Beijingusa Pace, 1999

Lee, Woo-Chul & Ahn, Kee-Jeong, 2023, Description of a New Species of Beijingusa Pace (Coleoptera: Staphylinidae: Aleocharinae) in Korea, The Coleopterists Bulletin 77 (4), pp. 601-605 : 601-605

Genus Beijingusa Pace, 1999

Beijingusa Pace 1999: 111 (type species: Beijingusa rougemonti Pace ).

2.2 mm long.

Beijingusa mandibularis Lee and Ahn , new species zoobank.org/ urn:lsid:zoobank.org:act:BF98B296-C212-4473-82D2-3048808923F7 ( Figs. 1–4 )

TYpe Specimens. HolotYpe, labeled as follows: “ KOREA: Gyeongnam Prov., Sancheong-gun, Chahwang-myeon, Beoppyeong-ri , N35°29′16.50′′ E127°57′36.93′′ 623m, 23 III 2017, JS Lee, JH Lee, leaf litter. HOLOTYPE Beijingusa mandibularis Lee and Ahn 2023 ”. Deposited in CNUIC . ParatYpes, 1 ex., KOREA: Gangwon Prov., Pyeongchang-gun, Jinbu-myeon, Mt. Odae , N37°47′03′′ E128°33′55′′ , 18 VI 2004, SJ Park, ex sifting; 1 ex., KOREA: Gangwon Prov., Pyeongchang-gun, Jinbu-myeon, Dongsan-ri , Mt. Odaesan , Sangwonsa , 4 VI 2001, S.-J. Park, ex sifting ; 1 ex., KOREA: Gangwon Prov., Pyeongchang-gun, Jinbu-myeon, Mt. Odaesan , Sangwonsa N37°47′10′′ E128°33′57.2′′ , 19 IV–11 V 2007, TK Kim, YH Kim, FIT; 1 ex., KOREA: Gangwon Prov., Pyeongchang-gun, Jinbu-myeon, Mt. Odaesan , Sangwonsa N37°47′10′′ E128°33′57.2′′ , 19-APR–11-MAY-07, TK Kim, YH Kim, FIT; 1 ex., KOREA: Gangwon Prov., Mt. Jeombongsan, Jindong-ri, Girin-myeon , Injae-gun , ex. sifting 18. IV. 2007, S. M. Yoon coll. E128°28′22.4′′, N38°02′13.1′′ ; 1 ex., KOREA: Chungbuk Provin., Boeu [n]-gun, Naesokri-myeon , Mt. Sokrisan , nr. Sesimjeong , VI 23 2001, Y. B. Cho, ex sifting; 2 exx., KOREA: Chungnam Prov., Daejeon-si , Seo-gu , Janan-dong , Mt. Jangtaesan , N36°13′03.3′′ E127°20′36.2′′ 258m , 28 III 2012, DH Lee, TK Kim, SG Lee, leaflitter; 5 exx., KOREA: Chungnam Prov., Daejeon-si, Seo-gu, Janan-dong, Mt. Jangtaesan , N36°13′03.3′′ E127°20′36.2′′ 258m , 5 IV 2013, JH Song, SG Lee, JS Lee, MA Cho, leaflitter; 8 exx., KOREA: Jeonbuk Prov., Namwon-si, Sannae-myeon, Mt. Jirisan , Baemsagol-valley , N35°22′14.3′′ E127°34′46.9′′ 500m , 17 VI 2010, TK Kim, YH Kim, JH Song, sifting leaf litter; 1 ex., KOREA: Jeonnam Prov., Kwangyang-city, eochi-2ri, 20 V 2000, U S Hwang, ex sifting; 2 exx., KOREA: Gyeonbuk Prov., Yongjang-ri , Naenam-myeon , Gyeongju-si , ex FIT; 21. V –26. VI. 2007, YB Cho coll. E129°12′42.9′′ N35°46′19.5′′ ; 1 ex., KOREA: Gyeongbuk Prov., Mochagol. Hwangyong-dong, Gyeongju-shi. ex. sifting 26. IV. 2007, H. K. Min coll. E129°22′22.7′′, N35°49′36.3′′ .

