A preliminary key to species of Trichotichnus s. str. from Yunnan

Since the fauna of Yunnan is still poorly known and distinctive characters of external morphology in many species are variable both individually and geographically, the examination of male genitalia is very desirable for accurate species identification.

1 Legs relatively short (as in Figs. 1, 2, 8–10, 35–37, 56–58, 74–76), pro- and mesotarsomeres 1–4 in both sexes with comparatively sparse moderately long ventro-lateral setae (as in Figs. 18, 19). Pronotum not cordiform, in most specimens relatively wider (PWmax/PL 1.45–1.63), with flat or only moderately deepened laterobasal depressions. Legs unicoloured pale or with infuscate femora. Protibia with or without longitudinal sulcus on dorsal side...................................... 2

- Legs relatively long (as in Figs. 94, 95, 107, 108), pro- and mesotarsomeres 1–4, particularly in male, with longer and denser ventro-lateral setae (as in Fig. 20). Pronotum more or less cordiform, in most specimens relatively narrower (PWmax/PL 1.34–1.48), with deep basolateral depressions. Femora infuscate. Protibia without longitudinal sulcus on dorsal side..... 12

2 Protibia with longitudinal sulcus on dorsal side. Mesotarsomere 1 of male without adhesive scales ventrally. Preapical sinuation of elytra very shallow (as in Fig. 39). Legs unicoloured brownish yellow, femora not darker than tibiae................. 3

- Protibia without longitudinal sulcus on dorsal side. Mesotarsomere 1 of male with adhesive scales at apex ventrally. Preapical sinuation of elytra shallow or rather deep. Legs unicoloured pale or with infuscate femora........................... 5

3 Left mandible in frontal view wide and truncate at tip (Fig. 55). Labrum more or less markedly concave anteriorly. Median lobe of aedeagus (Figs. 77–81) with very apex not bent dorsally or ventrally, internal sac with narrow spiny patches along sides apically; female genitalia as in Figs. 82 & 83. Habitus as in Fig. 74. Body length 7.7–9.6 mm .... T. subangulatus Ito, 2021

- Left mandible in frontal view markedly narrowed apically, blunted at tip (Fig. 53). Apical margin of labrum almost straight, at most only slightly concave medially. Male and female genitalia not as above...................................... 4

4 Median lobe of aedeagus (Figs. 47–52) in lateral view slenderer, angularly bent ventrally just at apex and slightly swollen at tip forming a small apical capitulum; internal sac without distinct spiny patches. Habitus as in Fig. 36. Body length 8.2–8.5 mm ............................................................................. T. doiinthanonensis Ito, 1997

- Median lobe of aedeagus (Figs. 59–64) more robust, with apex bent dorsally; internal sac with somewhat wide oval (in dorsal view) spiny patches apically. Habitus as in Figs. 56–58. Body length 7.3–8.4 mm ..................... T. schmidti sp. n.

5 Preapical sinuation of elytra rather deep (Fig. 38). Legs brownish yellow, femora not darker than tibiae. Median lobe of aedeagus (Figs. 40 & 41) in lateral view almost straight in basal two-thirds, terminal lamella in dorsal view wide and long; female genitalia as in Figs. 42 & 43. Habitus as in Fig. 35. Body length 7.7–9.2 mm ............ T. cyrtops (Tschitschérine, 1906)

- Preapical sinuation of elytra shallow. Legs unicoloured pale or with infuscate femora. Male and female genitalia not as above ................................................................................................... 6

6 Protibia in both sexes with three stout, similar sized preapical spines on outer margin (as in Fig. 18, 19). Legs brownish yellow or brown, at most femora slightly infuscate. Body larger: length 9.2–11.4 mm ..................................... 7

- Protibia on outer margin preapically with one stouter and two very thin spines in male (as in Fig. 20) and with three comparatively stout spines in female. Legs brownish yellow or reddish brown, with femora distinctly infuscate. Body smaller: length 6.7–8.8 mm (up to 10.4 mm in T. bouvieri)................................................................. 9

7 Metepisternum (Fig. 22) shorter, only slightly longer than wide. Body (Fig. 10) more robust, with appendages shorter; antennae not reaching pronotal basal edge; metatarsus slightly shorter than HWmin. Median lobe of aedeagus with a small transverse apical capitulum (Figs. 29–31), female genitalia as in Figs 32, 33. Body length 9.2–10.0 mm......... T. subrobustus sp. n.

