Stenus gestroi FAUVEL 1895

Puthz, V, 2011, On the Stenus LATREILLE 1797 from Taiwan with spotted elytra including remarks on the S. gestroi-group (Coleoptera, Staphylinidae) (316 Contribution to the Knowledge of Steninae), Linzer biologische Beiträge 43 (1), pp. 565-596 : 566-568

Stenus gestroi FAUVEL 1895 ( Figs 1, 2, 5, 8 , 11-15 , 46-54, 56 )

Stenus gestroi FAUVEL 1895: 212 ; PUTHZ 1969: 36 figs.

Stenus gestroi ssp.; ROUGEMONT 1987: 711.

Stenus callifrons L. BENICK 1926: 276 , syn.nov.

Stenus grandiculus L. BENICK 1926: 277 , syn.nov.

Stenus simulans CAMERON 1930 (not L. BENICK 1929).

Stenus stigmatipennis L. BENICK 1929: 90 , syn.nov.

Stenus ridiculus SCHEERPELTZ 1933: 1196 syn.nov.

Stenus chinkiangensis BERNHAUER 1938: 32 .

Stenus takara NAKANE 1963: 21 syn.nov.

Stenus submaculatus taiwanensis PUTHZ 1968: 47 figs.

M a t e r i a l studied from T a i w a n: Taipei Hsien: 1, 2: Wulai , 24.-30.IV.1972, A. Yoshii (cSh, cP) ; 1: Konden , 28.IV.1941, Y. Yano (cP) ; 2, 1: Sabiki-bansya near Kagi , 28.IV.1941, Y. Yano (cP, cR) ; Taoyuan Hsien: 1: Upper Palin , 1200 m, 18.IV.1990, A. Smetana (T 6) (cS) ; Taichung Hsien: 1: Wufeng , 100-120 m, 14.IV.1990, A. Smetana (T 1) (cS) ; Nantou Hsien: 3, 5: Nanshanchi ( Nanzankei ), 18.V.1977, 5.IV.1978, 29.VIII.1988, T. Niizato, S. Nomura (cN, cP) ; 6, 6: near Nanshanchi (830-850 m), 17.V.1971, 24.VIII.1973, 23.VII.1974, 26.V.1975, 25.VII.1976, 2.V.1978, 4.VIII.1978, Y. Shibata, K. Komiya, K. Matsuda, K. Sakai (cSh, cP) ; 8, 6: Lushan Wenchuan (1200 m), 28.V.1980, 28., 29.VII.1983, 3.VIII.1985, Y. Shibata, H. Makihara (cSh, cN, cP) ; 1: Lushan , 20.VI.1976, H. Makihara (cN) ; 7, 10: near Lushan (1200 m), 29.VII.1974, 24.VII., 26.VII.1976, 28.VII.1977, 26., 29.VII.1978, Y. Shibata, K. Matsuda (cSh, cP) ; 1: Lushan-Spa , 31.VII.1971, Y. Shibata (cSh) ; 1: Tungpu spa, 22.V.1981, T. Ito (cR) ; 3, 2: Koantanchi (650 m), 15.VIII.1970, 26., 27.VII.1973, Y. Shibata (cSh, cP) ; 2, 3: near Juisui Spa (400 m), 3.VIII.1974, 26.III.1980, Y. Shibata (cSh, cP) ; 1: Sun Moon Lake , 6.IV.1977, W. Suzuki (cSh) ; 1: near Wushe , 29.VI.1971, Y. Shibata (cSh) ; 1: Bukai-Musha [= Fatyu, Wuchieh-Wushe], 23.VII.1947, J.L. Gressitt ( BPBM) ; 1: near Tungpu , 25.VIII.1987, Y. Shibata (cSh) ; 1: near Lienhuachi , 3.VIII.1977, Y. Shibata (cSh) ; 1: near Penpuchio , 13.V.1973, K. Matsuda (cSh) ; 6, 2: Jihyetan , 16.V.1977, T. Niizato (cN, cP) ; 2: Shishitou , 19.VII.1988, S. Nomura (cN) ; 3: Piluchi , 10.VI.1980, H. Makihara (cN, cP) ; 1: Hori [= Puli], 6.VI.1934, J. L. Gressitt ( USNM) ; Chiai Hsien: 1: Shenmu , 21.V.1980, H. Makihara (cN) ; 1: Fenchihu , 23.V.1975, Y. Shibata (cSh) ; 1: Fenchihu 1500 m, 2.-3.VII.1982, N. Nishikawa (cP) ; 1: Alishan Road 129 km 33.5 (env. Chashan ), ca. 400 m, forest litter, 13.IV.2009, S. Vít ( MHNG) ; 1: Karapin [= Chaolipihg] near Mt. Ari , 28.III.1938, Y. Yano (cP) ; Kaohsiung Hsien: 5, 5: Kosempo (= Jiashianpu ), II.1908, Sauter ( FMCh, NHML, NHMW, cP) ; 1: Liukuei , 2.VIII.1988, S. Nomura (cN) ; 1: Shenping Forest Recreation Area near Lukuei , swept, 19.-21.XI.2002, L. Ronkay & O. Merkl ( TMB) ; Taitung Hsien: 4, 3: Peiyuan , 6., 7.VI.1968, Y. Watanabe (cWatanabe, cP) ; 3: Road no. 20 km 188.5 before Wulu , 750 m, mountainous forest litter, 8.IV.2007, S. Vit ( MHNG, cP) ; 1: Road no. 9 Luyeh , 750 m, decaying wood, 10.IV.2007, S. Vit (cP) ; 1: Road 20, km 173, 1200 m, Canacea litter, 13.IV.2009, S. Vit ( MHNG) .

