Key to the Macrophya sibirica group (Hymenoptera: Tenthredinidae) with description of a new species from China

The Macrophya sibirica group was proposed by Li et al. (2016). A new species in this group, Macrophya nigrotrochanterata sp. nov. from Liaoning Province, China, is here described and illustrated. A key to all Chinese species and a distribution map of the M. sibirica group in China are provided.


INTRODUCTION
is the third largest genus in Tenthredininae (Hymenoptera: Tenthredinidae). It contains 313 species worldwide, of which 174 extant species have been recorded from China up to April 2020 , 2019c, 2020a, 2020b.
The taxonomy and distribution of Macrophya in China has been studied by Liu and his co-workers since 1994 and an infrageneric classification of Macrophya into species groups was given by Li et al. (2016Li et al. ( , 2018. The Macrophya sibirica group, originally proposed by Li et al. (2016), is a large species group within Macrophya, with twenty-two extant species worldwide, fifteen of which are recorded from China. They are all similar in general morphology by having the body length usually 9-12 mm in female and 8-8.5 mm in male, posterior corner of metepimeron without appendage, anal cell of forewing usually with a short, erect cross-vein. Based on these characteristics, they constitute a clearly defined species group within Macrophya. In this study, a new species belonging to this group is described and illustrated from Liaoning, China. According to the available data, species in this group are mainly distributed in northern China. A key to all sixteen Chinese species is provided.

MATERIAL AND METHODS
Eleven specimens of the newly described species were obtain ed by sweeping in forest fringe zones in Liaoning Pro-vince from China (Northeast China) in June 2016. In addition, 1,039 specimens of known species were examined and studied for this work. These specimens were examined with a Motic-SMZ-171 stereomicroscope. Images of the adults were taken with a Nikon D700 digital camera and a Leica Z16APO. The genitalia were examined with a Motic BA410E microscope and photographed with a Motic Moticam Pro 285A. Images were focus-stacked using Helicon Focus (HeliconSoft, Kharkiv, Ukraine) and further processed with Adobe Photoshop CS 11.0.
The terminology of genitalia follows Ross (1945) and that of general morphology follows Viitasaari (2002). For a few terms (e.g., middle fovea and lateral fovea), we follow Takeuchi (1952).
The holotype and all paratypes of the new species are deposited in the Scientific Research and Management Center of East China Pharmaceutical Botanical Garden, Lishui, Zhejiang, China (formerly Lishui Academy of Forestry, LSAF). Most specimens of known species are deposited in the Insect Collection of Central South University of Forestry and Technology, Changsha, Hunan, China (CSCS), and other specimens are deposited in LSAF.
Abbreviations: (OOCL) the distance between a lateral ocellus and the occipital carina, or the hind margin of the head where this carina would be if it was developed (Benson 1954). (OOL) the shortest distance between an eye and a lateral ocellus. (POL) the distance between the mesal margins of the two lateral ocelli.

Macrophya Dahlbom, 1835
Type species: Macrophya montana (Scopoli, 1763) Macrophya sibirica species group Diagnosis. Species of the Macrophya sibirica group can be recognized using the diagnosis provided by Li et al. (2016), and in particular by the following combination of morphological characters: body mainly black, partly white, without metallic tinge; antenna entirely black; apical margin of labrum usually white; clypeus usually largely or entirely black; anterior margin of clypeus incised (usually not deeply), lateral lobe short; posterior corner of metepimeron sub-quadrate, without appendage; abdominal tergum 1 usually with white maculae, but sometimes completely black in a few species; anal cell of forewing usually with a short, erect cross-vein, or in some species with a middle petiole, shorter than vein cu-a; ergot of penis valve distinct.
The M. sibirica group comprises a large portion of the Macrophya species and is morphologically similar to the M. malaisei group by having the anterior margin of clypeus roundly incised, lateral corners short and broad; anal cell of forewing usually with short and erect cross-vein; serrulae of lancet usually protruding. The M. sibirica group differs from the latter group and from others in having additionally: posterior corner of metepimeron sub-quadrate, without appendages; abdominal tergum 1 usually with white maculae. The M. sibirica group is represented in China by fifteen previously described species and one new species described here. The collection site of the new species in northern China at Mt. Jiulongchuan in Liaoning Province, is shown in Fig. 1. They can be separated using the following key.
Key to adults of the Macrophya sibirica group from China  to 10 denticles, setae on annuli long and dense.  (Fig. 6); mesoscutellum slightly elevated, but without transverse carina; posterior margin of pronotum with narrow white band (Fig. 10) (Fig. 7); mesoscutellum with distinct transverse carina; posterior margin of pronotum with distinct and wide white band (Fig. 11) Type locality: China: Liaoning. Diagnosis. In the Macrophya sibirica group, this new species is morphologically similar to M. nigrotibia, from Yunnan Province, in having the pronotum entirely black; hind trochanter entirely black; ovipositor sheath approximately 1.2× length of metabasitarsus; anal cell without petiole in forewing, with short and erect cross-vein; serrulae of lancet protruding, middle serrulae with 6 to 8 denticles, setae on annuli short and sparse. Macrophya nigrotibia differs in having the following combination of characters: posterior margin of pronotum with distinct, narrow white band; hind trochanter mostly white, ventral surface with weak black macula; ovipositor sheath approximately 0.9× length of metabasitarsus; anal cell with middle petiole in forewing 1.35× length of vein 1r-m, 0.75× length of vein cu-a; serrulae of lancet straight, middle serrulae with 7 to 10 denticles, setae on annuli long and dense.
Description. Body length 10.5 mm (female holotype). Body black; palp mostly brown; a small triangular macula on anterior 1/3 of labrum pale brown; apical half of mandible, small weak macula on lateral corner of clypeus, two small maculae on posteromedial part of mesoscutellum, oval macula on outer surface of hind coxa, apical 1/3 on anterior surface of fore femur and stripe on anterior surface of fore tibia, white. Body hairs silver, setae on sheath blackish-brown. Wings hyaline, without smoky macula, pterostigma and veins largely blackish-brown (Fig. 12).
Male. Body length 10-10.5 mm (Fig. 13). Body color and structure similar to female; following parts white: small macula at lateral corner of clypeus, anterior surfaces of fore femur, tibia and tarsus, small apical macula on anterior surface of middle femur, small apical macula on dorsal surface of middle tibia. Anterior half of lateral furrow distinct but shallow, posterior half deep and broad, head in dorsal view as shown in Fig. 21; head in anterior view as shown in Fig. 22; ratio of antennomeres 6-9 as 18: 19: 19: 19, antennae in lateral view as shown in Fig. 23; mesopleuron and metapleuron as shown in Fig. 24; subgenital plate longer than broad, apical margin approximately round, gonoforceps as shown in Fig. 25; penis valve as shown in Fig. 26.
Distribution. China (Liaoning). Variation. Six male specimens with clypeus entirely black; one male specimen with hind tibia with a small white macula.
Host plants. Unknown. Etymology. The specific name nigrotrochanterata is derived from two Latin words "nigro" and "trochanter", in reference to the entirely black trochanters in both sexes.

DISCUSSION
The M. sibirica groupis the third largest of the defined species groups of Macrophya. At present, fifteen species belonging to this group were recorded from China by Li et al. (2018), plus the