Two new species of the Gonioctena mauroi species-group from China ( Coleoptera : Chrysomelidae : Chrysomelinae )

The Gonioctena mauroi species-group of the subgenus Brachyphytodecta Bechyně, 1948 is proposed to include four species: G. (B.) mauroi Cho & Borowiec, 2016 (Vietnam), G. (B.) medvedevi Cho & Borowiec, 2016 (Vietnam), G. (B.) kuatunensis sp. nov. (China: Fujian), and G. (B.) longshengensis sp. nov. (China: Guangxi). They are characterized by the presence of setae on the aedeagus, which is unique within the subgenus. A key to the species, habitus photographs, illustrations of diagnostic characters and a distribution map are provided. Ovoviviparity is newly recorded in G. (B.) longshengensis sp. nov.


Introduction
The genus Gonioctena Chevrolat, 1836 is one of the largest genera of the subfamily Chrysomelinae with approximately 110 valid species in nine subgenera distributed in the Holarctic and Oriental Regions (CHO 2016, CHO et al. 2016, SPRECHER-UEBERSAX & DACCORDI 2016).Brachyphytodecta Bechyně, 1948 is the third largest subgenus of Gonioctena and contains 24 species distributed in the Oriental and Eastern Palaearctic Regions.The subgenus is distinguished from other subgenera by the following combination of characters: body reddish brown to black mostly without distinct spots; labrum with anterior margin weakly concave to almost straight; pronotum without trichobothria on both anterior and posterior angles; elytral disc covered with 11 regular rows of punctures, rarely partially irregular; spermatheca present.Members of Brachyphytodecta exhibit high similarity in their coloration and morphology, therefore the structure of male genitalia has been commonly used to differentiate closely related species.
A new character state 'the presence of setae on the aedeagus' has been recently observed in G. (B.) mauroi Cho & Borowiec, 2016 and G. (B.) medvedevi Cho & Borowiec, 2016.It was used as a diagnostic character at the species-group or species level in several members of the subgenus Asiphytodecta Chen, 1935, which is very closely related to the subgenus Brachyphytodecta in the absence of pronotal trichobothria and presence of spermatheca (YANG et al. 2014;CHO & BOROWIEC 2016a,b;CHO et al. 2016).Here, I propose the Gonioctena (Brachyphytodecta) mauroi species-group, characterized by the presence of setae on the apicolateral region of aedeagus, body shape, and coloration.Four species are recognized from China and Vietnam, of which two are new to science, G. (B.) kuatunensis sp.nov.and G. (B.) longshengensis sp.nov.and described in this work.

