Platydracus juang Smetana, 2005

Hu, Fang-Shuo, 2020, New distributional records of Staphylinina in Taiwan, including a new species of Miobdelus Sharp (Coleoptera: Staphylinidae: Staphylininae: Staphylinini), Zootaxa 4768 (3), pp. 334-360 : 346-347

Platydracus juang Smetana, 2005

( Figs. 16 , 41–49 )

Type material. Holotype (female) by monotypy, in NHMW: China, N Fujian, 1.–4. VI. FENGSHUI GUAN, 27.9N 117.85E, ~ 1700m Jaroslav Tuma leg., 2004 / HOLOTYPE Platydracus juang A.Smetana, 2005 [red label]. The specimen is in good condition, both hind wings extended from elytra. Genital segment of the holotype was dissected, mounted on a plastic card in Euparal.

Material examined. TAIWAN: Miaoli County: 1 female, Zhuolan (ḓã), Zhuolan To., 09-II-2015, leg. W. R . Liang (in dead wood) (FSHc). Nantou County: 1 male, Husiun (èḵ), Renai To., 16-III-2019, leg. Y. H. Ho (collected from dead wood)// Host : Reticulitermes leptomandibularis Hsia & Fang, 1965 (FSHc) ; 1 female, same locality as above, 15-XI-2018, leg. W. R . Liang (collected from dead wood)// Host: Reticulitermes leptomandibularis Hsia & Fang, 1965 ( FMNH) ; 1 male, same locality as above, 11-I-2020, leg. R . H. Liu (in fallen dead wood)//Host: Reticulitermes leptomandibularis Hsia & Fang, 1965 (FSHc); 1 female, same locality as above, 30-I-2018, leg. W. R . Liang ( NHMW) ; 2 females, same locality as above, 18-V-2014 ~ 14-VI-2014, leg. W. R . Liang By MLT (FSHc, NHMW) ; 1 male, Huisun (èḵ), Renai To., 24.0898, 121.0320, 25-V-2019 ~ 07-VI-2019, leg. W. R . Liang by MLT ( TARI) ; 1 male, Huisun (èḵ), Renai To., 24.0888, 121.0300, 28-III-2019 ~ 05-V-2019, leg. W. R . Liang By FIT ( TARI) ; 1 female, Xin-yi, Renlun loging rd. (kǿIJǎ), alt. ca. 1500m, 23.7329N, 120.9145E, pitfall traps no. 11., 11–17.IX.2019, Project no. TFBC-1070517 ( FMNH) ; 1 male, Chunyang [Ɓọ], VIII/5–IX/9/2003, C. S. Lin & W. T . Yang, Malaise trap ( KCN) [ NMNS ENT 4955-1519 ] ( NMNS) ; 1 female, same data as above except VII/9–VIII/13/2002 [ NMNS ENT 5240-2370 ] ( NMNS) ; 1 spec., same data as above except No: II Sampling plots, VIII/7–IX/4/2007 [ NMNS ENT 7517-1691 ] ( NMNS) ; 1 spec., Jenai Sungkang [ Ḻṋ Ẹà ], V /22/1998, C.C. Lo ( NMNS) . Pingtung County: 1 female, Chun-jih, Ta-han-shan, ± ÀƜ , 1300m, 2019,III-19, Y.- T . Chung Leg. CCCC (FSHc) . Taichung City: 1 female, Daxue Mt. Forest Trail 14k (±ũƜIJǎ 14k), Heping Dist. , 18-VII-2014, leg .

Y. Hsiao ( TARI); 1 male, Daxue Mt. Forest Trail (±ũƜIJǎ) (alt. 1200m), 24.2475, 120.9111, 25-V-2018 leg. F. S. Hu (under wood) (FSHc). Taoyuan City: 1 female, Siling ( XŔ), Fuxing Dist. , 15-IV-2014, leg. W. R. Liang By FIT (FSHc) .

Description. Habitus and female description see Smetana (2005a). Xu & Tang (2019) provided the first male description but in Chinese. A re-description of the male of P. juang is provided below based on Taiwanese material.

Male. Sternite 7 ( Fig. 47 ) with a disc-shaped sunken area on middle of sternite, bearing numerous brownish long setae; sternite 8 ( Fig. 44 ) with distinct obtuse medioapical emargination; sternite 9 ( Fig. 43 ) with narrow and slender basal portion, apical portion with deep and narrow medioapical emargination. Tergite 10 ( Fig. 45 ) gradually narrowed toward subacute apex, apical portion obtuse, with numerous long, dense setae, other setae distributed as usual on tergite. Aedeagus ( Figs. 41–42 ). Median lobe symmetrical, gradually converging to apex in ventral view; apical portion in ventral view with a separated sclerotized region, this part rounded apically and with distinct, obtuse emargination in posterior margin; median lobe in lateral view with relatively membranous region at the midlength and at the base near bulbus. Paramere small, asymmetrical and triangular, relatively rounded apically; with a sclerotized keel at the base of paramere, sclerotized keel with a shallow emargination in ventral view; without sensory peg setae on paramere.

