Xistra zhengi Deng, 2024

Bai, Qiu-Xia, Long, Min & Deng, Wei-An, 2024, A new species of the genus Xistra (Orthoptera: Tetrigoidea: Metrodorinae) with comments on the characters of mitochondrial genome, Zootaxa 5447 (3), pp. 373-384 : 374-381

publication ID	https://doi.org/ 10.11646/zootaxa.5447.3.3
publication LSID	lsid:zoobank.org:pub:11870D7A-C747-43DB-8158-D2D89CAFF00B
DOI	https://doi.org/10.5281/zenodo.11164011
persistent identifier	https://treatment.plazi.org/id/03CF87CE-3D47-9925-ADFF-FACAFDB8A8E6
treatment provided by	Plazi
scientific name	Xistra zhengi Deng
status	sp. nov.

Treatment

Xistra zhengi Deng , sp. nov.

(Figures 1,2)

Description. Female. Body small, its surface interspersed with coarse protuberances and notches ( Fig. 1A View FIGURE 1 ).

Head. Head and eyes distinctly exserted above pronotal surface ( Fig. 1C View FIGURE 1 ). Vertex narrow, in dorsal view, width of vertex between eyes 0.8 times width of compound eye; a little narrower in front; anterior margin of fastigium narrowly rounded and not surpassing anterior margin of eye ( Fig. 2C View FIGURE 2 ); median carina visible anteriorly; lateral margins turned backward and slightly exserted above upper margin of eye; vertex uneven with paired fossulae. In lateral view, frontal costa nearly straight and slightly visible between eyes, protruded anteriorly and broadly rounded between antennal grooves ( Fig. 2B View FIGURE 2 ). In frontal view, vertex with V-shaped concavity, bottom of which reaching one-fourth of upper inner margins of eyes; lateral margins of vertex slightly exerted above upper margin of eyes; frontal costa bifurcated above lateral ocelli, longitudinal furrow divergent between antennae, width of longitudinal furrow of frontal ridge narrower than antennal groove diameter ( Fig. 2A View FIGURE 2 ). Antennae short, filiform, antennal grooves inserted between inferior margins of compound eyes ( Fig. 2B View FIGURE 2 ), 15-segmented, the 9th and 10th segment are the longest, about 6–7 times longer than its width. Eyes globose, lateral (paired) ocelli located in slightly below the middle of compound eye height.

Thorax. Pronotum coarse, its surface granulose and with sporadic protuberances and concavities ( Fig. 1A View FIGURE 1 ). In dorsal view, anterior margin of pronotum truncate; lateral carinae of prozona parallel; median carina of pronotum entire; before and behind humeral angles are depressed, behind middle of pronotum with sporadic protuberances and notches; obtuse humeral angles; without interhumeral carinae between shoulders; hind pronotal process narrow and long cone-shaped, slightly surpassing the apex of hind femur. In profile, median carina of pronotum slightly undulate before shoulders and straight behind shoulders. Lateral lobes of pronotum turning outwardly, posterior angles directed distinctly transversely and apex truncate. Posterior margins of lateral lobes of pronotum with ventral sinus and tegminal (upper) sinus. Tegmina long, ovate, apex rounded. Hind wings reaching or slightly surpassing apex of hind pronotal process.

Legs. Fore and middle femora with carinated, margins finely serrated, dorsal margins of fore and middle femora nearly straight, ventral margins of fore and middle femora slightly undulated ( Fig. 2D, E View FIGURE 2 ). Middle femur wider than visible part of tegmen in width. Hind femora robust and short, 3 times as long as wide; margins finely serrated ( Fig. 2F View FIGURE 2 ); antegenicular denticlesand acute genicular denticles right angled. Outer side of hind tibia with 6–7 spines, inner side with 5-6 spines ( Fig. 2G View FIGURE 2 ). First segment of posterior tarsi equal to third in length, first pulvillus and first segment of tarsus longer than the second and third, apices of three pulvilli obtuse ( Fig. 2H View FIGURE 2 ).

Abdomen. Ovipositor narrow and long, upper valve 4.7 times as long as wide, upper and lower valvulae with slender saw-like teeth ( Fig. 2H View FIGURE 2 ). Length of subgenital plate nearly equal to its width, posterior margin of subgenital plate triangular projecting ( Fig. 2I View FIGURE 2 ).

Coloration. Body yellow-brown. Antennae yellow-brown, apical segments dark. Tegmina with anterior part dark and posterior part yellow-white. Hind wings black. Fore and mid legs yellow-brown, with two dark spots on femora and tibia. Hind femur with two irregular dark spots on outer side. Hind tibia yellow-brown, with three black rings ( Figs. 1A, C View FIGURE 1 ). Sternites of thorax and abdomen dark brown, subgenital plate brown.

Male. Similar to female, but body slender and smaller ( Figs. 1B, D View FIGURE 1 ). Width of vertex between eyes 0.6-0.8 times width of compound eye. Middle femur much wider than visible part of tegmen in width. Subgenital plate short, coneshaped, apex biforked ( Figs. 2K, L View FIGURE 2 ).

Measurements (mm). Length of body ♀ 11.1–12.9 mm, ♁ 10.3–10.8 mm; length of pronotum ♀ 10.3–11.2 mm, ♁ 8.7–9.7 mm; length of hind femur ♀ 6.1–6.2 mm, ♁ 5.3–5.8 mm.