M a t e r i a l studied from o t h e r r e g i o n s / c o u n t r i e s India (16), Nepal (64), Burma (60), Thailand (17), Vietnam (1), China (19), Malaysia (1), Indonesia-Sumatra (9).

The complex of Stenus gestroi is an intricate one as can be seen from the different taxanames quoted above and from the different attributions of the taxa. The S. gestroi -group ( PUTHZ 1973: 83) is well characterized by very large eyes, deeply concave frons, oval paraglossae, deeply bilobed tarsal segment 4, apicolaterally acute sternum 9, simple legs in the male and the genitalia: in the males the median lobe has small setae along its apical half laterally (fig. 17) [exceptions: S. dentellus L. BENICK , S. nobilis BERNHAUER , S. kurbatovi PUTHZ ], parameres with setae along whole internal side like in many Dianous - species [exception: S. dentellus L. BENICK ], most species have a small triangular expulsion-hook in the median lobe (fig. 13) [exceptions: S. dentellus L. BENICK , S. cephalo PUTHZ ], in the females the spermatheca consists of a several times coiled spermathecal duct (figs 8, 9).

This group contains species with a distinctly but very narrowly margined abdomen. Most species have spotted elytra ( S. banghaasi L. BENICK , S. cephalo PUTHZ , S. circumflexus FAUVEL , S. crebriventris PUTHZ, S. gestroi FAUVEL , S. kurbatovi PUTHZ , S. masurianus CAMERON , S. nobilis BERNHAUER , S. tubiventris PUTHZ , S. tujuhmontis PUTHZ ) some uniformly blackish elytra ( S. boettcheri L. BENICK , S. dentellus L. BENICK , S. lacertosus L. BENICK , S. pernobilis PUTHZ , S. tenebricus PUTHZ ), some both ( S. cephalo PUTHZ, S. gestroi profundesulcatus SCHEERPELTZ, S. gestroi submaculatus BERNHAUER ).

Sister-group and very close by habitus is the S. guttalis -group ( PUTHZ 1973: 83), in which some species have immargined other narrowly margined abdomen. In this group males have preapical metatibial spurs, and the median lobe has a comparatively large expulsion clasp. The spermatheca is of different shape (see fig. 10).

Close to the S. gestroi -group are species of the complex of S. feae FAUVEL ( S. feae FAUVEL , S. tectifrons ROUGEMONT , S. ulcerosus L. BENICK and S. valens L. BENICK ) with apically serrate sternum 9 and different aedeagi.

Whereas most of the taxa are distinguished by distinct habitus- and/or aedeagus-characters, other exhibit different shapings of the elytral spot, different coarseness and density of abdominal punctuation, different sculpture of the pronotum (figs 11, 12) and different outlines of the median lobe.

