Taxonomic study of the leafmining genus Liocrobyla Meyrick , 1916 from China ( Lepidoptera , Gracillariidae , Ornixolinae ) with a description of one new species

Three species of the leafmining genus Liocrobyla Meyrick, 1916 from China are treated. Liocrobyla indigofera sp. n. feeding on the plant genus Indigofera is described as new to science. Liocrobyla lobata Kuroko, 1960 feeding on Pueraria montana var. lobata is newly recorded in China. Lespedeza bicolor is documented as a new host plant for L. desmodiella Kuroko, 1982. Photographs of adult habitus, male and female genitalia, as well as host plants, leaf mines and biology are provided.


Introduction
The genus Liocrobyla Meyrick, 1916 belongs to the subfamily Ornixolinae Kuznetzov & Baryshnikova, 2001, which was confirmed by a recent phylogenetic study (Kawahara et al. 2017).Liocrobyla is endemic to the Old World and hitherto includes eight species (De Prins and De Prins 2018), with six species known from Asia: L. paraschista Meyrick, 1916, L. brachybotrys Kuroko, 1960, L. lobata Kuroko, 1960, L. desmodiella Kuroko, 1982, L. kumatai Kuroko, 1982 and L. minima (Noreika, 1992) (Meyrick 1916, Kuroko 1960, Kuroko 1982, Noreika and Puplesis 1992), one from Solomon Islands: L. saturata Bradley, 1961 (Bradley 1961) and one from South Africa: L. tephrosiae Vári, 1961(Vári 1961).Larvae of all species with known host associations are blotch leaf miners on various genera of the plant family Fabaceae (De Prins overwinter and were transferred into the laboratory in early spring.All adults were collected by rearing from immature stages. Adult photographs were taken with a Leica S6D stereo microscope.Genitalia were dissected and mounted according to the methods introduced by Li (2002), but stained with Eosin Y and/or Chlorazol Black.The illustrations were prepared by using a Leica DM1000 microscope and refined in PHOTOSHOP CS4 software.Photographs of host plant and mines were taken in the field using a Canon PowerShot G10 digital camera or a Canon EOS camera.
Diagnosis.This species resembles Liocrobyla lobata Kuroko, 1960 in the general appearance of the forewing patterns, but can be distinguished by the blackish-grey forewing ground colour, which is brownish-grey in L. lobata.In the male genitalia, this species can be separated by the valva having a remarkable concavity at distal 1/4 and bearing a small ventro-apical hook; in L. lobata, the valva is almost parallel-sided and bears straight spines.The ninth tergite of the male L. desmodiella bears a pair of sclerotized lines originated from the middle of the posterior margin, which is absent in L. lobata.Adult (Fig. 1).Forewing length 3.0-3.5 mm.Head white on frons and face, with a tuft of black scales at base of antenna, vertex white with a black median line.Maxillary palpus black, about 1/3 length of labial palpus.Labial palpus white, black on distal part of second segment, with a mid-ventral black spot on third segment.Antennae black on scape, yellowish-fuscous and with black rings on other segments.Thorax yellowish-fuscous, tegula blackish grey.Forewing ground colour blackish grey, a greyish-fuscous stripe from costal 1/3 to 1/2, then curved downwards by white colour to near distal end of cell; two white stripes on distal 1/3 and 2/5 on costa obliquely to middle of wing; two longitudinal striae near apex, two longer striae near lower angle of cell; an yellowishfuscous stripe along dorsum from base to tornus, with three to four black spots above; cilia white with two black lines around apex, dark grey on dorsum.Abdomen: blackish grey dorsally, white ventrally.

Material
The forewing pattern of the specimens reared from Lespedeza bicolor is congruent to the Japanese specimens reared from L. cyrtobotrya (Kuroko 1960).
Male genitalia (Figs 5 and 8).Tegumen narrowed towards apex, with distal 1/6 triangular.Vinculum with a small round protrusion anteriorly.Valva concave at distal 1/4 and bearing a small ventro-apical hook and some 12 smaller teeth below.Phallus shorter than valva.The ninth tergite more or less semicircular, having paired sclerotized lines originated from the middle of the posterior margin.
Female genitalia (Fig. 11).Seventh sternite sharply projected postero-laterally, thus U-shaped on posterior margin.Antrum sclerotized short tube.Ductus bursae membranous, densely covered with granules on inner wall, about twice the length of antrum; ductus seminalis originated from ductus bursae near antrum, covered with dense teeth on opening, a sclerotized line extending from ductus bursae to ductus seminalis then curved back to near its beginning.Corpus bursae a membranous bag, about twice the length of ductus bursae.
Remarks.The host plant Lespedeza bicolor was newly recorded for this species.Kuroko (1982) stated in Japanese that the species identified as Liocrobyla paraschista Meyrick, 1916in Kuroko (1960) was a misidentification and he named it as a new species, L. desmodiella Kuroko, 1982.Because of the misidentification of the moth, the host plants recorded in Japan, L. cyrtobotrya, D. oldhamii, Desmodium racemosum (Thunb.)DC. and D. caudatum (Thunb.)DC., originally associated with Liocrobyla paraschista by Kuroko (1960), are actually belonging to L. desmodiella.Ermolaev (1987) recorded L. desmodiella in the Russian Far East but just followed Kuroko (1960)  Adult (Fig. 2).Head white on frons and face, tinged blackish fuscous on base of antennae, vertex white with a brownish-grey median line.Maxillary palpus black mixed with white, about 1/4 length of labial palpus.Labial palpus white, black on distal part of second segment, with a mid-lateral black spot on third segment.Antennae  with scape white on front and black dorsally, other segments brownish grey with darker rings.Thorax yellowish fuscous, tegula brownish grey.Forewing ground colour brownish grey, darker towards costa, a white stripe from costal 1/3 to before 1/2, then curved downwards to near tornus; two white stripes beyond distal 1/3 and 2/5 on costa obliquely to middle of wing; two longitudinal striae near apex, with the costal one indistinct, one white spot on tornus; a white stripe along dorsum from base to tornus, partially edged with black scales and largely covered by brownish-fuscous scales on dorsum; cilia white with two black lines around apex, grey on dorsum.Abdomen: light fuscous dorsally, white ventrally.identical in width, bears some 15 minute teeth along dorsal margin and two longer ventro-apical spines.Phallus shorter than valva.Paired clusters of slender scales and black short scales on membrane between seventh and eighth terga.Ninth segment with tergite heart-shaped, a line of slender scales along lateral side (Fig. 9).

