Euxaldar daweishanensis, Yang & Chang & Yang & Chen, 2021

Yang, Liang-Jing, Chang, Zhi-Min, Yang, Lin & Chen, Xiang-Sheng, 2021, A new species of the genus Euxaldar Fennah, 1978 (Hemiptera, Fulgoromorpha, Issidae) from China and revision on the molecular phylogeny of the family, ZooKeys 1021, pp. 19-35 : 19

Euxaldar daweishanensis sp. nov. Figs 1-7 , 8-17 , 19-26

Type material.

Holotype: ♂, China: Yunnan Province, Pingbian County, Mt: Daweishan National Nature Reserve (23°07'N, 103°20'E), 8 August, 2017, Qiang Luo, Nian Gong, Y. -J Sui, Yan Zhi. Paratypes : 7♂♂ 36♀♀, same data as holotype .

Measurements.

Total length (from apex of coryphe to tip of forewing): male 4.1-4.3 mm (N = 6), female 4.6-4.9 mm (N = 10); forewing length: male 3.8-4.0 mm (N = 7), female 4.2-4.4 mm (N = 10).

Diagnosis.

This species differs from other Euxaldar species by the following characters: (1) coryphe about 2.3 times wider than long (less, or more than 2.3 times as wide as long in other species of Euxaldar ); (2) first metatibiotarsal of hind leg with 8 intermediate spines (other species of Euxaldar with first metatarsomere of hind leg with 6 or 7 intermediate spines); (2) penis with 3 different ribbon-shaped processes at middle (Figs 16 , 17 , pp, paed), dorsal lobe of periandrium with 2 asymmetrical sword-shaped subapical processes in apical half (Figs 16 , 17 , sap) (other species without sword-shaped subapical processes in apical half of dorsal lobe of periandrium).

Coloration.

Male body brown yellowish, with irregular dark brown bands on forewings. Coryphe brown (Fig. 8 ). Metope with all margins, pustules, and median carinae pale yellow, disc dark brown (Fig. 9 ). Metopoclypeal suture light yellow. Anteclypeus straw yellow. Postclypeus pale yellow (Figs 9 , 10 ). Rostrum and antenna straw yellow (Fig. 10 ). Eyes dark brown (Figs 8-10 ). Pronotum straw yellow. Mesonotum dark brown (Fig. 8 ). Forewings slightly hyaline, with 2 irregular brown bands (Figs 1 , 2 , 11 ): a large one derived from costal margin to almost C2 of radial cell, small one derived from apical half of median cell, extended to areola postica (anterior cubital area). Legs (Figs 2 , 4 ) light brown. Abdomen brown, male genital segment light straw yellow. Females generally darker than males (Figs 3 , 4 ).

Head and thorax.

Coryphe transverse, about 2.3 times wider than long, anterior margin weakly prominent in the middle, posterior margin angularly concave (Fig. 8 ). Metope flat, median carinae weak, running from upper margin and reaching middle, with a row of distinct pustules along lateral margins, disc with weak pustules (Fig. 9 ). Metopoclypeal suture complete (Fig. 9 ). Anteclypeus with distinct median carinae (Figs 9 , 10 ). Pronotum with disc depressed (Fig. 8 ). Mesonotum about 2.1 times longer than pronotum. Forewings (Figs 1-4 , 11 ) with distinct claval suture and CuP venation, the other venation reticulate, poorly recognizable. Hind wings about 0.7 times as long as forewings, venation reticulate (Fig. 12 ). Hind tibiae with 2 lateral teeth. Metatibiotarsal formula (9-8)-8-2.

Male genitalia.

Anal tube (Fig. 13 ) enlarging from base to apical fourth in dorsal view, narrowing to apex, apical margin convex in the middle, laterally with 2 small triangular processes in apical fourth. Pygofer with hind margin distinctly convex (Figs 5 , 14 ). Gonostyli triangular, hind margin convex, caudo-dorsal angle rounded (Fig. 14 ). Capitulum of gonostyli style with wide and short neck, with a wide lateral tooth and 2 apical teeth (Figs 14 , 15 ). Corpus of connective rod-like (Figs 5-7 , 16 , 17 ), curved, cuticularized, reaching middle of periandrium; tectiductus of connective cup-shaped, third ventral part separated from corpus (Fig. 14 ). Periandrium asymmetrical (Figs 6 , 7 , 16 , 17 ), suspensorium V-shaped in dorsal view, membranaceous in the middle; base with process claval (Figs 16 , 17 , bp), dorsal periandrium lobe with 2 ribbon-like processes in center near right edge (Figs 16 , 17 , pp), directed dorsad, respectively curved caudad and cephalad; dorsal lobe in left lateral view with 2 subapical processes near apex (Fig. 16 , sap): one crescent-shaped, above base with another process shortly sword-shaped, directed caudad; in right lateral view (Fig. 17 , sap) with two subapical processes derived from apical third, directed apically, one process base movable, sword-shaped, below base another process crutch-like and sclerotized. Ventral periandrium lobe (Fig. 18 , vlp) with apical margin convex, shorter than dorso-lateral lobe of periandrium (Figs 16 , 17 , dllp, 18) in ventral view. Aedeagus (Figs 16 , 17 , aed) with dagger-shaped process, base slightly movable, directed dorsad, slightly inclined caudad (Figs 16 , 17 , paed).

Female genitalia.

