Tetratoma (Tetratoma) yunnanensis Nikitsky

Nikitsky, N. B., 2016, A new species of the genus Tetratoma Fabricius (Coleoptera, Tetratomidae) from China, Zootaxa 4154 (3), pp. 346-350 : 347-350

Tetratoma (Tetratoma) yunnanensis Nikitsky , sp. nov.

( Figs. 1 & 2 )

Diagnosis. This new species is assigned to the subgenus Tetratoma Fabricius, 1790 based on the following combination of characters: elytra pubescent, although rather weakly, with short decumbent hairs, strong metallic sheen, large antennal club, somewhat longer than all preceding antennomeres together, last visible abdominal sternite in males simple (without fovea), and parameres of aedeagus strongly divided. Within the subgenus Tetratoma the new species is most closely related to Tetratoma nobuchii Nakane, 1955 from Japan, but has a shiny metallic elytral surface, rather than black or black with a metallic dark blue tint as in T. nobuchii , and a shorter antennal club, which only slightly (1.03–1.13X) exceeds the length of all preceding antennomeres combined, whereas in the Japanese species it is considerably longer. The new species differs from all other species of the subgenus in a combination of distinctive characters, including upper side of body comparatively more pubescent than other taxa, although still with rather weak pubescence, unicolorous elytra, lacking spots or a pattern, first antennomere of club approximately as wide as long or slightly transverse (which distinguishes this species from T. cyanoptera Champion, 1924 from Sikkim, North India), shorter antennal club compared to other metallic-coloured species, legs and ventrites of metathorax and often at least partly of abdomen dark coloured. The distinctive bronze-greenish, or completely bronze coloration of the elytra distinguishes it from all other species of Tetratoma (although one paratype has greenish elytra).

All principal diagnostic are visible in the dorsal habitus, and an illustration of the whole insect and the male genitalia is provided ( Figs. 1, 2 ).

Description. Body somewhat elongate-oval, convex. Head (except for reddish labrum) and ventrite of metathorax black to brownish-black. Ventral surface of abdomen, at least medially, brown or reddish-brown to brown-black, and often (but not always) lighter-coloured towards margin; mesothorax infrequently slightly lighter coloured ventrally, compared to ventrite of metathorax. Legs and antennomeres 5–11 usually black, though tarsi and antennomeres 5–6 often somewhat lighter coloured; second and part of third antennomere may be even lighter, and first antennomere may be lighter still at base and apex. Apex of last maxillary palpomere and prothorax (above and below), i.e., pronotum and prosternum, are orange or orangey-yellow. Elytra are usually bronze-green, in some specimens more bronze or more greenish (as in one paratype) ( Fig. 1). Epipleura of elytra generally dark, but sometimes orange. Pronotum and elytra covered with relatively short, sparse, decumbent white or grey hairs. Ventrites of abdomen covered with relatively short, decumbent grey hairs.

Frontoclypeal suture prominent. Eyes widely separated. Distance between eyes 2.2–3.0 greater than transverse diameter of eye (as seen from above) ( Fig. 1). Eyes strongly emarginate in front part. Head with small, regular, relatively dense punctures. Maxillary palpi with second palpomere elongate-triangular, noticeably longer than short third palpomere, 1.3–1.6X length of elongate-oval and somewhat obliquely truncate fourth palpomere. Antennae relatively short, extending slightly beyond base of elytra ( Fig. 1). Antennal club 1.03–1.13X longer than length of all preceding antennomeres combined ( Fig. 1). First antennomere slightly widened, 1.2–1.4 longer than wide; second antennomere noticeably narrower and 0.76–0.67X length of first. Third antennomere elongate, triangular, 1.2–1.4 as long as second and 1.4 (rarely)–2.2 times as long as its width; fourth antennomere approximately as wide as long, and 0.71–0.59 length of third. Fifth antennomere slightly wider than fourth; sixth is weakly transverse (width 1.2–1.3 of length). Seventh antennomere relatively strongly transverse, often somewhat discoidal, 1.4–1.6 as wide as long; eighth antennomere (first antennomere of club) 1.4–1.7 wider than seventh and approximately as wide as long, or slightly transverse; ninth antennomere often 1.1X wider than eighth; 10th antennomere slightly shorter than ninth or approximately same size, not infrequently 1.1–1.2 as wide as long. Eleventh antennomere 1.4–1.6X as long as wide and 1.3–1.7X as long as tenth. Pronotum strongly transverse, approximately 1.8–1.85X wider than head with eyes and 1.8–1.9 as wide as long, its sides more strongly narrowing towards anterior margin, less so toward posterior margin, with a very uneven edge (e.g., 2–3 undulations) ( Fig. 1).