Male
Biology .Mines not restricted to a fixed placement, with apparent digital galleries.A white tunnel made of silk only from upper to lower side of leaflet.Often more than one mine per leaf (Fig. 19).

Liocrobyla indigofera sp. n.
http://zoobank.org/2D79B9E2-C197-4377-B9F0-43F507168183 Figures 3, 4, 7, 10, 12 and 23-28 Diagnosis.The new species resembles L. lobata in the male genitalia, but can be separated by the phallus longer than the valva and the minute cornutus; in L. lobata, the phallus is shorter than valva and the cornutus is more than 1/12 length of the phallus.In L. indigofera, the head is dark grey and the forewing ground colour is blackish fuscous, while in L. lobata, the head is white and the forewing ground colour is brownish grey.Adult (Figs 3 and 4).Forewing length 3.0 mm.Head with frons white, vertex dark grey with a black median line.
Maxillary palpus black, pointed apically, about 1/4 length of labial palpus.Labial palpus white, with black rings at middle and before apex.Antennae with scape dark dorsally, white ventrally, other segments dark with black rings.Thorax yellowish gray, with a dark central line, tegula blackish-fuscous; legs white with blackish-fuscous rings.Forewing blackish-fuscous, fuscous along dorsum, stripes and spots white; a sinuous stripe from costal 1/3 to apex of disc divided into three or occasionally two parts (which is continuous in L. lobata); one stria at costal 2/3; a transverse outwards arched stripe at 4/5, separated at middle, with violet reflection; two spots above the fuscous stripe on dorsum, with outer one larger; two minute spots near apex; cilia white, with three black lines.Hind wing blackish-grey.
Male genitalia (Figs 7 and 10).Tegumen weakly sclerotized.Valva more or less rectangular, divided by a sclerotized ridge, dorsal part more sclerotized than costal one; costal part densely covered with setae apically, dorsal part with two long digital processes apically and one or two minute processes below apex.Vinculum narrowly triangular.Phallus longer than valva, curved beyond middle, pointed apically, vesica roughened, with a minute inversed cornutus.Ninth tergite more or less oval (Fig. 10).
Biology .Larval mine is a white blotch, with several digital galleries, always located in the middle of the upper side of a leaflet (Figs 23 and 27).A frass opening on the lower side of the leaflet always locates close to the midrib, covered by a piece of white dry leaf tissue (Fig. 28).A single mine per leaflet .

Distribution. China (Shandong).
Etymology.The specific name is derived from the genus name of the host plants.

Discussion
Individual species of leaf miners, at least in many groups of Lepidoptera, are typically host-specific at a plant genus or family level (Regier et al. 2015), a fact which greatly facilitates the process of identification of a moth specimen with host association.The process involves two main parts: recognizing the family or genus of a moth specimen and identifying the host plant.The first part is generally easier for a lepidopterist than identifying a plant species.Besides the great differences between disciplines that results in this difficulty, botanists are undertaking revisions for the nomenclature of plants (The Plant List 2013), thus making the difficulty even greater.Host plant specimens are recommended to be identified by a botany taxonomist and the nomenclature of the host plant is recommended to be checked in The Plant List which may be the most comprehensive single information resource covering all plants (The Plant List 2013).The nomenclature of host plant names derived from the old literature have possibly changed, such as the host plant names of Liocrobyla desmodiella and L. lobata in the present study.The Plant List could thus be treated as advisory and a lepidopterist should check the nomenclature of these plant names derived from old literature.
for helping to identify the host plant of L. desmodiella; Bin Jiang, Mt.Kunyu National Nature Reserve, Yantai, for various help during the field work; Alexandra Rusakova, for translating the Russian description by Ermolaev (1987) into Chinese.Special thanks are due to Jurate De Prins for her insightful comments and corrections on an earlier version of the manuscript, to Jurate De Prins and Paolo Triberti and the editor for reviewing the manuscript.This work is supported by the Shandong Provincial Natural Science Foundation, China (No. ZR2017BC051).
Plant nomenclature follows APG (2016) and The Plant List (2013).The types of the new species are deposited in the Zoological Collection, Shandong Normal University, Jinan, China (SDNU).Other specimens are deposited in the Insect Collection, Nankai University, Tianjin, China or SDNU as stated in the text.

examined. China: Tianjin
. Leaf mines placed on upper side of leaflet and stretched across midrib; a black tunnel made of silk and frass aside midrib from upper to lower side of leaflet, covered by dry leaflet epidermis on lower side opening.One mine per leaflet.