Diartiger wangzheni Yin & He, sp. nov. is diagnosed, described, and illustrated based on a male specimen collected in Sichuan, southwestern China. The new species was found in association with Lasius ants (Hymenoptera: Formicidae) under a flat rock. An updated key to the males of Diartiger species known from China is provided.
INTRODUCTION
The pselaphine genus Diartiger Sharp, 1883 of the obligately myrmecophilous supertribe Clavigeritae contains twelve species and eight subspecies distributed in Japan (5 spp. & 8 subspp.), Korea (1 sp. & 1 subsp. shared with Japan), China (6), and Vietnam (1) (Newton, 2020). Since Nomura (1997) described the first Chinese species from Kunming, Yunnan, five more congeners have been reported from Beijing, Anhui, Zhejiang, and Jiangxi (Yin et al., 2010; Yin & Li, 2013, 2014; Yin, 2018). The diversity of Diartiger in China seems to be underexplored probably due to the lack of specific collecting efforts in most areas (i.e., a majority of the species can be collected only by searching ant colonies nesting under rocks or in decomposing logs), especially in the tropical regions of the country.
In the present paper, a seventh Diartiger species of China is described from Sichuan and distinguished from its Chinese congeners.
MATERIAL AND METHODS
The type material of the new species described in this paper is deposited in the Insect Collection of Shanghai Normal University, Shanghai, China (SNUC). The text of the specimen label is quoted verbatim in quotation marks (‘').
The genital parts were dissected and preserved in Euparal on a plastic slide that was placed on the same pin with the specimen; four individuals of host ants were glued on a broad card and pinned under the beetle. The habitus image was taken using a Canon 5D Mark III camera in conjunction with a Canon MP-E 65mm f/2.8 1-5X Macro Lens, and a Canon MT-24EX Macro Twin Lite Flash was used as the light source. Images of the morphological details were produced using a Canon G9 camera mounted to an Olympus CX31 microscope under reflected or transmitted light. Zerene Stacker (version 1.04) was used for image stacking. All images were optimized and grouped into plates using Adobe Photoshop CC 2018.
The abdominal tergites and sternites are numbered following Chandler (2001) in Arabic (starting from the first visible segment) and Roman (reflecting true morphological position) numerals, e.g., tergite 1 (IV), or sternite 1 (III).
TAXONOMY
Diartiger wangzheni Yin & He, sp. nov.
Figs 1-3
Type material: Holotype; ♂; CHINA, ‘China: Sichuan, Chengdu, Dujiangyan, Zipingpu Town, Ling-yan-guanyin-shan Park, 31°1′48.48″N, 103°36′47.12″E, 1190 m, 2.V.2020, Z. Wang, L. He & C. Zhou leg., under rock with Lasius ants, 四川成都都江堰紫坪铺镇灵岩观音山景区’ (SNUC).
Type locality: Ling-yan-guan-yin-shan Park, Zipingpu Town, Dujiangyan, Chengdu, Sichuan, China.
Diagnosis: Male body length 2.2 mm. Anterior margin of clypeus roundly angulate at middle. Antennomeres 4 slightly more than 1.4 times as long as antennomeres 3. Meso- and metatrochanters with large triangular spine; mesofemora angulate at middle of ventral margin. Aedeagus with small ‘apical part'. Female unknown.
Description: Male. Body (Fig. 1A) length 2.2 mm; reddish brown. Head (Fig. 1B) longer than wide, length from anterior margin of clypeus to head base (excluding occipital constriction) 0.43 mm, width across eyes 0.29 mm; anterior margin of clypeus angulate, pointed at middle; each eye composed of about 20 facets; antennomeres 3 and 4 each much longer than antennomeres 1 and 2 (Fig. 2A); length of antennomeres 2-4 0.05, 0.23, 0.33 mm, respectively; antennomeres 4 slightly more than 1.4 times as long as antennomeres 3, broadening from base toward apex, apically truncate. Pronotum (Fig. 1B) subglobose, about as long as wide, length along midline 0.44 mm, maximum width 0.42 mm. Elytra (Fig. 1A) much wider than long, length along suture 0.58 mm, maximum width 0.84 mm; disc lacking linear microsculpture; with sub-triangular tufts of setae at posterolateral margins (Fig. 2B). Prosternum (Fig. 2E) roughly sculptured medially. Mesoventrite (Fig. 2E) with short intercoxal ridge. Metaventrite (Fig. 2E) convex, densely setose medially, lateral areas with distinct linear microsculpture. Mesotrochanters (Fig. 2C) with large triangular ventral spine, mesofemora (Fig. 2C) angulate on ventral margin at middle; metatrochanters (Fig. 2D) with distinct ventral spine slightly smaller than that of mesotrochanters. Abdomen large, wider than long, much wider than elytra, length along midline 0.75 mm, maximum width 0.91 mm; composite tergite broadly and deeply concave mediobasally, with tufts of curved trichomes at basolateral region (Fig. 2B), first pair of paratergites with curved trichome (Fig. 2B). Sternite 6 (VIII) with bunch of short, thick setae at middle. Aedeagus (Fig. 2F, G) moderately sclerotized, length 0.46 mm; median lobe at apex narrowing and strongly curved ventrad, with membranous part at dorso-apical side. Female. Unknown.
