Syncosmetus yunnanensis, Jiang & Lopes-Andrade & Liu & Chen, 2022

Jiang, Ri-Xin, Lopes-Andrade, Cristiano, Liu, Hao-Yi & Chen, Xiang-Sheng, 2022, An extraordinary new species of the genus Syncosmetus Sharp, 1891 (Coleoptera: Ciidae) from Yunnan, China, Zootaxa 5214 (2), pp. 294-300 : 295-298

Syncosmetus yunnanensis sp. nov.

( Figs 1–3 )

Type material. Holotype: CHINA: ♂, labeled ‘China: Yunnan, Hani-Yi Autonomous Prefecture of Honghe (IJ河 Ḃ尼dzh治州), Pingbian Miao Autonomous County (屏ṁffidzh治县), Daweishan Nature Reserve (k围山Dz ẎNJh然保护区) 02.VIII.2021, H: 2046m, Hao-Yi Liu leg.’ ( GUGC) . Paratypes: CHINA: 3 m ♂, 4 f ♀, with the same label data as the holotype ( GUGC) .

Diagnosis. Body small and rounded, dark brown with antennae, palpi and tarsi reddish brown. Head covered with longitudinal and irregular microsculpture. Pronotum with four strong longitudinal ridges. Elytra with three convex longitudinal keels, formed by series of discontinuous and irregular tuberculation. Apex of prosternal process truncate. Disc of metaventrite with a pair of large and round impressions.

Description. Male. Body ( Fig. 1A–B ) rounded, extremely convex, dark brown with antennae, palpi and tarsi reddish-brown.

Head wider than long, surface densely covered with longitudinal and irregular microsculpture, without punctures. Eyes small, coarsely facetted, each with about 20 ommatidia, GW 0.10 mm. Each antenna ( Fig. 2B ) bearing ten antennomeres, with 3-segmented club; length of antennomeres (in mm) as follows: 0.17, 0.08, 0.08, 0.06, 0.04, 0.05, 0.04, 0.06, 0.08, 0.14.

Pronotum ( Fig. 1A ) covered with shallow punctures, distinctly denser at the posterior portion, sparser at disc and near the anterior edge. Surface covered by tiny polygonal microsculpture, and bearing two pairs of strong longitudinal ridges. Anterior margin broadly rounded; anterior angles slightly projected forward, bluntly rounded; lateral margins broad, coarsely crenulate, visible for almost their entire lengths when seen from above; posterior margin broadly rounded; posterior angles obtuse and not distinct.

Scutellar shield very small, almost indiscernible, concealed under the beginning of the medial keel of elytra.

Elytra ( Fig. 1A , 2A ) tightly locked but not fused; punctures coarse, deep, separated from each other by at least a puncture-width; surface between punctures, smooth. Pseudoepipleura impunctate, glabrous; surface covered by tiny microsculpture. Each elytron with three longitudinal, convex keels, each formed by series of discontinuous and irregular tuberculation; all keels extending from base to near apex of elytra; surface covered by tiny polygonal microsculpture. Each side of medial elytral suture with a distinct tuberculation located near its base.

Protibiae not expanded to apex, about three times as long as broad; inner side with a conspicuous tuft of long bristles at the apical half; apical angle broadly rounded, with edge bearing a row of spines; outer edge apparently devoid of spines. Meso- and metatibiae not expanded; outer apical angle rounded, not produced, with apical edge with a row of spines.

Prosternum ( Fig. 1B ) in front of coxae slightly biconcave, bearing a distinct longitudinal carina at middle; surface covered by tiny polygonal microsculpture and sparse shallow punctures. Prosternal process with truncate apex. Hypomera surface similar to that of prosternum, but without punctures.

