Miaotrechus mahua Tian & Chen & Ma 2020, n. sp.

Miaotrechus mahua n. sp.

(Figs. 1 –3, 4A, 5 –7)

Type material. Holotype male, cave Miaoting, Getuhe cave system, Ziyun Miao & Buyi Autonomous County, Anshun Shi, Guizhou Province, China, 23.16388°N / 113.35446°E, 1103 m in altitude, 2019-X-12, leg. Mengzhen Chen & Mingyi Tian; paratypes: 3 males and 1 female, idem.

Description. Length: 4.3–5.0 mm; width: 1.4–1.5 mm. Habitus as in Fig. 2.

Body stout, yellowish brown, but palps, tarsi and distal antennomeres pale. Microsculpture: meshes densely isodiametric on frons and vertex, strongly transverse on genae, and transversal striate on pronotum and elytraHead subquadrate, slightly longer than wide (excluding mandibles), HLl/HW = 1.15–1.22, HLm/HW = 1.58–1.67; as long as pronotum; frons moderately convex, widest at about middle of head from clypeus; anterior supraorbital pores at about third of head from labrum, while posterior at about sixth from base, just on frontal furrow; genae strongly convex and sparsely pubescent; clypeus quadrisetose, labrum emarginate at front, sex-setose; mentum bisetose, base widely concave, median tooth short and bifid at apex; submentum 8- or 9-setose; palps glabrous except labial palpomere 2 bisetose on inner margin, and with one or two additional setae near apex; labial palpomere 2 slightly longer (1.2 times) than 3, maxillary palpomere 3 as long as 4 (Fig. 3). Antennae extending to about apical 1/3, pubescent from antennomere 2; antennomeres 1 and 2 subequal in length, comparative length ratio of each antennomere as follows in the holotype: 1 st (1.0) / 2 nd (1.0) /3 rd (1.4) / 4 th (1.4) / 5 th (1.5) / 6 th (1.4) / 7 th (1.4) / 8 th (1.2) / 9 th (1.2) / 10 th (1.2) / 11 th (1.5).

Propleura invisible from above. Pronotum slightly transverse, PW/PL = 1.08–1.09, widest at about front fifth, lateral margins narrowly beaded throughout, bisinuate before hind angles which are nearly rectangular, front and base unbordered, nearly straight, front much wider than base, PfW/PbW = 1.13–1.15; anterior latero-marginal setae located at the widest portion, posterior ones located at just between the portion of two sinuations before hind angles; disc moderately convex, glabrous; basal foveae large and shallow, basal and frontal transversal impressions weakly marked. Scutellum small.

Elytra elongate oval, distinctly longer than fore body including mandibles, EL/(HLm+PL) = 1.14–1.2; EL/EW = 1.51–1.53, widest at about middle, shoulders broadly rounded, lateral margins expanded, ciliate at basal half; discal surface moderately convex, smooth and glabrous; striae evanescent though partly traceable, apical striole welldefined, its end more or less connected to stria 5; basal pores present, at level of scutellum and at origin of stria 2, anterior and posterior discal pores of stria 3 at about basal fifth and middle of elytra respectively, pre-apical pores located on the site of apical anastomosis of the 2 nd and 4 th striae, much closer to elytral suture than to apical margin; marginal umbilicate pores 2 and 8 close to marginal gutter, humeral group (the 1 st -4 th pores) of marginal umbilicate series equidistantly spaced, middle group (the 5 th and 6 th pores) closely spaced; apical group comprising three pores (Fig. 4A)Protibia longitudinally and distinctly sulcate; protarsomere 1 slightly enlarged, shortly but distinctly denticulate inwards at each apex in male, and with adhesive setae ventrally; tarsomere 1 much shorter than 2 nd to 4 th combined in fore legs, as long as the 2 nd to 4 th tarsomeres combined in middle and hind legs.

Male genitalia (Fig. 5): The median lobe of aedeagus short, slightly arcuate at median portion, apex shortly bent ventrally, broadly rounded; base large, sagittal aileron quite large and hyaline, inner sac armed with a long spooned copulatory piece, long as a third of the aedeagus; in dorsal view, apical lobe nearly parallel-sided, with a broadly rounded apex; parameres much shorter than median lobe, right and left parameres each bearing three and four long setae at apex respectively.

Etymology. The name of this new species is dedicated to “Mahua” (a nickname of Mr. Mingfu Zhao, a local caver) who provided us valuable assistance during our survey of cave Miaoting, Getuhe cave system.

Distribution. Guizhou (Ziyun). Known only from the cave Miaoting, Getuhe cave system (Figs. 1, 6 –7).

Cave Miaoting (Miao Chamber) is located at the lowermost part of the Getuhe (=Gebihe) cave system (Fig. 6). This world’s largest cave chamber is about 700 m long and 215 m wide, 80 m high in average, and a surface of 14.54 thousand square metres and 10.78 million cubic metres in volume (Barbary et al., 1991; Zhou, 2018). It is surprising that cave fauna is very poor in this huge chamber due to dry and lack of food. However, there is a small stream which is about 200 m long at the upper end of Miaoting, with a lot of decayed woods and debris carried into the cave by flood from outside in raining season. Along the stream M. mahua was found, together with two other carabid species, three species of millipedes, a pseudoscorpion and a scutigerellid species (Fig. 7)