Anal tube ovate in dorsal view, about 1.3 times longer than maximal width at second part (Fig. 19 ). Anal style long, located at basal fifth of anal tube. In ventral view, Sternite VII with hind margin convex medially, without any process in ventral view, disc arched ventrad (Fig. 20 ). Anterior connective lamina of gonapophysis VIII nearly rectangular, with 3 or 4 apical teeth on inner lateral margin and 3 lateral teeth bearing 3 keels on outer lateral margin (Figs 21 , 22 ); endogonocoxal lobe developed, membranous in distal part (Figs 21 , 22 ). Posterior connective lamina of gonapophyses IX triangular in dorsal view (Fig. 23 ), narrowing; median field with leaf-like process bearing apical margin, deeply incised in the middle (Fig. 23 , mdp); lateral field (Fig. 23 , lf) without obvious process; distal parts of laminae (Fig. 23 , slf) with tooth-like process on each lateral margin; posterior ventral lobes bent at slender angle (Figs 23 , pvb, 24). Gonoplacs in lateral view irregularly elliptical (Fig. 25 ), without carinae, with apical half fused, apical margin membranous (Fig. 26 ).

Etymology.

This new species is named after the type locality, Mt. Daweishan National Nature Reserve , Yunnan Province, China.

Distribution.

China (Yunnan Province)

Remark.

This new species resembles Euxaldar jehucal but differs from the latter by the following combined features: Anal tube with apical margin convex in the middle, lateral margin with a small triangular process in each side (anal tube wide, apical margin deeply concave medially in E. jehucal ); periandrium with two asymmetrical subapical processes sword-shaped in apical half (periandrium with subapical processes not as sword-shaped in E. jehucal ); aedeagus with one medial dagger-like process on lateral margins (aedeagus without any processes on lateral margins in E. jehucal ).

Phylogenetical analysis.

Four gene fragments of Euxaldar daweishanensis sp. nov. were sequenced and registered in GenBank with the accession numbers as follows: MK 441660 ( COI), MK 426664 (16S), MK 441661 (Cytb), MK 441662 (28S d6-d7). Nucleotide compositions are listed in Table 3 . A+ T content of 16S is the highest (76.0%) and 28S (d6-d7) is the lowest (39.2%).

This study deals with more molecular markers from Oriental and Western Palaearctic, Nearctic and Neotropical regions than previous reviews by Wang et al. (2016) and Gnezdilov et al. (2020). BI (Fig. 27 ) and ML (Fig. 28 ) topologies were mostly congruent, and the monophyly of Issidae was reconfirmed. The Issidae had lower support in the ML tree ( BS: 47) than Gnezdilov et al. (2020) and Wang et al. et al. (2016) and higher support in the BL analysis ( PP: 88). Subfamilies Hysteropterinae Melichar, 1906 sensu ( Gnezdilov et al. 2020) and Issinae Spinola, 1839 sensu ( Gnezdilov et al. 2020) are both recovered (nodes 1 and 2: ML: 47, 67; BI: 88, 89, respectively).

Node 1 includes almost all tribal level genera group of the subfamily Hysteropterinae sensu Gnezdilov (2016a, b, 2020) and the tribe Thioniini Melichar, 1906 sensu ( Gnezdilov 2018): 1) Node 4 ( ML: 75, BI: 100) corresponds to the subtribe Thioniina sensu Gnezdilov (2018) with the inclusion of American taxa, characterized by hind wings reduced or rudimentary, A2 vein branched; 2) Nodes 5 and 6 corresponds to the monophyletic Kervillea , and Mycterodus genera group sensu Gnezdilov (2016 a, b); monophyly of the Hysteropterum genera group was not supported by this analysis (node 3).

Node 2 ( ML: 67, BI: 89) includes five monophyletic tribes (nodes 7-11): Issini , Kodaianellini and Hemisphaeriini sensu (Gnezdilov 2020), Parahiraciini , and Sarimini sensu ( Wang et al. 2016), while the monophyly of Sarimini and Parahiraciini was not supported by Gnezdilov (2020).

Figures

Figure 27. Maximum likelihood (ML) tree estimated from the combined based on combined sequences (18 S, 28 S, COI, Cytb). At each node, values indicate bootstrap supports.

Figure 28. Bayesian 50 % consensus tree based on combined dataset. Nodes of the major clades are numbered and refer to text. Each node is documented with its posterior probability (PP) value.

Figures 1 - 7. Euxaldar daweishanensis sp. nov. (adult) 1 male dorsal view 2 male lateral view 3 female dorsal view 4 female lateral view 5 male genitalia, lateral view 6 penis, left lateral view 7 penis, right lateral view. Scale bars: 0.5 mm.

Figures 8 - 18. Euxaldar daweishanensis sp. nov. (male adult) 8 head and thorax, dorsal view 9 face, front view 10 head and thorax, lateral view 11 forewings 12 hind wing 13 anal tube, dorsal view 14 pygofer, anal tube and genital style, lateral view 15 capitulum of gonostyli, dorsal view 16 penis, lateral view (left) 17 penis, lateral view (right) 18 penis, ventro-apical view. Abbreviations: aed - aedeagus; bp - basal process of the periandrium; dllp - dorso-lateral lobe of periandrium; paed - process of aedeagus; pp - process of periandrium; sap - subapical processes of periandrium; vlp - venteral lobe of periandrium. Scale bars: 0.5 mm

Figures 19 - 26. Euxaldar daweishanensis sp. nov. (female adult) 19 female anal tube, dorsal view 20 sternite VII, ventral view 21, 22 gonocoxa VIII and gonapophysis VIII, ventral view 23 gonapophysis IX and gonaspiculum bridge, dorsal view 24 gonapophysis IX and gonaspiculum bridge, lateral view 25 gonoplacs, lateral view 26 gonoplacs, dorsal view Abbreviations: lf - lateral field of posterior connective lamina of gonapophyses IX; mdp - medial dorsal process; mf - medial field of posterior connective lamina of gonapophyses IX; pvd - posterior ventral lobes; slf - sublateral field of posterior connective lamina of gonapophyses IX. Scale bars: 0.5 mm.