Metaventrite ( Fig. 1B ) without discrimen; surface covered by tiny polygonal microsculpture; disc with pair of large and round impressions. Abdominal ventrites ( Fig. 1B ) with shallow and different-sized elliptic punctures, concentrated at the anterior portion of each ventrite and separated by less than a puncture-width; surface between punctures and elsewhere covered by tiny polygonal microsculpture. Length of the ventrites as follows (mm): 0.24, 0.05, 0.06, 0.07, 0.17. Ventrite bearing a circular, weakly margined setose sex patch at disc. Sternite VIII ( Fig. 2C ) subtrapezoidal; posterior edge slightly narrower, weakly curved inward at middle; posterior angles bearing a few long setae. Tegmen ( Fig. 2D ) slender with rounded apex. Penis ( Fig. 2E ) comparatively much slender than tegmen; basal two-thirds bearing lateral struts; lateral edges subparallel, slightly enlarged near apex and converging to a membranous apex.

Measurements (mm): TL 1.53–1.67 (1.58 ± 0.06), PL 0.63–0.70 (0.66 ± 0.03), PW 0.75–0.82 (0.78 ± 0.03), EL 0.90–0.97 (0.93 ± 0.03), EW 0.88–0.94 (0.91 ± 0.03), GD 0.80–0.85 (0.83 ± 0.02).

Females. Similar to males, but without abdominal sex patch. GW 0.10 mm. Abdominal terminalia with conspicuous gonostyli; gonocoxites transversely divided into two parts; paraprocts shorter than gonocoxites together.

Measurements (in mm; n = 4): TL 1.58–1.78 (1.68 ± 0.08), PL 0.65– 0.76 (0.71 ± 0.05), PW 0.77–0.85 (0.81 ± 0.03), EL 0.93–1.02 (0.97 ± 0.03), EW 0.87–0.95 (0.91 ± 0.03), GD 0.82–0.88 (0.85 ± 0.02).

Distribution. China: Yunnan.

Biology. All specimens of this species were collected in unidentified polypore basidiomes (similar to Trametes species) growing on rotten wood ( Fig. 4 ).

Etymology. The specific epithet refers to the type locality, Yunnan Province; adjective.

Comments. Species of Syncosmetus are known only from East Asia, in areas belonging to the Palearctic region ( Japan) and the Chinese transition zone ( Souza-Gonçalves & Lopes-Andrade 2017). They have narrow distributional ranges, are flightless, seldom collected and only adults were described up to date. Little information is available about their microhabitats and feeding habits. Syncosmetus japonicus has breeding records in Fomes fomentarius , Ganoderma applanatum , Inonotus mikadoi and Pyrrhoderma sendaiense ( Kawanabe 1998, 1999), with doubtful records in Inonotus cuticularis , Pleurotus sp. and Trametes versicolor ( Kawanabe 1995, 1996; Miyatake 1954). Syncosmetus reticulatus has breeding records in Fomes fomentarius and Ganoderma applanatum ( Kawanabe 1998) , and the previously described Chinese species were collected by sifting forest litter ( Lopes-Andrade & Grebennikov 2015). Flightless species of a few ciid genera are collected in forest litter, as summarized by Lopes-Andrade (2007), and it is still early to state whether these “litter” species are detritivores of dead plant material, consumers of microfungi, or are simply caught while dispersing through the litter. However, it can be stated that the collection of basidiomes alone does not guarantee a good sampling of ciid beetles for broad faunistic or taxonomic works on the family ( Lopes-Andrade 2007). Within the genus Syncosmetus , S. yunnanensis is extraordinary due to its pronotum bearing four conspicuous longitudinal ridges, a feature not observed in any other described Ciidae up to date.

Figures

FIGURE 1. Habitus of Syncosmetus yunnanensis sp. nov., male, paratype. A. Dorsal view; B. Ditto, ventral view. Scale bars: 0.5 mm.

FIGURE 2. Diagnostic features of Syncosmetus yunnanensis sp. nov., male, paratype. A. Lateral habitus; B. Antenna; C. Sternite VIII; D. Tegmen; E. Penis. Scale bars: 0.5 mm in A; 0.2mm in B & E; 0.1 mm in C & D.

FIGURE 3. Distribution of the described Syncosmetus species in China.

FIGURE 4. Habitat of Syncosmetus yunnanensis sp. nov. A. General environment; B. Rotten wood with polypore basidiomes; C & D. Polypore basidiomes; E. Live specimen of Syncosmetus yunnanensis sp. nov. on the surface of a polypore basidiome.