Type material. Holotype: ♀, China, Jiangxi prov., Ganzhou (Yudu), 25°42ʹ21ʹʹ N, 115°25ʹ10ʹʹ E, 1073m alt., 19 August 2020, collected by Wei-An DENG, CLSGNU GoogleMaps . Paratypes. 4♁ 1♀, same data, collected by Wei-An DENG GoogleMaps , Jin Yue HE and Qiu Mei YU, CLSGNU .

Diagnosis. New species can be easily distinguished from other species of the genus by pronotal surface granulose and with sporadic protuberances and concavities. The new species is similar to Xistra bannaensis Deng, Wang, Mao & Li, 2021 from which it differs in lateral margins of vertex slightly exerted above upper margin of eyes (lateral margins of vertex barely reaching the level of upper margin of eyes in X. bannaensis ); humero-apical carina absent (humero-apical carina conspicuous in X. bannaensis ); pronotal surface granulose and with sporadic protuberances and concavities (pronotal surface smooth and flat in X. bannaensis ); tegmina with anterior part dark and posterior part yellow-white (tegmina with upper part yellow and lower part brown in X. bannaensis ).

Etymology. The new species was named in memory of Professor Zhemin Zheng (1932–2021), a famous Chinese orthopterologist and a founder of Chinese tetrigides study.

Distribution. P. R. CHINA: Jiangxi.

Characteristics of Newly Sequenced Mitogenomes. In this study, the mitogenome of Xistra zhengi Deng , sp. nov. was circular molecule, with total lengths of 18148 bp ( Table 2). The structure of this newly sequenced mitogenome contains 13 protein-coding genes (PCGs), 22 tRNAs, 2 rRNA (rrnS and rrnL), and control regions rich in A+T bases ( Table 3). In all mitochondrial genes, 14 genes (4 PCGs, 8 tRNAs and 2 rRNAs) were located on the minority strand, and 23 genes (9 PCGs and 14 tRNA genes) were located on the majority strand. Among the 13 protein-coding genes, trn1, nad4, nad4L, and nad5 were located on the N strand, while the other genes (cox1, cox2, cox3, nad2, nad3, nad6, cytb, atp6, and atp8) were located on the J strand.

The gene arrangement of the newly sequenced mitochondrial genome was similar to those of other species of Tetrigidae (Lin, 2014) . The base composition of Xistra zhengi Deng , sp. nov. mitogenome is A (44.20%), T (28.30%), C (18.20%) and G (9.30%). The base composition was A+T-biased, and the proportion of A+T content was 72.50%. The AT-skew was 0.218, and the GC-skew was -0.325. This shows that the content of bases A is higher than that of T, and C is higher than G in the whole ( Table 3). The total length of the 13 PCGs is 11,107 bp. All of the 13 PCGs initiate with the standard start codon ATN. There are three types of stop codons, TAA (cox1, cox2, cox3, nad1, nad4l, nad6, atp8, atp6) and TAG (nad3, nad4, cytb), as well as T- (nad5). The relative synonymous codon usage (RSCU) values of the mitogenome were summerized ( Fig. 4 View FIGURE 4 ). The codon distribution analysis showed that the two codons UUA (Leu2) and UCA (Ser2) were the most frequently used in this new species.

The lengths of the 22 tRNA genes range from 61 to 69 bp. Two rRNA genes (rrnL and rrnS), separated by tRNA-Val, are located between tRNA-Leu1 and A+T-rich region. The lengths of rrnL and rrnS are 1,293 bp and 729 bp, respectively. The A+T-rich region of 3,062 bp, with an A+T content of 80.73%, is located between rrnS and tRNA-Ile. The secondary structures of tRNAs were illustrated in Figure 5 View FIGURE 5 . All tRNA genes could be folded into the typical clover-leaf structure. The mismatch of A–A occurred in trnG; A–G occurred in trnW and trnY; A–C occurred in trnG, trnM and trnS1; and C–U only occurred in trnA ( Fig. 5 View FIGURE 5 ). The mismatch of U–U existed in trnI, trnE, trnL2, and trnY. The G–U mismatch occurred most frequently, but it did not appear in trnA, trnD, trnE, trnI, trnK, trnL2, trnN, trnR, trnS2, trnW, or trnY, and there were 30 G–U mismatches.

Phylogenetic Analysis. Bayesian Inference (BI) and Maximum Likelihood (ML) tree were constructed using 13 PCGs from mitogenomes of 16 species of Tetrigoidea and one outgroup ( Mirhipipteryx andensis of Tridactyloidea) to validate the phylogenetic position of Xistra zhengi Deng , sp. nov. ( Table 1). ML and BI trees had the same topological structures ( Fig. 6 View FIGURE 6 ). The results of the phylogenetic tree showed that the new species was placed in Metrodorinae , and formed a separate clade from other species of Metrodorinae . The results of phylogenetic tree constructed by ML and BI methods were as follows: (Batrachideinae + (Tripetalocerinae + ( Metrodorinae + ( Metrodorinae + Thoradontini)))).The phylogenetic tree in this study appears to support the placement of the genus Thoradonta within the Metrodorinae subfamily ( Fig. 6 View FIGURE 6 ), however, the available data is insufficient to confirm this placement conclusively ( Adžić et al., 2020; Qin et al., 2023). More molecular and morphological data are necessary to provide a more robust understanding of the evolutionary relationships within this group. By incorporating more sequences and specimens, we can achieve a more comprehensive phylogeny that will aid in the accurate classification of Thoradonta and other Tetrigidae genera.