Material and methods
The specimens were examined with a Nikon SMZ800 microscope.Male and female genitalia were dissected from adult specimens softened in a closed Petri dish with wet tissue paper for 12-24 hours, cleared in 10% sodium hydroxide solution, and rinsed in distilled water.Photographs were taken by a Nikon D5200 digital camera attached to a Nikon SMZ1500 microscope, and were edited in Helicon Focus 5.3.12 and Adobe Photoshop CS5.Line drawings were made from photographs in Adobe Photoshop CS5 with a Wacom Intuos4 graphics tablet.
The specimens examined in the study are deposited in the following collections:  Description.Measurements in mm (n = 1): length of body: 6.30; width of body: 4.30; height of body: 2.80; width of head: 1.85; interocular distance: 1.20; width of apex of pronotum: 2.15; width of base of pronotum: 3.92; length of pronotum along midline: 1.75; length of elytra along suture: 4.50.
Head.Vertex weakly convex, covered with sparse punctures, becoming coarser and denser towards sides.Frontal suture V-shaped, reaching anterior margin, coronal suture weak.Frons fl at, strongly depressed at anterior margin, covered with dense punctures.Clypeus very narrow and trapezoidal.Anterior margin of labrum almost straight.Mandibles with two sharp apical teeth and large excavation for apical maxillary palpomere on outer side.Maxillary palps 4-segmented, with apical palpomere slightly widened, truncate apically.Antennae almost reaching pronotal base; antennomere I robust; II shorter than III; III longer than IV; VII-X distinctly widened, VIII-X each wider than long; XI longest, about 1.40 times as long as wide (Fig. 6).
Pronotum.Widest at base, roundly strongly narrowed anteriorly, anterior angles strongly produced.Anterior and lateral margins bordered, lateral margins barely visible in dorsal view.Trichobothria absent on both anterior and posterior angles.Disc covered with very sparse punctures; lateral sides covered with much larger and denser punctures; interspaces covered with fi ne and sparse punctures.Scutellum slightly wider than long, narrowed posteriorly.
Elytra.Lateral sides slightly widened posteriorly, widest before middle, thence roundly narrowed posteriorly.Humeral calli well developed.Disc covered with eleven regular rows of large punctures, including short scutellar row; interspaces covered with fi ne and sparse punctures.Epipleura visible except near base in lateral view.Hind wings well developed.
Venter.Hypomera weakly rugose, with few punctures near anterolateral corners of prosternum.Prosternum covered with coarse and dense punctures bearing long setae; prosternal process enlarged apically, bordered laterally, with sparse punctures.Metasternum covered with small and sparse punctures in median region, large and dense punctures in lateral region.Abdominal ventrites covered with sparse or dense punctures bearing short setae.
Head.Vertex weakly convex, covered with sparse punctures, becoming coarser and denser towards sides.Frontal suture V-shaped, reaching anterior margin, coronal suture weak.Frons fl at, strongly depressed at anterior margin, covered with dense punctures.Clypeus very narrow and trapezoidal.Anterior margin of labrum almost straight.Mandibles with two sharp apical teeth and large excavation for apical maxillary palpomere on outer side.Maxillary palps 4-segmented, with apical palpomere slightly widened, truncate apically.Antennae reaching pronotal base; antennomere I robust; II as long as III; III longer than IV; VII-X distinctly widened, VIII-X each wider than long; XI longest, about 1.47 times as long as wide (Fig. 8).
Pronotum.Widest at base, roundly strongly narrowed anteriorly, anterior angles strongly produced.Anterior and lateral margins bordered, lateral margins barely visible in dorsal view.Trichobothria absent on both anterior and posterior angles.Disc covered with very sparse punctures; lateral sides covered with much larger and denser punctures; interspaces covered with fi ne and sparse punctures.Scutellum distinctly wider than long, narrowed posteriorly.Elytra.Lateral sides slightly widened posteriorly, widest before middle, thence roundly narrowed posteriorly.Humeral calli well developed.Disc covered with eleven regular rows of large punctures, including short scutellar row, sometimes with additional punctures between striae; interspaces covered with fi ne and sparse punctures.Epipleura visible except near base in lateral view.Hind wings well developed.
Venter.Hypomera weakly rugose, with few punctures near anterolateral corners of prosternum.Prosternum covered with coarse and moderately dense punctures bearing long setae; prosternal process enlarged apically, bordered laterally, with sparse punctures.Metasternum covered with minute and sparse punctures in median region, large and dense punctures in lateral region.Abdominal ventrites covered with sparse or dense punctures bearing short setae.
Legs.Moderately robust.Tibiae widened apically, with tooth-like projection.Fore legs with tarsomere I distinctly narrower than III in both sexes.Tarsal claws appendiculate.
Genitalia.Aedeagus long and thin, subparallel-sided, setose apicolaterally, with apical process rather broad, distinctly widened to lateral tooth-like projections, apex triangular in dorsal view; moderately curved, apex pointed in lateral view (Fig. 9).Spermatheca C-shaped, swollen basally and apex rounded (Fig. 10).Etymology.The species is named after the type locality, Longsheng in China; adjective.Distribution.China: Guangxi (Fig. 13).Remarks.Several larvae were dissected from the female specimen, therefore this species is ovoviviparous (Fig. 5).  ) medvedevi in body shape, coloration and setose aedeagus.From these two species, G. (B.) mauroi can be distinguished only by aedeagus subparallel-sided with apical process widest in middle and slightly narrower than median lobe (subparallel-sided with apical process broad, widest in apical 1/3 and subequal to median lobe in width in G. (B.) longshengensis sp.nov.and moderately narrowed with apical process moderately widened to lateral tooth-like projections near apex in G. (B.) medvedevi).Gonioctena (B.) kuatunensis sp.nov.differs in semicircular apex of aedeagus (triangular or subtriangular in other species).Distribution.Vietnam: Lang Son Province (Fig. 13).
Differential diagnosis.Gonioctena (B.) longshengensis sp.nov. is almost identical with G. (B.) mauroi and G. (B.) medvedevi in body shape, coloration and setose aedeagus.From these two species, G. (B.) longshengensis sp.nov.can be distinguished only by aedeagus subparallelsided with apical process broad, widest in apical 1/3 and subequal to median lobe in width (subparallel-sided with apical process widest in middle and slightly narrower than median lobe in G. (B.) mauroi and moderately narrowed with apical process moderately widened to lateral tooth-like projections near apex in G. (B.) medvedevi).Gonioctena (B.) kuatunensis sp.nov.differs in semicircular apex of aedeagus (triangular or subtriangular in other species).