A new species of Elachista Treitschke, 1833 (Lepidoptera, Elachistidae, Elachistinae) from China, with identification keys to the Asian species of the Elachistasaccharella species group

Abstract A new species, Elachistaolekarsholtisp. nov., is described from Henan, China. The habitus and male genitalia are diagnosed and illustrated in detail. This is the first record of the Elachistasaccharella species group in China. Identification keys to the Asian species of Elachistasaccharella species group, based on male and female genitalia, are provided.

China is one of the mega-diversity countries of the world (Brooks et al. 2006). However, the Elachista species of China are almost unknown. In the recent catalogue of Elachistinae of the World (Kaila 2019), only four species from China were listed: Elachista cinereopunctella (Haworth, 1828); E. gleichenella (Fabricius, 1781); E. tinctella Sruoga, 1995 andE. utonella Frey, 1856. In the present paper, a new species of the Elachista is described from Henan, China. The new species is very close to species of the Elachista albrechti-heteroplaca species group (cf. Kaila 1998). This group is defined by uncus lobes being twisted basally and round apically, the basal arms of gnathos being strongly melanised, the very large juxta lobes bearing scale-like setae and valva being distally dilated and bilobed (Sugisima and Kaila 2005). Recently, in his World Catalogue of Elachistinae, Kaila (2019) merged the Elachista albrechti, heteroplaca and solena species groups into the E. saccharella species group. Synapomorphies for this group include: 1) the forewing with vein M2; 2) anterior margin of tegumen dorsomedially meeting the posterior margin (Kaila and Sugisima 2011); the latter also occurs in the E. freyerella species group. It also should be noted that M2 in the forewing is of quite homoplastic character, so the diagnostic value of this is very limited. Elachista saccharella species group now comprise 24 described and one described, but not named species (Table 1), which are distributed in Americas, Asia, Australia and New Guinea (Kaila 2019).
Asian species of the group are still poorly known, but recent discoveries of four new species from Thailand (Sruoga et al. 2019) suggest that real diversity is likely much higher. For the taxonomic keys, all known Asian species of the Elachista saccharella species group are included.

Materials and methods
Adult specimens were examined externally using MBS-10 and Euromex Stereo Blue stereomicroscopes. The forewing length was measured along the costa from wing base to the apex of the terminal fringe scales. For a wingspan, the forewing length was doubled and thorax width added. The width of the head was measured between the inner edges of the antennal bases. Genitalia were prepared following the standard method described by Robinson (1976) and Traugott-Olsen and Nielsen (1977). The genitalia were studied and some morphological structures were photographed in glycerol before permanent slide-mounting in Euparal. The male genital capsule was stained with fuchsin and the abdominal pelt with chlorazol black (Direct Black 38/Azo Black). The genital morphology was examined using a Novex B microscope. The photographs of adults were taken using a Leica S6D stereomicroscope and Leica DFC290 digital camera. The photographs of genitalia were made using a Leica DM2500 microscope and a Leica DFC420 digital camera. The descriptive terminology of morphological structures follows Traugott-Olsen and Nielsen (1977); Kaila (1999aKaila ( , 2011 and Kristensen (2003).  Kaila, 1998 Nepal Male only Kaila 1998E. heteroplaca Meyrick, 1934 India Male only Meyrick 1934; Kaila 1998 E. lorigera (Meyrick, 1921) Indonesia Female only Meyrick 1921; Kaila 1998 E. picroleuca (Meyrick, 1921) Indonesia  (Bradley, 1974) New Guinea Male only Bradley 1974;Kaila 1999a, 2019 E. angularis (Braun, 1918) USA  Kaila, 1999 USA Male and female Kaila 1999b E. hedionella Kaila, 1999 USA Female only Kaila 1999b E. helodella Kaila, 1999 Canada; USA Male and female Kaila 1999b E. saccharella (Busck, 1934) Cuba Antrum cup-shaped, anteriorly abruptly narrowing into ductus bursae (Kaila 1998, fig. 7;Sugisima and Kaila 2005, fig. 7 Apophysis anterioris 3/5-2/3 as long as apophysis posterioris; antrum with dense internal spines (Sugisima and Kaila 2005, fig. 7 Colliculum width about 0.2 times width of ostium bursae; corpus bursae with internal spines (Sugisima and Kaila 2005, fig. 12 It is a small, dark-coloured species with indistinct wing markings and a dorsoventrally flattened head. In wing pattern and male genitalia, the new species is most similar to E. albrechti Kaila, 1998, known from Nepal. The main differences between E. albrechti (cf. Kaila 1998) and E. olekarsholti are: (1) spinose knob of gnathos very long and narrow in E. olekarsholti, in E. albrechti, it is club-shaped, with large distal dilation; (2) digitate process in E. olekarsholti is short and narrow, in E. albrechti, it is strongly dilated; (3) saccus in E. olekarsholti very short, whereas it is three times longer than wide in E. albrechti; (4) phallus in E. olekarsholti strongly curved beyond the middle, with cornutus, in E. albrechti, it is strongly curved before the middle, without cornutus.
Male (Figs. 1-3). Forewing length 3.5-3.6 mm; wingspan 7.7-7.9 mm (n = 2). Head: frons shiny, creamy white; vertex whitish-brown; neck tuft greyish-brown; labial palpus upwards curved, diverging, about 1.7 times as long as width of head, whitish-creamy, distal part of second and third segment with few dark brown scales; scape creamy white below, with few dark brown scales above, without pecten; flagellum blackish-brown above, weakly annulated with paler rings, basal part creamy white below. Thorax and tegula greyish-brown, mottled with dark brown tipped scales. Forewing: ground colour blackish-brown, basal part slightly paler, intermixed with few rusty scales; indistinctly delimited oblique whitish-creamy streak from 1/3 of costa to fold where there is a small group of raised black scales; indistinct whitish creamy spot at 2/3 length of costa and similar one on dorsum just before it; fringe scales brownish-grey, fringe line brownish-black. Hind-wing brownish-grey, with fringe concolorous.

Female. Unknown.
Male genitalia . Uncus lobes very small, triangular-shaped, apex with few tiny setae. Basal arms of gnathos very long, heavily melanised and strongly bent towards posterior direction, apically fused; spinose knob about two times as long as wide, apically widened. Costa of valva almost straight; basal fold of costa meets distal fold at 1/3 from base. Cucullus medially deeply incised, thus divided into two lobes: triangular lobe where sacculus meets cucullus and another longer distal lobe. Digitate process short and slender, three times as long as its width, distally with few short setae. Juxta lobes large, about 1/4 length of valva, mesially somewhat produced, medial incision between juxta lobes very short (Figs. 4 and 10), distal margin medially slightly concave, ventral surface with short setae medially and long setae laterally. Vinculum with broad median ridge, tapered to short and broad saccus. Phallus about 1.6 length Figures 4-8. Elachista olekarsholti sp. nov. 4 general view of male genitalia (phallus removed), holotype 5 phallus, holotype 6 phallus, paratype 7 apical part of phallus, holotype 8 apical part of phallus, paratype. Scale bars: 0.1 mm.
Biology. Unknown. Flight period. Based on the specimens available, adults fly in September. Distribution. So far, this species is known only from east-central China.
Etymology. The new species is named in honour of Ole Karsholt (Copenhagen, Denmark) who collected the type specimens.
Remarks. The phallus of the holotype is slightly distorted during slide mounting and, therefore, looks somewhat skewed in Fig. 5.