Taxonomic notes on the rare ant genus Chrysapace with description of a new species from Brunei (Hymenoptera: Formicidae: Dorylinae) Author Yamada, Aiki Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan aiki.ymd@gmail.com Author Lin, Chung-Chi Department of Biology, National Changhua University of Education, Changhua, Taiwan Author Eguchi, Katsuyuki Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan text Acta Entomologica Musei Nationalis Pragae 2019 Acta. Ent. Mus. Natl. Pragae 2019-09-12 59 2 467 480 http://dx.doi.org/10.2478/aemnp-2019-0036 journal article 55894 10.2478/aemnp-2019-0036 872b5474-1d38-4d75-a20b-4d1bd4857f60 1804-6487 5341483 4CDE0401-572B-45CD-B7FE-5CC7F9C5606B Chrysapace costatus ( Bharti & Wachkoo, 2013 ) ( Figs 42–48 ) Chrysapace sauteri (misidentification): RADCHENKO (1993) : 76 , ♀ (dealate). Unconfirmed record (see under “Remarks”). Cerapachys costatus Bharti & Wachkoo, 2013: 1191 , ♀ . Type locality: “FRI [= Forest Research Institute]” ( Uttarakhand , India ); CHEN et al. (2016: 8 , ♀ ). Chrysapace costatus : BOROWIEC (2016) : 106 (new combination). Figs 41–43. Difference of worker’s head sculpture between Chrysapace sauteri ( Forel, 1913 ) and Chrysapace costatus ( Bharti & Wachkoo, 2013 ) . 41 – C. sauteri nontype from Taiwan, colony: Eg12v17-1214; 42 – C. costatus nontype from Yunnan; 43 – C. costatus holotype from India. Figs 44–48. Chrysapace costatus ( Bharti & Wachkoo, 2013 ) , holotype worker. 44 – head in full-face view; 45 – body in lateral view; 46 – label; 47 – head and mesosoma in dorsal view; 48 – metasoma in dorsal view. Type material examined. HOLOTYPE ( Figs 26–30 , 33 ): ♀ , 30.3416° N , 77.9903° E , 640 m alt., FRI, Uttarakhand , India , A.A. Wachkoo leg., 4.ix.2010 ( PUPAC ). Other material examined. CHINA : GUANGXI : 3 ♀♀ , 22°28′N , 106°57′ E , 320 m , Nonggang Natural Reserve, Liwei Liang leg., 24.vi.2013 , No. G130254 ( GNU ). YUNNAN : 3♀♀ , Banna Wild Elephant Valley, 8.iv.2017 , Chaotai Wei leg ( GNU ). Material used for DNA barcoding. Individual AIK20180228-6 (accession no. LC457503 ), Banna Wild Elephant Valley, Yunnan , China . Diagnosis. In the worker, cranium subrectangular in fullface view, with costae on vertex strongly and coarsely distorted; eye and median ocellus relatively large (EI, 22–24; OI, 7–8; EI + OI, 29–31); dorsum of mesosoma longitudinally costate; abdominal tergite and sternite III longitudinally costate; abdominal tergite and sternites IV smooth with relatively dense hair-bearing foveae. Redescription. Worker ( Figs 42–48 ). Body color, pilosity, and structure are similar to the worker of C. sauteri described above except for the following characteristics: costae on vertex of cranium strongly and coarsely distorted (see Figs 42–43 ); eye and ocelli relatively large (EI, 22–24; OI, 7–8; EI + OI, 29–31). Holotype worker ( Figs 43–48 ). HL 1.23 mm ; HW 1.07 mm ; EL 0.27 mm ; EW 0.20 mm ; ES 0.24 mm ; PEHL 0.28 mm ; OL 0.07 mm ; SL 0.81 mm ; WL 1.97 mm ; DML 1.59 mm ; MW 1.06 mm ; MFL 1.17 mm ; PH 0.85 mm ; PTL 0.87 mm ; PTW 0.73 mm ; A3L 0.88 mm ; A3 W 1.07 mm; CI 87; SI 76; EI 22; EPI 22; OI 7; DMI 67; DMI2 81; LMI 53; MFI 109; PTI 85; A3I 122. Nontype workers (n = 6). HL 1.10–1.17 mm ; HW 0.90–0.97 mm ; EL 0.23–0.26 mm ; EW 0.17–0.21 mm ; ES 0.21–0.23 mm ; PEHL 0.24–0.29 mm ; OL 0.06–0.08 mm ; SL 0.65–0.70 mm ; WL 1.60–1.77 mm ; DML 1.25–1.32 mm ; MW 0.85–0.89 mm ; MFL 0.95–0.98 mm ; PH 0.69– 0.74 mm ; PTL 0.68–0.73 mm ; PTW 0.63–0.69 mm ; A3L 0.74–0.82 mm ; A3 W 0.90 –0.95 mm; CI 81–84; SI 70–74; EI 22–24; EPI 21–25; OI 7–8; DMI 67–70; DMI2 71–80; LMI 53–59; MFI 101–105; PTI 88–98; A3I 114–122. Distribution. Northern India : Uttarakhand , Himachal Pradesh ( BHARTI & WACHKOO 2013 , BHARTI et al. 2016 ); China : Guangxi ( CHEN et al. 2016 ); Yunnan (new record); Northern Vietnam ? (see under “Remarks”, RADCHENKO 1993 ). Remarks. The original description of C. costatus ( BHARTI & WACHKOO 2013 ) stated that the worker of this species is easily distinguished from that of C. sauteri by “rectangular head with porcate-sinuate sculpture and longitudinal costate sculpture on postpetiole”. However, inconsistent with this original diagnosis, the characteristics of “rectangular head” and “longitudinal costate sculpture on postpetiole” are actually shared with Taiwanese C. sauteri . Nevertheless, the mainland Asian populations from Yunnan, Guangxi, and India differ from the Taiwanese population (= C. sauteri ) in the following morphological characteristics of the worker: the former has more strongly and coarsely distorted costae on vertex of cranium, and larger eye and ocelli than the latter. Based on these differences, we here tentatively retain the status of C. costatus asa distinct species, although the species delimitation needs to be tested based on more comprehensive data in the future. Pairwise distance (proportion of different sites) between Taiwanese C. sauteri and Yunnan C. costatus was 0.068 –0.070 in COI. RADCHENKO (1993) recorded a dealate queen from northern Vietnam as C. sauteri . Identity of this specimen is currently unknown, but the geographic range suggests its affinity with C. costatus .