often with peg-like, short, broad setae (the latter not present in Orthobrachia, but also not present in a number of other genera of Baptini, sensu Holloway (1994)); 5) gnathos weak or absent (in Orthobrachia separated lateral arms present only). All or most of these characters are present in the genus Orthobrachia. Related genera in the Baptini are Platycerota Hampson, 1893(= Crypsicometa Warren, 1894 and Heterostegania Warren, 1893. Orthobrachia species are distributed from NW India (Kashmir) to Zhejiang and Taiwan (E. China), S. China, N. Vietnam and N. Thailand (the China-Himalayan animal area, as considered by Huang et al. 2010). O. latifasciata and O. flavidior are the most widespread species, latifasciata occurring from Kashmir to Western Central China, flavidior from C. Nepal to E. China (Zhejiang), the latter also being the most abundant of all species. Most other species seem to be rare or are at least rarely collected. O. tenebrosa is only known from a few specimens from C. Nepal and Sikkim, NE. India, O. owadai from the latter region only. Species of the simpliciata-group are only distributed in E. and SE. China, including the more northern Sichuan region. O. simpliciata is endemic to Taiwan, and also the recently described O. maoershanensis and O. hirowatarii, described herein, were considered to be very local species firstly, but the discovery of both species in N. Vietnam and N. Thailand, respectively, proved them to be more widespread. More collecting at appropriate places (i.e. natural forests at elevations between 1500 and 3000 m a.s.l.) will probably reveal even more localities where these rare species occur. Considering the fact, that no Orthobrachia species are known at all to us from N. Myanmar and N. Laos, we also believe that the discovery of further new species is possible.