Sarothrias songi, Yin & Bi, 2018

Yin, Zi-Wei & Bi, Wen-Xuan, 2018, New and little known Jacobsoniidae (Coleoptera) from China, Acta Entomologica Musei Nationalis Pragae 58 (1), pp. 11-16 : 13-15

Sarothrias songi sp. nov.

Chinese common name: ẆKDaem

( Figs 1A , 2 , 3A–D )

Type material. HOLOTYPE:, ‘ China: Hainan, Ledong Co. (Ṭḵh), Jianfengling N. R. (ṪṞṀŊḨOiṖữ), Minfeng Valley ( Ŕ ṈỖ), 18°44′30″N, 108°50′29″E, 995 m, rainforest, decaying log, 23.i.2015, X.-B. Song leg.’ ( SNUC).

Diagnosis. Body moderate in size, slightly over 2 mm; antennomeres II–XI with spatulate setae in additional to normal sub-erected ones; anterior and posterior margins and lateral areas of pronotum covered with secretion forming broad bands; each elytron with 8 rows of striae or punctures, rows 1–3 and 7–8 impressed on their entire length; aedeagal median lobe curved in lateral view, lacking distinct constriction near base.

Description. Male ( Fig. 1A ). Body length 2.09 mm, elongate, convex, dark reddish brown, dorsal surface largely shiny except whitish gray secretion on parts of head, pronotum and elytra; legs (excluding tarsi) pubescent and covered with yellowish secretion except two narrow longitudinal shiny bands at both sides of femora and tibiae, tarsi reddish brown.

Head broader than long, slightly narrower than pronotum, length from anterior clypeal margin to base 0.28 mm, width across eyes 0.44 mm; clypeus ( Fig. 2A ) smooth, rounded anteriorly, frontoclypeal region distinctly impressed; frons ( Fig. 2A ) slightly broad anteriorly with sides moderately raised, sparsely punctate, secretion covering most area and extending posteriorly to form two longitudinal bands on disc; eyes rounded and moderately prominent, nearly half length of head. Venter of head ( Fig. 2B ) with secretion below eyes, on submentum, and along posterior margin. Length of antenna 0.79 mm, antennal club ( Fig. 2C ) three-segmented; scape elongate, antennomeres II–XI transverse, with secretion on antennomeres I–VIII, in addition to normal sub-erect setae, apex of scape and antennomeres II–XI with regularly placed spatulate setae.

Length of pronotum ( Fig. 2D ) along midline 0.66 mm, maximum width 0.47 mm; sides of pronotum sub-parallel, widest at middle; anterior margin rounded; disc with shallow median groove extending from anterior 3/4 to near base, slightly broadened posteriorly; punctures on disc of similar size, shape and distribution to those on head; median groove, anterior and posterior margins, and lateral area covered by secretion ( Fig. 2E ). Prosternum ( Fig. 2G ) largely covered with secretion.

Scutellum invisible. Length of elytra along suture 1.15 mm, maximum width 0.76 mm, elytral index (length/ width) 1.51; elytra fusiform, widest slightly posterior to middle; basal transverse bulge well-developed, with subbasal band of secretion. Each elytron with striae or punctures forming eight rows ( Fig. 2F; 1–8 ) extending from base of which lateral-most row not visible in dorsal view; rows 1–3 and 7–8 impressed on their entire length, remaining rows consisting of separate punctures, either entirely or partially, row 1 parallel to suture and ending subapically, rows 2 and 3 joined near level of metacoxae, rows 4 and 5 represented by separate punctures and disappearing at apical half, space between rows 5 and 6 with one supplementary series ( Fig. 2F; s ) composed of separate punctures, extending from basal 1/6 to just past midlength, row 6 represented by separate punctures, extending past elytral midlength and fused with secretion apically; row 7 entirely impressed, carinate at lateral side, with secretion apically; row 8 similar to 7, slightly carinate and apically fused to secretion; sparse spatulate setae irregularly placed on apical secretion of rows 2 and 3.

Mesoventrite largely covered with secretion ( Fig. 2G ). Metaventrite ( Fig. 2H ) covered with same secretion posterior to mesocoxal cavities and between metacoxal insertions, other parts shiny, sparsely and coarsely punctate; with deep, parallel-sided median impression at apical half, impression not delimited by lateral ridges.

Tergite VII ( Fig. 3A ) rounded at apex, with median longitudinal impression; sternite VIII and genital segments as in Fig. 3B . Length of aedeagus ( Figs 3C–D ) 0.42 mm, median lobe strongly sclerotized, slender, in ventral view gradually narrowing from base toward apex, in lateral view curved and slightly constricted on dorsal margin near base. Female unknown.

Etymology. The new species is named after Xiao-Bin Song, collector of the holotype.

Comparative notes. Sarothrias songi is externally most similar to S. amabilis Ślipiński & Löbl, 1995 from West Malaysia and S. hygrophilus Pal, 1998 from northeastern India in sharing a similar pattern of elytral striae, rows of punctation, and secretion (i.e., rows 2 and 3 fused at posterior half with longitudinal band of secretion), and presence of an additional series of punctures between rows 5 and 6 ( PAL 1998, ŚLIPIŃSKI & LÖBL 1995). The new species can be separated from S. amabilis by the larger body size (2.09 mm vs. 1.75–1.78 mm), relatively shorter pronotum (length/width 1.40 vs 1.45), more secretion area at anterior margin, sides, and posterior margin of the pronotum, and generally more distinct discal rows and much longer row 5 of the elytra. From S. hygrophilus , the new species differs in the presence of spatulate setae on antennomere XI, and entirely impressed row 3 of the elytra, while the antennomere XI lacks any spatulate setae, and the row 3 of the elytra is interrupted before joining row 2 in S. hygrophilus .

The only other Chinese species, S. sinicus from southeastern Tibet, is much larger in size (2.44–2.45 mm), lacks spatulate setae on antennomere XI, and the posterior 4/5 of elytral rows 1 and 3 are composed of interrupted punctures ( BI & CHEN 2015), thus can be readily distinguished from the new species.

Distribution. South China: Hainan.

Figures

Fig. 1. Male habitus of Sarothrias. A – S. songi sp. nov.; B – S. sinicus Bi & Chen, 2015. Scale bars: 0.5 mm.

Fig. 2. Morphological details of Sarothrias songi sp. nov., male. A – head dorsum; B – head venter; C – antennomeres VII–XI; D–E – pronotum, in dorsal (D) and dorsolateral (E) view; F – right elytron (‘1–8’ indicates striae or rows of punctures extending from elytral base; ‘s’ means supplementary series); G – prosternum and mesoventrite; H – metaventrite and sternite III. Scale bars: 0.1 mm in A–C; 0.2 mm in D–H.

Fig. 3. Morphological details of Sarothrias songi sp. nov., male (A–D), and S. sinicus Bi & Chen, 2015, males from Yunnan (E–H) and Tibet (I). A, E – tergite VII; B, F – sternite VIII and genital segments. C–D, G–I – aedeagus, in ventral (C, G) and lateral (D, H–I) view. Note: the aedeagus of the holotype of S. sinicus (I) is partially broken at the apex. Scale bars: 0.2 mm.