- Metepisternum markedly longer than wide (as in Fig. 21). Body (Figs 8, 9) less robust, with appendages longer; antennae slender, surpassing pronotal basal edge; metatarsus almost as long as or slightly shorter than HWmax. Male and female genitalia not as above......................................................................................... 8

8 Pronotum (Fig. 8) relatively larger, with shallower laterobasal depressions; microsculpture on disc strongly obliterated, not forming distinct meshes. In male, pro- and mesotarsomeres wider (as in Fig. 18), last visible abdominal sternite with two pairs of marginal setae. Median lobe of aedeagus (Figs. 11–14) with apex not bent dorsally and with a large spine in internal sac; female genitalia as in Figs. 15, 16. Habitus as in Fig. 8. Body length 9.7–11.3 mm ............... T. fukuharai Habu, 1957

- Pronotum (Fig. 9) relatively smaller, with deeper laterobasal depressions; microsculpture on disc more distinct, consisting of very fine, more or less isodiametric meshes. In male, pro- and mesotarsomeres narrower (as in Fig. 19), last visible abdominal sternite with one pair of marginal setae. Median lobe of aedeagus (Figs. 23–25) with apex bent dorsally and without spine in internal sac; female genitalia as in Figs. 26 & 27. Habitus as in Fig. 9. Body length 10.0– 11.4 mm ..... T. angustitarsis sp. n.

9 Sides of pronotum (Figs. 1 & 2) almost straightly converging in basal half; apical margin very shallowly emarginate; basal angles obtusangular, sharp at apex, generally with a very small obtuse denticle. Median lobe of aedeagus (Figs. 3 & 4) with apical portion angularly bent dorsally; female genitalia as in Figs. 5 & 6. Body length 7.2–7.7 mm ................................................................................................... T. anthracinus Landin, 1955

- Sides of pronotum generally rounded along entire length; apical margin shallowly or moderately deeply emarginate; basal angles of pronotum more obtuse, sharp or blunted at apex, generally without denticle (if sides of pronotum almost straightly converging basally, body length more than 7.7 mm). Male and female genitalia not as above........................ 10

10 Body robust, with wide and short elytra (EL/EW about 1.3). Last visible abdominal sternite of male with one pair of marginal setae. Median lobe of aedeagus arcuate in lateral view, with straight or slightly convex median portion of ventral margin; terminal lamella in dorsal view about as long as wide, with very small oblique apical capitulum. Body length 6.7–8.4 mm ................................................................................ T. arcuatomarginatus Ito, 2000

- Body more elongate, with relatively longer elytra (EL/EW about 1.4–1.5). Last visible abdominal sternite of male with one or two pairs of marginal setae............................................................................ 11

11 Pronotum widest at middle; basal fovea separated from lateral depression by convexity. Apex of left mandible in frontal view more or less truncate. Last visible abdominal sternite of male with two pairs of marginal setae. Median lobe of aedeagus arcuate in lateral view, with almost straight median portion of ventral margin; terminal lamella without apical capitulum, in dorsal view longer than wide. Body length 8.1–10.4 mm ..................................... T. bouvieri (Tschitschérine, 1897)

- Pronotum widest before middle; area between basal fovea and lateral margin flattened. Apex of left mandible in frontal view blunted. Last visible abdominal sternite of male with one pair of marginal setae. Median lobe of aedeagus in lateral view evenly arcuate along dorsal and ventral margins; terminal lamella in dorsal view slightly wider than long, with very small oblique apical capitulum (recognizable in lateral view). Body length 7.8–8.8 mm ....................... T. aquilo Andrewes, 1930

12 Metepisternum shorter, 1.18–1.25 times as long as wide. Wings wholly or partly reduced. Median lobe of aedeagus (Figs. 98–100) stout, sharply hooked ventrally at apex, female genitalia as in Figs. 101 & 102. Habitus as in Fig. 94. Body length 9.0– 10.5 mm ....................................... T. hamulipenis sp. n. (in Yunnan, the nominotypical subspecies)

- Metepisternum longer, 1.40–1.60 times as long as wide. Wings well developed. Median lobe of aedeagus slenderer, not hooked at apex ventrally.................................................................................... 13

13 Body (Fig. 107) with head and pronotum relatively wider, pronotal basal angles in most specimens less protruding laterally. Median lobe of aedeagus (Figs. 114–118) evenly arcuate, with shorter terminal lamella (114, 117); internal sac with a mediumsized elongate spine on the left side behind the middle. Gonocoxite (119, 120) narrower and with wider base. Body length 8.0– 9.4 mm .................................................................. T. miwai continentalis ssp. n.

- Body (Fig. 108) with head and pronotum relatively narrower, pronotal basal angles in most specimens more protruding laterally. Median lobe of aedeagus (Figs. 122–124) in lateral view more arcuate and slenderer, with much longer terminal lamella (Fig. 122); internal sac with a group of small spines instead of a medium-sized spine. Gonocoxite (125, 126) wider and with narrower base. Body length 8.5–9.6 mm ................................................... T. kavanaughi sp. n.