When only single specimens are at hand, one could easily regard them as different species, as has been shown by L. BENICK 1926. The study of many specimens from different localities leads to the result, that S. gestroi is a very variable and widespread species. The ratio HW: EW varies between 0.95 and 1.06 (ø 0.997; N = 24), the ratio SpL: EL between 0.23 ( Nepal: Annapurna Mts.) and 0.45 ( Burma: type locality) (ø 0.33). In the Taiwan specimens, which formerly had been identified as S. gestroi stigmatipennis the same ratios are: HW: EW = 1.00- 1.12 (ø 1.06), SpL: EL = 0.22-0.39 (ø 0.30; N= 21). While in the specimens from Java, Bali, Lombok and Sumbawa, formerly identified as S. submaculatus BERNHAUER , these ratios are: HW: EW = 0.96- 1.05 (ø 0.987; N= 21), SpL: EL= 0.10-0.24 (ø 0.153; N= 21; 2 specimens spotless). Although the aedeagus of these Sunda-Island-specimens fits into the range of variability of S. gestroi , I propose to regard these specimens for the present as a subspecies: Stenus gestroi submaculatus BERNHAUER nov.stat.

The anterior portion the median lobe of S. gestroi is shown in figs 46-54, 56: the apex can be ± button-shaped and ± slender. In most of the Taiwanese males (which all have been dissected by me) the apical portion is slender (fig. 52), but both forms, the slender and the broader one (fig. 51) are found in specimens from the same locality, which are indistinguishable by characters of the exoskeleton. Most of the Taiwanese specimens have a comparative coarse and dense abdominal punctuation (fig. 14), but even this is not a stable character, there are also specimens with less coarse and less dense punctuation on the tergites (fig. 15). This range of variability is also found in specimens from Burma- Thailand-China. Also the length of parameres varies in the same series, f. e. from 14 males collected at Kalaw/ Burma in 13 of them the parameres are slightly longer than the median lobe but in1 of them distinctly shorter.

Stenus patruelis L. BENICK from the Philippines also belongs to this complex. Since the available material is too short, a decision on the state of this taxon should remain open. It looks very similar to S. gestroi submaculatus and is probably a synonym of that subspecies.

Distinctly different from S. gestroi is S. lacertosus L. BENICK , which has been regarded as a subspecies of S. gestroi . The shape of the aedeagus and the reduced internal expulsion hook (fig. 57) show that this taxon is a distinct species: S. lacertosus L. BENICK 1917 , Ent. Bl. 13: 311 f. spec.propr.

Examination of the types of all other above quoted taxa leads to the result that they belong into the variability range of S. gestroi FAUVEL.

Figures

Figs 1-10: Paraglossae (1-4), head (5-7) and spermatheca (8-10) of Stenus gestroi FAUVEL (1, 2, 5, Wulu; 8, Alishan Rd. 129), S. bilunatus PUTHZ (3, 4, near Litao), S. habropus PUTHZ (6), S. bilunatoides nov.sp. (7, PT), S. cephalo PUTHZ (9, Java, Tretes), S. guttalis FAUVEL (10, Tioman).

Figs 11-25: Pronotum (11, 12), expulsion hook (13), dorsal aspect of abdominal segments 6 and 7 (14, 15), spermatheca (16, 20-25), lateral portion of median lobe (17), ventral aspect of a detail of the anterior portion of median lobe (18, 19) of Stenus gestroi FAUVEL (11, Carin Cheba; 12, Arni Gad; 13, 17, Tokara Is.; 14, Nanshanchi; 15, Peiyuan), S. electrigemmeus nov.sp. (16, PT 152; 18, HT), S. electrigemmatus nov.sp. (19, HT), S. mithracifer nov.sp. (20, PT), S. miwai BERNHAUER (21, Mt. Karapin), S. virgula FAUVEL (22, Lebong), S. bicolon posticus FAUVEL (23, Malaysia: Bringchang), S. stigmosus nov.sp. (24, PT, T 3) and S. stigmifer nov.sp. (25, PT, Kaolin).

Figs 46-69: Ventral aspect of the anterior portion of median lobe of Stenus gestroi FAUVEL (46, lectotype; 47, Carin Cheba; 48, Cameron Hills; 49, Arni Gad; 50, Doi Pui; 51, Shishitou 1; 52, Shishitou 2; 53, Luyeh; 54, Tokara Is.; 56, Wuyi Mts.), S. cephalo PUTHZ (55, Sumatra), S. lacertosus L. BENICK (57, Java), S. bilunatus PUTHZ (58, HT; 59, Piluchi; 60, Arisan; 61, T 28; 62, T 48; 63, T 149), S. bigemmosus nov.sp. (64, HT), S. bigemmatus nov.sp. (65, HT), S. bilunatior nov.sp. (PTT, 66, T 43 a; 67, T 43 b), S. biluminatus nov.sp. (68, HT), S. bistigmosus nov.sp. (69, HT). Scale bar = 0.1 mm.