Comparative notes: The males of the new species can be readily separated from those of all congeners by the relatively stouter habitus, the unique spination of the legs, and the configuration of the aedeagus. An identification key to males, updated from Yin & Li (2014), is provided below to aid in the discriminations of the Chinese species:
Biology: The male was found with Lasius ants (Fig. 3C) under a flat rock (Fig. 3B) in a mixed forest (Fig. 3A).
Distribution: China (Sichuan).
Etymology: The new species is named after Zhen Wang, one of the collectors of the holotype.
Fig 1.
Diartiger wangzheni sp. nov. male. (A) Dorsal habitus (B) Head dorsum and pronotum. (C) Tergite 5 (VIII) and sternite 6 (VIII), showing black thickened setae at middle. Scale bars: 0.5 mm in A; 0.2 mm in B-C.
Fig 2.
Diartiger wangzheni sp. nov. male. (A) Right antenna (B) Elytral apex and abdominal base, showing trichomes. (C) Right middle leg (D) Right hind leg (E) Prosternum and meso- and metaventrite. (F, G) Aedeagus, in lateral (F) and ventral (G) view. Scale bars: 0.2 mm.
1A Dorsal surface of head and pronotum with sparse, thick, and suberect setae (Yin et al., 2010: fig. 1). Mesotrochanters lacking spine (Yin et al., 2010: fig. 4); mesofemora with large, curved projection. (Zhejiang) D. songxiaobini (Yin & Li, 2010)
1B Dorsal surface of head and pronotum with dense, fine setae. Mesotrochanters with spine of various forms 2
2A Fourth antennomeres more than twice as long as third antennomeres 3
2B Fourth antennomeres less than twice as long as third antennomeres 4
3A Mesofemora with sharp ventral spine at base (Yin & Li, 2013: fig. 2C); mesotibiae with triangular tubercle near middle (Yin & Li, 2013: fig. 2C); mesal margin of metatibiae distinctly protuberant at basal 1/4, then strongly curved, curved area with very dense setae (Yin & Li, 2013: fig. 2D). (Anhui) D. dentatus Yin & Li, 2013
3B Ventral margin of mesofemora regularly protuberant at base, lacking spines (Yin & Li, 2014: fig. 2C); mesotibiae lacking tubercles near middle (Yin & Li, 2014: Fig. 2C); mesal margin of metatibiae moderately protuberant at basal 1/4, then moderately curved, curved area with relatively sparse setae (Yin & Li, 2014: Fig. 2D). (Zhejiang) D. zhejiangensis Yin & Li, 2014
4A Mesofemora angularly protuberant at middle (Fig. 2C). Sternite 6 (VIII) with bunch of short, thick setae at middle (Fig. 1C) (Sichuan) D. wangzheni Yin & He, sp. nov.
4B Mesofemora smooth at middle, lacking protuberances nor tubercles or spines. Sternite 6 (VIII) lacking bunch of short, thick setae at middle 5
5A Anterior margin of clypeus distinctly angulate (Yin & Li, 2013: fig. 1B) (Anhui) D. yaoluopingensis Yin & Li, 2013
5B Anterior margin of clypeus approximately rounded 6
6A Mesotrochanters with large, long, and blunt ventral projection (Nomura, 1997: fig. 6km., km-a). Median lobe of aedeagus with large ‘apical part’, area near apex lacking dense setae (Nomura, 1997: fig. 12km.). (Yunnan) D. kunmingensis Nomura, 1997
6B Mesotrochanters with large and sharp ventral spine (Yin, 2018: fig. 2D). Median lobe of aedeagus with small ‘apical part’, area near apex with dense setae (Yin, 2018: fig. 2F, G) (Beijing) D. beijingensis Yin, 2018
ACKNOWLEDGMENTS
LH thanks Chao Zhou and Zhen Wang (both Chengdu, China) for a pleasure company during the field trip. Two anonymous reviewers provided helpful comments on the draft manuscript. The present study was supported by the National Natural Science Foundation of China (No. 31872965), and the ‘Phosphor’ Science Foundation, Shanghai Municipal Science and Technology Commission, China (19QA1406600) awarded to ZWY.