Description. Length 2.2–2.4 mm. Body ( Fig. 1 ) subparallel-sided; black, glossy, densely pubescent; antenna, maxillary palpus and legs reddish brown. Head. Circular with narrow neck; approximately 1.2 times as wide as long, widest near eye; similar in width or slightly wider than pronotum. Frontal suture absent. Eye moderate in size, prominent; approximately 0.6 times as long as temple in ventral view; four long setae present between eyes; gular sutures moderately separated. Antenna ( Fig. 2A ) relatively short; antennomeres 1–2 elongate, 3 an inverted triangle, 4 slightly transverse, 5–10 strongly transverse, 11 elongate and longest. Mouthparts. Labrum ( Fig. 2B ) transverse, rounded, with about 9–10 macrosetae on each side of midline and one thick seta located in anterior midline; α-sensillum very thick, located on the anterior margin; β- and γ-sensilla reduced and short, located between both α-sensilla. Mandible ( Fig. 2C ) asymmetrical, long, slender, right one with small internal tooth, internal middle margin serrulate, five setae present on outer surface. Galea and lacinia of maxilla ( Fig. 2D ) long and slender, galea with approximately 18–20 spinules; lacinia with more than about 13 spines in distal comb region, 6 isolated spines present posteriorly; last spine of distal comb region and isolated spines close together; maxillary palpus elongate and pubescent; palpomere 1 smallest, 3 longest, length ratio of palpomeres 7:25:83:29, outer sclerites of stipes with two setae; anterior one longer than the other. Labium ( Fig. 2E ) with ligula elongate, unilobed; length longer than half of labial palpomere 1. Prementum with two medial setae widely separated, a few median pseudopores present; one setal pore, two real pores, and a few pseudopores present on each side of midline; labial palpus with many setulae; palpomere 1 longest and 2 shortest; ratio of lengths 20:7:14. Mentum anteriorly emarginate, trapezoidal, v-seta short, close to u-seta, w-seta longest, 3–4 other short setae present on each side of midline. Thorax. Pronotum with about 5 distinct and long setae present on each side of midline; approximately 1.1 times as wide as long, narrowest near neck, shallow furrow present; hypomeron visible in lateral view. Mesocoxal cavities moderately separated at middle; mesoventrite with oblique lateral carina, mesoventral process with apex truncate, slightly longer than metaventral process with apex truncate. Elytron. 1.44 times as long as pronotum, slightly lighter at posterior margin, antero-lateral region with two macrosetae and one macroseta present laterally at one-half length of elytron; posterolateral margin sinuate, hind wing fully developed. Legs. Tarsal formula 5-5-5, length ratio of tarsomeres 31:28:30:26:46 (protarsus), 31:33:34:30:62 (mesotarsus), 61:42:43:37:72 (metatarsus). Abdomen. Parallel-sided, pubescent with fine punctation; tergites III–VI impressed, with several dimples present; sternites III–VII with posterior margin crenate; male tergite VIII ( Fig. 3A ) with about 12 macrosetae present; male sternite VIII ( Fig. 3B ) with about 14 macrosetae present, posterior margin convex; male tergite X with many setae ( Fig. 3C ); female tergite VIII ( Fig. 3D ) with about 12 macrosetae present; female sternite VIII ( Fig. 3E ) with about 22 macrosetae, several setae present on posterior margin; female tergite X ( Fig. 3F ) with many setae. Aedeagus. Median lobe ( Figs. 4A, B ) ovate, apical process slightly bent with pointed protrusion at median region; preputial sac curved in lateral aspect. Paramere ( Fig. 4C ) narrow, proximal part elongated and base of proximal part slightly curved; apical lobe of paramerite ( Fig. 4D ) elongate with punctures and 4 setae; a-seta shorter than d-seta; b-seta very short; c-seta longest. Spermatheca ( Fig. 4E ). Bursa bent and narrowed at base of duct; duct elongate and curved.

Distribution. Korea (South).

Remarks. Pace (1999) described B. rougemonti based only on a single female specimen from China. Nevertheless, B. mandibularis can be distinguished from B. rougemonti by the larger and different shape of the spermatheca ( Fig. 4E ). The new species has a less distinctly V-shaped umbilicus, shorter bursa, and narrowed anterior part of duct of the spermatheca compared to B. rougemonti .

We found intraspecific variation in body coloration (dark brownish to black) and head shape (some have a more circular shape) among individuals of the new species. However, all specimens examined showed the same form and structure of the median lobe of the male genitalia, which has been regarded a good character to delimit and identify species within Oxypodini .

Figures

Fig. 1. Beijingusa mandibularis, new species. Habitus,

Fig. 2. Beijingusa mandibularis, new species. A) Antenna, B) Labrum, dorsal view, C) Mandibles, dorsal view, D) Maxilla, dorsal view, E) Labium, ventral view. Scale bar = 0.1 mm.

Fig. 3. Beijingusa mandibularis, new species. Male: A) Tergite VIII, dorsal view, B) Sternite VIII, ventral view, C) Tergites IX and X, dorsal view. Female: D) Tergite VIII, dorsal view, E) Sternite VIII, ventral view, F) Tergites IX and X, dorsal view. Scale bar = 0.1 mm.

Fig. 4. Beijingusa mandibularis, new species. A) Aedeagus, dorsal view, B) Aedeagus, lateral view, C) Paramere, lateral view, D) Apical lobe of paramerite, lateral view, E) Spermatheca. Scale bar: 0.1 mm.