Anterior angles of pronotum clearly rounded, posterior angles more often slightly obtuse-angular, but clearly outlined. Base of pronotum bi– or weakly trisinuous. Base of pronotum on each side with large pit-like depression, at distance from posterior edge of pronotum of half of the longest diameter of depression. Pronotum with moderately dense, irregular, relatively large punctuation. Interval between punctures smooth, not or very feebly shagreened. Scutellum relatively strongly transverse, approximately 1.5X as wide as long, in posterior part more or less rounded. Punctures of scutellum dense and usually somewhat smaller than those of elytra. Elytra somewhat elongate-oval, first slightly widened apically, but in apical third somewhat rounded-narrow ( Fig. 1). Base of elytra only slightly wider than pronotum, elytral length is 1.8–1.9 Х greater than their width at shoulders. Surface moderately densely and coarsely punctured, punctures slightly larger than those on pronotum, distance between punctures in anterior region of elytra on average slightly smaller than diameter of punctures. Spaces between punctures usually have, at least in basal region of elytra, very slight but noticeable shagreen. Posterior wings typical for Tetratoma ( Nikitsky, 2004) .

Anterior coxal cavities strongly transverse, coxae with exposed trochantins. Length of prothorax anteriad of anterior coxae approximately equal to their longitudinal diameter. Prothoracic punctuation coarse ventrally. Prosternal process completely separating anterior coxae, width approximately 0.4X length of prothorax from anterior edge of coxae to anterior edge of prothorax. Middle coxae separated by mesosternal process, which, in anterior region measures approximately 0.7X transverse diameter of middle coxal cavity. Ventrite, metathorax, and metepisternum coarsely punctate. Metepisternum relatively weakly narrowed posteriorly and parallel-sided for most of its length. Length approximately 3.0–3.5X greater than greatest width in anterior region. Tibiae of all legs straight, slender. First segment of anterior tarsi 1.3–1.4X longer than second, third approximately same as second, fourth noticeably narrower than third. Claw segment approximately as long as three preceding segments combined. First segment of mid tarsi slightly shorter than two succeeding combined. First segment of posterior tarsi approximately 1.3–1.5 longer than two succeeding segments combined. Claw segment of posterior tarsi approximately same or slightly shorter (0.77–0.9) than two preceding segments combined. First visible abdominal sternite (length measured along lateral margin) approximately 0.7–0.85X length of metathorax (length measured from posterior edge of middle coxae); length of second sternite 0.71X first sternite. Third visible abdominal sternite noticeably shorter than second. Fifth visible abdominal sternite simple, rounded apically, lacking a depression. Third–fifth abdominal sternites considerably more finely punctured compared to first sternite. Aedeagus typical of subgenus Tetratoma , with widely spaced parameres, slightly curved inwards apically ( Fig. 2 ). Males are distinguished from females by more elongate elytra, length usually 1.87–1.9X their width at humeral angle, whereas in females they are usually 1.8–1.83 as long as their humeral width. In addition, antennomeres of antennal club are slightly more transverse in females than in males, including a weakly transverse first antennomere of club, which in males is usually as wide as long.

Etymology. The species is named after its type locality, Yunnan Province of China.

Material. Holotype ( NMPC), ♂ (right anterior leg missing tibia and tarsus), China: Yunnan prov., 1.3–2.0 km S. of Haba, 17–20.VI.2007, Haba Xueshan Mts. 2830–3000 m., 27º 22. 1’ N 100 º08.2’ E. J. Hájek and J. Růžička leg., individually collected on soil, surface and on plants and shrubs, sparse mixed forest (with dominant Pinus ), in / near a brook ; paratypes: 3 ♂ and 2 ♀, with the same label data, and a further nine unsexed paratypes with same label data. Two paratypes are housed in ZMMU, one paratype at BMNH, and the holotype and an additional 11 paratypes in NMPC.

Figures

FIGURE 2. Tetratoma yunnanensis Nikitsky, sp. nov. Holotype, aedeagus.