Nomuraius excavatus Huang and Yin, 2018

Huang, Meng-Chi & Yin, Zi-Wei, 2018, Two new species of Nomuraius Hlaváč (Coleoptera: Staphylinidae: Pselaphinae) from southern China, Zootaxa 4399 (4), pp. 571-578 : 572-574

Nomuraius excavatus Huang and Yin , new species

( Figs 1–2 , 5 )

Type material (1 ex.). Holotype: CHINA: ♂, labeled ‘ China: Guangxi, Hechi City (河池市), Mulun N. R. (木论 自然 保护区), 25°7’20”N, 108°2’8”E, mixed leaf litter, sifted, 350–400 m, 25.VII.2015, Chen, He, Hu & Wang leg.’ ( SNUC)

Diagnosis of male. Length 3.06 mm; head unmodified at base; pronotum ( Figs 1B , 2B ) with broad and deep cavity occupying from basal 1/3 to near apex, with tuft of golden setae inside cavity; metaventrite with pair of stout triangle projections lateral to slim, short median processes; protibia with small, blunt apical spur; metatibia not expanded near apex.

Description. Male ( Fig. 1A ). Length 3.06 mm. Head longer than wide, length from anterior margin of clypeus to head base 0.68 mm, width across eyes 0.62 mm, with median carina extending anteriorly from head base to half head length; head base simple, not concave along posterior margin; eyes each composed of about 35 facets; with well-developed ocular canthi. Antennomeres IX moderately longer than X, antennomeres IX–XI forming distinct club. Pronotum about as long as wide, length along midline 0.68 mm, pronotal maximum width 0.65 mm, with nude median and lateral antebasal foveae; disc ( Figs 1B , 2B ) broadly concave medially, with deep, transverse incision anteriorly, with tufts of golden setae at middle of incision. Elytra wider than long, length along suture 0.92 mm, elytral maximum width 1.17 mm, each elytron with two distinct basal foveae, discal stria extending posteriorly from second fovea and exceeding elytral midlength. Metaventrite with pair of large, triangular lateral processes in addition to slender median possesses ( Fig. 2C ). Legs simple ( Fig. 2D, G–H ), except protibia ( Fig. 2E– F ) with one blunt apical spur, metatibia simple, not expanded near apex ( Fig. 2I ); tarsomeres II short ( Fig. 2F ), not extending beneath tarsomeres III. Abdomen broad at base and narrowed apically, length along midline 0.78 mm, abdominal maximum width 1.17 mm. Sternite IX as in Fig. 2J . Length of aedeagus 0.59 mm; aedeagus with asymmetric median lobe bent rightwards at apex; endophallus composed of one elongate and one short sclerites ( Fig. 2K–M ).

Female. Unknown.

Distribution. Southern China: Guangxi.

Etymology. The specific epithet refers to the strongly and broadly concaved pronotum in the male of the new species.

Comments. The new species is most similar to N. nanlingensis (described below) in sharing relatively short tarsomeres II, which are long and extending beneath tarsomeres III in the other three known species. Nomuraius excavatus can be readily separated from N. nanlingensis primarily by the much larger and deeper cavity on the pronotal disc in the male, combined with other minor differences including the much shorter median processes of the metaventrite, and the blunt apical denticle of the protibia.

Figures

FIGURE 1. Nomuraius excavatus sp. n. male. A. Dorsal habitus.B. Forebody. Scale bars:1 mm in A; 0.3 mm in B.

FIGURE 2. Diagnostic features of Nomuraius excavatus sp. n. male. A. Antennal club. B. Pronotum, in dorsolateral view. C. Meso- and metaventrite, in ventrolateral view, showing metaventral processes. D. Profemur. E. Protibia. F. Protarsomeres. G. Mesotrochanter and mesofemur. H. Metatrochanter and metafemur. I. Apex of metatibia. J. Sternite IX. K–M. Aedeagus, in dorsal (K), lateral (L), and ventral (M) view. Scale bars:0.3 mm in A‒E, G, H; 0.2 mm in K‒M; 0.1 mm in F, I; 0.05 mm in J.

FIGURE 5. Distribution of Nomuraius species (1‒5), and Dayao pengzhongi (6) (squares: known species; circles: new species), and morphological disparity of head and pronotum in the male. 1. N. sinicus. 2. N. vietnamicus. 3. N. piaoacus. 4. N. excavatus sp. n. 5. N. nanlingensis sp. n. 6. D.pengzhongi.