Descriptions of two new Vietomartyria species (Lepidoptera, Micropterigidae) from China

Micropterigidae is a family of Lepidoptera characterized by plesiomorphic morphological characters. Presently, this family consists of more than 22 genera and is distributed throughout all biogeographic realms. Vietomartyria Hashimoto & Mey, 2000 presently consists of six species mainly from South China. Two new species of the genus, V. wuyunjiena sp. nov. and V. maoershana sp. nov., are described herein from China; adult genitalia and wing venation are illustrated. Some biological accounts of the new species are also provided. A key to all described Vietomartyria species is given.


Introduction
The family Micropterigidae Herrich-Schäffer, 1855 consists of more than 160 species in 20 extant genera worldwide (van Nieukerken et al. 2011;Imada & Kato 2018). The micropterigids form a sister clade to all the other families of the extant Lepidoptera (Kristensen et al. 2007;Regier et al. 2015). The adults are devoid of proboscis and instead possess well developed functional mandibles, by that they are regarded as a plesiomorphic group of moths together with the other non-glossatan moth families Agathiphagidae and Heterobathmiidae (Kristensen 1984(Kristensen , 1999. Micropterigidae are easily distinguished from the other non-glossatans by the following combiantion of characters: ocelli present; spur formula of 0:0:4; Sc vein of forewing forked; and pterostigma absent (Kristensen 1984(Kristensen , 1999Hashimoto 2006). Although the biology of micropterigids is underexplored, food sources of the larvae of some species are known.
The genus Vietomartyria was established by Hashimoto & Mey (2000) with Paramartyria expeditionis Mey, 1997 from Vietnam as the type species, based on the long basal stalk of each flagellomere and the position of the gonopore opening. Some additional distinguishing characters of Vietomartyria are: the large number of flagellum segments, more than 55 in males and 42 in females; foretibial epiphysis absent; primary R fork of forewing equal or more distal to the Sc fork; posterior margin of segment IX expanded ventro-posteriorly in male genitalia; and signum absent in female genitalia (Hashimoto & Mey 2000). Hirowatari et al. (2009) described two new species of Vietomartyria from South China of which females have a signum in the corpus bursae and considered that the absence of a signum in the female may be unique to V. expeditionis. Subsequently, Hirowatari et al. (2010) added one new species, V. gladiator Hirowatari & Huang, 2010from South China and transferred two species of Paramartyria Issiki, 1931, P. jinggangna Yang, 1980and P. baishanzuna Yang, 1995

Material and methods
Adult specimens were collected in Wuyunjie National Nature Reserve, Hunan Province and Mao'ershan National Nature Reserve, Guangxi Province, China and the wings were spread. Male and female genitalia were dissected after maceration in 10% NaOH solution heated in a waterbath, and preserved in glycerol after scales were removed. The wings were treated using the same methods. The photos of adults were taken using a Leica S8APO microscope and Leica DFC435 with LAS v4.9 software. The photos of male and female genitalia and wings were taken with a ZEISS Axio Vert.A1 inverted microscope. Terminology for adults and genitalia used in this paper follows Hashimoto & Mey (2000), Hirowatari et al. (2009) and Davis & Landry (2012). All studied materials are deposited in Hunan Agricultural University, China (HUNAU).

Diagnosis
The adults of this species are very similar to Vietomartyria nankunshana Hirowatari & Hashimoto, 2009 and V. nanlingana Hirowatari & Jinbo, 2009 because of their same ground color, but are separable from these two species by the dorsal process of the valva slightly curved inwardly (but almost right-angularly curved inwardly in V. wuyunjiena sp. nov.), and by tergite X slightly emarginate at the middle (but broadly emarginate in V. nankunshana and narrowly in V. nanlingana).

Etymology
The specific epithet is derived from the name of the type locality, Wuyunjie National Nature Reserve. Paratypes CHINA • 19 ♂♂, 9 ♀♀; same data as for holotype; HUNAU.
head. Vertex densely covered with long piliform scales except for exposed part between compound eye and ocellus; tufts of scales yellow brown, mixed with dark brown hairs. Maxillary palpus pale yellow. Antennal scape and pedicel with dark brown hair-like scales; flagellum 58-segmented (46 segments in female), covered with dense black hairy scales.
thorax. Tegular tufts of piliform brown scales; mesonotum densely covered with golden broad scales, possessing metallic blue luster. Legs with dark brown scales; inner surface of fore-and mid-femur and apical band of each tarsal segment yellow; fore-tibia without epiphysis, mid-tibia without spur, hindtibia with two pairs of spurs. Forewing ground color dark brown, basal 2⁄₅ with golden luster, apical 3⁄₅ with purple luster; metallic blue luster along costa; cilia brown, paler on posterior margin. Hindwing dark fuscous except costal margin with metallic blue luster, covered with slender scales on basal half and broad scales on apical half; cilia dark brown.
wing venation ( Fig. 2A). Forewing with humeral vein (h) present at base; Sc deeply bifurcate; R with five branches, primary R fork equal to Sc fork, R 4 and R 5 long stalked; Sc-R crossvein near basal ⅓ of Sc 2 ; M with three branches; CuA with two branches, M-CuA crossvein present; CuP separate; 1A and 2A fused at basal 3⁄ ₅. Hindwing venation very similar to forewing venation, except Sc and R1 fused; M-CuA crossvein absent; 1A fused with CuP basally, then independent and fused with 2A.
Female genitalia (Fig. 5A-C). Segment IX sclerotized, short in dorsal part (approximately 2⁄₅ length of ventral part), slightly concave dorsally and laterally. Segment X and XI formed two pairs of well sclerotized lateral plates; anterior plates triangular, dorso-posterior angle slightly rounded; posterior plates irregular quadrilateral, with minute digitate projections along posterior and ventral margins. Corpus bursae membranous, elongate, apical half covered with minute wrinkles; signa with two pairs of scale-like plates with many long hairs.