Diagnosis. Though there are still numerous undescribed species of Platydracus from Taiwan and even the Palaearctic and Oriental regions in general, Platydracus juang may be distinguished from other Taiwanese Platydracus by the parallelsided abdominal shape and relatively narrow (non-dilated) temples.

Bionomics. The bionomics of P. juang were primary described by Xu & Tang (2019) who indicated that this species is strongly associated with dead wood in the forest. Based on an import of locality name into Google Earth from collection data (this study), the species occurs from 700–1500 m in Taiwan. Some specimens reported here were collected by various traps (etc. flight interception trap, Malaise trap or pitfall trap) or collected from the nest of Reticulitermes leptomandibularis Hsia & Fang, 1965 in fallen, moist dead wood near the trail in medium elevation mountainous areas ( Fig. 48 ).

Behavior. In the laboratory, I used one species of cockroach, Blatta lateralis Walker , and five species of termites ( Coptotermes formosanus Shiraki, 1909 , Nasutitermes parvonasutus (Shiraki, 1911) , Odontotermes formosanus (Shiraki, 1909) , R. flaviceps Oshima, 1908 and R. leptomandibularis ) to test the feeding preferences of P. juang . Platydracus juang showed predatory behavior toward both species of Reticulitermes Holmgren, 1913 but only fed upon R. leptomandibularis (both workers and soldiers) ( Fig. 49 ). The other three species of termites and cockroach did not elicit a predatory response. Based on these observations, P. juang may be a termitophilous species and associated with R. leptomandibularis . However, further tests of feeding behavior, including more samples, are needed.

Live specimens of P. juang were also observed to sometimes tap the ground with their abdomen, similar to some wasps, but the function of this behavior in P. juang remains unknown.

Distribution. The species is widespread in southeast mainland China (Anhui, Fujian, Jiangxi, Zhejiang) ( Xu & Tang 2019) and also widespread in Taiwan (Miaoli, Nantou, Pingtung, Taichung, Taoyuan) (new record).

Remarks. Smetana (2005a) provided the illustrations of tergite 10 of female genital segment of both P. brachycerus Smetana & Davies, 2000 and P. juang . However, the illustrations as labelled didn’t fit the description. His description of P. juang (“Tergite 10 of genital segment relatively narrow, markedly narrowed toward subacute apex densely setose medioapical”) matches figure 1 not figure 2. Also, P. juang with relatively larger body size, corresponds to figure 1 in Smetana (2005a) rather than P. brachycerus .

Taiwanese specimens of P. juang were observed to have a thicker sclerotized keel on the base of the paramere and a narrower paramere than Chinese specimens. However, no additional characters differed between the two populations. Here, I suggest that these differences represent intraspecific variation until DNA grade specimens from both mainland China and Taiwan are available to test the status of the Taiwanese population.

The termite recorded with some specimens of P. juang , R. leptomandibularis , is a relatively rare species of the genus Reticulitermes , that occurs in mainland China and Taiwan. However, the Taiwanese population is considered to be restricted to medium elevations in central Taiwan ( Wu et al. 2019). Platydracus juang is also restricted to these elevations but is more broadly distributed than just central Taiwan. It is possible that R. leptomandibularis is also widespread in Taiwan. However, my feeding behavior experiments did not include R. kanmonensis as prey, which are also distributed at medium elevations in Taiwan and rather widespread. It would be interesting to test whether P. juang also feeds on this and other termite species.

Figures

FIGURES 14–19. 14–15. Ontholestes oculatus: male and female. 16. Platydracus juang: male. 17. Thoracostrongylus formosanus: male. 18–19. Thoracostrongylus miyakei: male, lectotype and attached labels; male. Scale bar: 3 mm

FIGURES 41–46. Platydracus juang 41. Aedeagus in ventral view; 42. Aedeagus in lateral view; 43. Sternite 9, male; 44. Sternite 8, male; 45. Tergite 10, male; 46. Tergite 10, female. Scale bar: 0.5 mm

FIGURES 47–49. Platydracus juang 47. Long setae on sternite 7 of male (scale bar: 1 mm); 48. Habitat of P. juang in Huisun, Nantou County, Taiwan; 49. Platydracus juang feeding on Reticulitermes leptomandibularis in the laboratory.