Immature stages
Unknown.

Distribution
This species is known from Wuyunjie National Nature Reserve (Taoyuan, Changde, Hunan, China).

Remarks
Adults of V. wuyunjiena sp. nov. were observed flying or perching on low shrubs and ferns along a muddy road leading to the mountain, of which the other side faces a river valley (Fig. 1C-D). It was cloudy and humid while the collections were made during 4-6 p.m. on April 21 st 2019. Adults flew relatively slowly making them easy to collect with sweep nets (Fig. 1E). Unfortunately, we could not observe feeding and mating behaviors of adults, nor did we collect any specimens in immature stages. Additionally, we observed one adult attracted to a light trap at 11:30 p.m. on April 21 st 2019 (Fig. 1F). The female adults of Agrionympha capensis Whalley, 1978 can also be attracted by lights at night (Gibbs & Kristensen 2011).

Diagnosis
This species is very similar to V. wuyunjiena sp. nov. and V. expeditionis, but can easily be distinguished by the following characters: paired X tergal lobes slender and digitate (slightly emarginate in V. wuyunjiena sp. nov. and broadly emarginate at the middle in V. expeditionis); basal process of valva long and pointed (absent in V. wuyunjiena sp. nov. and short obtuse in V. expeditionis); slightly curved dorsal process of gonopod (strongly curved in V. expeditionis).

Etymology
This specific epithet is derived from the name of the type locality, Mao'ershan National Nature Reserve. wing expanse. 6.6-7.1 mm (6.7 mm in holotype).

Holotype
head. Vertex densely covered with long piliform scales except for an exposed part between compound eye and ocellus; tufts of scales yellow to brown, mixed with dark brown hairs. Maxillary palpus pale yellow. Antennal scape and pedicel with pale brown hair-like scales; flagellum 58-segmented (46 segments in female), covered with dense black hairy scales, some basal segments with somewhat metallic blue luster.
thorax. Tegular tufts of piliform brown scales; mesonotum with dense golden scales which possess metallic blue luster. Legs with black scales; inner surface of fore-and mid-femur yellow; fore-tibia without epiphysis, mid-tibia without spur, hind-tibia with two pairs of spurs. Forewing ground color yellow, basal 2⁄ ₅ with golden luster, apical 3⁄₅ with blue and purple luster; cilia dark brown, paler on posterior margin. Hindwing pale fuscous, covered with slender scales on basal half and broad golden scales on apical half; cilia dark brown.
Female genitalia (Fig. 5C-D). Segment IX sclerotized, short in dorsal part (approximately ⅓ length of ventral part), slightly concave laterally. Segment X with a pair of triangular, well sclerotized lateral plates with broad digitate projections along apical half margin, and densely covered with minute spines on basal half ventrally. Corpus bursae membranous, oval, apical half covered with minute wrinkles; signa with two pairs of rhombus-shaped plates with many long hairs.

Immature stages
Unknown.

Distribution
This species is known from Mao'ershan National Nature Reserve (Xin'an, Guilin, China).

Remarks
Adults of V. maoershana sp. nov. were collected along a paved road at 1500 m a.s.l., half way up Mt Mao'ershan. Similar to V. wuyunjiena sp. nov., the adults were observed flying or perching on low shrubs and ferns in cloudy conditions and even in weak rainfall.  (Yang, 1995) 6. Dorsal process of valva broad, overtly curved inwardly .

Discussion
In this study, we add two new species of Vietomartyria from China based on the distinguishing characters defined by Hashimoto & Mey (2000) and Hirowatari et al. (2009): i) each flagellomere with long basal stalk; ii) aedeagus with many minute serrate projections near gonopore; iii) gonopore situated dorsally near apex. Additionally, we provide a distribution map (Fig. 6) of all known species of Vietomartyria.
Among eight species of Vietomartyria, V. gladiator is unique in that it lacks the dorsal projection of the gonopod (valva) (Hirowatari et al. 2010). Furthermore, several other autapomorphic characters of V. gladiator make it possible to distinguish this species from other species, such as non-bilobed tergite X (while bilobed in other species), prominent sword-like process of anal cone sclerite (extending lateroventrally but not distinct beyond tergite X), and type and position of the gonopore. The female genitalia are similar to V. expeditionis in the absence of signa, but it seems to be a homoplastic condition (i.e., secondary loss). In the present study, we also found a characteristic feature of V. wuyunjiena sp. nov., whereby segments X+XI of the female are not fused into a pair of lateral plates as in other species, but form two pairs. In addition, V. gladiator apparently differs in habitat compared to other species: this species lives in moist habitats along a stream in a valley in Mt Nankunshan, Guangdon (Hirowatari et al. 2010), whereas the other species (e.g., V. nankunshana, V. nanlingana, V. wuyunjiena sp. nov. and V. maoershana sp. nov.) live in comparatively drier habitats such as exposed lower shrubs, weeds and ferns along mountain road-sides. The differences of habitats between these two groups may reflect differences in their host-plant uses. This study contributes to filling a knowledge gap in the diversity of micropterigids in China. To clarify the phylogenetic position of the genus, specimens of Vietomartyria should be examined based on morphological and molecular data and compared to some closely related genera (e.g., Paramartyria). Kristensen (1997) hypothesized that liverwort-feeding is a plesiomorphic feeding habit of Lepidoptera. As it is shown that most species of micropterigids in Japan feed on a single liverwort species (Imada et al. 2011), species of Vietomartyria may also be associated with some specific groups of liverworts. Elucidating the immature stages, particularly identifying their host plants, will give us insights into the evolution of host-plant use.